Increasing population levels, booming economy and rapid urbanization have greatly accelerated the municipal solid waste (MSW) in our country; in our cities (Bamenda, Buea, Douala, Yaoundé etc.), poor management of solid waste constitutes an urgent problem: flood, deterioration of the urban environment in the form of air, water, and land pollution. Options like recycling and material recovery for subsequent re-use present enormous opportunities for waste management with economic and ecological benefits, wastes as well as plastic and palm nut shell have not yet been recycled satisfactorily; the performances of palm nut shell-plastic composites of 30% palm kernel shell with particle sizes varying from 1mm to 5mm and 70% of polyethylene were used to produce different samples The effects of palm kernel shell particles’ size on mechanical and physical properties of the new composite were studied by the help of different mechanical (flexural and compressive test) and physical tests (density and water absorption). Results showed a better interaction of polyethylene and palm kernel shell particles at 1mm sieve with compressive stress and water absorption higher at 1mm, ultimate flexural stress and the young’s modulus of the material increased as the particle size of the palm kernel shell increased, relatively higher density were obtained at 3mm of the palm kernel shell (PKS) size.  

One of the major factors influencing the variation of friction between surfaces in contact is the speed; we are faced here with the problem of determining the optimum speed between surfaces in contact in order to improve on the mechanical properties and performance of the entire system. This project investigates experimentally the effect of rotational speed on the (CoF) between aluminum disk test samples in contact with stainless steel pin using plum oil as a lubricant under thin film lubrication conditions. We first extracted plum oil using the manual pressing method and then carried out friction tests on a pin-on-disk tribometer as per ASTM-G 99 standards at room temperature. Rotational speeds between 500rpm and 3000rpm and normal loads of 10N and 20N were deployed as the operating variables and the variation of the (CoF) at predefined rotational speeds and normal loads was studied. Working time for each test was 20 minutes and each test was run twice and average value of friction force calculated. It was observed the CoF decreases with increasing rotational speed from 500rpm-1500rpm speed range and increases with increasing rotational speed from 1500rpm-2500rpm speed range while there is a slight drop from 2500rpm-3000rpm and an optimum speed range attained between 1250rpm-1500rpm where we experienced the least value of coefficient of friction for this specific material combination and test conditions. To further investigate other factors that affect the coefficient of friction and the validity of these results, more studies are needed.

Agricultural and Industrial wastes have created waste management and pollution problems. The replacement of conventional ingredients in concrete production would reduce construction cost and proper waste management. The percentages of spikelet fibers in the composites were 0%, 0.25%, 0.5%, 0.75% and 1%. Concrete cubes and rectangular bricks of sizes 150mm x 150mm x 150mm and 40mm x 40mm x 160mm respectively with different percentages of spikelet fibers cured and tested after 7 and 28 days. The flexural strength, compressive strength, Density, slump workability, rate of water absorption and grain size were analyzed. It results that palm kernel shells was well graded and a good replacement for conventional aggregates. The density and compressive strength after 28 days curing were within the range 1645 to 1749kg/m3 and 15.35 to 19.21kg/m3 respectively. It was observed that slump workability reduced while compressive strength, water absorption, density and flexural strength increases proportionately with fiber contents.