Effect of the compounding of an antifoaming agent and a viscosity modifying agent on the frost resistance of mold bag concrete

Abstract

Channel lining mold bag concrete in the cold area of ​​northern China needs to achieve high frost resistance under the conditions of large fluidity and low strength grade. However, the extensive use of a high range water reducer (HRWR) and an air entraining agent (AEA) brings about the problems of a large air content loss, a large fluidity loss and many harmful big bubbles to fresh concrete, reducing the pumping performance and frost resistance of mold bag concrete. In this study, the effects of compounding an AEA, an antifoaming agent (AFA), and a viscosity modifying agent (VMA) on the workability, mechanical properties and frost resistance of concrete are studied by using the response surface methodology (RSM). The results showed that AEA and AFA were significant factors that affected the relative dynamic elasitic modulus. The interaction of AFA and VMA on the relative dynamic elasitic modulus was significant. The compounding of AFA and VMA achieved the effects of synergistically improving the workability, air-void structure and frost resistance of concrete. When the dosage of AEA was 0.0055%, the compounding of AFA and VMA synergistically reduced the air content loss rate by 42.30%, reduced the slump flow loss rate by 47.29%, reduced the number of large bubbles by 57.96%, increased the number of fine bubbles by 16.55%, reduced the spacing factor by 18.09%, increased the specific surface area by 41.16%, increased the relative dynamic elasitic modulus by 16.11%. Using RSM optimization and validation, an optimal mix proportion for mold bag concrete with a desirability of 0.998 was proposed to be the following: AEA of 0.006%, AFA of 0.176%, and VMA of 0.019%.