Principles of Producing Cement Blocks
Cement blocks or concrete blocks can produce by differently aggregates but cement is the main aggregate in producing cement blocks, other materials used in with cement are pumice, perlite, sand and leca, sand is an old aggregate to produce cement blocks but using sand in cement blocks makes them heavy and it isn't suitable for buildings because of heavy structure has many problems specially in earthquakes so recently in block making factories or workshops they use other aggregates as mentioned above to decrease the weight of the blocks up to 50 percent and these blocks called lightweight blocks.
Note that these blocks are lightweight blocks because of their material but clc and aac blocks are lightweight because of their producing process.
Cement Blocks Standards
Cement blocks standard is different in each country and this is done by Engineering Organization but in total blocks should have a flat face, without any fracture and acceptable strength, simply this means when we want to carry or pick up blocks they mustn't break easily.
Dimension of cement blocks normally are height: 20, 25cm length: 30, 40, 50cm width: 10, 15, 20, 25cm thickness of crust: 2, 2.5, 3cm
Specific weight of light weight blocks is 1200-1450 kg/m3 and normal pushing resistance at least must be 60kg/cm2 and sand blocks weight is 2000 kg/m3.
Cement Blocks Mixing Plan
Sand blocks 20x40x20:
cement 1 mete
gravel 3.5 mete
sand 2.5 mete
water 160-180 lit
Pumice block 15x40x20:
cement 1-1.5kg/ 1 block
pumice 6kg/ 1 block
Cement Blocks Process:
In small workshop where the block producing capacity is low mostly uses the heater because of easy installation and low cost that way the blocks placed the front of the heater and the heat goes through the blocks, to not lose the heat blocks must be covered to keep the heat.
This process used in where there isn't the roof, so blocks are under direct sunlight and losing their moisture so it needs that workers sprinkle the blocks to keep their moisture, usually in this process blocks will take 1 week to be ready for sale
In big factories with high demands for blocks and large capacities, they have to use the steam process to decrease the process time and increase the blocks quality, In the steam system, there is a separate room in factory stuffed with fog and 80-degree heat.
Note that regardless of process methods, the location of blocks must not be under direct sunlight and wind blow to keep them 3weeks in this situation to be processed well and uniform, so that their moisture, be (2% with more than 1400 special weight/m3) and (5% with less than 1400 special weight/m3)