STUDY ON THE EFFECT OF RICE HUSK IN GEOPOLYMER COMPRESSIVE STRENGTH

Geopolymerization is a field where the main concern is the utilization of solid waste and by products. Industrial waste products such as fly ash, rice husk ash or silica fume are used as the source of alluminosilicate powder. Geopolymerization is found to be cost effective and environmentally friendly. Geopolymer involves the silicates and aluminates of by products to undergo process of geopolymerization. Rice is a primary source of food in the Asian region. A total of 600 million tons of rice paddy are produced every year. The husks causes disposal problems. Rice Husk ash is a super pozzolan and would act as a suitable material for geopolymer cement. The project attempts to propose MIRHA geopolymer cement as a substitute to OPC for well cementing purposes by studying whether it fulfills the compressive strength requirement for well cement. There are several problems identified in the current usage of OPC. It is found that the manufacturing of OPC, the current well cement, consumes a lot of energy and resources. Currently, cement production is responsible for 5% to 8% of yearly manmade CO2 global emissions, or nearly 1.6 billion ton of CO2 and therefore is the second largest CO2 emitting industry behind power generation. Manufacturing of geopolymer cement releases up to 80% less CO2 compared to OPC. The project aims to find out the factors affecting the MIRHA geopolymer’s compressive strength and study them. This would further on lead to the possibility of substituting OPC with MIRHA geopolymer cement. By substituting OPC with MIRHA geopolymer cement, we could solve the RHA disposal issue and at the same time tackle the greenhouse gas emission from cement manufacturing that we are currently facing. The project manipulates several variables mainly the water/cement ratio, the concentration of NaOH solution, curing time, curing temperature, MIRHA grain size and ash/activator ratio in order to determine its effect on the MIRHA geopolymer compressive strength. The scope of study includes conducting research on MIRHA geopolymer cement. Devising the experiment procedures and methods of carrying them out is also researched. A few sets of experiments were conducted. In each experiment, a variable is manipulated and its effect on the geopolymer compressive strength is observed. From the experiments
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conducted, we are able to figure out the optimum condition for MIRHA geopolymer cement that would result in a higher compressive strength. It is concluded that a water ration of 40% or lower should be used. It is found that a MIRHA to alkali activator ratio of 2:1 results in a better compressive strength. As for alkali activator, a 10M sodium hydroxide solution results in a higher compressive strength and can be concluded as the optimum molarity for geopolymer synthesis. A finer grain size results in a better compressive strength. A longer curing time results in an increased compressive strength. Finally, it is found that an optimum temperature of 60˚C should be used for curing rather than an elevated temperature. All of these results has been presented and discussed. The objectives of the final year project has been achieved.