Evaluation of waste metallic powder as fine aggregate replacement in Roller compacted concrete: Impact on physical and mechanical properties

Abstract

Rapid advances in technology and industry, coupled with the increase in human population, generate large amounts of waste materials, and the storage or disposal of these large quantities of waste materials poses both an environmental threat and a significant economic cost. Characterized by a low cement content, a high proportion of aggregates, and a zero slump, Roller compacted concrete is especially popular in pavement construction due to its cost-effectiveness, durability, and ability to withstand high traffic loads. In order to meet the aggregate demand, in roller compacted concretes, require high volume aggregate in their mixtures, which has reached high levels due to the rapid growth and development of the construction industry worldwide, the partial or complete substitution of waste materials for aggregate is an effective, economical and sustainable method to reduce the potential environmental damages and hazards that may arise from both waste materials and the depletion of natural aggregate resources. In this context, in this study, a large amount of waste metallic powder released after the sandblasting process in iron and steel production was partially substituted for fine aggregate in different proportions (0 %, 0.25 %, 0.50 %, 0.1 % and 2 %) in the production of roller compacted concrete. Various experiments [Density, compressive strength, ultrasonic pulse velocity, rebound hammer test, splitting tensile strength, flexural strength, capillary water absorption, static modulus of elasticity, etc] were then performed on the produced roller compacted concrete specimens to comprehensively investigate the effect of waste metallic powder on the physical and mechanical properties of roller compacted concrete. As a result of the experiments, the substitution of waste metallic powder increased the rebound hammer values, splitting tensile strength, flexural strength and static modulus of elasticity compared to the reference specimen. Using waste metallic powder in the mixtures significantly decreased the workability and compressive strength. In addition, the substitution of waste metallic powder increased the water absorption, porosity and capillary water absorption values compared to the reference specimen. The significant increase in flexural strength, an important design parameter especially in road pavements subjected to repetitive loads, indicates that waste metallic powder can be used in roller compacted concrete. However, this study highlights the importance of optimizing waste metallic powder and shows that substituting waste metallic powder for aggregate can contribute to a more sustainable RCC production.