Response of two lateritic soils to cement kiln dust-periwinkle shell ash blends as road sub-base materials

The stabilization potential of cement kiln dust (CKD) and periwinkle shell ash (PSA) was investigated using laboratory analysis. This was aimed at evaluating the effect of CKD and PSA on the stabilization of two lateritic soils for use as pavement layer materials. Two soils (Soil A and B) were treated with various percentages (by weight of dry soil) of CKD at 0, 5, 10, 15 and 20% and PSA at 0, 2, 4, 6, 8 and 10% and compacted using British Standard light (BSL) energy. Their effects were evaluated on the compaction characteristics: maximum dry density (MDD), optimum moisture content (MDD), unconfined compressive strength (UCS) and California bearing ratio (CBR) tests based on American Standard Testing Materials (ASTM) codes. Microstructural analysis using the Scanning Electron Microscope (SEM) was used to identify the morphological changes in the properties of the stabilized soils. Significant improvement with the addition of CKD and PSA was observed with increased MDD, UCS, and CBR for both soils. Peak MDD of 1.745 mg/m(3) and 1.810 mg/m(3) was recorded for both soil samples considered. The results of the peak unconfined compressive strength (UCS) for all the curing ages considered and California bearing ratio (CBR) were obtained at 10% CKD/8% PSA. Peak UCS of 994.17 and 1019.46 kN/m(2) was obtained for soil A and B respectively. Microstructural analysis of the stabilized soils resulted in strength improvement through the formation of new compounds. Based on this study, PSA and CKD can be used to improve deficient lateritic soils for road construction.