This research investigates the potential use of groundnut shell ash (GSA) as soils strength enhancer. The GSA was used as admixture on selected soil samples from four different locations and samples were named T1, T2, T3 & T4. The tests carried out on the samples include Atterberg limit, sieve size analysis, soil hydrometer, compaction and California bearing ratio (CBR), X-ray fluorescence (XRF). Sieve size analysis, soil hydrometer test, Atterberg limit test were used to classify soil samples'

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... properties and classification was done as per AASHTO soil classification system. Sample T1 was classified as A-6, samples T2, T3 and T4 were classified as A-4. GSA was added to the soil samples; 2, 4, 6, 8, 10 and 15% of GSA by weight of soil samples. Compaction test and California bearing ratio (CBR) were carried out on soil samples with added GSA. Results from XRF showed that SiO2 + Al2O3+ Fe2O3 = 25.61%. For GSA to be classified as pozzolan, SiO2 + Al2O3+ Fe2O3 ≥ 70% as per ASTM C618 – 08. Therefore, GSA cannot be classified as pozzolan as it does not meet requirement stipulated in ASTM C618 but rather as inert pores filler. Based on the results from compaction and CBR, the study showed that 4-8% of GSA was found to have improved and enhanced the strength of the soil samples.