Factors affecting concrete strength:
1. One of the main indicators of concrete quality is compressive strength . It is not difficult to see from the expression of concrete strength that the compressive strength of concrete is proportional to the strength of concrete cement. According to the formula, when the water-cement ratio is equal, the compressive strength of cement concrete is much higher than that of low-grade cement.
2. Generally speaking, the water-cement ratio is inversely proportional to the strength of concrete. In the case of a certain water-cement ratio, it is wrong to increase the strength of the concrete by increasing the amount of cement. At this time, the concrete can only be increased and the shrinkage deformation of the concrete can be increased.
3. Therefore, the main factors affecting the compressive strength of concrete are cement strength and water-cement ratio. To control the quality of concrete, it is important to control the quality of cement and the water-cement ratio of concrete. In addition, there are other factors that cannot be ignored.
4. Coarse aggregate also has a certain impact on the strength of concrete. Therefore, when the project starts, the technical person in charge first determines the coarse aggregate on site. When the stone strength is the same, the surface of gravel is rougher than pebbles, and the binding force with cement mortar is stronger than pebbles. When the water-cement ratio is the same or the mix ratio is the same, the concrete strength of the gravel is higher than that of the pebbles. How to remedy if concrete rebound strength is not enough.
5. Therefore, the particle size of concrete coarse aggregate is generally controlled to adapt to different engineering parts; the impact of fine aggregate on concrete strength is less than that of coarse aggregate, but the quality of sand also has a certain impact on the quality of concrete. During construction, the mud content of the sand should be strictly controlled within 3%. Therefore, the quality of sand must meet the requirements of the quality standards of concrete sand of each grade.
6. Due to the uneven quality of sand and gravel at the construction site, on-site construction personnel must ensure the quality requirements of sand and gravel and adjust the water-cement ratio in time according to the moisture content of sand and gravel. Gravel ensures the concrete mix ratio on site, as well as the test mix ratio and construction mix ratio .
Concrete surface reinforcement has a low surface tension , which can penetrate quickly into the concrete, react with the by-products of cement hydration in the concrete, such as calcium hydroxide , and generate a large number of silica gels. These gels can clog the capillary pores inside the concrete, thereby increasing the compactness, compressive strength, hardness and wear resistance of the concrete surface, and generally improve the concrete strength by 5-10MPa. The chemical reaction between concrete surface reinforcers and related components in concrete is more complicated. In addition to the formation of silica gel, some hard and dense substances will also be generated, making the strength of concrete more obvious.
