A laboratory investigation of coastal sand stabilization using biochar-enhanced alkali-activated slag

Abstract

In the past decades, efforts have been made to substitute Ordinary Portland Cement (OPC) by developing novel cement materials using industrial byproducts such as Alkali-Activated Slag (AAS), in which Granular Ground Blast Furnace Slag (GGBS) is a popular one. So far, numerous studies on AAS show that its superiority in high early strength, resistance to sulfate attack compared with OPC. Besides, different chemicals, fiber, and additives have been amended with the AAS, trying to achieve more engineering application. Biochar is an additive produced from the anerobic pyrolysis of biowastes such as leaves, which can effectively reduce the carbon dioxide emission from the decaying of biowastes. When biochar is added to AAS system, the high interior surface area will increase water capacity, cation exchange capacity and surface sorption capacity to achieve a better hydration degree. Currently, the engineering properties of the biochar-enhanced AAS stabilized soils have not yet been investigated. In this study, the admixture of GGBS, hydrated lime and biochar is applied to stabilize the local coral sand for the purpose of coastal erosion control. The unconfined compression test, pH, water content, microstructural of the biochar-enhanced AAS stabilized coral sand are measured and observed. The results show that with the addition of biochar in AAS system, an optimum content for biochar can make the stabilized soil display better ductility without compromising its strength.