Optimal design of geopolymer grouting material for semi-flexible pavement based on response surface methodology

Abstract

Composite grouting material (CGM) is an important part of constructing the semi-flexible pavement (SFP). The usage of CGM can improve pavement durability and rutting resistance in heavy-duty traffic. Owing to the environmental protection and performance requirements for grouting in loose sediments, the geopolymer grouting material (GPGM) as a new type of CGM is designed by a combination of powder materials, alkali and activator. The response surface method (RSM) is used to study the influence of three independent constituents (powder quality ratio, sodium oxide content, and water-binder ratio) as well as their interactions on four response variables (fluidity, 7 d dry-shrinkage ratio, 7 d compressive strength, and 28 d compressive strength) of GPGM. Furthermore, three types of additives, including water reducer, shrinkage reducing admixture and polymer latex, are taken into account to design the expected responses of GPGM by using the orthogonal test design method (OTDM). Finally, the micro detection experiments are built to compare the micro characteristics of GPGM blended with and without additives. The results show that the optimal mix proportion of GPGM can be obtained by RSM and OTDM. The micro performance tests and analysis can well explain the mechanism of inner constituents in GPGM.