1. Precautions for the use of retarder

In the use of retarder, should be based on different construction temperatures, through the test to find the best mixing amount of retarder.
Then according to the construction requirements of the initial solidification time. In the range of the best dosage with the corresponding reasonable dosage. In order to achieve both economic and meet the construction requirements of the purpose.

Excess retarder and raw materials occur when the role of overtime retardation occurs. In the mechanism of action and the general retarder retardation mechanism is not essentially different. Just often due to the high dosage of retarder, the remaining content of retarder in the liquid phase of fresh mortar is very high.

At this time, the hydration reaction of raw materials needs to overcome a larger energy barrier. So it often takes a longer time. Even the hydration reaction of raw materials stops completely. Condensation can not be completed eventually. Thus producing non-coagulation phenomenon, which must be avoided.

2. The effect of retarder on mortar

First of all, the effect of retarder on the initial and final coagulation time of desulfurization construction gypsum.

Due to the short setting time of construction gypsum, in order to meet the construction requirements, gypsum mixed in the retarder needs to meet the retardation effect, small dosage, small crystal morphology and strength loss and other advantages.

Secondly, the effect of retarder on the strength of desulfurization construction gypsum.

Retarders have serious negative effects on the strength of desulfurization construction gypsum. Most of the retarding agents besides obviously change the setting time of gypsum. At the same time, they bring about a significant reduction in strength. With the increase in the dosage of retarders. Compressive strength and flexural strength are reduced.

Finally, retarders affect the exothermic process of gypsum.

The hydration process of gypsum is an exothermic process. With the increase of time, the temperature profile can be expressed by the hydration rate of gypsum. Heat of hydration is generated while the gypsum is hydrating, and the temperature of the gypsum will be increased. The increase in temperature accelerates the coagulation process of gypsum. The heat released from the hydration of desulfurization building gypsum is very prominent. The speed of gypsum heat release is also very fast. Retarder inhibits the concentrated exothermic of gypsum.