Preparation and Properties of Retarded Cellulose-based Polycarboxylic Superplasticizers

Abstract Cellulose is an important biomass, and the synthesis of chemical products using cellulose is the current hotspot for sustainable economic development. A cellulose-based polycarboxylic acid superplasticizer (CBPCS) was prepared from cellulose hydrolysate, and its properties and mechanism of action were investigated. Through orthogonal experiments, the optimal synthesis process was identified: synthesis temperature of 45 ℃, synthesis time of 3 h, acid-ether ratio of 3:1, cellulose maleate content of 10%, thioglycolic acid (TGA) and hydrogen peroxide (H2O2) content of 0.55% and 0.45%, respectively. The initial fluidity of polycarboxylic acid superplasticizers prepared by this method in cement slurry is 285 mm, 298 mm after 30 minutes, and 305 mm after 60 minutes. The product exhibits excellent retarding and water reduction properties. The test results of different retarding cellulose-based polycarboxylic superplasticizer show that when the amount of cellulose maleate is 10%, the polycarboxylic superplasticizer not only has a good retarding effect on the cement, but also improves the hydration strength of the cement. Specifically, by adding 0.5% of polycarboxylic acid superplasticizer to cement, the water reduction rate reached 28.3% and the setting time was extended to 69 min. The compressive strength of cement mortar at 3, 7 and 28 d increased by 35.4%, 70.0% and 25.2%, respectively. The flexural strength of the cement mortar was increased by 35.4%, 70.0% and 25.2% at 3, 7 and 28 d. The XRD and SEM analyses showed that the retarded cellulose-based polycarboxylic superplasticizers inhibited the hydration of C3S, which confirmed its retarded property.