1.1 Strength does not meet the requirements
1.1.1 Material reasons
In cement concrete raw materials, cement is an important component. The cement and water form a cement slurry that wraps around the surface of the aggregate and fills its voids, lubricates it before hardening, and binds the aggregate together to form a solid whole after hardening. Whether the cement can firmly bind the aggregate together is an important factor in determining the quality of cement concrete. Now commonly used is mainly Portland cement, its performance is also 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 two processes of setting and hardening, the main factors affecting the cement setting and hardening are temperature and humidity.
1.1.2 Maintenance reasons
The cement reacts with water to form a hydrate, and soon the solution around the cement particles becomes a supersaturated solution of the hydrate, and the hydration products such as calcium silicate hydrate gel and calcium sulfoaluminate hydrate are deposited on the surface of the cement granules. As time goes on, the new hydrate increases, the hydrate film thickens, the void between the particles shrinks gradually, and condenses into a porous space network. With the continuous progress of hydration, the solid hydration continues to increase, and the contact points between the particles continue to increase, making the structure more dense and the strength correspondingly increased. However, the high temperature in summer can meet the requirements of cement hardening, but at the same time, the water evaporates quickly, and the hydration reaction of cement and water in the newly poured concrete has not been fully carried out, and the water has been lost, the strength of cement can not increase, and the strength of concrete can not be guaranteed.
The high temperature in summer makes the moisture dissipate quickly, and the setting time of the newly poured concrete is short. If the maintenance can not be carried out in time during daily maintenance, it will certainly affect the strength growth of concrete in the later period.
1.2 Appearance quality does not meet requirements
The hydrolysis or hydration of clinker minerals and water in cement is called hydration. Hydration produces hydration products and releases some heat. Hydration is a continuous process, and heat release is ongoing. The continuous accumulation of heat energy will also cause certain harm to the quality of cement concrete. When the hot summer temperature takes away too much moisture in the molded concrete, the temperature of the cement concrete will also rise, prompting the setting speed to accelerate. When the surface of cement concrete sets prematurely, and the internal condensation heat release continues, it is easy to cause the surface of cement concrete drum cracking, thus affecting the overall quality of cement concrete.
