Preparation and Performance of A Novel Type of Concrete Air Entraining Agent

Abstract

This article uses 1,4-dibromobutane, hexadecyl primary amine, sodium 3-chloro-2-hydroxypropionate, formaldehyde and formic acid as raw materials to synthesize a new type of concrete air entraining agent of (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane through the reaction of ammonia alkylation and quaternization. The article characterizes the molecular architecture of the product, the surface activity of the aqueous solution, the bubble properties, the air entraining and air stabilizing properties of the fresh concrete, and the pore structure of the concrete after hardening. The research results show that the synthesized (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane has good surface activity in aqueous solution, and its critical micelle concentration (cmc) is 5.3×10-4 mmol/L, γ cmc is 28.86 mN/m; (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane has better air-entraining performance and bubble stability in aqueous solution and concrete than SDS and AOS air entraining agents. The average chord length and spacing coefficient of bubbles in hardened concrete are smaller than that of SDS and AOS air entraining agent, giving rise to a better overall pore structure of the concrete. Compared with SDS and AOS, the concrete mixed with (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane air entraining agent shows better mechanical property and durability.