Recyclability of Broken Pile Head Concrete in Structural Use

Abstract

H A Rashid*, B A Nur and R Ahsan

To improve sustainability, the use of recycled concrete aggregate in the construction industry has increased globally. Urban areas are experiencing a critical shortage of natural aggregate for concrete production. Recycling construction and demolition waste, generating recycled aggregates and using them as an alternative material, could be a solution. This paper presents the recyclability of broken pile head concrete in structural use. The broken pile heads were collected from various sources of newly constructed structures and crushed to a suitable aggregate size with a mechanical crasher. Laboratory tests were conducted on both recycled and virgin aggregate. The test results revealed that aggregate gradation, aggregate crushing value, ten percent fine value, abrasion, rodded unit weight, flakiness index, elongation, wash passing, water absorption, clay lumps and friable particles, soundness, and soft fragments were all within acceptable limits. These coarse aggregates were used in the design of C 15 and C 25 class concrete. Eighteen set cylindrical molds from the concrete mix design were taken. At 7, 14, and 28 days, the compressive strengths (MPa) of concrete molds were tested. The C 15 class concrete strength was found to be 19.6, 22.9, and 24.8 with virgin aggregate and 18.1, 21.2, and 22.6 with recycled concrete aggregate, respectively. Similarly, C 25 concrete strength was found to be 28.2, 33.2, and 35.05 with virgin aggregate, whereas 25.9, 30.9, and 32.2 with recycled concrete aggregate. These findings indicate that broken pile head recycled concrete aggregate could be used as a substitute material for virgin aggregate, reducing the need for virgin aggregates.

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