1 The strength is not up to the requirements
1.1.1 Material reasons
Cement concrete raw materials, cement is its important component. The cement and water form a slurry that coats and fills the aggregate, lubricating it before hardening and binding it together into a solid whole. Whether cement can bond aggregate firmly together is an important factor to determine the quality of cement concrete. Portland cement is now commonly used, and its performance is mainly determined by the main mineral properties of its main components. Cement from the beginning of mixing to the formation of hard cement stone, is a continuous, complex physical and chemical process, artificially divided into condensation and hardening two processes, the influence of cement condensation hardening factors mainly temperature and humidity.
1.1.2 Maintenance reasons
React with water to cement hydrates formation, cement particles around the solution quickly become supersaturated solution of hydrates, precipitation hydrated calcium silicate gel, hydrated calcium aluminate in the cement hydration products, such as package material surface, with the passage of time, the new natural gas hydrates, the natural gas hydrates film layer thickening, narrowing the gap between particles, condenses into the space of the porous network. With the continuous hydration, the solid hydrate is increasing, and the contact point between particles is increasing, which makes the structure more dense and the strength is also improved accordingly. But the summer temperature is high, can achieve the requirement of cement hardening, but at the same time moisture evaporation is very fast, the hydration reaction of cement and water in the new pouring concrete has not been fully carried out, moisture has not been, the strength of cement can not grow, the strength of concrete can not be guaranteed.
