Development of geopolymer mortar and concrete containing eco-processed pozzolan (EPP) from palm oil industry / Ahmat Mahamat Ahmat

Ahmat Mahamat , Ahmat (2023) Development of geopolymer mortar and concrete containing eco-processed pozzolan (EPP) from palm oil industry / Ahmat Mahamat Ahmat. Masters thesis, Universiti Malaya.

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Abstract

The utilisation of natural resources causes serious environmental impacts. After water, concrete is the second most widely used substance in the world. The most commonly used building material is ordinary Portland cement (OPC), which is responsible for carbon dioxide (CO2) emissions. The loss of biodiversity, as well as the dumping of industrial by-products and waste materials, are major environmental concerns. There are other serious consequences of over-exploitation of natural resources that include flooding, lack of sand and coarse aggregates etc. One of the damage control mechanisms is the utilization of supplementary cementitious materials (SCMs) and other alternative industrial by-products to replace the conventional cement, sand, granite aggregates etc. This research investigates the feasibility of using eco-processed pozzolan (EPP), a palm oil industrial by-product, as a partial replacement for fly ash (FA) in geopolymer concrete (GPC) and mortar. Various percentages of EPP replacement were used to design a total of nineteen mixtures. Thus, the percentages of EPP utilised in the mortar and concrete mixtures were 10, 30, and 50%, and 10 and 30%, respectively. The alkaline activator/binder and sodium silicate/sodium hydroxide were constant, and the samples were cured at 60°C for 24 hours. The influence of EPP in GPC and mortar on the fresh and hardened properties such as mechanical properties, durability, and microstructural analysis was examined. The test result showed that using a large proportion of EPP decreases the flow of the mortar. This is due to the occurrence of a high number of irregular and porous particles in EPP, which causes the mixture to flow more slowly. It is recommended to use 10-30% EPP since it yields the optimum 28-day compressive strength of 35-41 MPa. However, the use of a higher quantity of EPP with relatively low specific gravity and porous particles produced a weaker geopolymer mortar. The splitting tensile strength of both lightweight (LW) and normal weight (NW) GPC, except for M6 containing 30% of EPP substitution, have satisfied the minimum requirement (2.0 MPa). In addition, the flexural strength of GPC mixes produced approximately 9.54–11.51% of their respective 28-day compressive strength. Both LW and NW GPC achieved comparable flexural strength. The MOE of LW GPC is lower than NW GPC. The decrease in MOE is attributed to the low specific gravity of POC aggregates. Moreover, the GPC specimens exhibited no physical damage or surface erosion after 56 days of submersion in 3% HCl and 5% MgSO4 solution. Therefore, the use of EPP as a construction material reduces the disposal of vast quantities of waste from the palm oil industry and lessens the negative impact of construction on the environment.

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