Factors affecting the early strength performance of early-strength superplasticizer-cationic monomer

Early-strength superplasticizers with different introduction amounts of cationic monomer methacryloyloxyethyltrimethylammonium chloride (DMC) were synthesized and Fourier transform infrared spectroscopy was used. Structural confirmation was performed. Through tests on cement slurry fluidity, setting time, and compressive strength of slurry and mortar, the effects of different introduction amounts of cationic monomers on the dispersion, setting time, and early strength performance of early-strength superplasticizers were studied. The mechanism of action was analyzed through XRD and TG. The results show that when the amount of DMC introduced accounts for 4% of the monomer, the fluidity of the clean slurry reaches the maximum value; after the introduction of DMC, the setting time of the clean slurry is shortened, and the strength of the clean slurry and mortar specimens in the early compressive period is significantly improved; when the amount of DMC is introduced The early strength performance is best when it accounts for 12% of the large monomer. It can be seen from XRD and TG analysis that the introduction of DMC promotes the early hydration of C3S and generates more hydrated calcium silicate and calcium hydroxide.

With the continuous advancement of construction industrialization, concrete precast technology has received increasing attention. Ordinary early-strength superplasticizer (Polycarboxylate superplasticizer. PC) is currently the most produced type of high-efficiency water-reducing agent in my country and is widely used in cast-in-situ pumping concrete projects. However, its characteristics such as retarding setting and air entrainment are not suitable for the production of concrete products that require early strength. The development of early-strength early-strength water-reducing admixture is conducive to promoting its application in precast concrete.

The molecular structure of early-strength superplasticizers is highly designable. Early-strength superplasticizers with different properties can be obtained through molecular structure design. At present, there are usually two ways to synthesize early-strength early-strength superplasticizers. One is to change the side chain length, grafting density and other structural parameters of the early-strength superplasticizer molecules; the other is to graft into the early-strength superplasticizer molecules. Some early strong functional monomers, such as AM (acrylamide), AMPS (2-acrylamide-2-methylpropanesulfonic acid), etc.

This article synthesizes an early-strength early-strength superplasticizer by introducing the cationic monomer methacryloyloxyethyltrimethylammonium chloride, and its dispersion , procoagulant and early strengthening effects were studied, and its early strengthening mechanism was analyzed.

(1) Introducing an appropriate amount of DMC into PC molecules can improve its dispersion ability, but if the amount is too large, its dispersion ability will decrease;

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(2) Compared with anionic PC, after the introduction of DMC, the setting time of cement paste is shortened, and the cement paste 1d and mortar 1d, 3d and 28d resist The compressive strength has increased, and the effect is most obvious when the amount of DMC introduced is 12%;

(3) Through XRD and TG analysis, it can be seen that the introduction of DMC promotes C3S And the early hydration of C3A produces more C-S-H and Ca(OH)2. </p