Influence of Periwinkle Shell Ash on the Strength Properties of Cement-Stabilized Lateritic Soil

The study investigated the use of Portland limestone cement (PLC) and periwinkle shell ash (PSA) under laboratory conditions on geotechnical properties of lateritic soil to enhance its suitability as pavement layer material. The soil was treated with varying percentages of PLC at 0–8% and PSA at 0–10% (each at an increment of 2%) and compacted using standard Proctor. Microstructural tests such as scanning electron microscope (SEM) and Fourier transformation Infrared (FTIR), respectively, were used in identifying the mineralogical changes, morphological changes and functional groups present in the soil-PLC-PSA admixtures. The results show a general decrease in Atterberg’s limit, an increase in maximum dry density (MDD) followed by a decrease in optimum moisture content (OMC). Peak California bearing ratios (CBRS and CBRU) and unconfined compressive strength (UCS) for various curing ages considered were obtained at 6% PLC/6% PSA threshold. The peak UCS of 920 kN/m2 was within the acceptable range specified by Ingles and Metcalf for use as sub-base materials. The Fourier transformation Infrared (FTIR) spectroscopy shows uniqueness in functional groups with respect to their specific bands for both the natural soil, cement, PSA and the optimally treated soil. The SEM incorporating fibremetric analysis for the treated soil, shows that pores were filled with cementitious compounds with an attendant reduction in length, respectively. The improvement in soil strength is associated with the presence of calcite which was qualitatively confirmed from the FTIR spectroscopy and SEM analysis of optimally treated soil. On the overall, PLC and PSA can be used in improving the properties of weak soils to make them fit for road highway construction.