Durability of geopolymer mortars using agro-industrial waste

• Main Author: Ariffin, Nur Farhayu
• Format: Thesis
• Language: English
• Published: 2012
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utm.my/id/eprint/36983/1/NurFarhayuAriffinMFKA2012.pdf; http://eprints.utm.my/id/eprint/36983/
• Institution: Universiti Teknologi Malaysia

Geopolymer is a binding material produced from the reaction of silica and alumina (in a source material of geological origin or in by-product material), with alkaline solutions. The use of geopolymer as cement replacement material in concrete might be able to reduce the pollution due to the emission of carbon dioxide to the atmosphere generated from the production of Ordinary Portland Cement (OPC). This thesis presents the results of laboratory investigation on geopolymer mortar cubes in which the durability of specimens was studied. The cement replacement materials used were Palm Oil Fuel Ash (POFA) and Pulverized Fuel Ash (PFA), with a mass ratio of sand to blended ash of 3:1, while the alkaline solution was made of sodium silicate and sodium hydroxide with the mass ratio of 2.5:1 and has concentration of 14 Molar. In order to determine the optimum mix proportion at a specified compressive strength of normal mix using OPC, mortar cubes containing various ratios of POFA to PFA were tested with the target of using as much POFA as possible in the mixture. With the optimum mix proportion, that is 30:70, geopolymer mortar in the forms of 70x70x70 mm cubes were cured at room temperature of 28ºC for 28 days and heat cured at 90ºC for 24 hours, were tested for durability. The performances were measured in terms of water absorption, water permeability coefficient, drying shrinkage, sulphate resistance, acid resistance, chloride ion penetration resistance, dry-wet cyclic resistance and elevated temperature resistance. The evaluations were done through visual observation, measurement of mass change and residual compressive strength. The test result shows that the heat cured geopolymer mortars possess higher degree of durability compared to those using OPC. This suggests that geopolymer with correct proportion may be used as cement replacement material in the production of a more environment-friendly concrete.