Structure: 1. Clay: It should contain a certain amount of loose particles to facilitate cement mixing. Clay with low sand content can be mixed with sand in the soil. Clay with low sand content and relatively hard texture needs to be ground before adding sand.
2. Cement: Adding 10% of 425 # ordinary Portland cement can improve the strength and water resistance of bricks, and will not crack after immersion in water. Otherwise, the bricks will generally crack.
3. Admixtures: Adding a small amount of admixtures (strengthening agents) can not only improve the hardening strength of bricks, but also reduce the amount of cement used and lower product costs.
4. Water: With appropriate water usage, the strength of bricks will be high. Low moisture content during molding results in poor strength of the bricks, high resistance of the material in the mold, single-sided pressure, and insufficient compactness of the brick bottom surface; There is a lot of moisture in the molding process, and the bottom surface is damp, which makes it easy to damage during molding. When the moisture content of sand is 3-5%, it is advisable to use 10% of water during molding.
Preparation:
1. Mixing time: If the mixing time is long, it can be mixed evenly. The strength of dry mixed material increases by 15-23% after 20 minutes compared to 10 minutes; The wet mixing time should be such that the material does not clump. It is advisable to store the mixed materials for about 2 hours. If the storage time is too long or too short, it will reduce the compressive strength of the bricks.
2. Forming pressure: The pressure required for forming clay cement bricks is preferably 500 kilograms per square centimeter. Under this pressure, its products have high compressive strength and good water resistance. The pressure is too low, making it difficult to compact.
3. Maintenance conditions: Cement bricks, also known as non fired bricks, can be cured by pouring water in a natural environment after forming. The strength at 7 days of curing is equivalent to 67-90% of the strength at 28 days of curing; The 28 day age intensity is 80-95% of the quarterly age intensity. Therefore, if the maintenance site is small, cement bricks can be naturally cured for 7 days before leaving the factory.