Strength Characteristics of High-Volume Fly Ash–Based Recycled Aggregate Concrete

Abstract

The use of recycled aggregate from construction and demolition wastes is showing prospective application in construction as an alternative to natural aggregates. It conserves natural resources and reduces the space required for landfill disposal. In this paper, strength characteristics of high-volume fly ash (FA)–based concrete with recycled aggregate of M50 grade were studied. The recycled aggregates were collected from a demolished structure 20 years of age. Natural aggregate (NA) was replaced with recycled aggregate (RA) in different percentages of 25, 50, and 100% to study the effect of recycled-aggregate concrete (RAC) on compressive and tensile strength characteristics. Similarly, the amount of cement was also replaced with fly ash in different percentages such as 40, 50, and 60% to study the effect of fly ash on compressive and tensile strength of concrete. The experiments were conducted for different ages of concrete such as 7, 14, 28, and 56 days. From the detailed investigations with 16 mix combinations, 50% replacement of cement with FA and 50% replacement of NA with RA give satisfactory results by compromising strength 40 to 50% with a major reduction in cost. Depending on the field requirements, a construction engineer can go for designing M50-grade concrete where M30-grade concrete is to be deployed for structural purpose with the previously said combination.