ABSTRACT

The construction industry's extensive use of concrete necessitates new infrastructure to meet evolving human needs. Consequently, the demolition of outdated or low-rise Structures generate substantial quantities of demolition waste, becoming a global environmental concern. Moreover, the demand for construction activities depletes natural resources, leading to increased quarrying for aggregates. The combination of Growing waste and high resource consumption pose environmental challenges. particularly in developing countries. Recycling and reusing demolition waste as Recycled concrete aggregates offer viable solutions. Similarly, the quarrying of marble results in the production of significant quantities of Marble Dust Production (MDP). Utilizing marble powder as an alternative material in concrete can enhance concrete's hardened properties. Marble, a Metamorphic rock, derived from pure limestone, exhibits various appearances and colors based on its purity. The marble waste generated during the cutting process can reach millions of tons, contributing to environmental problems. Utilizing MDP as a partial replacement for Portland slag cement, not only mitigates environmental pollution, but also conserves natural aggregates, reduces energy consumption, and carbon dioxide emissions during construction processes.

In this study, we evaluate the flexural strength of binary blended concrete composed of recycled aggregates and marble dust under two-point loading. Natural coarse aggregates were replaced with coarse aggregates from demolition waste at a 50% proportion, and cement is replaced with marble dust from 1% to 10% with an increment of 1% in each batch. We prepared 30 prisms in ten hatches of 100×100 500mm size. using a 1:2:4 mix and a 0.5 water-to-cement ratio. In addition One batch was prepared with all-natural aggregates, while the rest incorporated recycled aggregates and marble dust. Specimens were cast following ASTM specifications and cured for 28 days. After the curing period, we determined the prism weights and tested them in a universal testing machine under gradually applied loads. The results showed that Prisms with all-natural aggregates had the highest load capacity and flexural strength. It may be observed that minimum loss of strength (about 18%) at 5% dosage of the marble dust. Hence it is concluded that 5% dosage is the optimum beyond which marble dust losses its bonding properties due to which required bonding strength lowers. The strength of concrete decreases and deflection increases with increase in dosage of marble dust.