TECHNICAL STUDY ON THE USE OF FLY ASH AS COMPLEMENT OF CEMENT IN CONCRETE CASE STUDY: RWANDA

Abstract

The construction industry is one of the main fields making up the worldwide development today and it is also developing fast similarly as in our country Rwanda. The use of concrete that has been commonly adapted in this development era in construction should suit the quality and economy. To achieve this, the materials to be used in construction is the main issue to be addressed. That brought us to think about the assessment use of locally available material, Peat coal Fly Ash (PFA) that can be applied as complement of cement in concrete which does not yet have a perfect application. This project intends to reduce the cost of construction projects by taking into account the appropriate technology of maximizing the use of residue material. The project was carried out by doing various tests to get optimum PFA percentage to be used. The use of fly ash as complement of Ordinary Portland Cement (OPC) in concrete was evaluated. OPC was replaced with PFA by weight at 5%, 10%, 15% and 20%, where 0% PFA was used as a reference. Compressive strength test was carried out on 150mmx150mmx150mm steel mould after 3 days curing in a water bath. Although, the results revealed that the compressive strength of the hardened concrete increases as percentage of replacement with PFA increases, it was shown that optimum percentage of PFA is 10% of replacement corresponds with compressive strength of 18.053Mpa at 3 days. Slump test result showed with a partial replacement of cement by PFA that the increase in percentage PFA reduces the slump. But the amount of the water was kept the same W/C=0.5. At the 10% replacement of PFA the slump was 95mm, this complement is environmentally friendly and cost effective. It is advised that more research be done to learn more details regarding the suitability of partially replacing OPC with PFA in concrete.