2010年8月8日星期日

Jointing and Pointing

Jointing and pointing are used for the finish given to both the vertical and the horizontal joints in external faces of wall irrespective of whether the wall is of brick , block , solid or cavity construction

Brickwork or blockwork is jointed or pointed for 2 reasons:
  • To ensure that all horizontal and vertical mortar joints in external brickwork or blockwork are solidly filled with mortar to make them watertight
  • For decorative reasons . THe appearance of brickwork or blockwork can be varied considerably by the use of coloured mortar for pointing and by making the kointing and pointing recessed or protruding .

  • Differences between jointing and pointing
  • Jointing is the finish of the mortar joints between bricks or blocks , in rbickwork or blockwork that is finished fairface example not subsequently covered with plaster rendering or other finish
  • Jointing is executed as the brickwork or blockwork is buildt
  • Pointing is the finish given to the joints by raking out to a depth of approximately 20mm and filling in one the face with a hard-setting cement mortar which could have a colour additive
  • The mortar for pointing is a special mix of lime , cement and sand or stone dust chosen to produce a particular effect of colour and texture
  • Pointing is executed as an operation separate from bricklaying
  • Pointing can be applied to both new and old brickwork or blockwork

Types of mortar

1) cement mortar (cement-sand )
-1:3 -suitable for brickwork exposed conditions such as parapets and for brickwork in foundations.

2)Lime mortar (lime-sand )
-1:3 -for internal use olny

3)gauged mortars ( cement :lime :sand )

1:1:6-suitable for most conditions of severe exposure
1:2:9-suitable for most condition except those of severe exposure
1:3:12 -internal use olny

  • Mortar for general brickwork may be made from a mixture of cement , lime and sand .
  • These mixtures combine the strength of cement with the plasticity of lime
  • A rich mix of mortar is one in which there is a high proportion of matrix , that is lime or cement or both , to sand as in the 1:3 mix and a weak mix is one in which there is a low proportion of lime or cement to sand as in the mix 1:3:12
  • The richer the mix of mortar the greater its compressive strength and the weaker the mix the greater the ability of the mortar to accommodate moisture or temperature movements
  • If the mortar is weaker than the bricks , shrinkage cracks will tend to follow the joints of the brickwork , and these are resonably easy to make good
  • If the mortar is stronger than the bricks , shringkage cracks will tend to be vertical through the joints and the bricks , thus weakening the fabric of the structure.

Mortar for brickwork and blockwork

  • It is essential that brickwork and blockwork be laid in true horizontal courses , and the olny way this can be done with bricks and blocks is to lay them on mortar
  • Mortar is a mixture of sand and lime or a mixture of sand and cement with or without lime
  • Proportioning of the material can be carried by volume or weight
  • Mortar should never be re-tempered , and shouls be used within 2 hours of mixing or be discarded
Functions of mortar
-To join the brickwork or blockwork of a wall into one solid mass , thus increasing its strength and stability
TO transfer the rensile comprresive and shear stresses uniformly between adjacent bricks or blocks
-TO transfer up any inequalities of the bricks or blocks
-To make the wall reasonably waterpoof and airproof under ordinary conditions

TO perform its fucntions , mortar must satisfy certain requirement :
  • It must have qdequate stregth , but not greater than that required for the design strength
  • It must have good workability
  • It must retain plasticity long enough for the bricks to be laid
  • It must be durable over a long period
  • It must band well to the bricks
  • It must be able to be produced at the economic cost.

Advantages and disadvantages of blockwork

THe main advantages of blockwork over brickwork are :
  1. Labour saving (easy to cut , larger units )
  2. Easier fixing ( must take direct fixing of screws and nails
  3. Lower density
  4. higher termal insulation properties
  5. Provides a suitable key for plaster and cement rendering
THe main disadvantage are :
  1. lower strength
  2. Loss resistance to rain penetration
  3. loadbearing properties less ( one- or two storey application )
  4. lower sound insulation properties .

blockwork bonding at junctions

  • Concrete blocks are laid in stretcherbond and joined to other walls by block bonding or by leaving metal ties or strips projecting from suitable bed courses .
  • Mortar used in blockwork should be weaker than the material of the walling unit ,generally a 1:2:9 gauged mortar mix will be suitable for work above ground level .
  • Because the block units are comparatively large , any settlement movement in a wall will show more abvious cracking in mortar joints

blockwork bonding

  • Blocks are made in various thicknesses to suit most wall requirement and are laid in strecther bond
  • Thin blocks , used for non-loadbearing partitions , are laid in strecther bond wit each block centred over and under blocks above and below
  • At return angles , full blocks bond into the return wall in every other course
  • So as not to disturb the full width bonding of blocks at angles , for the sake of stability , a short length of cut block is used as closer and infill block
  • Thicker blocks are laid in off centre strecther bond with a three quarter length block at stop ends and sides of openings
  • THe off centre strecther bond is acceptable with thicker blocks as it avoids the use of cut blocks to complete the bond at angles
  • Concrete blocks walls of specially produced blocks to be used as a fairface finish are bonded at angles to return walls with specially produced quoin blocks for the sake of appearance
  • THe L shaped quoin blocks are made to continue the strecther bond around the angle into the return walls
  • Quoin blocks are little used for other than fairface work as they are liable to damage in handling and use and add considerably to the cost of materials and albour.
QUoin block at angles

material for blocks

1. Clay blocks
  • Standard size of 290mm long x 215mm high x 75 , 100 or 150mm width.
  • &5mm cavity block is intended primarily partitions
  • 150mm cavity block has been used for the inner skin of cavity walls , but also used in the warmer climates countries such as Malaysia as a single-leaf external walling with rendered and emulsioned finish
  • THey are made from selected brick clays that are press moulded and burnt
  • THese hard , dense block are hollow to reduce shrinkage during firing and also to reduce their weight
  • THey are grooved to provide a key for plaster
  • Clay blocks are comparatively lightweight , do not suffer moisture movement , have goof resistence to damage by fire and poor thermal insulating properties
2.Concrete blocks
  • Density of a concrete block gives an indication of its compressive strength
  • THe greater the density , the stronger the block
  • Classification is by compressive strength categoties : 2.8 , 3.5 , 5 , 7 , 10 , 15, 20 and 35 N/mm square
  • Density will also give an indication as to the termal conductivity and acounstic properties of a block
  • THe lower the density , the lower is the thermal conductivity factors , whereas the higher the density , the greater is the reduction of airborne sound through the block
  • For use as a facing material , a wide range of concrete blocks is manufactured from accurate fair face blocks to rough exposed aggregates finishes
  • Standard concrete blocks are manufacture as solid , hollow or cellular blocks from cement and either dense or lightweight aggregates
  • A cellular block has one or more holes or cavities that do not pass wholly through the block
  • A hollow block is one in which the holes pass through the block
  • The thicker blocks are made with cavities or holes to reduce weight and drying shringkage
  • The most commonly used size of both dense and lightweight aggregate concrete blocks is 440mm long x 215mm high
  • The height of the block is chosen to coincide with three courses of brick for the convenience of buildings in wall ties and also bonding to brickwork
  • For the leaces of cavity walls and internal loadbearing walls , 100mm thick concrete blocks are used .
  • For non-loadbearing partition walls , 60 or 75mm thick concrete blocks are used .
  • Concrete block or blockwork

block and blockwork

  • A block can be defined as a walling unit exceeding the BS dimensions specified for bricks , and its height should not exceed either its length or six times it thickness
  • BUilding blocks are made of clay or concrete
  • Extensively used for both loadbearing and non-loadbearing walls , externally and internally .

english bond

  • A 1/2B thick wall , finished fairface both sides and showing English bond both sides , requires considerably less cutting of bricks to compltete the bond
  • It is olny necessary to cut closers and three quarter length bricks to complete the bond at angles and stop ends

bonding at angles or jambs

At the end of a wall at a stop end , at an angle or quoin and at jambs of openings , the bonding of brick has to be finished up to a vertical angle
  • To complete the bond , a brick 1/4 wide has to be used to close or complete the bond of the 1/4 overlap of face brickwork
  • A brick , cut in half along its length , is used to close the bond at angle . THis cut brick is termed a queeen closer.
  • If the narrow width queen closer were laid at the angle , it might be displaced during bricklaying
  • TO avoid this possibility , the closer is laid next to a header
  • THe rule is that a closer is laid next to quoin ( corner ) header.
  • Walls 1 1/2 B thick may be used for susbstantial walling for laggrer buildings where the walling is finished fairface both sides
  • Fairface describes a brick wall finished with a reasonably flat and level face for the sake of appearance
  • TO complete the bond of a solid wall 1 1/2B thick in Double Flemish bond , it is necessary to use cut half brick in the thickness of the wall
  • At angles and stop ends of a wall , queen closer are laid next to quoin headers and a three quater length cut brick is used .
  • Cutting half-length ( 1/2 bats ) and three quater brick and closers is time consuming and wasteful .

2010年8月7日星期六

types of bonding

5.single felmish bond
  • A combination of english and flemish bonds . having flemish bond on the front face with a backing of english bond
  • It is considered to be slightly stonger than flemish bond
  • The thinnest wall that can be buit using this bond is a 1 1/2B wall
6. Garden wall bonds
  • Garden wall bonds are designed specifically to reduce the number through headers to minimise the labour in selecting bricks of rougly the same length or use as headers
  • Usual garden wall bonds are :
-english garden wall bond consists of three courses of strectjers to one course of header
-Flemish garen wall bond consist of one header to every three strecther in every course
  • THe reduction in the number of through header does to an extent weaken the through bond of the brickwork
  • OTher combination such as two or four strecther to one header may be used

types of brickwork bonding

3. english bond
  • A very strong bond consisting of alternate courses of header and strecthers with a header face lying directly over the centre of a strecther face below
  • English bond avoids the repetition of header faces in each course
  • THe colour of header faces may differ from the colour of strecther faces
  • In english bond , this difference of colour is shown in succesice horizontal courses
4.FLemish bond
  • This bond is sometimes reffered to as double-flemish bond
  • Each course consists of alternate headers and strecthers
  • THe bond is laid in which header faces lie directly above and below a strecther face .
  • This bond requires fewer facing bricks than english bond
  • This bond is generaly considered the most attractive bond for facing brickwork because of the variety of shades of colour between header and strecther faces dispersed over the whole face of the building
  • ITs appearance is considered to be better than english bond , but it is not quite so strong

2010年8月6日星期五

Types of brickwork bonding

It has been practice for some time to describe the thickness of a wall by t he length of a brick example 1/2B . 1B , or 1and 1/2B wall

strecher bond ( 1/2B thick wall )
  • Consists of all strecthers in every course
  • The bricks are laid with the vertical joints between bricks lying directly under and over the centre of the bricks in the courses under and over .
  • It is used for 1/2B walls and the 1/2B skins of cavity walls
  • At the intersection of two 1/2B walls at corners or angles and at the jambs , sides f openings , the bricks are laid so that a header face showns in every other course to complete the bond
  • THe appearance of a wall laid in strecther bond may look momotonous because of the mass of stretcher faces showing
Header bond ( 1B thick wall )
  • A solid wall 1B thick may be bonded with every brick showing a header face with each header face lying directly over two header faces below
  • This bond is little used as the great number of vertical joints and header faces is generally considered unatteactive.

brickwork terminology

  • Strecther is a masonry unit laid horizontally with the longer edge exposed or parallel to the surface
  • Header is a masonry unit laid horizontally with the shorter end exposed or parallel to the surface
  • Solder is a brick laid vertically with the longer edge face exposed
  • Course is a continuous horizontal range of masonry units
  • Bed joints is the horizontal joint between two masonry courses . THe term bed may refer to the underside of a masonry unit , or to the layer of mortar in which a masonry unit is laid
  • Head joint is the vertical joint between two masonry units , perpendicular to the face of a wall

Cutting bricks

A range of standard cutting bricks can be produced by cutting a whole brick to filled in or closed the bonds


Faces of a bricks
  • The 4 faces of brick , which may be exposed in fairface brickwork , are the 2 long strecher faces and the 2 header faces
  • The face on which the brick is laid is the bed
  • Some bricks have no indent or frog
  • Some brick have an indent or frog formed in one of the bed faces
  • The purpose of the frog or indent is to assist in compressing the wet clay during moulding
  • The frog also serves as a reservoir of mortar on to which bricks in the course aboce may more easily be bedded .

brickwork bonding

Brickwork bonding
  • stacks of bricks with continuous vertical joints between the stacks
  • bricks stacked pyramid fashion
Special brick
  • Half round coping
  • double bullnose
  • saddleback coping
  • bullnose double strecther
  • plinth header
  • plinth strecther
A range of standard special bricks is produced for use in facing brickwork for angles , offsets and returns

Brickwork bonding

Purpose of bonding
  • When building with bricks , it is necessary to lay the bricks to some recognised pattern or bond in order to ensure stability of the structure and to produce pleasing appearance
  • Various bonds are designed so that no vertical joint in any one course is directly above or below a vertical joint in the adjoining course .
  • To give various bonds , special bricks are produced . Alternatively , the bricklayer can cut from whole bricks on site

cellular bricks

THose in which the holes are closed at one end and exceed 20 percent of the volume of the brick.

Types of brick
  1. Cellular and perforated bricks are lighter n weight than solid bricks and the cells and perforations facilitate drying and burning.
  2. The saving in clay and consequent reduction in weight is an advantage in non-;loadbearing walls but does not significantly improve thermal insulation in external walls
  3. Cellular bricks are laid with the cells or hollows downwards and perforated bricks should be laid so that the mortar does not fill the perforations
Other classifications

Brick may also be classified by one or more of the following:
  1. Place of origin
  2. Raw material
  3. Manufacture , for example clay
  4. Use , for example foundation
  5. Colour , for example , red
  6. Surface texture , for example sand-faced

Classification based on types of bricks

  • Solid brick
  1. Those in which small holes passing through or nearly through the brick do not exceed 25 percent of its volume , or in which frogs do not exceed 20% of its volume
  2. A small hole is defined as a hole less than 20mm wide or less than 500mm square in area .
  • Perforated bricks
  1. THose in which holes passing through the brick exceed 25 percent of its volume and the holes are small as defined above
  • Hollow bricks
  1. Those in which the holes passing through the brick exceed 25 percent of its volume and the holes are larger than those defined as small holes.

classification based on qualities

1) Internal quality bricks
  • Suitable for internal use olny ; may need protection on site during bad weather
2)Ordinary quality bricks
  • Less durable than special quality but normally durable in the external face of a building .Some types are unsuitable for exposed situations
3)Special quality bricks
  • For use in conditions of extreme exposure where the structure may become saturated and frozen , such as retaining walls and pavings

brick classification

  • Brick may be classified in accordance with their uses as commons , facings and engineering bricks or by their quality as internal quality , ordinary quality , and special quality
  • THe use and quality classification roughly coincide as commons are much used for internal walls , facings or ordinary quality for external walls and engineering or special quality bricks for their density and durability in positions of extreme exposure.
  • In cost , commons are cheaper than facings and facings cheaper than engineering bricks
Classification based on used

Common brick
  1. These are bricks that are sufficiently hard to carry the loads normally supported by brickwork safely.
  2. Because they have a dull texture or poor colour , they are not in demand for use as facing bricks
  3. Common bricks are used for internal walls tat are not usually exposed to view .
  4. Suitable for general building work but having no special claim to give an attractive appearance

Facing brick
  1. This incules any brick that is sufficiently hard burned to carry normal loads , is capable of withstanding the effects of rain , wind and frost without breaking up and that is thought to have a pleasant appearance
  2. Specially made or selected to have an attractive appearance when used without rendering or plaster.(good attractive appearance without plastering )
Engineering bricks
  1. THese are bricks that have been made from selected clay , that have been careefully prepared by crushing , have been very heavily moulded and carefully burned so that the finished brick is very solid and hard and is capavle of safety carrying much heavier load than other types of brick .
  2. THse bricks are very hard , dense and do not readily absorb water .
  3. These bricks are mainly used for walls carrying exceptionally heavy load , for brick pier and general engineering works

brick

Concrete brick
  • Concrete brick are manufactured in the same size as clay bricks
  • THey tend to be more consistent in shape , size and colour than clay bricks
  • THey come in a variety of colours and finishes
  • Appearance and properties vary between manufacturers , although the concrete bricks does have a different appearance from clay brick , which extends the choice to the designer.


Bricks classifications
  • Bricks may be classified in accordance with their uses as commons , facings and engineering bricks or by their quality as internal quality , ordinary quality and special quality .
  • THe use and quality classifications roughly conincide as commons are much used for internal walls , facings or ordinary quality for external walls and engineering or special quality bricks for their density and durability in positions of extreme exposure.
  • In cost , commons are cheaper than facings and facings cheaper than engineering bricks

Brick and brickwork

  • A brick is defined in BS 3921 as a walling unit with standard size of 215mm length, 102.5mm width and 65mm height
  • With a 10mm mortar joint, the working size became 225x 112.5 x 75
  • The majoriti of the bricks used today are made from clay , although bricks can also made from sand and lime or concrete
  • Brickwork is used primarily in the construction of walls by the bedding and jointing of bricks into established bonding arragement
  • A brick wall has very good fire resistance , is a moderately good insulator against transfer of heat , does not , if well built , deteriorate structurally and requires very little maintenance over a long period of time
Material for bricks
Clay brick
  • Clay is ground mills , mixed with water to make it plastic and then moulded , either by hand or machine , to the shape and size of brick.
  • Bricks that are shaped and pressed by hand in a sanded wood mould and then dried and fired have a sandy texture , are irregular in shape and colour
  • Machine made bricks are either hydraulically pressed in steel moulds or extruded as a continuous band of clay
  • THe continuous band of clay is cut into bricks by a wire frame . Bricks made this way are called wire cut
  • THe moulded brick is baked to dry out the water and burned at a high temperature so that part of the clay fuses the whole mass of the brick into a hard durable unit
Calcium silicate Brick
  • Generally known as sand-lime bricks
  • THe bricks are made from a carefully controlled mixture of clean sand and hydrated lime , which is mixed together with water , heavily moulded to brick shape , and then the moulded brick is hardened in a steam oven
  • THe resulting bricks are very uniform in shape and colour and are normally a dull white
  • THe material from which they are made can be carefully selected and accurately proportioned to ensure a uniform harness , shape and durability that is quite impossible with the clay used for most bricks

2010年8月5日星期四

Material for dpcs

  • Bs 743 gives 7 suitable material for the construction of damp-proof courses , all of which should have the following properties:
  • Be completely impervious
  • Be durable , having a longer life than the other components in the buildings and therefore not needing replacing during its lifetime
  • Be in comparatively thin sheet so as to prevent difigurement of the building
  • Be strong enough to support the loads placed upon it without exuding from the wall
  • Be flexible enough to give any settlement of the building without fracturing

seven suitable material for the construction of dpcs:

  • Lead

-It is a flexible material supplied in thin sheets , and therefore large irregular shapes with few joints can be formed , but it has the disadvantage of being expensive

  • Copper

-This should have a minimum thickness of 0.25mm , like lead it is supplied in thin sheets and is expensive .

  • Bitumen

-THis is supplied in the form of a felt , usually to brick widths , and is therefore laid quickly with the minimum numbers of joints

Mastic asphalt

-Applied in two layers giving a total thickness of 25mm , it is applied in-situ and is therefore jointless , but is expensive in small quantities

  • Polythene

-Black low-density polythene sheet of single thickness not less than 0.5mm thick should be used , it is easily laid but can be torn and puntured easily

  • Slates

-These should not be less than 230mm long nor less than 4mm thick and laid in two courses set breaking the joint in cement mortar 1:3

  • Slates have limited flexibility but are impervious and very durable

-Bricks

  • THey are laid in two courses in cement mortar and may constrast with the general appearance of other brickwork in the same wall

Dunction and position of dpcs

The function of a damp-proof course is to provide a barrier to the passage of moisture from an external source into fabric of the building , or from one part of the structure to another.

Damp-proof courses may be either horizontal or vertical , and can generally be divided into three types:

  • Those below ground level to prevent the entry of moisture from the soil
  • Those placed just above ground level to prevent moisture creeping up the wall by capillary action
  • THose placed at openings , parapets and similar locations to exclude the entry of the rainwater that falls directly onto the fabric of the structure
  • There should be a continuous horizontal dpc above ground in walls , to prevent moisture from the ground rising through the foundation to the wall above ground , which otherwise would make wall surfaces damp and damage wall finishes .
  • THe dpc should be continuous for the whole length and thickness of the wall and be at least 150mm above finishes ground level to avoid the possibility of a build up of material against the wall acting as a bridge from moisture from the ground

moisture rises through material to wall above , DPC too close to ground

  • A DPC in external walls should unite with the dpm in , on or under the concrete bed , by the same level as the dpc in the wall or by uniting dpm and dpc laid at different levels with a vertical dpc

Damp Proof Courses (DPCs)

It is possible for dampness to penetrate into a building through the walls by one or more of three ways:
  • By the rain penetrating the head of the wall and soaking down into the building below the roof level
  • BY the rain beating against the external wall and soaking through the fabric into the building
  • By ground moisture entering the wall at or near the base and creeping up the wall by capillary action and entering the building above the ground floor level.
Dampness pentration can be overcame by :
  1. Inserting a suitable damp-proof courses in the thickness of the wall
  2. Applying to the exposed face of the wall a barrier such as cement rendering or some suitable cladding such as vertcal tile hanging
  3. COnstructing a cabity wall , whereby olny the external skin becomes damp , the cavity providing a suitable barrier to the passage of moisture throught the wall

Types of walls

  • A solid wall is constructed either of blocks or brick , stone or concrete laid in mortar with the blocks laid to overlap in some form of bonding , or as a monolithic , that is , one fluid uniterrupted material such as concrete which is poured wet and hardens into a solid monolithic
  • A solid wall of blocks is termed masonry wall , and a solid wall of concrete is termed monolithic wall
  • A framed wall is constructed from a frame of small sections of timber , concrete or metal joined together , with thin panels of some material fixed over both sides or between the members of the frame
  • Each of the types of wall may serve as internal or ecternal wall and as loadbearing or non-loadbearing wall.
  • Each of the types of wall has different characteristics in fulfilling the functional requirement of a wall so that one type may have good resistance to fire but be a poor insulator against transfer of heat , and the other poor resistance to rain penetration yet goof insulation against transfer of heat.
  • THere is no one type of wall that will fulfill all the functional requirement of a wall with maximum efficiency

  • Masonry wall
  1. Build on individual blocks of materials such as bricks , blocks or stones
  2. Usually in horizontal courses , cemented together with some form of mortar.
  3. May be solid ( single thickness ) or with a space/gap between two thicknesses
  4. The cheapest structure
  • Monolithic wall
  1. Build of materials requiring some form of support or shuttering in the initial stage ( formwork ).
  2. Plain concrete or reinforced concrete
  3. Traditional earth wall and modern concrete wall are examples of this
Frame wall
  1. Constructed as a frame of relatively small members
  2. Usually formed or constructed by timber
  3. Less strength but cheaper
  4. Lower degree of sound insulation
  5. Better thermal insulation.
Membrane wall
  1. Constructed as a sandwich of two or more thin skins or sheets of plywood , reinforced plastic , metal or other suitable materials
  2. Thin in general but of high strength and lightweight
  3. Can be used for load or non-loadbearing walls or as panels to a structural frame

walls

The function of wall is to enclose and protect a building or to divide space within a building.

The functional requirement of a wall are :
  1. wall
  2. stability
  3. Durability
  4. Resistance to ground moisture
  5. Resistance to wheather
  6. Fire resistance (30 minute )
  7. Thermal insulation
  8. Sound insulation
  9. Security
  10. Aesthetics
Types of wall
Some of the most popular materials that are used for walls are :
  • Stone , both natural and artificial stone
  • Bricks , blocks , primarily of clay or concrete
  • Timber , used as a cladding and also in a structural capacity
  • Concrete , used in decorative and structural capacity
  • Steel , used primarily in a structural capacity
  • Glass , used as a rainscreen and also in a structural capacity
  • Basically , there are 2 major types of walling system , namely solid and frame walls
  • Membrane wall is another type of wall which is less popular
  • Solid wall has been the most common type of walls being used in Malaysia .
  • Solid wall is made by brick , stone or concrete whereas frame wall consist of small secction of timber , metal or concrete.

walls

A wall is a continuous , usually vertical structure of brick , block , stone , concrete , timber or metal , thin in proportion to its length and height , which encloses and protects a buildings or serves to divide buildings into compartments or rooms

walls are described as external or internal to differentiate functional requirements , and as loadbearing or non-loadbearing to differentiate structural requirement,

  • External wall are those that enclose and protect a building.
  • Internal wall are those that divide buildings into compaetments or rooms
  • Load bearing walls are those that carry loads from floors and roofs , in addition to their own weight.
  • Non-load bearing walls are those that carry olny their own weight and freestanding .
  • Partition is generally used to describe a non-loadbearing internal dividing wall.

2010年8月4日星期三

physical considerations

  1. Natural contours of land
  2. Natural vegetation and trees
  3. Size of land and /or proposed buildings
  4. Shape of land and /or proposed buildings
  5. Approach and access roads and footpaths
  6. Service available
  7. Natural waterways , lakes and ponds
  8. Restrictions such as rights of way ; tree preservation and ancient buildings
  9. Climatic conditions created by surrounding properties , land or activities
  10. Proposed future developments

Example

  1. Split level construction to form economic shape
  2. Shape determine by existing trees
  3. Plateau or high ground solution giving dry site conditions on sloping sites
  4. Stepped elevation or similar treatment to blend with the natural enviroment

physical considerations

environmental consideration

examples
  1. Entrance bethrooms studio
  2. Dining and kitchen areas
  3. Rest areas lounge
  4. studios laboratories art rooms
  5. handicraft rooms
  6. workshops
  7. library
  8. classrooms
  9. staff rooms offices
  10. operating theatres
  11. wards
  12. solariumds and offices
  13. workshops
  14. machine shops
  15. storage areas
  16. light assembly work and similar activities offices
  17. Oreintation aspectr

environmental considerations

  1. Planning requirement
  2. Building Regulations
  3. Land restrictions by vendor or lessor
  4. Avalability of services
  5. Local amenities including transport
  6. subsoil conditions
  7. levels and topographs of land
  8. Adjoining buildings or land
  9. Use of buildings
  10. Daylight and view aspects

Building enviroment

environment+surroundings which can be natural , man-made or a combination of these

Built Environment= Created by man with or without the aid of the natural environment

Natural enviroment
  1. Grasses and wild flowers
  2. decidous and coniferous trees
  3. shrubs and bushes
  4. rick out craps
  5. waterways and lakes

Man built environment external

  1. Buildings
  2. retaining walls
  3. paved areas
  4. rockeries
  5. planted areas
  6. pools and ponds
  7. trees and shrubs

Element of the built environment (internal )

  1. artificial light
  2. daylight , ventilation and vision out
  3. indoor plant cultivation
  4. internal space heating
  5. circulation space
  6. furniture
  7. Texture and colour of internal finishes

2010年7月29日星期四

Reinforced Concrete Floor : Cast in-situ vs Precast

The disadvantage of cast in-situ concrete floors are :
  • The need for formwork
  • The time taken for the concrete to cure before the formwork can be released for reuse and the floor made available as a working area
  • The very small contrubution by a large proportion of the concrete to the strength of the floor

Before any system of precast concrete flooring can be considered , the following factors must be taken into account :

  1. Maximum span
  2. Nature of support
  3. Weight of units
  4. Thickness of units
  5. Thermal insulation properties
  6. Sound insulation properties
  7. Fire resistance of units
  8. SPeed of construction
  9. Amount of temporary support required

The advantages of precast concrete floor are :

  1. Economies that can reasonably be achieved through reduction in the volume of concrete , the weight of reinforcement and the size of foundations
  2. Elimination of the need for formwork
  3. Curing time of concrete is eliminated therefore the floor is available for use as a working platform at an earlier stage
  4. Superior quality control of product is possible with factory produced components

The disadvantage of precast concrete floor when compared with cast in-situ concrete floor are :

  • Less flexible in design term
  • FOrmation of large openings in the floor for dust , shafts and stairwalls usually have to be formed by casting an in-situ reinforced concrete floor strip arounf the opening position
  • Higher degree of site accuracy is required to ensure that the precast concrete floor units can be accomodated without any alrerations or making good

Precast concrete beam and Block floor

Advantage and disadvantage
  • Service can be housed within the constructional concrete topping , or within the voids of the filler blocks
  • Advantage of this floor is that two workers can safely handle the units without the need for lifting gear
  • This comparatively cheap floor system provides reasonable resistance to airborne sound and resistance to fire.
  • This type of reinforced concrete floor is olny suitable to be used for small spans and loads

Precast concrete beams and block floor 2

  • THe T beams are placed at 270 mm centres with their ends bearing 1.2 on or into brick walls
  • The hollow blocks are then placed between the beams
  • The floor is finished with a layer of construction concrete topping , 50mm thick spread and levelled ready for a screeed or power floated finish
  • The purpose of the constrictional concrete topping is to spread the loads on the floor over the blo ks and column and beams
  • THe underside , or soffit , of the floor is covered with laster or will provide support for a suspended ceiling .
  • WAll taised to acts as formwork for concrete
  • 1B wall raised after concrete has set
  • Hollow concrete block and between beams
  • T section pre cast concrete beams
  • eams built 1.2 into walls

Precast concrete Beam and block floor

  • This type of reinforced concrete floor is much used for comparatively small spans and loads
  • For floors that need a greater bearing capactiy , the beam or block floors can be finished with a constructional concrete topping
  • The constructional concrete topping ties the beams and blocks together making a composite floor .
  • Solid reinforced concrete beams generally shaped like an inverted T in section are precast in the manufactures factory
  • Depth of the beams caries from 130 to 250 mm and they are90mm wide at the bottom
  • The beams are made in lengths up to 6.0m
  • Precast hollow blovks are made lightweight for lightness in handling and to reduce weight of the finished floor
  • These blocks are usually 225mm wide , 130 to 250 mm deep and up to 225mm long

Hollow Concrete Beam Floor

  • Hollow reinforced concrete beams are precast in rectangular secton
  • Concrete walls of these beams are from 15 to 20mm thick with the steel reinforcement cast in the lower angles of the beam .
  • the sides of the beams are indented to provide a key for the concrete topping .
  • The beams are usually 355mm wide, from 130 to 205mm deep and up to 6m long
  • The depth of the beam depends on the superimposed loads and the span
  • Because of their length and weight , lifting gear is necessary to raise and lower the beams into place
  • The beams are placed side by side with the edge joints being grounted together and their ends bearing 1/2 B on or into brick load bearing walls
  • IF the ends of the beams are built into walls , the ends should be solidly filled with concrete because the hollow beam is not strong enough to bear the weight of heavy brickwork
  • THe wall of the beams are made thin so that they are light in weight for transporting and hoisting into position
  • When beams have been placed , brickwork is raised to act as formwork for concrete
  • !b walls
  • ENds of beams built in must be filled with concrete
  • Constructional concrete topping 50mm thick on top of beams
  • Pre-cast hollow reinforced concrete floor beams
  • The thin walls of the beams are not strong enough to carry the direct weight of furniture , a layer of constructional concrete topping usually 50mm thick , is spread over the beams to distrubute point loads
  • THe constructional concrete topping is an integral part of this floor systemn
  • THe concrete is miced on the buildin site and is spread and levelled on top of the beams
  • THe hollow beams give a flat soffit ,which can be left in its natural state or be given a skim coat of plaster
  • The voids in the units can be used to house the services

Advantage and disadvantages

  • The units are self-centering , therefore temporary support is not required
  • THe conctruction period is considerably shorter
  • Generally the overall weight of floor is less
  • THey are not considered suitable where heavy points loads are encountered unless a constructional concrete topping is used to spread the load over a suitable area

ALternative sign

Hollow terracitta block floor

Advantages and disadvantages
  • The main advantages of this floor are its light weight , which is generally less than comparable floors of concrete construction , and its relatively low cost.
  • Advantage of this type of floor is its good resistance to damage by fire , and it is sometimes termed "fire-resisting reinforced concrete floor '
  • Considerable labour is involved in placing the hollow TC blocks , reinforcement and temporary support .

2010年7月28日星期三

Avantages and disadvantages of reinforcement concrete

  1. The centering required to give temporary support to a monolithic reinforced concrete floor tends to obstruct and delay building operations
  2. Such monolithic reinforced concrete floors are suitable to be sued for heavily loaded and specially designed construction and for stairs and small spans

Reinforcement of concrete

  • Steel reinforcing bars are cast into the underside of the floor with 20mm or more concrete cover below them to prevent the steel rusting and to give it some protection in case of fire
  • THe thicker the concrete cover to reinforcement , the greater the resstance of the floor to fire
  • Structural floors are reinforced with a combination of high tensile steel and mild steel reinforcement .
  • High tensile steel is usually positioned at the bottom of the concrete floor to withstand any tensile forces
  • The main purpose of mild steels rods is to assist in distributing point loads on the floor uniformly over the mass of the concrete .
  • THe main reinforcement usually consists of 12mm diameter high tensile steel rods spaced from 150 to 225mm apart
  • There high tensile steel will span across the floor between walls supporting the floor
  • THe diameter will increase as the loads imposed and the span of the floor increases
  • Mild steel rods , 6mm in diameter , are wired across the main reinforcement spaced 450 to 900mm apart and are called distrivution rods or bars
  • THese distribution rods are ties to the main reinforcement with wire and keep the main reinforcing rods correctly spaced when the concrete being placed .

Reinforced concrete upper floor options

-centering is the temporary platform (formwork ) on which cast in-situ concrete floors are constructed and supported until the concrete has sufficient strength to be self-supporting
-Self-centering is used to define those precast concrete floors that require no temporaray support
-Self-centring is used to define those precast concrete floors that require no temporary support
Self-centering concrete floors are precast in the manufacturers factory and are delivered to the building site where they are hoistd to the level of the floor and placed in position
-oce in position , they require no support other than the bearing of their ends on walls or beams

Monolithic reinforced concrete floor
  • A monolithic reinforced concrete floor is one unbroken solid mass , between 100 and 300mm thick , cast in-situ and reinforced with steel reinforcing bars
  • To support the concrete while it is still wet and plastic , and for few days after it has been placed , temporary support ( formwork or centering ) has to be used .
  • Centering takes the form of rough timber boarding or steels sheets , supported on timber or steel beams and posts
  • Steel reinforcement is laid out on top of the centering and raised 20mm or more aboce the centering by means of small concrete blocks (called spacers) , which are tied to the reinforcing bars with wire
  • Wet concrete is then placed and spread over the reinforcement and the formwork , and it is compacted and levelled off.
  • It is usual to design the floor so that it can safely span the least width of rooms
  • Two opposite sides of the concrete are built into walls and brick partitions 1/2B each end.

Lecture 6 (RC Frames and floors )

Suspended Concrete Upper Floor : self-centering Vs NOn self-Centering
Reinforced concrete ,with its flexibility in design , good fire resistance and sound insulating properties , is widely used for the construction of suspended upper floors for all types of building

Reinforced concrete upper floors can safety support greater superimposed loads than timber upper floors of similar depth

Reinforced concrete upper floor options :
Non self-entering concrete floor
  • Monolithic reinforced concrete floor
  • Hollow terracotta block film

Self-entering concrete floors

  • Hollow concrete beam floor
  • Precast concrete beam and block floor

Reinforced concrete floors can be constructed as cast in-situ or precast .

THe advantages of beam and block floor system are :

-A cost and time effective means on constructing domestic ground floor
-Quality controlled factory manufacture of components
Simple site assembles with the aid of a mobile crane to host the beam
-Potential to span over unsound infilling common to slopping sites
-Application over movable subsoils such as shrinkable clay
-Suitability where ventilation uver the ground floor is required to dilute intrusne gases

Beam or block floor

Incorporating precast concrete beams with lightweight concrete blocks as an infilling

Floor screed dpm and insulation

Beams or block

COncrete bed

Hardcore


  • Precast concrete beams
  1. Shaped like an inverted T in section
  2. THe depth of the beams is from 130 to 250mm
  3. THe beams are precast in lengths of up to 6m
  4. The T beams are reinforced with mild steel reinforcing bars to provide adequate support for the anticipated dead and imposed loads

  • LIghtweight concrete blocks
  1. Made to fit between and bear on the T beams
  2. Some of the blocks are hollow for lightness
  3. It is possible to use rigid insulation between the beams , instead of concrete blocks

  • Sleeper walls are built off the concrete bed to support the precast concrete T beams
  • THe precast concrete T beams are located on the external perimeter walls and internal sleeper walls
  • Lightweight concrete block are then inserted between the beams
  • A concrete toppping or screed is spread and levelled over the precast concrete untis
  • A minimum clear boid depth of 75mm is required below these floors , but it is usual practise to leace at least 150mm'
  • Ventilation of the void should be procided to dilute and prevent concentration of gases from the ground and possible leakage from pipid services

Suspended concrete Ground floor

Suspended concrete Ground floor are used whee the ground
  • Slopes
  • has poor or uncertain bearing capacity
  • Is liable to volume change (swealls)

IT may be wise to form the ground floor as a suspended floor supported by external or internal loadbearing walls , which are independent of the ground .

Suspended concrete ground floors can be constructed using :

  1. In situ reinforced concrete slab
  2. Precast reinforced concrete slab
  3. Beam or block floor system

Unbonded screeds

  • Where a screed is laid on an impermeable dpm , there will be no bond between the screed and the concrete base so that drying shrngkage of the screed is unrestrained
  • The screed should be at least 500mm thick so that it does not dry too rapidly and suffer shringkage cracking

(screed laid onto impermeable DPM unbonded to concrete slab )

Floating screeds

  • A screeds laid on a layer of compressible thermal or sound insulating material should be at leat 65mm thick and teinforced with light mesh,
  • THis will prevent the screed cracks due to drying shringkage and deflection under loads on the floor

Monolithic screeds

  1. A screed lay on a concrete base within 3 hours of placing the concrete
  2. It will bond strongly to the concrete
  3. THe screeds will also dry slowly with the concrete so that drying shringkage and cracking of the screed will be minimised .
  4. For this monolithic consctuction of screed , a thickness of 12mm of screed will suffice

BOnded screeeds

  • A screed lain on a concrete base that has set and hardened
  • It should be at least 40mm thick
  • TO provide a good bond between the screed and the concrete ,, the surface of the concrete should be hacked by mechanical means , cleaned and dampened and then covered by a thin grout of water and cement before the screed is laid
  • With a good bond to the concrete base , a separate screed at least 25 mm thick will dry sufficiently slowly to aboid serious shrinkage cracking.Screed laid using bonding agent onto prepared slab

THere are number of ways in which the floor screed may be laid :

  • Monolithic screed
  • Bonded screeds
  • unbonded screeds
  • Floatings screeds

Choice of screeed laying depends on the nature of the building use and the likely loads in addition to the type of finish selected

Floor screeds

  1. The purpose of a floor screed is to provide a smooth level surface on which a floor finish can be applied
  2. usual materials for a floor screed are cement , sand (1,3) and water which are thorougly mixed , spread over the surface of the concrete bed , compacted levelled and trowelled to a smooth finish wth a wood or steel float.
  3. A wood float dinish is used for wood block and thick tile floors and a steel float finish is used for the thin sheet and tile floor finishes
  4. Screeds should be mixed with just sufficient water for workability
  5. Screeds should be cured , that is allowed to dry out slowly over several days , by covering it with polythene sheeting , to minimise rapid drying shringkage and cracking

Floor finishes

Floor finishes are materials that applied to a floor surface as a finished surface, such as tiles
IT is important to distinguish clearly between the level of the structural floor finish (SFF) and the finished floor level (FFL)

  • For workshops , stores and garages , the structural floor finish of the concrete is sometimes used as the finished floor surface to save the cost of an applied floor finish
  • Concrete floors have poor resistance to wear and in a short time the surface of the concrete DUsts
  • Being a coarse grained material , concrete cannot be washed clean , and if it becomes stained the stains are permanent
  • Extensive areas of concrete floor may be levelled and finished by power floating
  • Concrete floors provide a satisfactory base for the thicker floor finishes such as mastic asphalt , tiles and wood blocks
  • FOr the thin finishes such as plastic , linoleum , rubber sheet and tile , the more precisely level ,smooth surface of a screeded base is necesaary

insulation under concrete bed

  1. With the insulation layer and the DPM below the concrete bed , it is necessary continue the DPM and insulation up vertically around the edges of the concrete bed to unite with the DPC in walls
  2. AN advantage of positioning the DPM above the insulation is that it can be used to secure the upstand edge insulation in place while concrete is being placed
  3. IF the DPM is laid below the insulation , it is necessary to spread a separating layer over the insulation to prevent wet screed running into the joints between the insulation boards
  4. THe separatng layer should be building paper or 500-gauge polythene sheet
  5. TO avoid damage to the insulation layer and the DPM , it is necessary to take care in tipping , spreading and compacting wet concrete or screed

THermal insulation

  • THe practical way of improving the thermal insulation of a solid concrete ground floor is to add a layer of rigid insulation board to the floor
  • ANy material used as an isulation layer to a solid concrete ground floor must be sufficiently strong and rigid to support the floor loads without undue compression and deformation
  • The material commonly used for floor insulation are mineral wool slabs , extruded polystyrene , cellular glass and rigid polyurethane foam boards
  • THe layer of insulation may be laid below the floor screed or under the concrete bed
  • With insulation under the floor screed or concrete bed , it is important that the density of the insulation board is sufficient to support the load of the floor itself and imposed loads on the floor
  • THe advantage of laying the insulation below the concrete bed is that the high density concrete bed will not lose hear to the ground

THe insulation below floor screed

  1. sand-cement screed with nominal reinforcement
  2. Dpm
  3. Insulation
  4. Concrete floor slab
  5. hardcore
  6. FOrmation level (ground)

Note: the dpm and insulation sandwiched between the sceed and concrete

THe insulation concrete bed

Without vapour barrier it is possible that interstitial condensation may form on top of the damp proof membrane(dpm) is plcaed below the rigid impermeable insulation

sequence of cold ground

  1. Concrete floor slab
  2. Dpm
  3. Insulation
  4. Hardcore
  5. Formation level (ground)

Dpm placed above the rigid impermeable insulation

Surface damp-proof membrane

  • Floor finishes such as mastic asphalt and pitch mastic that are impermeable to water can serve as a combined DPM and floor finish
  • A DPm placed above the concrete bed is the easiest method

Sandwiched damp-proof membrane below floor screed

  • An alternative method is to place the DPM between the floor screed and the concrete bed
  • THe floor screed should be at least 50mm thick to minimise the possibility of folding , due to unrestrained shrinkage
  • A sandwiched DPM will delay wet floor screed over it drying out to the concrete below and will prevent adhesion of the floor screed to the surface below

Damp-proof membrane below concrete

  • DPM is placed on a blinding layer over the hardcore
  • Being impermeable to water , DPM will delay the druing out of wet concrete to ground.
  • A DPM placed below the concrete bed has 3 advantages :
  1. It will be protedted from damage during sussequent building operation
  2. It will keep the concrete bed dry and make it a better thermal insulator
  3. During construction , it will act as a separating layer preventing leakage of the cement matrix into the harcore layer, which could result in a weak concrete mix

Position of DPM

THe dpm is position between the sand blinding top of hardcore and the screed

Damp proof membrane

Hot poured bitumen
  • A continuous layer of hot applied bitumen is poured on the surface and spread to a thickness of not less than 3mm
  • The surface of the concrete bed should be brushed to remove dust
  • Properly applied bitumen layers serve as an effective DPM both horizontally and spread up inside wall faces to unite with DPC in walls

Cold-applied bitumen/Rubber emulsions

  • These cold applied solutions are brushed onto the surface of concrete bed in 3 coats to a finished thickness of not less than 2.5mm , allowings each coat to harden before the next is applied

Mastic asplhalt /pitch mastic

  • Could be dual-purpose finish and damp-proof membrane
  • These material are spread hot and dinished to a thickness of at least 12.5mm
  • This expensive damp-proof membrane is used where there is appreciable water pressure under the floor

Concrete bed or slab

  1. Suitable concrete mixes are produced in accordance to British Standard .
  2. Thickness generally specified are :
  • Plain in-situ concrete , 100-150mm thick
  • Reinforced concrete , 150 mm minimum

3.In floors which are to take high loadings , or where the load bearing capacity of the ground is low , the concrete bed may be reinforced with steel bars or steel fabric.

There are 4 types of steel bar that is square twisted bar , plain round bar , ribbed bar , twisted ribbed bar .

Steel fabric

  • reinforcement used in concrete beds for domestic work is usually in the form of a welded steel fabric to BS 4483.
  • Sometimes , a light square mesh fabric is placed 25mm from the upper surface of the concrete bed to prevent surface crazing and limit the size of any cracking

2010年7月27日星期二

Blinding

  1. Before the concrete is laid , it is usual to blind the top surface of the hardcore .
  2. If hardcore is well graded with a mixture of fine and course material , when the hardcore is adequately compacted , the surface finish is relatively smooth and level , thus a blinding layer is unnecessary
  3. Consists of a layer of sand 25-50mm thick or a 50-75mm layer of weak concrete (1;12 mix usually suitable )

THe functions of blinding are :

  1. To prevent the wet concrete running down between the lumps of broken brick or stone .
  2. TO even off the surface of hardcore if a damp-proof membrane is to be placed under the concrete bed
  3. To prevent the damp-proof membrane from being punctured by the hardcore
  4. To provide a true surface from which the reinforcement can be positioned .

Hardore 2

The material used for hardcore should be chemically inert , not appreciably affected by water and be free from water-soluble suphates.

Material used for hardcore are :
  • -Brick or tile rubble
  1. Clean , hard broken brick or tile crushed and graded
  2. Bricks should be free or plaster
  • Concrete rubble
  1. Clean , broken , well graded concrete is a good material for hardcore
  2. THe concrete should be free from plaster
  • Gravel and crushed hard rock
  1. Clean , well graded gravel or crushed hard rock are both excellent , but expensive materials for hardcore
  • Chalk
  1. Broken chalk is a good material for hardcore providing it is protected from expansion due to frost
  • Road planings
  1. When roads are resurfaced , the top of the road is planed off
  2. THe planings provide a very good strong hardcore , which binds together when compacted

Hardcore

  1. Hardcore is the infill of materials such as crushed and graded bricks , stone or concrete , which are hard and do not readily absorb water or deteriorate
  2. Hardcore is spread and levelled over the site within the external walls of the buildings
  3. Usually laid in 100-150mm layers to the required depth of 100-300mm.
  4. Each layer must be well compacted using a vibrating roller , to prevent any unacceptable settlement below the solid concrete grounf floor

The Functions of hardcore are :

  1. To fill in any small packets that have formed during oversite excavations
  2. To provide a firm base on which to place a concrete bed
  3. To help spread any point loads over a greater area
  4. To act against capillary action of moisture within the soil

Solid Concrete Ground Floors

Most ground floors are constructed as solid concrete ground floors on which a floor is finish is usually laid .

THe construction of a solid concrete ground floor consists of the followings:
  1. Hardcore
  2. Blinding
  3. Concrete bed or slab
  4. Damp proof membrane (DPM)

Ground floor options:

  1. Solid concrete ground floor
  2. Suspended concrete ground floor
  3. Suspended timber ground floor

Upper floor options:

  1. Suspended timber upper floors
  2. Suspended concrete upper floor

Types of floor : solid vs Suspended

Concrete and timber are the two material most used for the construction of ground and upper floors

Floors can be constructed in 2 forms:

SOlid floors are formed such that the underside of the floor is in continuous contact with and is supported by the ground

Suspended floors are formed such that the structural elemments of the floor span between supports , not relying on the ground for support of the floor sturcture . THis may result in the creation of a void beneath the floor and the ground .

THe functional requirement of a floor are :

-strength
-stability
Durability
Resistance to ground moisture
Thermal insulation
sound insulation
fire resistance

Definition , Function and Functional Requirement

Floor is a horizontal plane that serves as a working platform for human activities and storage space for equipment and furniture

The primary functions of ground floors are :
  1. To provide a level surface with sufficient strength to support the imposed loads of people and furniture
  2. To exclude the passage of water vapour to the interior of the buildings
  3. To provide resistance to unacceptable heat loss through the floor

The primary functions of uppers floors are :

  1. To provide a level surface with sufficient strength to support the imposed loads of people and furniture
  2. To provide required degree of sound insolution
  3. To provide required degree of fire resistance

2010年7月26日星期一

PEMBENTUKAN MASYARAKAT PLURALISTIK DI MALAYSIA

DI SABAH , KAUM BUMIPUTERA YANG UTAMA IALAH ORANG KADAZANDUSUN , BAJAU , MURUT DAN SULUK . SYARIKAT BERPIAGAM BORNEO UTARA BRITISH YANG MEMERINTAH DI SABAH TELAH MENGGALAKKAN PENGHIRAHAN MASUK ORANG CINA UNTUK BEKERJA DI LADANG-LADANG GETAH DAN TEMBAKAU . BILANGAN PENDUDUK CINA DI SABAH TELAH MENINGKAT DARIPADA 27,801 ORANG PADA TAHUN 1911 KEPADA 50,056 ORANG PADA TAHUN 1931

DI SARAWAK PULA , KAUM BUMIPUTERA YANG UTAMA IALAH ORANG IBAN , BIDAYUH , MELAYU DAN MELANAU . KELUARGA BROOKE YANG MEMERINTAH DI SARAWAK TELAH MENGGALAKKAN KEMASUKAN ORANG CINA UNTUK BEKERJA SEBAGAI PEDAGANG , PETANI DAN PELOMBONG . BILANGAN PENDUDUK CINA DI SARAWAK TELAH MENINGKAT DARIPADA KIRA-KIRA 5000 ORANG PADA TAHUN 1871 KEPADA 123626 ORANG PADA TAHUN 1939

APA YANG AMAT JELAS IALAH PERLUASAN PENTADBIRAN BRITISH TELAH MEMISAHKAN AGAMA (DIBACA ISLAM ) DARIPADA URUSAN SEKULAR SEPERTI POLITIK M ENTADBIRAN , UNDANG-UNDANG ,EKONOMI PENDIDIKAN DAN SEBAGAINYA . RINGKASNYA , AGAMA ISLAM DAN ADAT ISTIADAT MELAYU SERTA KUMPULAN BUMIPUTERA LAIN TERLETAK DI BAWAH URUS TADBIR DAN KUASA SULTAN ; SEGALA PERKARA LAIN TERLETAK DI BAWAH KUASA BRITISH . NAMUM , BRITISH KEMUDIANNYA GAGAL MEMENUHI JANJIAN MEREKA APABILAA MEREKA MENGKHIANATI DASAR "TIDAK CAMPUR TANGAN " MEREKA SENDIRI DALAM URUSAN BERKAITAN DENGAN AGAMA ISLAM DAN ADAT ISTIADAT MELAYU .

Pada umumnya , terdapat persefahaman dan hubungan yang baik antara kimuniti etnik Melayu, CIna dan India .

kEHARMONIAN HUBUNGAN ETNIK INI WUJUD BERTERUSAN DAN TERBUKTI APABILA MEREKA SAMA-SAMA BERJUANG UNTUK MENDAPATKAN KEMERDEKAAN TANAH MELAYU DARIPADA PENJAJAH BRITISH PADA 31 OGOS 1957 DAN PEMBENTUKAN MALAYSIA PADA 16 SEPTEMBER 1963 . KEHARMONIAN TERSEBUT BERTERUSAN KEKAL SEHINGGA KE HARI INI .

KOLONIALISME BRITISH MEMBERI DAMPEK YANG SANGAT BESAR TERHADAP MASYARAKAT DI MALAYSIA SAMA ADA DALAM BENTUK MATERIAL MAHUPUN BUKAN MATERIAL . SUNGGUHPUN PEMERINTAHAN BRITISH TELAH MENYUMBANG TERHADAP PENAMBAHBAIKAN KEHIDUPAN RAKYAT MALAYSIA , TERDAPAT KRITIKAN BAHAWA MEREKA BERTANGGUNGJAWAB SECARA BERANSUR-ANSUR MENYISIHKAN DOMINASI ISLAM DARIPADA KEHIDUPAN MASYARAKAT MALAYSIA . SEBAGAI CONTOH , AL-ATTAS TELAH MENGKRITIK KEHADIRAN KOLONIALISME BARAT (TERMASUK BRITISH ) SEBAGAI SUATU DASAR TEKAL MEMISAHKAN ORANG ISLAM DARIPADA AGAMA MEREKA .

PARA SEJARAHWAN MENCATATKAN BAHAWA DAMPAK DASAR DAN BIROKASI BRITISH BOLEH DILIHAT DENGAN JELAS DALAM PERKARA-PERKARA BERIKUT . PERTAMA , BRITISH MULA BERTAPAK KUKUH MENERUSI SATU CAMPUR TANGAN SECARA TIDAK LANGSUNG PADA TAHUN 1786 APABILA PULAU PINANG DIPEROLEH DARI KEDAH . BRITISH SETERUSNYA TELAH CAMPUR TANGAN SECARA LANGSUNG DAN MENGUASAI PENTADBIRAN NEGERI-NEGERI MELAYU YANG SECARA TRADISIONALNYA TERLETAK DI BAWAH TADBIR URUS SULTAN MELAYU . MENGIKUT PERJANJIAN PANGKOR 1874 , SULTAN PERAK BERSETUJU MENERIMA SEORANG RESIDEN BRITISH YANG AKAN MENASIHATI BAGINDA DALAM SEMUA PERKARA KECUALI YANG MENYENTUH AGAMA DAN ADAT ISTIADAT MELAYU . MENJELANG TAHUN 1895 , SISTEM RESIDEN INI TELAH DIASASKAN DENGAN KUKUHNYA DI PERAK , SELANGOR , PAHANG DAN NEGERI SEMBILAN . MELALUI PERJANJIAN PERSEKUTUAN 1895 YANG DIKUATKUASAKAN PADA 1 JULAI 1896 , KEEMPAT-EMPAT NEGERI BERKENAAN TELAH DISATUKAN DI BAWAH SATU PEMERINTAHAN PUSAT DAN MULA DIKENALI SEBAGAI NEGERI-NEGERI MELAYU BERSEKUTU (FEDERATED MALAY STATES ). BRITISH SETERUSNYA MEMPERLUAS KUASA MEREKA KE ATAS KEDAH , PERLIS , KELANTAN DAN TERENGGANU MELALUI PERJANJIAN BANGKOK 1909 DENGAN SIAM (THAILAND ) , SEORANG PENASIHAT BRITISH DILANTIK BAGI TIAP-TIAP NEGERI BERKENAAN .

Pembentukan masyarakat pluralistik di malaysia

Perbincangan mengenai pembentukan masyarakat pluralistik di Malaysia kerap kali tertumpu pada tiga komuniti etnik utama iaitu Melayu , CIna dan India walaupun sebenarnya terdapat pelbagai lagi kaum dan suku kaum lain di Malaysia . Hal ini disebabkan kerana ketiga-tiga komuniti etnik tersebut telah memainkan peranan yang paling menyerlah dalam memenuhi tututan keperluan ekonomi-politik British di Tanah Melayu . Hal ini tidak sama sekali menagikan kewujudan dan kepentingan peranan yang dimainkan oleh kesemua kaum dan suku kaum lain .

Sebelum tahun 1848 , hampir kesemua penduduk Tanah Melayu terdiri daripada orang Melayu . Namum demikian , perkembangan perusahaan bijih timah mulai pertengahan abad ke -19 dan perusahaan getah mulai awal abad ke -20 telah mengakibatkan penghirahan orang Cina dan India secara besar-besaran ke Tanah Melayu . Menjelang tahun 1931 , jumlah penduduk bukan Melayu melabihi jumlah penduduk melayu . Kewujudan pelbagai kaum yang mengekalkan kebudayaan masing-masing telah mengakibatkan satu masyarakat majmuk di Tanah melayu . Tiap-tiap kaum mempunyai agama , bahasa dan cara hidup yang berlainan .

message baharu(perarakan jawi dan serani )

Pembentukan masy -Baharu Era penjajahan

1)PERANAKAN JAWI
  • Lelaki India muslim ( selatan India ) dengan wanita melayu Pulau Pinang
  • Bahasa
  • (gemar menggunakan bahasa Melayu )
  • Memahami Bahasa Tamil
  • Agama ISlam

2)SERANI

  • Portugis dan penduduk tempatan
  • Agama Kristian (mazhab katolik Roman ) , Islam

Pembentukan masyarakat pluralistik oleh penjajah 2

Ketibaan pemerintah kolonial telah membawa pertemuan menarik antara "agama " ( dibaca Islam ) dan "negara' ( pentadbiran kolonial British ) . Pertemuan ini berlaku dalam suasana empirikal yang berbeza , iaitu antara " islam sebagai agama dan para penganutnya " dan "negara kolonial sekular ". Pertemuan ini berlaku dalam konteks permodenan yang diperkenalkan dan dirancangkan oleh kerajaan kolonial .
Sesungguhnya , Malaysia bukanlah negara pertama dalam kalangan koloni British yang melalui pengalaman ini . Negara-negara Asia selatan seperti India , Pakistan , Bangladesh , Bhutan , Sri Lanka dan Nepal telah melalui proses ini jauh lebih awal dari Malaysia.

Para sarjana yang pakar dalam bidang kajian India British seperti Bernard Cohn (seorang ahli antropologi berbangsa Amerika ) mengutarakan bahawa kolonialisme bukan hanya terlibat penaklukan ruang fizikal ; apa yang lebih penting ialah kolonialisme turut melibatkan penaklukan terhadap ruang epistemologi atau sistem permikiran peribumi yang mengakibatkan hilangnya kekuatan sistem pemikiran tersebut sebagai kuasa pentakrif kehidupan . Proses ini seterusnya digantikan dengan sistem pemikiran asing menerusi aplikasi sistematik siri "modus penyiasatan " kolonial . Cohn yang telah menghabiskan seluruh hidupnya mengkaji seharah India berdasarkan kaca mata ilmu antropologi mencatatkan :

"An investigative modality includes the definition of a body of information that is needed , the procedures by which appropriate knowledge is gathered , its ordering and classification , and then how it is transformed into usable forms such as published report , statistical returns , histories , gazetters , legal codes , and encyclopaedias ( Cohn , 1996 )

Pembentukan masyarakat pluralistik oleh penjajah

Faktor yang menjadikan masyarakat berpegang kepada kepercayaan bahawa agama hanya perlu pada peringkat individu sahaja ialah agama dianggap sebagai penyumbang kepada perselisihan pendapat dalam kalangan manusia dan seterusnya akan membawa kepada pergaduhan dan peperangan . Sebaliknya , ilmu sains mempunyai sifat sarwajagat yang boleh menyatukan manusia di bawah payung kefahaman yang sama dan ini membolehkan manusia hidup secara aman dan damai . Berasaskan fahaman ini , ilmu sains telah diterima sebagai ilmu penting dan asasi dalam kehiduan sosial duniawi manusia . Ringkasnya , ilmu sains menjadi asas kepada segala aspek kehidupan duniawi manusia , termasuklah ilmu permerintahan dan pentadbiran .

Agama tidak lagi menjadi faktor penting dalam kehidupan duniawi manusia . Kesannya , agama berada pada satu pihak yang lain dan kehidupan duniawi berada pada satu pihak yang lain . Dasar ini diteruskan oleh penjajah British menguasai pentadbiran negara manakala hal ehwal agama . ( Islam di Tanah Melayu ) dan adat istiadat Melayu diletakkan di bawah pengawasan sultan . Di samping itu , penjajah British turut memperkenalkan sistem pentadbiran berdasarkan pengagihan kuasa antara tiga unsur penting iaitu kehakiman , eksekutif dan perundangan . Masing-masing pihak hanya menjalankan bidang kuasa masing-masing dan tidak boleh bercampur aduk . Keadaan ini berbeza dengan sistem pemerintahan zaman sebelum kedatangan British menyebabkan tiada agihan kuasa berlaku kerana raja atau sultan mempunyai kuasa mutlak .

Budaya ,Islam , Kristian

Budaya hidup

  1. makan kegemaran (masakan cina pedas , kuih tradisional melayu )
  2. Bahasa Hokkien , Baba , kontonis
  3. Pakaian -kebaya nyonya dan kain batik

Pembentukan Masy-Baharu semasa kesultanan melayu melaka

1) Melayu Arab

  • Masy Arab ( syeal sayyaid ) pedagang ) + masy tempatan ( puteri raja )
  • Golongan elit
  • Syed ( syyid )-pengetua , pemimpin , ketua suku , bangsawan , suami , tuan , ahli suti
  • Bahasa Arab dan Bahasa Melayu

2)India-muslim

  • Pedagang dari India (lelaki )
  • Masy India ( pedagang ) + masy tempatan
  • Bahasa Tamil
  • Bukti , tanjung kling , melaka

3) Peranakan Baba dan nyomya

-Peranakan ( anak-anak hasil perkahwinan campur imigran )

Cina dengan penduduk tempatan

-Asal usul seperti dari CHina puteri Hang Li Po ( puteri maharaja Cina ) dengan sultan mansur shah

Bab 3 Kesan Kolorinalisme dan penjajah

Apabila penjajah British datang menjajah Alam Melayu , khususnya Tanah melayu , Etopah telah mengalami perubahan epistemologi iaitu pemisahan antara negara dan agama . Akibat daripada pertelingkahan antara para agamawan dan saintis di Eropah , ilmu pengetahuan akhirnya terpisah dua iaitu afama dan sains moden .Kedua-duabta dinamakan sebagai Rock of Ages : Science and Religion in the Fullness of Life oleh Stephen Jay Gould ( 2002 ) apabila beliau menulis buku mengenai dua perkara pokok di sepangjang sejarah kehidupan manusia . Masyarakat secara umumnya terpisah kepada dua : pihak menyokong agama ; dan pihak menyokong sains moden . Ilmu berasaskan sains moden mendapat sokongan majoriti penduduk Eropah dan ini akhirnya menyebabkan agama menjadi anutan individu sahaja .

Bab 3 Kesan Kolorinalisme dan penjajah

3.4 Pembentukan Masyarakat Pluralistik oleh penjajah

Topik utama yang akan dibincang dalam bahagian ini ialah prinsip , sistem , strucktur dan dasar pentadbiran yang diperkenalkan oleh penjajah British di ALam Melayu . Kedatangan British ke ALam Melayu bukanlah dengan tangan kosong tetapi mereka telah lama maju dari segi ilmu pengetahuan . Universiti tertua di Eropah , iaitu Universiti Oxford , telah wujud sejak abad ke sepuluh Masihi lagi . Ertinya , mereka merupakan penjajah yang telah mempunyai ilmu pengetahuan tinggi dalam bidang sosial , kemanusian dan sains tulen . Perdebatan ilmu begitu hangat selama berabad-abad do dunia mereka sehingga berlakunya pemisahan besar antara agama dan sains moden pada abad ke lima belas Masihi.

3.3 Kemuncak Pluraliti ALam Melayu : Kesultanan Melaka

Zaman kesultanan Melayu Melaka merupakan Zaman keemasan dan kemuncak keagungan kerajaan Melayu . Melaka diperintah oleh para sultan dan pembesar yang berpandangan jauh ( visionary ) . Empayar Melaka merupakan tempat pertemuan para pedagang dari seluruh pelosok dunia sehingga digelak THe Venice of THe East . Pelabuhannya begitu sibuk dengan ribuan kapal berulang-alik melalui Selat Melaka . Pemerintahan dijalankan dengan sikap penuh diplomasi dan terbuka . Para pegawai istana bukan sahaja terdiri daripada kalangan orang Melayu tempatan . Terdapat orang India yang dilantik menjawat jawatan dalam istana sultan Melaka . Perjahwinan campur telah berlaku antara pemerintah Melaka dengan anak perempuan kira keharmonian antara kaum .

Pedagangan di Melaka berjalan dengan begitu lancar . Semua ini ialah hasil daripada sistem pemerintahan terbuka ( menerima sesiapa sahaja yang ingin berdagang ) di samping pelabuhan ditadbir dengan cekap . Keselamatan laut daripada ancaman perompak dan lanun dapat dikawal oleh laksamana Melaka yang proaktif . Situasi ini menjadikan suasana selamat dan aman untuk para pedagang datang berdagang di pelabuhan Melaka . Keadaan ini disokong kuat oleh Undang-undang Laut melaka yang berteraskan ajaran islam

Zaman Empayar Kesultanan melayu melaka merupakan Zaman pluraliti kerana proses penghirahan berlaku secara semula jadi tanap ada pemaksaan daripada mana-mana pihak . Zaman ini bukanlah zaman negara bangsa sebagaimana yang diperkenalkan oleh British dan seterusnya mewujudkan masyarakat pluralistik yang nyata . Para pedagang tidak memerlukan pasport atau visa sebagai pengenalan diri untuk memasuki sesuatu kawasan . Keadaan ini membolehkan para pedagang dari Arab , India , China dan negara-negara lain datang berdagang secara sukarela . Mereka telah berakmosasi dengan penduduk tempatan dan sistemnya dengan baik . Akomodasi antara pedagang dari CHina dan India dengan masyarakat tempatan telah mewujudkan kategori masyarakat yang tidak pernah wujud sebelumnya seperti masyarakat Baba . Mereka terus menetap di Melaka . Ringkasnya , pada zaman kesultanan Melayu melaka terdapat interaksi aktif dalam kalangan pelbagai bangsa dan kaum .

Ilmu pengetahuan alam melayu

Soalan yang sering ditanya apabila membincangkan epistemologi ialah : Bagaimanakah kita mengetahui sesuatu perkara ?' Jadi , perubahan epistemologikal bermaksud perubahan dari segi ilmu pengetahuan yang melibatkan cara berfikir dan cara kita melihat sesuatu . Hal ini seterusnya akan melibatkan perubahan terhadap cara kita memahami sesuatu .

sebelum kedatangan penjajah British , ilmu pengetahuan dalam Alam Melayu lebih banyak berasaskan epistemologi bercorak metafizik . Menurut istilah orang Melayu , ilmu metafizik secara mudahnya ialah ilmu bersumberkan alam ghaib . ALam ghaib ialah alam bukan material yang wujud di luar pengalaman pancaindera manusia . Salah satu manifestasi ketara mengenai ilmu metafizik Alam Melayu ialah amalan perubatan perdukunan atau perbomohan menggunakan jampi serapah ketika berinteraksi dengan makhluk alam ghaib untuk mengubati sesuatu penyakit .

Kedatangan British mengubah epistemologi metafizik bersifat bukan material kepada epistemologi fizikal bersifat rasonal atau saintifik.Asas kepada epistemologi baharu ini ialah pembuktian sesuatu pengetahuan menerusi pancaindera , kemudiannya dipertingkat dengan alat saintifi seperti mkroskop dan sebagainya . Sesuatu itu hanya diiktirat kewujudannya jika boleh dibuktikan secara material oleh pancaindera sama ada menerusi bantuan alatan saintifik atau pun tidak . Epistemolog ini kemudiannya memperkenalkan ilmu , konstruksi sosial , perbendaharaan kata , idiom san institusi yang tidak diketahui oleh masyarakat peribumi sebelum ini seperti peta , banci , muzium dan kategori etnik . Kesemua ini kemudiannya dikenali sebagai ilmu kolonial

Bab 3 pengaruh Hinduisme dan Buddhisme dalam masyarakat Melayu

Konsep raja dan kerajaan ialah istilah yang dipinjam daripada kebudayaan Hindu sementara konsep negeri atau negara ialah perkataan Sanskrit ( Ismail Hamid ,1988). Pelantikan para pegawai kerajaan awal dalam Alam melayu secara berangka seperti Orang Besar Empat , Orang Besar Lapan , Orang Besar Enam Belas dan Orang Besar Tiga Puluh DUa dipengaruhi oleh astrologi Hindu . Menurut kepercayaan Hinduisme , raja ialah anak tuhan yang diutus ke muka bumi bagi menunjukkan kepada rakyat bahawa mereka mesti mentaati dan mematuhi segala perintah raja . Kebesaran raja digamabarkan menerusi pembinaan candi-candi besar . Antara candi yang paling indah ialah Boribudur di Indonesia dan Angkor Wat di Kemboja.
Hal ini secara psikologi diterapkan dalam hati nurani penduduk Alam Melayu bahawa institusi raja merupakan sesuatu yang amat besar dan perlu ditaati secara mutlak sesuai dengan kedudukannya sebagai anak tuhan , Hasilnya , raja ialah ketua kerajaan dan mempunyai kuasa mutlak dalam pentadbiran negeri . Sistem ini terus dikekalkan , walaupun dengan beberapa perubahan , apabla Islam bertapak dalam Alam Melayu kemuduannya dan berterusan sehinggalah kedatangan penjajah Eropah , terutamanya British . Penjajah Eropah telah mengubah sistem kepada sistem politik kerajaan yang memisahkan agama dan pemerintahan di bawah dua pentadbiran yang berbeza . Tegasnya , agama diletakkan di bawah tadbir urus sultan dan negara pula di bawah tadbir urus kerajaan

Penjelmaan dari segi material dan bukan material dapat dilihat dan difahami berdasarkan perubahan bersifat epistemologikal yang dibawa oleh penjajah British .Secara mudah dan ringkas , epistemologi bererti asak mula sesuatu ilmu pengetahuan .

hubungan etnik bab 3

Dalam majlis perkahwinan ialah asimilasi penduduk tempatan dengan pendatang dari india

Pembentukan pola masyarakat pluralistik selepas kedatangan orang eropah berbeza berbanding dengan zaman sebelum kedatangan mereka . Sebagai contoh , penghijrahan masuk orang cina dan india ke Tanah Melayu digalakkan oleh British untuk memajukan kepentingan ekonomi dan politik mereka . Orang Cina digalakan membuka lombong-lombong bijih timah dan emas . Mereka umumnya dibawa masuk oleh British tanpa disetai kaum keluarga seperti isteri dan anak mereka . Oleh sebab tumpuan dan hasrat kedatangan mereka adalah untuk memenuhi keperluan ekonomi-politik British , maka asimilasi budaya dan cara hidup antara kumpulan etnik tidak berlaku . Masing-masing menjalankan kehidupan dalam kelompok masyarakat masing-masing . Namum , ini tidak bermakna tiada kehidupan yang harmonis . Kehidupan yang harmonis antara kaum tetap dan terus wujud dalam bentuk akomodasi sosial . Akomodasi sosial telah membenarkan setiap kaum iaitu Melayu , Cina dan India menjalani kehidupan berasaskan sistem sosial masing-masing secara harmonis . Keharmonian ini terus berkekalan sehingga ke hari ini .
Hubungan antara peradaban Alam Melayu dengan peradapan China dan India telah wujud sejak beratus-ratus tahun dahulu . Oleh itu , dipercayai bahawa pedagang-pedagang India telah datang ke GUgusan Kepulauan Melayu sejak selewat-lewatnya pada abad pertama Masihi . Hubungan Perdagangan secara langsung antara Gugusan Kepulauan Melayu dengan China telah diasaskan pada awal abad ke-5 Masihi .
Hubungan tersebut terjadi disebabkan oleh beberapa faktor seperti perdagangan dan pendidikan . Malahan , Alam Melayu terkenal sebagai pusat pengajian dan penyebaran ilmu pengetahuan sejal abad ke tujuh Masihi lagi . Menurut I-Tsing ( seorang sami Buddha dari CHina yang telah singgah di perlembang , Sumatera pada tahun 671 Masihi dalam pelayarannya ke India ) , terdapat lebih 1000 sami Buddha di Srivijaya .

Pengaruh Hinduisme dan Buddhisme dalam masyarakat Melayu .
Perkembangan tamadun awal dalam Alam Melayu amat dipengaruhi oleh agama dan kebudayaan India . Masyarakat Alam Melayu ( terutamanya dalam kalangan raja dan kaum bangsawan ) telah menerma unsur-unsur agama Hindu dan Buddha yang tidak bercanggah dengan kepercayaan tempatan . George Coedes ( 1948 ) menggunakan istilah Indianisation atau "Pengindiaan" bagi melambangkan proses perluasan pengaruh agama dan kebudayaan India di Asia Tenggara . Menurut Syed Muhammad Naquib AL-Attas (1972 pula ), Hinduisme dan Buddhisme sebenarynya tidak memberi kesan besar dalam kehidupan orang melayu (rakyat biasa ) dalam Alam Melayu . Pendapat beliau berasaskan hakikat bahawa jarang sekali terdapat nama berunsur Hindu dan Buddha dalam kalangan anak Melayu daripada kalangan rakyat biasa . Hal ini berbeza dengan agama Islam kerana hampir kesemua nama orang Melayu diberikan berdasarkan nama ISlam . Satu aspek lagi menurut AL-Attas , tidak terdapat kitab membincangkan idea besar seperti falsafah , ketuhanan ,metafizik dan sebagainya berasaskan Hinduisme dan Buddhisme dalam Alam Melayu sama ada dalam Bahsa melayu mahupun bahasa Jawa yang kedua -duanya merupakan bahasa besar dalam Alam Melayu . Apa yang ada hanyalah kitab bersifat kesenian terutamanya dalam bahasa Jawa .

Namum , kenyataan AL-Attas tidak menafikan wujudnya pengaruh Hinduisme dan Buddhisme dar segi seni budaya dan adat dalam kalangan orang MElayu rakyat biasa . WAtak-watak dalam wayang kulit yang memakai nama-nama Hindu seperti Ramayana , Hanuman dan Sita Dewi sangat terkenal dalam kalangan orang Melayu . Demikian juga halnya dengan adat istiadat perkahwinan orang Melayu yang dipengaruhi oleh Kebudayaan india yakni peralatan-peralatan seperti bunga manggar daan bunga telur serta acara bersanding itu sendiri . Hinduisme dan Buddhisme menurut AL-Attas lagi , diterima baik dan memberi dampak besar dalam kalangan pemerintah ALam Melayu sebelum kedatangan ISlam .

2010年7月8日星期四

are there different types of portland cement ?

and 111A are cement us to make air-entrained concrete , They have the same properties as types 1234 , except that they have small quantities of air entrained material comvined with them


white portland cement is made from raw material conrtaining little or no iron or manganese m the substances that give conventional cement its gray colour .

what is alkali -silica reactivity ( asr ) ?

Alkali-silica reactivity is an expansive raction between reactive forms of silica in aggregates and potassium and sodium alkalis mostlu from cement , but also from aggregates m pozzolans , admixtures and mixing water , External sources of alkali from soil , decers and industrial processes can also contribute to reactiviry , THe raction forms an alkali-slica gel that sweelss as it draws water from the surrounding cement paste , therby inducing pressure , expansion and cracking of the aggregate and surrounding paste . This often results in map pattern crack , sometimes referred to as alligator pattern cracking , ASE can be avouded throught 1 ) proprt aggregates selection , 2) use of blended cement , 3 ) use of proper pozzolaic material and 4 ) contaminant -free mixing water

Is there a universal international specification for portland cement ?

Ezch country has its own standard for portland cement , so there is no universal international standard . The united states uses the specification prepared by the american society for testing and materials -ASTM c-150 standard specification for portland cement . There are a few other countries that also have adppted this as their standard , however , thera are countless otehr spexifications . Infortunately , they do not use the same criteria for measuring properties and defininf physical characteristic so they are vietually " non-translatable ". The european Cement association located in Vrussels , belgium , publishes a book titled " cement standards of the world ?

How do ypu protect a concrete surface from aggressive material like acids

Many material have no effect on concrete . However , there are some aggressive material , such as most acids , that can have a deteriorating effect on concrete with maximum chemical resistance , followed by the application of protective treatments to keep corrosice substances from contacting the concrete . Principles and practise that improve the chemical resistance of concrete include using a low water-cement ratio , selacting a suitable aggrtegates , water and wir entrainment , A large number of chemical formulations are available as sealers and coatings to protect concrete from a variety of environments ; details recommendations shuld be requested from manufacturers , formulators or material suppliers .

what are the decorative finishes that can be applied to concrete surfaces ?

colour may be added to concrete by adding pigments before or after concrete is place and using white cement rather than conventional gray cement , by using chemical stains , or by exposing colourful aggregates at the surface . Textured finished can vary from a smooth polish to the roughness of gravel . Geometric patterns can be scored , stamped , rolled , or inlaid into the concrete to resemble stone , brick or tile paving . Other interesting patterns are obtained by using divider strips ( commonly redwood ) to form panels of various sized and shapes rectangular , squate , circular or diamond . Special techniques are available to make concrete slip-resistanct and sperking .

How do you remove stain from concrete ?

Stains can be removed from concrete with dry or mechanical method s, or by wet method using cehemical or water .
Common dry methid include sandblasting , flame cleaning , and shotblasting , grinding , scabbing , planning and scouring , Steel -wire brushed should be used with care because they can leave meta partcles on the surface that later may rusht and stain the concrete
Wet method involve the application of water or specific chemicals according to the nature of the sain . The chemical treatment either dissolves the staining substances so it will not show .

To remove blood stains , for example , wet the stains with water and cover them with a layer of sodium peroxide powder : et stand for a few minutes , rinse with water and scrub vigorosuly . Folloe with the application of a 5 percent solutuin of vinegar to neutralize any remaining sodum perroxide .

how do you control the strength of concrte ?

The easiest way to add strength is to add cement . The factors that most predominatly influences concrete strength is the ratio of water to cement in the cement paste that binds the aggregates together , The higher this ratio is , the weaker will be and vice versa . Everdy desirable physical property that you can measure will be adversely effected by adding more water ,

what is 3000 pound concrete ?

It is concrete that is strong enough to carry a compressive stress of 3000 psi , ( 20.7Mpa) at 28 days . Concrete may be specified at other strength as well . Conventional concrete has strenfths of 7000 psi or less : concrete with strength between 7000 and 14500 psi is considered high strength concrete

what does the 28 day strength mean ?

COncrete hardens and gain strength as it hydrates . THe hydration process conrinuess over a long period of time . It happens rapidly at first and slows down as time goes by . TO measure the ultimate strength of concrete would require a wait of several years . This would be impractical , so a time period od 28 days was selected by specification writing authorities as the age that all concrete shuld be tested . At this age , a substantal percentage of the hydration has taken place .

Will concrete harden under water ?

Portland cement is a hydraulic cement which means that it sets and hardens due to a chemical reaction with water . Consequently , it wil harden under water .

why do concrete surface flake and spall?

Concrete surface flake and spall for one or more of the followings reasons :
  • In areas of the country that are subjected to freezing and thawing the concrete should be air-entrained to resist flaking and scaling of the surface . If air entrained concrete is not used , there will be subsequent damange to the surface
  • The water /cement ratio should be as low as possible to improve durability of the surface . Too much water in the mix will produce a weaker , less durable concrete that will contribute to early flaking and spalling of the surface
  • THe finishing opereations hould not begin until the water sheen on the surface is gone and excess bledd water on the surface has had a chance to evaporate . IF this excess water is worked into the concrete because the finishiong operation are begun too soon , the concrete , on the surface will have to high a water content and will be weaker and less durable .

How can you tell if you are getting the amount of concrete you are paying for?

The real indicator is the yield , or the actual volume produced based on the actual batch quantities of cement , water and aggregates . The unit weight test can be used to determine the yiled od asample of the ready mixed concrete as delivered . Its a simple calculation that rewuires the unit weifht of all materials batched . The total weight information may be shown on the delivery ticket or it can be provided by the producer . Many concrete producers actually overs yield by about 1/2 percent to make sure they aren;t short;changing their customers . But other producers may not even realize that a mux desgned for one cubic yard might only produce 26.5 cubic feet or 98 percent of what they designed .

test for fresh concrete

  • Compressive strength s tested by pouring cylinders of fresh concrete and mesuring the force needed to break the concrete cylinders a t proscribed intervals a s they harden .
  • According to Building code Requirements for Reinforced Concrete ( ACI 318 ) , as long as no single test is more than 500 psi below the design strengh then the concrete is acceptable . If the strength tests don;t meet these criteria , steps must be taken to raise the average.

What are the most common tests for fresh concrete ?

Slump , air content , unit weight and compressive strength test are the most common tests

  • Slump is a measure of consistency , or relative abiliry of the concrete to flow , If the concrete can't flow because the consistency or the slump is too low , there are potential problems with proper consolidation . If the concrete won't stop flowing because the slump is too high , there are potential problems with mortar loss throught the formwork , excessive formwork pressures , finishing delays and segregation
  • Air content measures the total air content in a sample of fresh concrete , but does not indicate what the final in-place air content will be , because a certain amoint of air is lost in transportation , consolidating , olacement and finishing . THree field tests are widely specified : the pressure meter and volumetric method are ASTM standards and the chace Indicator is an AASHTO procedure .

Why test concrete ?

Concrete is tested to ensure that the material that was specified and bought is the same materal delevered to the job site . THere are dozen different test methods for freshly mixed concrete and at least another dozen tests for hardened concrete m not including test methods unique to organizations like the army corps of engineers , the fereral highway administration , and state depaertments of transportaion .

Why does concrete crack ?

Concrete , like all other materials , will slightly vhange in bolume when it dries out , In typical concrete this change amounts to abouts 500 millionths . Translated into dimesnions -this is about 1/16 of an inch in 10 feet ( 4cm in 3 meters ) . The reason that contractors put joints in concrete pavements and floors is to allow the concrete to crack in a neat , straight line a t the joint when the volume of the concrete change due to shringkage .

Good concrete can be obtained by using a wide variety of mic proportions if proper mix design procedures are used . A good general rule to use is the

  • A minimum cement content of 6 bags per cubic yard of concrete ,
  • A maximum water content of 6 gallons per bag of cement ,
  • A curing period ( keeping concrete moist ) a minimum of 6 days , and
  • AN air content of 6 percent ( if concrete will be subject to freezing and thawing ) .

What is air-entrained concrete ?

Air-entrained concrete contains billions of microscopic air cells percubic foot . These air pockets releive internal presseure on the concrete by providing tiny chambers for water to expand into when it freezes . AIr -entrained concrete is produced through the use of air-entraining portland cement , or by the introduction of air-entraining agents , under careful engineering supervision as the concrete is mixed on the job . The amount of entrainrd air is usually between 4 percent and 7 percent of the bolume of the concrete , but may be varied as rewuited by special conditions

Can it too hot or too colf to plave new concrete ?

Temperature extremes make it diddicult to properly cure concrete . On hot days , to mu hh water is losty by evaporation from newly placed concrete . If the temperature drops too close to freezing , hyfration slows to nealy a standstill . Under these conditions , concrete ceases to gain strength and other desirable properties . In general , the temperature of new concrete shoulkd not ne alllowed to fall below 50 farhrenheit ( 10 celsius ) during the curing period .

What does it mean to cure concrete?

Curing is one of the most important steps in concrete construction , because proprrt curing greatly increases concrete streength and durability , COncrete hardens as a result of hydration L the chemical reaction between cement and water . However , hydration occurs only if water is available and if the concrete's te,[eratre staus witjom a suitable range . During the curing period from five to seven days after placement for conventional conctrete-the concrete surface needs to be kept moist to permit the hydration process , new concrete can be wet with soaking hoses , sprinkers or covered with wet burlap , or can be coated with commercially availabble curing compounds , which seal in moisture .

How is portland cement made ?

Materials that contain appropriate amounts od calcium compounds , silica m alumina and iron oxide are crushed and screened and placed in a rotating cement kiln . Ingredient used in this process are typically materials such as limeston e,marl , shale , iron ore , clay , and fly ash .

The kiln resembles a large horizontal pipe with a diameter of 10 to 15 feet ( 3 to 4.1 meters ) and a length of 300 feet ( 90 meters ) or moe , One endi is raised slightly . THe raw mix is placed in the high end and as the kiln rotates the materials move slowly toward the lower end . Flame jets are at the lower end and all the materials in the kiln are heated to high temperatures that range between 2700 and 3000 Fahrenheit ( 1480 and 1650 Celcius ) . This high heat drives off , or calcines , the chemically combined water and carbon dioxide from the raw materials and forms new compounds ( tricalcium silicate , dicalcium silicate , tricalcium aluminate and tetracalcium aluminiferrite ) . For each ton od material that goes ionto the fedd end of the kiln , two thirds od a ton the mes out the discharge end , caled clinker . THis clinker is in the form of marble sized pellets . THe clinker is very finely ground to produce portlanc cement , A small amoount of gypsum is added during the drinding process to conrrol the cement set or rate od hardening .

What is the different between cement and concrete?

Althought the terms cemenet and concrete odten are used interchangeably , cement is actually an ingredient of concrete . Concrete is basically a mixture of aggregates and paste . THe aggregates are sand and gravel or crushed stone : the paste is water and portland cement . Concrete gets stronger as it gets older . Portland cement is not a brand name , but the feneric terms for the type of cement used in virtuallly all concrete , just a stainless is a type of steel and sterling a type of silver . Cement comprises from 10 to 15 percent of the concrete mix , by volume . Throught a process called hydration , the cement and water arden and binf the aggregates into a rocklike mass , THis hardening process continues for uyear meaning that conxrete gets stronger as it get older .

So , there is no such thing as a cement sidewalk , or a cement mixer l; ther proper terms are concrete sidewalk and concrete mixer .

2010年7月4日星期日

Aggregates

  1. Classified under 2 categories
  2. Coarse aggregates -pass through 75mm mesh sieve and are entirely retained on 4.75 mm ( 3/16 in )
  3. Aggregates greater than 75 mm know as cyclopean aggregates
  4. Fine aggegates ( sand ) -size smaller than 4..75 mm but completely retained on 0.07 mm mesh
  5. Silt -0.06-0.02 ,,,
  6. Clay -smaller than 0.02 ,,

Learning outcomes

-Upon completion od this section , you should be able to :
  1. Describe the characteristic and properties of aggregates
  2. Outline the tests for aggregates ; namely bulking test , colorimetric test and siece analysis
!! percent porland cement , 16 percent water , 6 percent air , 26 percent sand ( aggregates ) 41 percent gravel on crushed stone ( coarse aggregates )

concrete aggrrgates

Aggregates
  1. Mineral filler material
  2. Collection of small particles
  3. 60-70% of concrete are aggregates ( 3/4 Volume )
  4. Cheap : economical to have more aggregates in concrete
  5. High volume of stability
  6. Reduce the heat of hydration of concrete
  7. Better durability

Concrete component :Cement is the key ingredient of concrete , but makes up just 11 percent of the mix

Summary

Final setting time

initial setting time

min 45 minute
At the point water is added , start the stopwatch

max 10 hour
End of test , stop the watch

To determine final setting time

-steps:
  1. Fiz a 1mm square needle fitted with a metal attachement hollowed out to leave a curcular cutting edge
  2. Gently lowered needle to surface of cement
  3. When needle make an impression on cement but circular cutting edge does not , final set has taken place
  4. Final setting time is taken from the moment water was added to cement
  5. Not more than 10 hour for OPC

To determine initial setting time

-Steps:
  1. A cement paste of standard consistency is prepared using water content determined earlier
  2. A needle of 1mm2 cross sectional area is fixed to appratus and released
  3. Check penetration
  4. When needle penetrate to 5mm from bottom , initial set have taken place
  5. Initial set is the time elaspsed since water has added to cement
  6. Minimum of 45 minutes for OPC

To determine standard consistency

-For this test , cement paste with standard consistency has to be used
-Steps:
  1. steps :

-Fix 10mm plunger to apparatus

-Adjust to contact with cement paste in the mould and release

-paste is consirered consistent when pluger penetrates 5-7 mm from bottom of mould

-usual water content is 26-33% by weight of dry cement

Vicat test

-TO determine:
1.Initial setting time
2. Final setting time

-using Vicat apparatus

Vicat test

Fineness of cement

-Finer powder of cement will increase the rate of setting and hardening due to greater surface area available for reaction .

Additives
-Gypsum retards and slows down the rate of setting ( retarder)
-Calcium chloride increases the rate of setting and hardening (accelerator )

Temperature

-Temperature increases the rate of setting and hardening , and also the rate of heat evolution
-Low temperature retards setting
-Temperature below 0 celcius -the setting and hardening will stop
-THe most suitable temperature for setting and hardening is around 14-18 Celcius,with humidity not less than 90 % ( as specified by B.S 12 1958 )

Increase In fineness

  1. The rate of hydration increases . This leads to both a higher rate of strength gain and higher rate of evolution of heat .
  2. Decrease the amount of bleeding , but the amount of water required for workability for non -air entrained concrete is increases , which results in increased drying shringkage result in surface cracking.
  3. Reduce the durability of concrete to freeze-thraw cycles
  4. Requires a greater amount of gymsum for proper set control , owing to the increased aailabitlity of C3S for reaction
  5. Increase in production cost
  6. Quality can easliy be detrimental when expose to air .
  7. Increases in reaction with some aggregates = aggregates degradation