Browsing by Author "Ufot Ekpo, David"

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    Effect of micro sized quarry dust particle on the compaction and strength properties of cement stabilized lateritic soil
    (Cleaner Materials, 2021) Kufre Etim, Roland; Ufot Ekpo, David; Attah, Imoh Christopher; Chibuzor Onyelowe, Kennedy
    Laboratory investigation on the effect of micro sized quarry dust on engineering behaviour of cement stabilized lateritic soil was carried out. The specific concentration was on the effective way of curtailing, managing and disposing solid wastes generated from quarry activities by incorporating them as admixture in cement amelioration protocol of weak lateritic soil bound for sustainable subgrade material. In airfield, embankment, railways, pavement foundation structures, special attention/consideration/interest is continually laid on how moisture percolation affect the bearing capacity or strength of the subgrade layer. The quarry dust of 0 to 10 % was admixed with cement of 0 to 8 %, both in step increment of 2% by dry weight of the soil forming a combination matrix of twenty‐five test specimens in an amelioration protocol. The test results show that quarry dust admixture steadily improved the plasticity index of cement stabilized soil through the reduction in plasticity index. The maximum dry density in most part of the test, improved with increase in percentage stabilizers blend for the individual corresponding optimum moisture content of the treated soil. The mechanical properties (California bearing ratio and unconfined compressive strength) of cemented lateritic soil increased significantly with increase in the micro sized quarry dust stabilizer. The resistance to loss in strength showed that more than 80 % durability values was recorded. The SEM/EDS analysis of the optimally stabilized specimen in contrast to untreated soil established the development of calcite as C‐S‐H and C‐(A)‐S‐H. The formation of C‐S‐H and C‐(A)‐ S‐H which was also confirmed through the FTIR and XRD test was responsible for strength development.
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    Understanding the impacts of binary additives on the mechanical and morphological response of ameliorated soil for road infrastructures
    (Journal of King Saud University-Engineering Sciences, 2021) Christopher Attah, Imoh; Kufre Etim, Roland; Ufot Ekpo, David; Chibuzor Onyelowe, Kennedy
    In an attempt to promote a cleaner environment, the deployment of waste materials in soil amendment protocols have been a major concern for civil engineers. Recent discoveries in the study of soil mechanics have revealed the pozzolanic tendencies demonstrated by these waste materials, which are beneficial in the development of road infrastructure. This has necessitated the need for this research to document the impacts of exploring the usage of combined solid waste derivatives in ameliorating the geotechnical parameters of deficient soil. The current stabilization exercise was geared towards the improvement of the mechanical properties of soil and surpassing the detrimental tendencies especially caused by seasonal variations. Moving forward, the microstructural response of the unaltered and additive ameliorated soil was investigated via qualitative means such as scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The additives including cement kiln dust (CKD) and rice husk ash (RHA), were added by air-dried weight of the soil and compacted based on the standards of British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH). With regard to the compaction exercise, incorporation of these additive materials into the soil facilitated a gradual increase in the maximum dry density (MDDs) followed by a decrease in the optimum moisture contents (OMCs). In view of these research findings, soil treatment studies facilitated a substantial upsurge in the strength (California bearing ratio (CBR) and unconfined compressive strength (UCS)) values of the ameliorated soil, in agreement with the requirements of Nigeria general specification for all compactive efforts. Finally, the usefulness and efficacy of combining these wastes in deficient soil treatment were validated qualitatively via the SEM and FTIR strategies. The results of the SEM analysis revealed some disparities between the unaltered and altered soil specimens, providing insights into the direction of calcite formation in the additive-treated soil.