Volume 5 Number 11 November 2019
The Influence of Partial Replacement of Some Selected Pozzolans on the Drying Shrinkage of Concrete
Authors: Ikumapayi C. M. ; Akingbonmire S. L. ; Oni O.
Concrete is prone to cracking and one of the major causes of cracking is drying shrinkage of the hardened concrete. This research work was carried out to study the influence of partial replacement of some selected pozzolans on the drying shrinkage of concrete. Four pozzolans used in this study, were made to replace cement at various percentages resulting in various concrete mixes. Setting time test was conducted for the various cement mixes using Vicat’s apparatus and drying shrinkage test was done for the concrete test specimens. The results of the setting time indicate that partial replacement of pozzolans with ordinary Portland cement increases both the initial and final setting time of cement as the percentage replacement increases. Similarly, drying shrinkage results show that concrete made with Groundnut Shell Ash (GSA) and Locust Bean Pod Ash (LBA) at 12% replacement will have a stable and better shrinkage resistance than the control at both 56 days and 90 days. Meanwhile, the control concrete gives a better drying shrinkage at 28 days curing. In conclusion, the results show that pozzolanas [Bamboo Leaves Ash (BLA), Locust Bean Pod Ash (LBA), Sugarcane Bagasse Ash (SBA) and Groundnut Shell Ash (GSA)] can successfully replace cement up to 12% without necessarily affecting the shrinkage ability of the produced concrete. It also shows that Groundnut Shell Ash (GSA), Locust Bean Pod Ash (LBA) and Bamboo Leaves Ash (BLA) are more resistance to drying shrinkage than the control.
Study on the Granulation of FLY Ash from Thermal Power Station
Authors: Ganka Kolchakova
The effect of the type and amount of binding substance on the yield and strength of granules prepared from fly ash was studied. The highest yield of granules was achieved with clayish slip used as binder. The granules obtained are brittle, with compression strength 0,1МРа. The apparent density of the sintered granulates was in the range1200-1500kg/m3 and the total porosity was 55-40%.