Physical and mechanical properties of foam concretes containing granulated blast furnace slag as fine aggregate

In recent years, industrial by-products have been considered as a promising waste-based material in the production of concrete for development of an eco-friendly construction material. An experimental study on the properties of foam concretes, made with a protein-based foam agent, containing fly ash (FA) as binder and granulated blast furnace slag (GBS) as fine aggregate is presented in this paper. A total of nine batches of foam concretes were manufactured and tests were performed to evaluate the porosity, bulk density, compressive strength, water absorption, ultrasound velocity, and thermal conductivity. To explain the reasons for the obtained experimental results microstructural analysis was also conducted. The results show that an increased water-to-binder ratio (w/b) owing to a decreased binder content results in an increase in the porosity of the foam concretes, which consequently leads to a decrease in the bulk density, compressive strength, ultrasound velocity, and thermal conductivity, and an increase in the water absorption of foam concretes. It is also found that foam concretes with 100% GBS as sand replacement, at a higher w/b exhibits a lower bulk density, ultrasound velocity, and thermal conductivity than those of the companion control foam concrete, and they provide a higher compressive strength at a lower w/b. The results indicate that the foam concrete with 100% GBS at w/b of 0.68 develops superior properties than the companion control foam concrete by exhibiting a lower porosity, bulk density, ultrasound velocity, thermal conductivity, higher compressive strength, and a similar water absorption compared to those of the companion control foam concrete. These results are promising and point to the significant potential of developing an eco-friendly light-weight concrete by full replacement of natural sand with GBS industrial by-product material.