Williams K. Kupolati

Mechanical properties of sisal fibre-reinforced polymer composites: a review

Abstract There has been a growing interest in the utilization of sisal fibres as reinforcement in the production of polymeric composite materials. Natural fibres have gained recognition as reinforcements in fibre polymer–matrix composites because of their mechanical properties and environmental friendliness. The mechanical properties of sisal fibre-reinforced polymer composites have been studied by many researchers and a few of them are discussed in this article. Various fibre treatments, which are carried out in order to improve adhesion, leading to improved mechanical properties, are also discussed in this review paper. This review also focuses on the influence of fibre content and fabrication methods, which can significantly affect the mechanical properties of sisal fibre-reinforced polymer composites.

Influence of fly ash, ground-granulated blast furnace slag and lime on unconfined compressive strength of black cotton soil

Utilisation of industrial waste products with black cotton soil (BCS) in the improvement of its engineering properties has gained attention to the sustainability of the natural resources and cost efficiency. This paper evaluates the influence of fly ash, ground-granulated blast furnace slag and lime at 12%, 8% and 1–9%, respectively, on BCS obtained from the N4 road North West Province, South Africa, to improve the soil. The performance of the modified BCS cured for 7, 28, 60 and 90 days was evaluated using compaction, California bearing ratio (CBR) and unconfined compressive strength (UCS) test according to standard specifications. The CBR value increases with increase in the level of compaction. The influence of the waste materials added for different compaction levels and curing periods improved the CBR and UCS values significantly. UCS of the stabilised BCS meets with the specification for sub-base material at 97% and 100% compaction for all the curing periods.

Appraisal of access to safe drinking water in southwest Nigeria

The importance of developing effective water supply services is universally recognised as a basis for improving the overall health of the population. This study ascertained the quality of water supplied by a water treatment scheme in southwest Nigeria. One hundred and twelve samples were collected during the wet and dry seasons. Tests on physico-chemical and bacteriological parameters were conducted. Statistical analysis of variance was carried out on the results of the test. The effectiveness of the treatment processes on the parameters considered showed that the aeration, sedimentation and filtration processes were 70.13% effective in colour removal; sedimentation and filtration processes were 94.78% effective in turbidity removal; sedimentation and filtration process were 28.84% effective in the removal of total suspended solids (TSS) and 9.88% effective in the removal of total solids (TS); the disinfection and filtration processes were 100% effective in bacterial and coliform removal. The treatment system was found to be 71.38% effective in pollutant removal.

The use of polypropylene in bamboo fibre composites and their mechanical properties – A review

Bamboo fibre has gained significant interest as a sustainable reinforcement fibre in natural fibre/polymer composites, which is as a result of specific mechanical properties and being a biodegradable material compared to glass fibres. The article also gives a summary of how to improve the mechanical properties of bamboo fibre reinforced polypropylene (BFRP) composites as presented in various researches and the methodology of attaining these ultimate properties of bamboo fibres with polymeric matrices leading to improved BFRP. Mechanical properties of BFRP composites are improved by introducing coupling agent. Fibre treatment and nanoclay addition, in the right proportion, as reported have improved mechanical properties of BFRP composite.

Impact of Surface Modification and Nanoparticle on Sisal Fiber Reinforced Polypropylene Nanocomposites

The use of plant fibers, polymer, and nanoparticles for composite has gained global attention, especially in the packaging, automobile, aviation, building, and construction industries. Nanocomposites materials are currently in use as a replacement for traditional materials due to their superior properties, such as high strength-to-weight ratio, cost effectiveness, and environmental friendliness. Sisal fiber (SF) was treated with 5% NaOH for 2 hours at 70°C. A mixed blend of sisal fiber and recycled polypropylene (rPP) was produced at four different fiber loadings: 10, 20, 30, and 40 wt.%, while nanoclay was added at 1, 3, and 5 wt.%. Maleic anhydride grafted polypropylene (MAPP) was used as the compatibilizer for all composites prepared except the untreated sisal fibers. The characterization results showed that the fiber treatment, addition of MAPP, and nanoclay improved the mechanical properties and thermal stability and reduced water absorption of the SF/rPP nanocomposites. The tensile strength, tensile modulus, and impact strength increased by 32.80, 37.62, and 5.48%, respectively, when compared to the untreated SF/rPP composites. Water absorption was reduced due to the treatment of fiber and the incorporation of MAPP and nanoclay.

Phytoremediation of Water Using Phragmites karka and Veteveria nigritana in Constructed Wetland.

Constructed wetland is an innovative and emerging ecological technology for wastewater treatment. This study was conducted to investigate the effectiveness of a Vegetated Submerged Bed Constructed Wetland (VSBCW) for removal of heavy metals from industrial wastewater in a steel manufacturing company. A pilot Effluent Treatment Plant (ETP) consisting of equalization basin, two VSBCW basins and a storage tank was constructed. The VSBCW was constructed using 10–30 mm round granite for the different zones. This was overlaid by 200 mm deep granite and 150 mm washed sand with Phragmites karka, Vetiveria nigritana and Cana lilies as macrophytes. Irrigation of macrophytes using effluent from the industry was done after 3 months of planting and ETP monitored. Industrial wastewater samples were collected and analyzed for heavy metals such as zinc (Zn), lead (Pb), iron (Fe), manganese (Mn), magnesium (Mg) and chromium (Cr) to know the treatment efficiency of the ETP. Results indicated that the removal efficiencies of the VSBCW for Pb, Mg and Cr were 15.4%, 79.7% and 97.9% respectively. Fe and Mn were seen to increase by 1.8% and 33% respectively. The ETP using locally available macrophytes is effective in the phytoremediation of heavy metals, particularly Cr from the wastewater.

Assessment of the effects of climate change on the performance of pavement subgrade

This research investigated the effects of future climate change on pavement life in South Africa by simulating prolonged moisture presence in the pavement subgrade. The study was conducted on roads P435 and P443 within uMkhanyakude District Municipality. Climatic data were collected from the Council for Scientific and Industrial Research (CSIR) and Climate Systems Analysis Group (CSAG) from 1940 to 2001 and simulated from 2012 to 2062. Sampling was done using the standard procedure described in Technical Methods for Highways (TMH) 5 and soil laboratory tests carried out according to TMH 1. Results of laboratory tests classified the materials as G10 based on their California bearing ratio (CBR) and plasticity index (PI). Relative compaction of 91.4 and 94.3% were obtained from the CBR test on the subgrade layers of roads P435 and P443 respectively. The research showed that 50 years into the future will bring a climate change signal that will be minimal in terms of precipitation. However, natural weather variability threatens to be the dominant signal. The pavement life has been shown to decrease in a way that would threaten the road category and design reliability.

Electrical Conductivity of Cu and Cu-2vol.% Nb Powders and the Effect of Varying Sintering Temperatures on their Mechanical Properties Using Spark Plasma Sintering

The growing demand for relatively inexpensive non-hazardous copper alloys with a good combination of electrical conductivity and high strength has led to increasing researches on Cu-Nb alloys for their excellent predictions over Cu-Be alloys. Cu-2vol.% Nb was produced using spark plasma sintering and the effect of the additive on its electrical conductivity, densification, hardness, corrosion resistance and wear resistance were investigated. It was observed that the additive improved the electrical conductivity of Cu powder from 0.28 to 5.89 S/m within 19–406 ∘C. Relative densities of 97.08% for Cu-2vol.% Nb and 97.33% for pure Cu were obtained at 600 ∘C, while at 650 ∘C, they were 96.08 and 96.82% respectively. The microhardness values were 77 and 72 Hv0.1at 600 ∘C, while at 650 ∘C, they were 83 and 66 Hv0.1 for Cu-2vol.% Nb and pure Cu respectively. The corrosion potential of Cu-2vol.% Nb was noble with a lower anodic current density, suggesting better corrosion resistance at 600 ∘C. Cu-2vol.% Nb showed a better wear resistance at 600 ∘C and an improved electrical conductivity at 650 ∘C.

Utilization of pulverized cow bone (PCB) for stabilizing lateritic soil for road work

This research explored the possibility of improving the engineering properties of lateritic soil with pulverized cow bone (PCB), a processed animal waste obtained from slaughtered cows, for road construction. The effects of PCB on the lateritic soil samples were evaluated by adding 5–12.5% PCB with a constant increment of 2.5% to the lateritic soil. The lateritic soil had a liquid limit of 36%, a plastic limit of 25.06% and a plasticity index of 10.94%. The plasticity of the lateritic soil is low; hence the lateritic soil may not be susceptible to cracking or shrinkage. The specific gravity of the lateritic soil is 2.59 while that of the PCB is 2.25. Though the values of the California bearing ratio and unconfined compressive strength increased from 15.50–22.3% and 67.25–204.18 kN/m2, respectively with the addition of 0–12.5% PCB, the compaction results did not suggest that PCB can be added to the lateritic soil endlessly. The chemical reaction between silicon and calcium oxides, which were predominant in PCB and lateritic soil respectively, may have implication for the engineering properties of the soil. From the results of the study, an addition of 5% PCB is recommended to improve the engineering properties of the lateritic soil for road construction.

Stabilization of lateritic soil with pulverized palm kernel shell (PPKS) for road construction

This paper discusses the stabilization of lateritic soil with pulverized palm kernel shell (PPKS), an agricultural waste, for road construction. Samples of lateritic soil with the addition of 5.00–12.50% PPKS at an increment of 2.50% were prepared for index and strength tests. The lateritic soil had a liquid limit, plastic limit and plasticity index of 36.00, 26.18 and 9.82% respectively. The control sample with 0% PPKS has low plasticity and may not be liable to shrinkage or cracking. The specific gravity (SG) of the lateritic soil and PPKS are 2.67 and 2.84 respectively. Maximum dry density (MDD) of the lateritic soil increased from 1.76–1.94 kN/m3 for 0–12.50% PPKS. There was a reduction in the optimum moisture content (OMC) of the lateritic soil from 14.69–12.65% for 5–12.50% PPKS. Addition of 12.5% PPKS increased the soaked California bearing ratio (CBR) of lateritic soil by 121% from 24–53%. The unconfined compressive strength (UCS) value increased from 46.69–127.98 kN/m² by 174% for 0–12.50% PPKS. The strength properties of the lateritic soil improved with the addition of PPKS.