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 .

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

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

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 .

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 .

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

moisture of cement

1. Dampness makes the cement to reach its ultimate strength
2. Hydrogen from water binds the C-S-H
3. 1 Kg of cement requires 0.22-0.25 Kg of water for hydration
4. Excessice water creates capillary voids which increases permeability and reduces strength

Composition of cement

C3S and C2S

1. Most stable
2. 70-80 % of the constitution in cement
3. C3S hydrates rapidly and develop strength early during the first 14 days . In contrast , C2S hydrates slowly and develop strength after 7 day . Rich in C2S = greater resstance to chemical attack and has a smaller drying shringkage than other portland cements

C3A

1. Least stable
2. Hydration is extremly exothermic and takes very quickly , produce little strength after 24 hour
3. Susceptible to sulphate attack

C4AF

1. Less important
2. Is coloured due to red brown ferric oxide

factor affecting the strength of cement

-C3A

1. resct with water extremely fast but produces little strength after 24 hours
2. the setting time is short ; the strength of the set material is also reduced ;
3. This kind of immediate setting or " flash " setting can be prevented by adding a small amount of gypsum , to retard the process .

Factor affecting setting and hardening of cement

THe volume of the volumetric porportion of cement paste at different stages of hydration

1. compostition of cement
2. temperature
3. Moisture
4. Particle size of cement ( Fineness)
5. Additive

COmposition of cement

-C3S

1. hydrates very quickly when contact with water , large amount of heat evolved and develop a high early strength
2. More C3S in cement , shorter setting time

-C2S

1. Reacts slowly results in slow strength development
2. More C2S in cement , longer time it takes to develop strength

heat of hydration of cement

H 3day= 240 (C3S) + 50 (C2S) +880 (c3A) + 290 (C4AF)
H1 yEAr = 490 (C3S) + 225 (C2S) + 1160 ( C3A) + 375 (c4AF)

ANS
Composition calculated earlier from table 3.3 , the values of H3days and H 1year are 265J/G and 473 J/G , respectively

hydration of cement

spaces between the cement grains are liled with hydration product as cement paste develops strength and durability

Figure 6.3 Development of structure paste CSH place for forming of gets , (initial set ) - Development of weak skenin

hydration of cement

The initial set occurs with the development at a weak skeleton in which cement grains are held in place.


Final set occurs as the skeleton becomes rigid , cement particles are locked in place , and specing between cement grains increases due to the volume reduction of the grains .

Hydration of cement

The product

-Calcium silicate Hydrate ( C-S-H)

1. Small interlocking crystals which grows out slowly from cement grains to occupy previously water -fillled spaces

Heat of hydration

COmpound heat of hydration (j/G)
C3S 502
C2S 260
C3A 867
C4AF 419

symmary of hydration process

The c-s-h phase is initially komed , c3A lorms a gel lastest

the volume of cement grain decreases as a gel forms at the surface . Cement grains are still able to move indepening but as hydration grows , weak einterdocking begins . Part of the cement is a thcotropic state vibration can break the weak bonds

hydration of cement

-when water is added to cement , ph value rises , temperature rises
-c3s and c2s react with water to set and harden
-c3s mainly responsible for hydration

hydration process
2c2s +4H - C3S2H3 + Ca (OH ) 2
(calcium silicate hydrate ) (calcium hydroxide )


2c3s+ 6H - c3s2 H3 + 3Ca(OH )2

Flash Set

-DUe to insufficient of the gypsum to control the rapid reaction of C3A with water .

-Is a rapid development of rigidity in freshly mixed cement paste .mortar or concrete
-Further mixing can;t dispel this rigidity , and a large amount of heat is prodiced in the process
- Can be overcome by adding more water and reagitating the mix . However , concrete strength will be reduced

False set

-ALso produces a rapid stiffering of the paste but is not accompanished bt exccesive heat
-Abnormal premature sttiffening of cement within a fewminutes of mixing with water .
-Remixing the paste without adding water to regain ts lasticity and its subsequent setting and hardening
-The results of intergiding gypsum with very hot clinker in the final stages of cement production .

Hydration of cement - Terms

-Hydration of cement involves two stages : setting and hardening
-Setting

• When cement paste chenges from fluids state to solid state
• Cement becomes stiff ( stiffening process )
• Process control by the quantitty of gypsum present in cement

Initial set - Foramtio of a gel ( plastic ) around cement particle and in contact with other to loose its fluidity , occurs after 1 hour .

Final set - Formation of riged gel , within 10 hours

• Further setting ( stiffening occurs until increment of volume of gel has completed ) and just before hardening is known as the final test .

Learning outcomes

-Upon the completion of this chapter , you should able to :

1. Describe hydration of cement
2. Discuss factors affecting cement setting
3. Outline the Vicast Test

Hydration of cement

-Setting time

1. The time taken from addition of water to initial set and final set
2. Vicat test - To test cement setting time

-Hardening

Hardening also means useful strength development

Concrete ( hydration of cement )

-Hydration = the chemical combination of cement and water .
-Will produce a very hard and strong binding medium for aggregates particles in concrete
-Hydration may continue over a period of a month
-The heat generated during hydration wil affect the durability of concrete due to micro craking

Moisture

-Saturated , surface dry

1. Ideal state
2. Do not require alteration to mixing water

-Wet

1. Surface moisture is present
2. Most common
3. Require deduction of water when mixing

Moisture

-4 states which aggregates may exist in
-oven-dry

• On heating to 105 celcius , no loss of weight
• Seldom occur
• Require extra water when mixing

-Air-dry

• No free moisture and surface are dry
• Occur at upper part of stockpiles in dry wheather
• Require extra water when mixing

strength

-Strength of aggregates generally higher than compressive strength of concrete
-Factors affecting strength of concrete :
- Aggregates size
Aggregates shape and texture
-Cleanliness

sieve analylisis

1. To establish the grading of an aggregate
2. steps:

• AIr-dried sample passed through series of sieves of decresing dimensions
• Use mechanical vibrator / carried out shaking by hand
• Material retained on each sieve is weighed and recorded
• The % passing through by weight is calculated
• Grading is determined by comparing to grading rewuirement ( BS 882 )

Grading

Purpose : to assit in producing concrete with
-satisfactory plastic properties ( workability , cohesion , resist bleeding )
-satisfactory hardened properties ( strength , durability , surface finish )

well-graded aggregate

-Consist of aggregate with different sizes
-Fill as much as possible of the total space
-Voids between large particel can be filled efficiently with slighly smaler ones

Grading

-Purpose: to assist in producing concrete with :
-satisfactory plastic properties ( workability ,, cohesion , resist bleeding )
-satisfactory hardened properties ( strength , durability , surface finish )

Well graded aggregates

-consist of aggregates with diffeent sizes
-Fill as much as possible of the total space
-Voids between large particles can be filled efficiently with slightly smaller ones.

Grading

1. Particle size distribution of aggregates is called grading
2. Coarse aggregates -size gigger than 5mm
3. sand-size as low as 0.07mm
4. Silt-0.06-0.02mm
5. Clay -smaller than 0.02 mm

Bulking test

-To determine % bulking of a damp sand sample
-steps :

1. Fill in container with damp sand sample (VD)
2. Add water until saturated , with further addition of water , films of water merge , water moces into voids . THis volume is the same as volume of dry sample (V)
3. Calculate % of bulking

Bulking of sand

-volume may increse up t 25% of initial volume
-Affect proportioning of material in volume batching
-BUlkinng results in less sand occupying the fixed volume of measuring box

Colorimetric test

Results
-The darker the colour the greater the organic impurities
-If the colour is darker than the satandard yellow colour specified ( colour chart available fot checking ) the aggregates has high organic content

colorimetric test

-To test effects of organic matter
-steps:

1. Put aggregates sample in bottle
2. Fill in with 3% of Na Oh to neutralise acid in sample
3. -shaked mixture vigorously to allow chemcal reaction
4. leave to stand for 24 hour
5. Check the colour of mixture to judge for content of organic impurities

cleanliness of concrete

-clay , silt and dust

1. present in gravel and sand deposit as surface coating
2. large quantity ,ay reduce strength of concrete due to weak bonding

-Salt contamination

1. sand from seashore
2. can be removed by washing
3. If high level , salt may cause efflorescence in concrete and corrosion of steel reinforcement

cleanliness

-should be clean and free from the followings :
-organic impurities

1. organic matter such as decay of vegetable matters
2. interfere with hydration process
3. washing may remove organic impurities in sand

shapes and texture of concrete

1. summary

Angular shape and rough texture aggregates - provide highest bonding strength

Rounded shape and smooth texture aggregates - provide best workability but lower strength

shapes of concrete

-shape

• rounded

less specific surface area

weaker bond

better workability

• irregular

High surface area

good bond

low workability

properties and characteristic of concrete

1. grading
2. shapes/strength
3. texture
4. cleanliness
5. density
6. bulking

Classification of concrete

1. heavyweight

-contain heavy metal atoms such as iron

1. Normal
2. -Natural or artificial
3. lightweight

natural or artificial

porous , less strong , and specially prepared

learning outcome

-upon completion of this section , you should be able to :
-describe the characteristic and properties of aggregates
-Outline the test for aggregates , namely bulking test ,m colorimetric test and sieve analylysis

source of concrete

1. -natural

-crushed rocks , sand and gravel

-from river beds , quarries , sea-beds , cooled volcanos

1. Artificial

-broken bricks , blast furnace slag

concrete aggregates

Aggregates

1. collection of small particles
2. 60-70 of concrete are aggregates ( 3/4) volume
3. cheap: - economical to have more aggregates in concrete
4. High volume of stability
5. Better durability