Manufacturing of Concrete Blocks

The concrete mix for concrete blocks shall not be richer than one part of cement to six parts of volume of combined aggregate. Lean mixes up to 1:8 are also commonly used . coarse aggregate of size 6 to 12 mm is generally used. Sixty percent fine and forty percent coarse aggregate is the recommend mix. The choice of aggregate for block is of at most important as cost of aggregates account for a large part of the total cost. Hence, baby jelly aggregates are not generally used for conventional concrete work are found of much use in making these concrete blocks. A simple machine can make up to 1600 blocks in an eight hour shift. The block is then cured in a water tank or yard for at least 14 days .  when immersed in the tank the water shall be changed at least every 4 days. After curing , the blocks are dried for a period of 4 weeks before being used in the work. They should be stacked with voids in the horizontal direction to facilitate easy drying. Otherwise, they should steam cured and dried. This process allows the complete shrinkage of the block to take place before they laid on the wall. The freshly made and uncured blocks should never be allowed on the work.