Investigation on the sustainable use of electric arc furnace slag aggregates in eco-friendly alkali-activated low fineness slag concrete as a green construction composite

Abstract

The construction industry uses a high amount of energy in various forms. The main energy-consuming processes in this industry are ordinary Portland cement (OPC) production and aggregate crushing. The high energy consumption level can be interpreted as a high amount of CO2 and other greenhouse gas emissions. There are different approaches to reduce these harmful impacts, such as using alkali-activated slag concrete (AASC) and incorporating recycled and by-product aggregates like Electric arc furnace (EAF) slag. Also, using low Blaine fineness (lower than 3000 cm2/g) ground granulated blast furnace slag (GGBFS) in AASC can lead to lower energy consumption.In this research, EAF slag (EAFS) aggregates were considered as substitution of natural aggregates in AASC with low Blaine fineness GGBFS (about 2700 cm2/g) for the first time. Different mechanical and durability tests such as compressive strength, tensile strength, modulus of rupture, water absorption, water penetration, RCPT, and oxygen penetration in addition to XRD, SEM, and EDX were carried out to evaluate the properties of AASC with EAF aggregates. Also, the CO2 emissions due to the production of concrete with the mix designs were calculated.The results indicated that AASC containing low Blaine fineness GGBFS had an outstanding performance in terms of mechanical properties. Replacing coarse natural aggregates with EAFS in AASC resulted in no significant decrease in mechanical properties. However, using EAFS fine aggregates caused a decrease in mechanical properties. AASC with low Blaine fineness GGBFS showed inferior yet acceptable durability properties compared to OPCC. Overall, an eco-friendly, recycled concrete is proposed with low energy consumption and low emission of CO2 (about 50% reduction) and lower cost (about 30%), compared to OPCC.