Research on macro-microscopic mechanical evolution mechanism of cement-stabilized steel slag

Abstract

In this paper, the chemical composition, phase composition, physical properties and expansibility of steel slag in Xinjiang, China are analyzed, and the feasibility of steel slag as pavement base material is demonstrated. At the same time, through the tests of unconfined compressive strength, X-ray diffraction, scanning electron microscope and nuclear magnetic resonance, the relationship between macroscopic strength and microstructure of cement-stabilized steel slag at different ages is discussed and compared with that of cement-stabilized macadam. The results show that the mechanical properties of steel slag aged more than one year can fully meet the requirements of relevant specifications for all kinds of pavement base. Compared with cement-stabilized macadam, the compressive strength of cement-stabilized steel slag at the age of 7 d, 14 d and 28 d increased by 15.4%, 22.0% and 23.7%, respectively. Due to hydration and pozzolanic action, the C–S–H content in the interfacial transition zone of cement-stabilized steel slag is higher, while the contents of Ca(OH)2 and AFt are lower. Due to the internal curing effect of steel slag, the interfacial transition zone width of cement-stabilized steel slag at the age of 7 d and 28 d decreased by 9.4% and 31.0% respectively compared with cement-stabilized macadam; with the increase of curing time, the adsorption porosity of cement-stabilized steel slag increased, while the amount of seepage pore and migration pore decreased significantly, and the pore span and total porosity decreased by 47.7% and 7.29%, respectively.