Effects of Curing Environment on the Strength and Mineralogy of Lime-GGBS–Treated Acid Sulphate Soils

This paper investigates the effect of curing environment on the strength and modal mineralogy of synthetically prepared acid sulphate soils (ASS) treated with lime and ground granulated blast furnace slag (GGBS). The treated samples were cured under various environmental conditions for up to 365 days and tested for pH, unconfined compressive strength (UCS), and changes in modal mineralogy using powder X-ray diffraction (XRD). Quantitative analysis of XRD patterns (QXRD) was carried out using the Rietveld method. Results show that a lower temperature curing environment (<5°C) significantly retards the hydration and pozzolanic reactions, thereby inhibiting the strength development. It has been demonstrated that a GGBS content of 15 wt.%, representing a GGBS-to-lime ratio of 1.5, is optimum for a sustainable development of UCS of treated ASS cured at temperatures ranging from 19 to 22°C and humidity ranging from 45 to 100%. Higher GGBS contents (>15 wt %) are observed to have an adverse effect on the UCS after 180 days of curing because of the formation of deleterious minerals (i.e., thaumasite).