Cement-Lime-Fly Ash Bound Macadam Pavement Base Material with Enhanced Early-Age Strength and Suppressed Drying Shrinkage via Incorporation of Slag and Gypsum

Abstract

In this study, a novel cement-lime-fly ash bound macadam (CLFBM) as pavement base material was designed by incorporating Portland cement, dihydrate gypsum (CaSO4·2H2O), and ground granulated blast furnace slag (GGBS) into the lime-fly ash bound macadam (LFBM) for the purpose of the early opening to traffic. The multifactors orthogonal test method was used to evaluate the effects of Portland cement, dihydrate gypsum, and GGBS on the early-age strength of CLFBM. Moreover, the compressive and flexural strengths at 28 days as well as the drying shrinkage development in 56 days were investigated. By conducting the comprehensive analysis for the better mechanical properties and the lowest drying shrinkage, Portland cement : dihydrate gypsum : lime : fly ash : GGBS : gravels = 2 : 1 : 6 : 5.6 : 8.4 : 80 is determined as the optimal mix proportion of CLFBM. In addition, scanning electron microscope (SEM) results confirmed the formation of a large number of ettringite and C-S-H gels, providing a powerful support for the enhanced early-age strength and suppressed drying shrinkage of CLFBM.