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. 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: 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. Therefore, it is important to identify your requirements and select the appropriate plywood thickness for your application.Hollow and Solid Concrete Blocks 1. When cutting plywood on a CNC router or a laser cutter, the specification of your machine determines the optimal thickness of the plywood. However, if the application demands prolonged distance between the supports, it is advised to use thicker plywood with more number of plies to provide greater strength. Increasing the distance between the supports will lead to buckling of the plywood and eventually cracking under the action of the load. This can be understood from the example that, when using a 3/4" thick plywood, with support elements separated by a distance of 24", the plywood sheet can easily take up a load of a grown man's weight. A plywood sheet is the strongest along this axis.Īpart from that, the distance between the supports also plays an important role in determining the optimal plywood thickness. The strength axis of the plywood runs parallel to the direction of the grains of the face and back veneers of the plywood. Although both provide the same thickness, the plywood with more plies provides greater strength and rigidity.įurthermore, aligning the strength axis of the plywood with the direction of load ensures high load-bearing capability with minimal thickness. Generally, the thickness requirement of the plywood depends upon the number of plies, the strength axis, and the available support to the plywood.ġ/4" thick plywood can be available in 3-ply and 5-ply options. The optimal plywood thickness mainly depends upon the dimensional requirements of the project and the type of application.