Adsorption mechanism of the novel amphoteric dispersant and its effect on structure and properties of hydration products

Abstract

The novel amphoteric dispersant (NAD) was prepared by free radical polymerization of acrylic acid (AA), vinyl butylpolyoxyethylene ether (VBPE), N,N-dimethyl-methacryloxyethyl-aminopropyl sulfonate (DMAPS) and acrylate sulfated starch (ASS). It is characterized that the introduction of zwitterionic monomer as side groups and modified starch as branch chains. The chemical structure and its effects on the fluidity, strength, durability and microstructure of cement-based composites containing clay were tested. The results indiacted that zwitterions can improve the chelating adsorption capacity and eliminate the influence of chloride ions, while modified starch branch chain can improve the effect of slow coagulation and water retention. NAD has excellent dispersing and mud resistance effect, which makes the interface of cement hydration products clear, regular shape, uniform distribution and compact structure.The dispersion mechanism was proposed and it is think that NAD was mainly adsorbed on the interface of cement particles by zwitterion chelation adsorption and on the interface of the mud particles by anion groups. Meanwhile, the polyoxyethylene and the starch branch chains synergistic to form spatial barrier layer, showing excellent effects on blocking mud water absorption, improving dispersing and regulating hydration products structure. The research results have positive significance for the developing highly effective anti-mud dispersants.