Mechanical and durability properties of concrete incorporating weathered coarse Linz-Donawitz (LD) steel slag

Abstract

Concrete usage in recent decades has skyrocketed, which has led to immense pressure on the natural resources such as sand and aggregates involved in its production. The circular economy concept, i.e., usage and recycling of waste products, can be incorporated into concrete production to alleviate the overutilization of natural resources. LD slag is presently dumped as a landfill, aggravating limited land availability and polluting groundwater by leaching heavy metals in it. Previous studies employed Linz-Donawitz (LD) Slag as an alternative to natural aggregates in concrete production. However, none of the studies has focused on the comparative behavior of weathered LD slag incorporated in normal concrete (NC) and metakaolin-based high-strength concrete (HSC). The present experimental study focuses on determining the optimum replacement level of coarse aggregates with LD Slag. Coarse aggregates were replaced with LD Slag at 25, 50, 75 and 100%. Mechanical and durability properties such as hardened concrete density, ultrasonic pulse velocity, compressive strength, split tensile strength, flexural strength, modulus of elasticity, drying shrinkage, water absorption, sorptivity and abrasion resistance were evaluated. Results showed that replacing 75% of coarse aggregates with LD Slag displayed better results for said properties compared to the control mix, both for NC and HSC. Compressive strength, split tensile strength, flexural strength and modulus of elasticity were improved in the range of 7–9%, 19–29%, 6–11% and 7–16% for 75% replacements at 90 days of testing, respectively. Along with lower water absorption, abrasion, and drying shrinkage, the sorptivity coefficient was also reduced compared to control mixes at all testing ages. The usage of LD slag in concrete will result in waste elimination and management and prevent soil contamination.