Utilization of Quarry Fines as a Sustainable Admixture for Suppressing Ettringite-Induced Heaving

The performance and longevity of lightweight infrastructure depend on the engineering behavior of the underlying soil. Such infrastructure systems typically do not perform satisfactorily when built on expansive soils owing to the moisture-induced volume change characteristics. Lime stabilization has been successfully used worldwide to address the problems associated with expansive soils. However, lime treatment is often ineffective when the expansive soil has appreciable soluble sulfates. This research study has been designed to assess the scope of utilizing a novel admixture derived from quarry fines to suppress sulfate heaving in an expansive soil having a sulfate content of 20,000 ppm. Strength testing, before and after capillary soaking, and one-dimensional free swell tests were conducted on cured chemically treated specimens to evaluate the moisture-induced strength loss and volume-change characteristics of the problematic soil. Different dosages of quarry fines (QF) (0%, 15%, and 30%) were considered to assess the efficacy of the novel admixture in mitigating ettringite- induced heaving. Supplementary mineralogical and micro-structural analyses using X-ray diffraction, scanning electron microscopy imaging with energy dispersive X-ray spectroscopy, and differential thermal analysis were used to understand the underlying causes of the observed changes in engineering properties. These test results were analyzed to investigate the role of co-additive dosage and curing period on the efficacy of the novel admixture. Test results indicate that the quarry fines can effectively suppress ettringite-induced heaving when used as a co-additive with lime stabilizer; the benefits are pronounced at higher dosages and after longer curing periods.