Mechanical behaviour of waste powdered tiles and portland cement treated soft clay

Abstract

The main objective of this study is to evaluate and compare the efficiency of ordinary Portland cement (OPC) inenhancing the unconfined compressive strength of soft soil alone and soft soil mixed with recycled tiles. The recycled tiles havebeen used to treat soft soil in a previous research by Al-Bared et al. (2019) and the results showed significant improvement, butthe improved strength value was for samples treated with low cement content (2%). Hence, OPC is added alone in this researchin various proportions and together with the optimum value of recycled tiles in order to investigate the improvement in thestrength. The results of the compaction tests of the soft soil treated with recycled tiles and 2, 4, and 6% OPC revealed anincrement in the maximum dry density and a decrement in the optimum moisture content. The optimum value of OPC wasfound to be 6%, at which the strength was the highest for both samples treated with OPC alone and samples treated with OPCand 20% recycled tiles. Under similar curing time, the strength of samples treated with recycled tiles and OPC was higher thanthe treated soil with the same percentage of OPC alone. The stress-strain curves showed ductile plastic behaviour for theuntreated soft clay and brittle behaviour for almost all treated samples with OPC alone and OPC with recycled tiles. Themicrostructural tests indicated the formation of new cementitious products that were responsible for the improvement of thestrength, such as calcium aluminium silicate hydrate. This research promotes recycled tiles as a green stabiliser for soilstabilisation capable of reducing the amount of OPC required for ground improvement. The replacement of OPC with recycledtiles resulted in higher strength compared to the control mix and this achievement may results in reducing both OPC in soilstabilisation and the disposal of recycled tiles into landfills.