Cement concrete pavement, floor ashing, sand is a common quality problem, once the ash and sand quality problems occur, the concrete surface hardness will decrease, and the wear resistance will become worse. In the later stage of concrete pavement use, there will be stone leakage, which seriously affects the quality and service life of concrete pavement. How to prevent concrete pavement, floor powdering, sand is a technical problem that concrete technicians must face, in view of this phenomenon, to prevent the occurrence of powdering, sand accidents is an important work. Commercial mixing ERP unmanned weighbridge digital mixing plant unattended mixing plant management system
(1) FootSufficient concrete strength grade
The level of concrete strength grade directly affects the surface strength and wear resistance of concrete, generally speaking, the lower water-glue ratio concrete has higher concrete strength, and the concrete surface strength (hardness) and wear resistance are improved. Therefore, concrete pavement, floor ash and sand have a great relationship with concrete surface strength and wear resistance, in order to prevent concrete ashing, sand should make concrete pavement have sufficient strength grade, improve concrete pavement, floor surface strength and wear resistance, and shall not arbitrarily reduce the concrete strength grade.
In the design of pavement and floor concrete mix ratio, how to improve the surface strength of concrete, improve wear resistance, and reduce the powder and sand of concrete pavement. Generally speaking, the pavement concrete cementitious material should not be less than 300kg m3, and the amount of mineral admixture should be reduced as much as possible, and the water-glue ratio should not be greater than 05. To maintain sufficient concrete strength and improve the surface strength and wear resistance of concrete. In the case of meeting the construction requirements of the project, the water consumption should be reduced as much as possible, and the low sand rate and low slump should be adopted to reduce water leakage. In addition, the amount of admixtures and water consumption should not be too large, so as to prevent the surface water-glue ratio caused by concrete water leakage, reduce the surface strength of pavement and floor concrete, and increase the probability of silting and sanding.
(2) Quality control of raw materials
Concrete raw materials have an important impact on the quality of concrete, and the quality of concrete directly affects the quality of pavement and floor, such as concrete water leakage has an important impact on powder and sand. Therefore, controlling the water leakage of concrete and reasonably selecting raw materials are important contents to prevent powder and sand from concrete pavement. The coarseness of cement and the setting time have a certain influence on the water leakage of concrete, generally speaking, the cement is coarse, the specific surface area should not be too small (generally not less than 350m2 kg), and it is easy to produce water leakage when producing concrete. Mineral admixtures also have an effect on the water leakage of concrete, for example, the fineness of the slag powder is easy to make the concrete leak water, fly ash can improve the water retention of concrete. However, it should be noted that when using fly ash, due to the small density of fly ash, it is easy to float under the action of vibration, resulting in the reduction of concrete surface strength, the decrease of wear resistance, and even the ash and powder may be caused. In addition, moisture-conditioned fly ash or cement cannot be used, because moisture-conditioned cement or fly ash tends to have reduced activity, and agglomeration is not easy to stir evenly, and the bonding performance is poor, resulting in a significant reduction in strength, hardness and wear resistance. In the production of concrete, try to avoid the use of aggregates with large mud content to prevent the increase of mud content and reduce the strength of concrete. In addition, it is not advisable to use fine sand with less fineness, 0The particle content below 315mm is too large, and it is easy to cause ash and sand under the action of vibration.
ThreeThe construction unit should pay attention
1) In the process of pouring concrete pavement, water shall not be added to the concrete mixture without permission, and water shall be added without permission, on the one hand, the original water-glue ratio shall be changed, and the concrete strength shall be reduced, and on the other hand, the water added in the pouring process shall be easily stirred unevenly, resulting in water secretion or local water accumulation, and the water-cement ratio of the water-accommodating part of the concrete becomes larger, and it is easy to powder and sand.
2) In the construction process, there can be no water accumulation on the pavement surface, and the water accumulation of the subgrade in the concrete pouring process is easy to accumulate to the concrete surface, and the water-cement ratio is increased and the pavement strength and wear resistance are reduced.
3) In the process of concrete vibration, the vibration is not leaked, but the vibration is not vibrating, on the one hand, the surface of the concrete leaks water, increases the water-glue ratio, reduces the surface strength and causes ash and sand, on the other hand, the vibration makes the slurry float, and the particles with small density in fly ash and sand rise to the surface, resulting in ash and sand.
4) After the concrete is poured, it is necessary not only to prevent the concrete surface from being washed by rain before hardening, but also to prevent the surface cement from being unable to hydrate and reduce the surface strength due to the evaporation of water in the hardening of the concrete.
5) The pavement floor concrete should be wiped and closed before and after the initial setting, and covering measures (such as: straw bags, sacks, plastic films, etc.) should be taken immediately after the light is collected. In the process of concrete plastering, it is not advisable to close the surface while sprinkling water. The construction and maintenance methods of concrete pavement should be adjusted in time according to different climate and construction conditions and concrete of different strength grades, so as to ensure that the concrete has sufficient wet curing after construction and before establishing sufficient strength. Especially for concrete mixed with fly ash or slag, the curing time is not less than l4 days.
6) The water-glue ratio on the surface of the concrete is increased, the surface structure is loose, and the strength is reduced. When there is water leakage on the concrete surface, attention should be paid to treating the surface water leakage, and strengthening the wiping pressure and lightening, and compacting the concrete surface. When the surface layer of concrete leaks water, it is not possible to simply use the plastering treatment method of sprinkling dry cement powder.