Strength Characteristics of Sand Amended with Two Waste Materials - Fly Ash and Scrap Tyre

Abstract

The effectiveness of the inclusion of tyre buffings, which is a scrap tyre derived material, on the strength characteristics of sand-fly ash mixtures has been investigated. At first, untreated sand, sand-fly ash, and sand-fly ash-tyre buffing specimens were subjected to compaction tests followed by unconfined compression tests. Considering compaction and unconfined compressive strength characteristics, triaxial compression tests were carried out on different sand-fly ash and tyre buffing added sand-fly ash mixtures. Sand-fly ash mixtures were modified by mixing with tyre buffing contents of 5% and 10%. Test results indicated that the increase in fly ash content in sand-fly ash mixtures improves the compressive strength. Further addition of tyre buffings to sand-fly ash mixtures decreases the compressive strength, but the strength is greater than that of the untreated sand. At 35% and 50% fly ash content, the shear strength of sand-fly ash-tyre buffing mixtures is found to be more than that of the sand-fly ash mixtures, especially at higher confining pressures. The stiffness of the sand-fly ash mixtures is affected by the inclusion of tyre buffings to the mixtures. The curing period also improves the strength of different sand mixtures. It is found that sand-fly ash-tyre buffing mixture containing 35% or 50% fly ash and 5% or 10% tyre buffing content may be used as a lightweight composite material in the construction of embankment for road and dam or as backfill material behind retaining walls. Thus, environmental problems associated with the disposal of fly ash and scrap tyres are also reduced.