Investigation of the suitablity of coffee husks ash as a partial cement replacement for blocks production.

Abstract

The project aimed at investigating the composition of Coffee Husks Ash and evaluating the strength and durability properties of blocks produced with varying percentages of coffee husks ash as a cement replacement and finally determining the cost effectiveness of the blocks. The Coffee husk were collected from Mpororo Coffee in Ntungamo. The coffee husks were burnt at a constant temperature of 600oC for consecutive 4 hours to produce the coffee husks ash. Blocks were produced with different partial cement replacement with coffee husk ash in ratios of 5%,10%,15% and 20% while keeping the 0% as the control. For chemical composition, the combined percentage contribution of Alumina, Silica and Iron oxides was determined as 32.5% which was categorized as having low pozzolanic activity. The compressive strength test was carried out and it was established that 5% replacement had the best partial replacement ratio in comparison with the other ratios of 10,15,20. This ratio gave off a strength of 8MPa at 28days. The water absorption test also revealed that the absorption rate reduced for increasing number of curing days but increased for the higher ratio replacements and as thus the 5% replacement had the least water absorption of 5.47% in reference to the other ratios of 10%,15%,20%. Under the cost effectiveness study it was also established that it was cheaper producing blocks with Coffee Husks as compared to those without. The project's outcomes will provide valuable insights into the potential use of coffee husk ash as a sustainable partial replacement in cement for block production.