Method for controlling setting and hardening processes of magnesium phosphate cement

Abstract

The invention relates to a method for controlling setting and hardening processes of magnesium phosphate cement. According to the method, the heat releasing speed of the magnesium phosphate cement is reduced by increasing addition of borax retarder to delay setting of magnesium phosphate cement mortar and adjust the setting time of the mortar within 20-150 minutes effectively, then a heat-transfer process between the mortar and an environment and the setting and hardening processes of the mortar are accelerated by increasing early environmental temperature of the mortar, and the early strength is form quickly and reaches 20-30MPa in an hour. The method solves the problem that the early strength of a magnesium phosphate cement system develops slowly due to the short setting time and a larger mixing amount of the borax retarder when the magnesium phosphate cement serves as a quick repairing material for a repairing project to some extent. Available test results indicate that the method can control the setting and hardening processes of the cement conveniently and effectively.

Description

technical field [0001] The invention relates to the field of magnesium phosphate cement, in particular to a method for controlling the coagulation and hardening process in the construction of magnesium phosphate cement. [0002] Background technique [0003] Magnesium phosphate cement has the characteristics of rapid hardening and early strength, and is especially suitable for rapid repair of structures such as concrete pavements and industrial plants. Since magnesium phosphate cement sets very quickly, in order to meet the operating time required by different construction conditions, retarders such as borax and boric acid are often added to the magnesium phosphate system; however, when the amount of retarder is small, the retarding effect is limited. For example, when the amount of retarder borax is not more than 5%, the initial setting time of magnesium phosphate cement paste should not exceed 15 minutes at most; and when the amount of retarder is large, the early strengt...

AI Technical Summary

Problems solved by technology

For example, if the content of constant retarder borax is 5%, when the ambient temperature is 5°C, the setting time of magnesium phosphate cement slurry is greater than 15 minutes, but the strength is less than 5MPa in 3 hours; when the ambient temperature rises to 35°C, although 1 The hourly strength can reach 40MPa, but the initial setting time of the magnesium phosphate cement slurry is less than 5 minutes

When the construction process is under low temperature conditions or the amount of retarder is increased in order to provide an appropriate preparation time for the construction process, the early strength of the magnesium phosphate cement system will be greatly reduced, so it cannot meet the strength requirements of the repair project

[0006] Existing technical measures can already ensure that the magnesium phosphate cement system can simply meet the requirements of preparation time or hourly strength required for construction, but how to coordinate the contradiction between the setting time and early strength of the magnesium phosphate cement system in rapid repair projects is currently a problem. There is no relevant effective technical method

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