A study of the microstructure of a bio-ash stabilized sandy clay soil

Abstract

This research work studies the microstructure of a sandy-clay soil as it is stabilized with corn cob ash (CCA) in dosage rates of 0-3%, in steps of 0.5%, and comparing with OPC-CCA blends (2:1) and OPC alone. The aim being to study the progressive flocculation and agglomeration of the molecules of the soil, upon the addition of varying blends of CCA- OPC in small doses. The samples were taken for microstructural examination using the scanning electron microscope (SEM), and for elemental composition using the Energy Dispersive X-ray Spectroscope (EDS). Corresponding samples of the stabilized soil were subjected to the unconfined compressive strength (UCS) tests. The cat-ion exchange capacity of the soil was also computed. The SEM images indicate that for the CCA stabilized soil, the lattice structure of soil molecules is most clearly defined at 1% CCA content. This is comparable to the cat-ion exchange capacity of the soil (1.17%), and also corresponds to the point of maximum UCS (313.7KN/m2). Significantly, the UCS value returned for CCA stabilized soil was higher than that for OPC alone and for the OPC-CCA blend, within the test range of this study. The paper concludes that a significant level of stabilization could be attained with this soil type, with small doses of CCA, without the need for OPC, whose effect is more pronounced at higher doses and at the pozzolanic phase.