Field Tests of Cement Fly-Ash Steel-Slag Pile Composite Foundation

Abstract

Abstract Steel slag is one of the main waste materials in the steelmaking process. As a result, a tremendous amount of steel slag is produced and deposited into storing yards every year. Recycling of the abandoned steel slag is of great environmental and economic value. This study investigates the usage of steel-slag concrete with fly ash as a kind of composite foundation pile material, which can be applied to multi-pile composition foundations for ground improvement involving different pile types. The micromorphology of the concrete, which uses steel slag as aggregate, is analyzed using scanning electron microscopy (SEM). The bearing characteristics of cement fly-ash steel-slag pile (CFS pile) composite foundations are investigated via field load tests, including settlement of the foundation base, horizontal displacement at different depths, distribution of vertical stress increase of the composite foundation, and stress increase of the soil around the pile hole. In addition, the effect of soil squeezing caused by the construction of a CFS pile is studied. To accomplish this, the variation in the increase in stress of the foundation at different distances in the horizontal direction is measured. The results suggest that the usage of steel slag as an aggregate can effectively satisfy the strength requirement of the pile. CFS pile composite foundations have the advantages of high bearing capacity, small settlement deformation, and limited horizontal deformation. This study demonstrates the potential usage of steel slag as aggregate in pile composite foundations, which can bring significant economic and environmental benefits.