The annual consumption of plastics in Nigeria has increased drastically and plastic wastes recycling has become one of the major challenges in recent times. Polyethylene Terephthalate (PET) has been selected in this study to ascertain its possible use as an additive in concrete construction. The study used the experimental research design in carrying out its work. The PET was pulverized so that it can mix with the concrete. The pulverized PET was used in concrete with percentages of 5 %, 10 %, and 15 % by weight of conventional fine aggregate. Four types of concrete specimens including the control were prepared. The flexural and compressive strength of the concrete specimens were tested, after a curing period of 3 days, 7 days, 14 days, and 28 days respectively. The result showed that the concrete specimen containing PET at 5 % by weight showed higher compressive strength than other specimens. The flexural strength of concrete specimens containing PET aggregate was below that of the control concrete.

This paper studied the fire resistance of rice husk ash concrete. An experimental method was adopted as the research design in this work, which produced one hundred and eighty four (184) concrete specimens with the addition of rice husk ash in weighted percentages of 5%, 10% and 15% respectively. They were cured and tested at 7 days, 28 days, 30 days, 60 days, 90 days, 120 days, 150 days and 200 days. After the targeted curing days, the specimen were exposed to temperatures of 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C and 700 °C for 2 hours in a muffle electric furnace.The results show that the pozzolanic concrete and control concrete fire resistance ranged between (60%-96%) for (200 °C-400 °C), (41%-55%) at 500 °C, and (13%-26%) for (600 °C-700 °C). It is concluded that 5% weighted RHA concrete performs better in fire than others.

This paper studied the evaluation of the compressive strength of the binary blend of groundnut shell ash concrete and curing period. The purpose of the study was to source for local materials like agricultural waste that could replace some percentages of cement in order to make it more economical in concrete in order to ascertain its usefulness in the construction industry. An experimental (quantitative) method was adopted as the research design in this work. The total concrete specimens of size 100mm x100mm produced in the laboratory were one hundred and twenty (120). The groundnut shells were completely burnt in an electric furnace to obtain the ash and 0%, 5%, 10% and 15% of the ashes were used to replace cement for a designed mix of concrete strength of 20N/mm2 at w/c ratio of 0.6, after varying the w/c ratios from 0.4 to 1.0, according to basic guidelines stated in Department of Environment method. They were cured at 7 days, 28 days, 30 days, 60 days, 90 days, 120 days, 150 days and 200 days. The concrete cubes were taken to the compression machine for compression test. The result shows that compressive strength of the groundnut shell ash concrete increases as the curing period increases and there was decrease in the compressive strength of the pozzolanic concrete as the percentages of groundnut shell ash increases in the concrete. The binary blend of groundnut shell ash at 5% replacement had the maximum compressive strength of 23.3N/mm2 at 200 days while the control concrete compressive strength was 22.0N/mm2. This represents an increment of 1.06% of compressive strength over the control at 200 days.

The effects of periwinkle shell, curing duration and methods of curing on the compressive strength of concrete using response surface methodology were evaluated. However, the periwinkle shells were added to the concrete at 5%, 10% and 15% dosage by weight as partial replacement to the coarse aggregate. The concrete were cast at 0.5 w/c ratio and cured between 7 days and 28 days in both water and air. Regression equations relating the blended concrete compressive strength with both the curing duration and periwinkle shell were developed. The results show that the water cured periwinkle blended concrete gave a better compressive strength than the air cured blended concrete at 5% replacement, with a 22.1% increase in the compressive strength. The adjusted R 2 of 0.9516 and 0.6838 for both water and air cured periwinkle concrete reveal that 95.16% and 68.38% of the systematic variations in the compressive strength of the periwinkle concrete is accounted for by the independent variables.

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