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Abstract:There have been global efforts to reduce environmental pollution of agricultural and industrial waste products by utilizing such wastes as stabilizing agents to improve soils for various uses, especially road construction. In this research, lateritic soil sample obtained from a borrow pit was tested with varying percentages of Pulverized Palm Kernel Shell (PPKS). The soil was classified as A-6 (AASHTO classification) using standard soil laboratory tests. Laboratory tests such as Atterberg Limits, Compaction, Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) were conducted on the soil + PPKS mix only and also on soil + PPKS + 3% Ordinary Portland Cement (OPC) mix. The liquid limit (LL) and plasticity index (PI) values decreased steadily with increase in PPKS while the plastic limit (PL) value increased with up to 4% PPKS addition after which the values started decreasing. The shrinkage limit (SL) value increased with a peak value at 8% PPKS addition after which the values began to decrease. The Optimum Moisture Content (OMC) results on PPKS addition increased from 16% to 19.5% while the Maximum Dry Density (MDD) decreased by 45.18% from 1.669g/m 3 to 0.915g/m 3 . Addition of PPKS decreased the Unsoaked CBR by 10.79% from 68.60 to 61.20% while the Soaked CBR increased by 74.12% from 18.05% to 69.75%. UCS values for the lateritic soil and PPKS for the uncured sample, at 7 days and 14 days had peak values of 85.03, 96.46 and 100.44 respectively. From the study, it can be concluded that the properties of the Lateritic soil improved when stabilized with Cement and pulverized palm kernel shell compared to when it was stabilized with pulverized palm kernel shell alone.

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Roads are essential necessity of every nation and it is possible that even with proper designs, the roads might not be constructed to the design standard due to poor quality assurance and control resulting in poor pavement quality. This study presents experimental results carried out on various hot - mix asphalt (HMA) samples obtained across different Asphalt plants in South West Nigeria. This was done to determine the extent to which the HMA used in the construction and rehabilitation of Nigerian roads affect their service life. Six samples of the asphalt binder (bitumen) were obtained from each plant over a period of six months and tested. The tested properties were assessed based on the level of conformance with the specifications and requirements from the FMWH General Specification (Roads and Bridges). The results revealed that HMA from plant B had a specific gravity of 1.01, penetration of 65.00 mm, softening point of 53 oC, flash point of 237.00 oC, peak Marshall Stability of 18.25 kN, flow of 3.87 mm and voids in total mixture peak value of 5.08 %. HMA from plant E had a specific gravity of 1.03, penetration of 65.00 mm, softening point of 51 oC, flash point of 239.00 oC, peak marshall stability of 18.26 kN, flow of 3.67 mm and voids in total mixture peak value of 4.99 % and these were adjudged the best in conformance with the FMWH specifications. Adequate monitoring of HMA quality for either binder or wearing courses by carrying out quality control and assurance tests is thereby recommended as it affects pavement durability and performance. Keywords: Hot-mix asphalt, quality assurance, quality control, marshall stability, flow test