Capillary rise, suction (absorption) and the strength development of HBM treated with QD base geopolymer

Abstract

Test soil sample was investigated and characterized under the laboratory conditions with the preliminary tests. It was classified as A-2-6 group soil according to the AASHTO classification method. It was also classified according to USCS as poorly graded (GP) with high clay content (CH). It was also classified as highly plastic with plasticity index above 17% and expansive. The soil sample was further treated with synthesized Quarry dust (QD) base Geopolymer cement (GPC) at room temperature and the effects of the varying proportions of the GPC added in the proportions of 2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, 25%, 27.5%, 30%, 32.5%, 35%, 37.5% and 40% by weight of solid on the cemented and non-cemented test soils under varying curing times on the soil capillary rise, suction and strength development parameters (UCS, CBR and MRD) were investigated. The results obtained showed a consistent reduction in capillary rise and suction with increased proportion of QD base GPC and an increase in these properties with increased curing time. But cemented soil showed a slight higher reduction in capillary rise and suction than the non-cemented soil, but at 15% QDbGPC all the trials have capillary rise below 25%. The strength development consistently improved with increased proportion of QDbGPC, that at 12.5% GPC, the trials achieved CBR above 30%, a minimum required for a material to be used as base course material and reduced with prolonged curing time due to loss of strength on prolonged water absorption. Portland cement has high shrinkage, and less capillary and absorption tendencies, though it showed lesser values of capillary rise and suction but the difference between cemented and non-cemented soils is too small that QD base GPC can totally replace OPC because of the construction properties it exhibits. It also shows that QD base GPC beyond 40% by weight will keep improving the strength of treated soils and achieve higher compressive strengths.