![]() ![]() With high mortar strength, cracks will be less and very large, but with low mortar strength, cracks will be small and distributed. The mortar strength should not be more than the strength of the blocks.The width of blocks use for load-bearing walls is 200 mm and for parapet or filler walls is 100 mm. These dimensions can easily be achieved in machine-made blocks than handmade blocks. The thickness for loadbearing walls is 190 mm, compound walls 140 mm and for filler walls 90 mm. ![]() Width - 50, 75, 100, 150, 200, 250 or 300 mmĪctual sizes will be less than 10 mm of mortar thickness. For Concrete and Hollow concrete blocks nominal length 390 mm and height 190 mm.The nominal dimensions of concrete block as per BIS are as follows: The autoclaved cement product is crystalline, which is different from the product obtained by normal wet curing or by ordinary steam curing. These blocks do not shrink on drying as the material is obtained by autoclaving. Very light blocks for partition and moderate-weight blocks for light loadbearing walls can be obtained from aac blocks. After some time, the mixture sets and ready to cut into a serious of individual blocks of required size using taut steel wires. The final result is a mixture of thick liquid which is then poured into steel moulds to form large cakes. They are prepared as solid blocks from cement, water and materials like ground sand, pulverized fly ash together with additives to aerate and stabilize the air bubbles. These blocks are also termed as light-weight hollow blocks. These blocks are solid concrete blocks of different shapes specially made for exterior ground paving on sidewalks, parking lots, driveways, petrol pumps, industrial floors, etc.ĪAC blocks refer as Autoclaved Aerated Concrete Blocks. These blocks are used as load-bearing walls and have a density of not less than 1800 kg/m³. They should be manufactured for specific concrete strength of 4.0 and 5.0 N/mm² in 28 days. Grade C - These blocks are used for non-load bearing walls and have density more than 1000 kg/m³.Īll these blocks are available in decorative facings like fluted facing to provide artistic effects.Grade B - They have a density below 1500 kg/m¬³ and used for load-bearing walls.Grade A - They possess a minimum density of 1500 kg/m³ and are used for load-bearing walls.Open and Closed cavity-type hollow concrete blocks are classified into three grades: Classification of Concrete Blocks Hollow concrete blocks ![]() The whole process allows the complete shrinkage of the block to take place they are laid on the wall, which is very important for strong walls. They should be stacked with voids in the horizontal direction to facilitate easy drying, or they should be steam cured and dried. The cast block is then cured in a water tank or yard for at least 14 days (water need to be changed at least every 4 days).Īfter curing, the blocks are dried for 4 weeks before being used in masonry construction. Concrete mix for concrete blocks should not be richer than one part of the cement to six parts of the volume of combined aggregate.Ĭoncrete blocks can be handmade and also machine-made. Manufacturing of Concrete BlocksīIS recommends a fineness modulus of the combined aggregate between 3.6 to 4 and coarse aggregates used are of size 6 to 12 mm. Blocks can also be with cement and sand called cement-sand blocks or with cement and soil called soil-cement blocks which are of low strength and use for low-cost construction. Hollow blocks are specially made for loadbearing walls, which are useful in reducing a dead load of masonry in buildings. All these blocks are extensively used for compound walls and non-loadbearing walls. The cellular concrete blocks are generally referred to as lightweight aerated concrete blocks. ![]() If the percentage of the voids is more than 25%, then they are hollow blocks and blocks with voids less than 25% are only perforated blocks. They are available in three types namely solid, hollow and cellular, widely used for the construction of filler walls and boundary walls in RC framework.Ĭoncrete blocks are usually made in large sizes to make blockwork faster and consume less cement in joints than the brickwork. Concrete blocks are nowadays replacing bricks in masonry construction, notably in many multi-storeyed buildings. ![]()
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