How to avoid mortar quality problems caused by excessive hydration reaction caused by high temperature?

In the summer when the temperature is high and the air humidity is low, due to the accelerated hydration reaction at high temperature, the moisture is easy to evaporate, the mortar fluidity loss is fast and the setting time is shortened, the construction is difficult, and the mortar is prone to blistering, cracks, uneven and other defects. When the temperature gradually increases, the corresponding water consumption of mortar will increase, which will lead to the decrease of mortar strength. Therefore, in view of the characteristics of summer construction, the following measures should be taken to prevent the occurrence of quality accidents.

First of all, in terms of raw materials, early strength cement will prematurely carry out hydration reaction and consume water, resulting in excessive water consumption in the early stage, which will affect the construction performance of mortar, so we can choose cement that is not early strength for production.

The common admixtures of mortar are stone powder and fly ash, and the microscopic shape of fly ash is honeycomb, which will absorb part of the water and increase the water demand of mortar, and the secondary hydration will also consume part of the water, which will accelerate the water loss of mortar. it is not conducive to the protection of water at high temperature. Stone powder mainly plays a filling role in mortar. Adding appropriate amount of stone powder into mortar can fill the capillary pipe in mortar, protect the moisture in mortar, and reduce water consumption at the same time. An appropriate amount of stone powder admixture will better retain the moisture in the mortar, and the selection of stone powder admixture can better cope with the high temperature in summer.

The gradation of sand has an important influence on the water retention of mortar, which is more important when the temperature is high and moisture is fast. The water retention of natural sand is higher than that of machine-made sand. For the gradation of sand, the sand with fineness modulus of 2.3-2.7 meets the requirements of wet-mixed mortar, especially in summer when the water retention of mortar is high, it is particularly important to select suitable sand.

The proper addition of mortar additives can thicken the water retention of mortar and obviously reduce the shrinkage and deformation of mortar, which can effectively avoid high temperature weather, rapid evaporation of water, uneven defects such as mortar blistering and cracks, and greatly improve the construction efficiency of workers. in order to solve the adverse effects of high temperature in summer.

In addition to adjusting the material of the mortar, it can also be solved by properly improving the consistency of the mortar. If the consistency of the mortar sent the first day is controlled at 90 ±5, it can meet the site requirements well, at the same time, it can improve the water retention performance of the mortar and slow down the moisture emission of the mortar, but this method needs to be verified in the laboratory before it can be put into production.

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