UTILISING READY-MIX CONCRETE WASTE FOR PRODUCTION OF SUSTAINABLE CONCRETE AND CREATING CIRCULAR ECONOMY

Abstract

Circular economy in ready mixed concrete and construction industry is becoming popular all over the world and India is no exception to this. In this article the authors explore the use of ready-mix concrete industry waste when put back into concrete how the properties of concrete change and its effectiveness and suitability to ready-mix concrete industry. The authors also try to explore possibility of making a simple model for circular economy in ready-mix concrete industry especially with respect to use of ready-mix concrete waste. Ready-mix waste recycled aggregate (RWRA) obtained from the crushing of the ready-mix concrete waste can be used in the construction industry. Ready mix concrete waste is generated due to a result of poor workmanship, improper mix design, waste due to cleaning of equipment and various other reasons, which is dumped in the RMC plant or used as a landfill. Hence an attempt has been made to study the possibility of the reusing of the Ready-mix waste recycled aggregate (RWRA) in the place of the normal crushed aggregates. The Ready-mix waste recycled aggregate (RWRA) is divided into two different types i.e. Ready-mix waste recycled fine aggregate (RWRFA) and Ready-mix waste recycled coarse aggregate (RWRCA). The basic properties of the aggregates such as water absorption, specific gravity, sieve analysis, abrasion & impact resistance were considered. The replacement of the normal crushed aggregates by the Ready-mix waste recycled aggregate (RWRA) was carried out in five stages of 20%, 40%, 60%, 80% & 100% replacement. To enhance the properties of the concrete GGBS and PC based superplasticizer was used. The workability of the fresh concrete and the compressive strength of the hardened concrete were studied. The preceding properties were tested for three different periods of curing of 7, 14, and 28 days. All these mixes were designed for M25 grade of concrete. A comparison made between the results of a laboratory investigation on various physical properties of the concrete with Ready-mix waste recycled aggregate (RWRA) and the concrete with normal crushed aggregates found that the results are encouraging to use the Ready-mix waste recycled aggregate (RWRA) in the preparation of concrete. The study also discusses cost of normal crushed aggregate and Ready-mix concrete waste recycled aggregates collected from Ready-mix concrete plant in Bengaluru region. Novelty & Uniqueness: As of the twenty-first century, ready mix concrete (RMC) in India refers to pre-mixed concrete that is made in controlled conditions at a batching plant and delivered to construction sites in a ready for use state. It is primarily utilized in commercial buildings, residential developments, and projects related to infrastructure and offers benefits like consistent quality, shorter construction times, less material waste, and improved site cleanliness. The Indian RMC market is currently estimated to be around 240 million cubic meters, and it is projected to grow at a compound annual growth rate of 7-8% until 2030 due to the country's expanding urbanization and infrastructure development. Out of total production, Bengaluru, a leading city in construction, is expected to contribute significantly to India's ready