No abstract

The use of bamboo leaf ash as cement supplement can contribute to reduction in cost and environmental hazard associated with cement production as well as waste pollution caused by the littered bamboo leaves. Therefore, the characteristics of cement paste and mortar incorporating bamboo leaf ash were investigated. The results of the physical properties of the pastes were within the requirements stipulated by relevant standards while that of the mortar cubes indicated that the compressive strength generally increased with curing age, and that the mix containing 15% Bamboo Leaf Ash (BLA) by mass competes favorably with that of the reference mix at 28days and above. The water absorption and apparent porosity were observed to increase with increase in BLA content, while the bulk density decreases as the percentage of BLA increases from 5% to 25% by mass. The study concluded that 15% BLA replacing cement is adequate for the production of masonry mortar.

The objective of this study is to examine the effect of accelerator (NaNO3) on the strength properties of High volume Periwinkle shell ash blended cement concrete. A mix ratio and water-binder ratio of 1:2:4 (cement: sand: gravel) and 0.60, respectively was used as the reference. The cement was then replaced with 30% Periwinkle Shell Ash (PSA) by weight of cement. Sodium nitrate in the dosages of 1, 2, and 3% by weight of cement was added to the blended mixture of cement and PSA. The strength properties investigated were compressive and splitting tensile strength tested at 7, 14 and 28 days hydration. The results indicated that the compressive strength and the splitting tensile strength generally increases with curing age, and that sodium nitrate of up to 2% dosage greatly improved the strength performance of high volume PSA blended cement concrete over that of the reference. The study concluded that the inclusion of 2% sodium nitrate by weight of cement in the mixture could be considered the optimum dosage for the improvement of both compressive and splitting tensile strength of concrete incorporating up to 30% PSA content.

The study examined the compressive strength of periwinkle shell ash (PSA) blended cement concrete in magnesium sulphate medium. Specimens were prepared from designed characteristics strength of 25 MPa. The cement replacement with PSA ranged between 0 and 40% by volume. A total of 180 cube specimens were cast and cured in water. At 28 days curing, 45 specimens each were transferred into magnesium sulphate of 1%, 3%, and 5% solution, while others were continuously cured in water and tested at 62, 92, and 152 days. The results revealed a higher loss in compressive strength with the control mix, and that it increases with increased in MgSO4 concentration and exposure period, whereas, the attack on the PSA blended cement concrete was less and the least value recorded by 10% PSA content. Therefore, the study concluded that the optimum percentage replacement of cement with 10% PSA could mitigate magnesium sulphate attack.