Use of steel slag aggregate in asphalt concrete mixes

TLDR

Steel slag from Jordan’s three major steel factories is dumped in open areas, creating environmental hazards. The study aimed to evaluate whether steel slag aggregate could enhance the engineering performance of locally produced asphalt concrete mixes. Researchers assessed the slag’s toxicity and physical‑chemical characteristics, then replaced 0–100 % of limestone aggregate with SSA in AC mixes and measured tensile strength, modulus, rutting, fatigue, creep, and stripping resistance. Replacing up to 75 % of limestone with SSA improved mechanical properties, with 25 % identified as the optimal replacement level. Keywords: steel slag aggregate, asphalt concrete, Superpave, indirect tensile strength, fatigue, rutting, creep.

Abstract

There are three major steel-manufacturing factories in Jordan. All of their by-product, steel slag, is dumped randomly in open areas, causing many environmentally hazardous problems. This research was intended to study the effectiveness of using steel slag aggregate (SSA) in improving the engineering properties of locally produced asphalt concrete (AC) mixes. The research started by evaluating the toxicity and chemical and physical properties of the steel slag. Then 0%, 25%, 50%, 75%, and 100% of the limestone coarse aggregate in the AC mixes was replaced by SSA. The effectiveness of the SSA was judged by the improvement in indirect tensile strength, resilient modulus, rutting resistance, fatigue life, creep modulus, and stripping resistance of the AC samples. It was found that replacing up to 75% of the limestone coarse aggregate by SSA improved the mechanical properties of the AC mixes. The results also showed that the 25% replacement was the optimal replacement level. Key words: steel slag aggregate, asphalt concrete, Superpave, indirect tensile strength, fatigue, rutting, creep.