![concrete block weight chart concrete block weight chart](https://image.slidesharecdn.com/buildingcnstrctnspclconcrete-160908193652/95/building-construction-special-concrete-13-638.jpg)
The blocks shall be cured in a curing yard or in an immersion tank and shall be kept in a moist condition for 14 days. When the blocks are cured in an immersion tank, the water of the tank shall be changed at least every four days.Īfter curing, the blocks shall be dried in the shade before being used for work. They shall be stacked with void-face horizontal to facilitate the passage of air. Total web thickness per course in any 200 mm of walling The thickness of the web shell and face shell should not be less than the values given in Table-4. Depending upon the core molds used, the face shells and webs of the concrete blocks shall be flared and tapered or straight tapered. The face shells and webs shall increase in thickness from the bottom to the top of the unit. The water absorption (average of three blocks) shall be not more than 10% by mass. The moisture movement (average of three blocks) shall not exceed 0.09%. The drying shrinkage of the blocks (average of three blocks), when unrestrained, shall not exceed 0.1%. Table-1: Compressive Strength and Density of Concrete Blocks The average compressive strength and density of eight blocks shall not be less than as specified in Table-1 below. The solid concrete blocks shall have a block density of not less than 1800 kg/m 3. These shall be manufactured for minimum compressive strengths of 4.0 and 5.0 N/mm 2, respectively. These grades of concrete blocks are used as non-load bearing units and shall have a block density of less than 1500 kg/m 3 but not less than 1000 kg/m 3. These shall be manufactured for minimum average compressive strength of 1.5 N/mm 2 at 28 days. These are also used as load-bearing units and shall have a block density of 1500 kg/m 3 but not less than 1000 kg/m 3. These shall be manufactured for minimum compressive strengths of 2.0, 3.0, and 5.0 N/mm 2 respectively, at 28 days. These are used as load-bearing units and shall have a minimum block-density of 1500 kg/m 3. The concrete blocks shall be manufactured for minimum compressive strengths of 3.5, 4.5, 5.5, and 7.0 N/mm 2 respectively, at 28 days.
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The hollow concrete blocks shall be classified in the following four types: 1. The tolerance in the length of the units shall not be more than +/- 5 mm and maximum variation in height and width of the unit, not more than +/- 3mm. In addition to the blocks mentioned above, blocks shall be manufactured in half lengths of 200, 250, and 300 mm to correspond to the full-lengths. The nominal dimensions of the concrete blocks are given below:
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The concrete block -hollow (open or closed cavity) or solid shall be referred to by its nominal dimensions. They include stretcher, corner, double corner or pier, jamb, header, bullnose, and partition block, and concrete floor units. The concrete block units shall be made in sizes and shapes to fit different construction needs. Hollow and solid concrete blocks shall be sound and free from cracks, broken edges, honeycombing, and other defects that would interfere with the proper placing of block or impair the strength or performance during construction.