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Performance of geopolymer concrete in fire

Mohd Ali, Ahmad Zurisman (2015) Performance of geopolymer concrete in fire. PhD thesis, Swinburne University of Technology.

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Abstract

Ordinary Portland Cement (OPC) concrete can be classified as a fire resistant construction material. However, spalling may occur in fire especially in high strength concretes. The need to address this spalling problem in fire has intensified since the use of high rise buildings. Geopolymer is a cementless concrete binder which is based on aluminosilicate reaction of fly ash, a power plant by-product and activated by alkaline solution. Recent research has shown that geopolymer concrete has great potential in resisting fire. In addition, without the presence of Portland cement in the concrete has led to more sustainable construction material since cement is the second highest CO2 emitter after fossil fuels. In this research, the severity of large scale high strength concrete spalling under hydrocarbon fire was investigated. The results show that high strength OPC concrete severely spalled during the first 30 minutes of fire exposure in explosive manner. There is a thermal diffusivity drop when the temperature is between 110oC and 155oC due to water in concrete changing phase to steam. Maximum steam pressure corresponds to 155oC temperature is 0.44 MPa which shows that steam pressure alone is not a critical factor for concrete spalling. Further investigations on factors affecting concrete spalling show that larger specimen spalled more than smaller scale specimen based on 3 m x 3 m walls, 1 m x 1 m walls, columns and cylinders. Aggregates size effect was also observed with increasing spalling with decreasing aggregate size. No obvious trend observed for different aggregate types (granite and basalt). For making geopolymer, fly ashes from Gladstone, Tarong and Microash were examined for physical properties. Gladstone fly ash demonstrated the best workability compared with Tarong and Microash. The reasons for workability differences were investigated and the conclusion was agglomerated particle size distribution was the cause Effect of dry and wet condition on strength of geopolymer was investigated. Strength reduction of 17% was observed. The high strength geopolymer 1 m x 1 m wall panels and two sizes of cylinders (150, 100 mm) were tested. From hydrocarbon fire test, high strength geopolymer concrete exhibited good fire resistance performance due to no explosive spalling observed. Two iii panels and all cylinders remained un-spalled. Less than 1% spalling (excluding moisture loss) observed on 2 spalled panels. There are 11% - 65% of residual strengths observed on fire tested specimens as compared to OPC which has no remaining strength. To investigate aggregate and geopolymer binder thermal incompatibility factor on spalling, aerated geopolymer panels were tested. From hydrocarbon fire test, no spalling observed was further proof of thermal incompatibility was the cause of spalling. Under room temperature, bearing load, axial load, corner bearing and flexural tests on aerated geopolymer panel were conducted. Results show that aerated geopolymer panel has the capacity and strength to be used as structural wall in fire application.

Item Type: Thesis (PhD)
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials
Depositing User: En. Sharul Ahmad
Date Deposited: 08 May 2016 07:11
Last Modified: 08 May 2016 07:11
URI: http://eprints.uthm.edu.my/id/eprint/7737
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