First, the analysis of the five causes of the cement mortar floor sanding
1, the cement label is low, raw materials are not required, sand is too fine and so on.
2. Excessive water-cement ratio leads to the reduction of cement mortar strength. Do not use too much water in the construction, otherwise the strength of mortar will be reduced, thus the surface of loose cement ash.
3, the process arrangement is not appropriate, do not understand the basic principle of cement hardening, resulting in early or late surface calendering time. Premature calendering, the hydration of cement has just begun, the gel has not been fully formed, free water is still more, there will be surface floating water, reduce the strength of cement mortar surface layer; Calendering too late, the cement has finally set and harden, cement mortar surface layer of capillary stoma and wipe mark can not eliminate, and will also disturb the surface has been hardened, so greatly reduced the strength of the surface layer and wear resistance.
4, cement into the hardening stage, cement hydration will continue, and to the cement particles inside the deeper hydration, cement mortar strength is also increasing. Cement in hydration due to lack of water and affect hydration, will slow down the rate of hardening or even stop hardening, resulting in cement mortar dehydration and affect the strength and anti-wear ability. This is the reason for improper maintenance.
5. In the construction summary, the construction level of the next working procedure is not reached, that is, the finished product is not properly maintained, which will also cause the sand rising on the mortar floor. Cement ground mortar strength does not reach a certain strength on the person walk or carry on next working procedure construction, make the ground suffers friction to cause rise sand. Cement mortar floor or because of the damage to the bonding force, the formation of loose particles.
Two, cement mortar floor cracking analysis of the five reasons
1. The cement used is hot cement just out of the mill, which has a large shrinkage when setting and hardening. Different grades of cement are used together in the same floor.
2, the finer the sand surface area is, the larger the amount of cement slurry adsorbed on the sand surface will increase, in the case of the same amount of cement, the strength of cement mortar will decrease. The mud content in the sand is too large, the volume of the soil in the cement mortar will shrink during the process of hardening and dehydration, resulting in the crack of the floor surface.
3, cement mortar after the final setting, hydration will continue, in the season of high temperature, dry air, if not curing or curing is not timely, will appear the cement surface layer dry shrinkage crack.
4. Poor soil quality of backfill soil or improper compaction result in uneven subsidence and cracks on the ground after the completion of the ground surface layer, and cracks in the ground surface layer will be cracked if there is no construction seam left on the ground or if the structure is deformed in a large area.
5. Uneven mixing of cement mortar leads to decreased tensile strength of mortar.
Three, cement mortar floor empty drum analysis of three reasons
1, the base surface is too dry, after laying mortar, resulting in the mortar strength is not high, the base surface is too dry, will absorb a layer of powder layer, there is an isolation effect between the surface layer and the base, resulting in the bond between the two is not strong, resulting in empty drum.
2. The base surface is not clean and the base surface is too smooth. The adhesion between the base layer and the surface layer is seriously affected, the surface of the base layer is too smooth, in the casting and ramming process of cast-in-place reinforced concrete floor, the surface treatment of concrete is not smooth and rough, resulting in the lack of adhesion between the base layer and the surface layer, resulting in the surface layer empty drum.
3, is the construction brush cement mud too early, after the hardening of air drying not only did not increase the bond, but play a role in the isolation between the base layer and surface layer. If use first spread dry cement with sweeping mud construction, will lead to cement mud wet dry uneven, this is the cause of cement floor empty drum hidden trouble.
