▎ 摘　　要

NOVELTY - Multifunctional auxiliary agent comprises a high-efficiency polycarboxylic acid water-reducing agent, inorganic nanoparticles, modified cellulose, a silane coupling agent and water, where the high-efficiency polycarboxylic acid water-reducing agent (I). The modified cellulose is made by grafting modification of hydroxyethyl cellulose and carbon nanotubes. USE - Multifunctional auxiliary agent for building materials. ADVANTAGE - The multifunctional auxiliary agent has good miscibility, can perform multiple functions in a synergistic effect, has larger steric hindrance effect and electrostatic repulsion acting force, and good dispersion stability of the cement, strong mechanical property, certain shrinkage resistance and air entraining performance, and enables the concrete to have anti-cracking and anti-freezing capabilities. DETAILED DESCRIPTION - Multifunctional auxiliary agent comprises a high-efficiency polycarboxylic acid water-reducing agent, inorganic nanoparticles, modified cellulose, a silane coupling agent and water, where the high-efficiency polycarboxylic acid water-reducing agent having formula (I). The modified cellulose is made by grafting modification of hydroxyethyl cellulose and carbon nanotubes. n=5-20; and GO=graphene oxide. An INDEPENDENT CLAIM is included for a method for preparing multifunctional assistant for construction materials, which involves: (A) mechanically stirring inorganic nanoparticles, a silane coupling agent and 50% modified cellulose uniformly; (B) adding 40% water under heating at 40 degrees C for 0.5 hours; (C) cooling to room temperature to obtain a premixed solution; (D) adding 50% modified cellulose and high-efficiency polycarboxylic acid water reducing agent into the premixed solution; and (E) adding water under stirring for 0.5 hours to obtain the multifunctional auxiliary agent for the building material.