Preparation and performance of ultra-early strength polycarboxylate superplasticizer

Abstract

The rapid development of subway and prefabricated building industry, along with the adoption of the “dual carbon” strategy, have put forward higher demands on early strength, environmental protection and high efficiency for precast concrete products and concrete segments. In this study, a ultra-early strength type polycarboxylate superplasticizer (ES) was synthesized successfully by a design molecule structure such as introducting ultra long polyoxyethlene side chains, functional monomer (2-acrylamide-2-methylpropanesulfonic acid), and cationic monomer (Methacrylatoethyl trimethyl ammonium chloride) composition. Discovered through performance testing, the dispersion capacity of ES firstly are increased and then decreased with increasing the acid-ether ratio, and the same trend as the compressive strength harden concrete with ES at the age of 1, 3, and 7 days. The sulfonate groups and cationic monomers into molecular structure, they have little effect on the dispersion capacity, but the compressive strength of concrete at the age of 1, 3, and 7 days get improved. Through camparative study in the setting time of concrete and compressive strength of concrete between ES and an engineering application product SX. The results show that addition of ES does not retard cement hydration, and accelerates the coagulation of cement. Moreover, the compressive strength of concrete is better than SX at all ages, its further verified with X-ray diffraction and Scanning electron microscopy. This study indicates that rational design of molecular structure through the introduction of ultra-long side chains and functional monomers can maximize the early strength performance of polycarboxylate superplasticizer without affecting later strength development.