Abstract
In this study, the effect of fly ash characteristics, the content of the fly ash and mix proportion of the Fly Ash-Based Geopolymer Concrete (FBGC) on the bond strength between the FBGC and steel reinforcement were examined. Australian fly ashes from five different sources (Eraring, Mt-Piper, Bayswater, Gladstone and Collie) were used in producing FBGC. A total of 45 FBGC mixes with different fly ash content (300, 400 and 500 kg/m3) and different proportions of alkaline activator were prepared. The use of different fly ashes and in different amounts showed significant differences in the bond strength between the FBGC and steel reinforcement. It was found that the fly ash characteristics including particle size distribution and the content of SiO2 Al2O3 and CaO influenced the bond strength of the FBGC significantly. The results showed that the FBGC that was mixed with Gladstone (GL) fly ash exhibited the highest average bond strength between the FBGC and steel reinforcement (25 MPa). While the FBGC that was mixed with Bayswater (BW) fly ash showed the lowest average bond strength between the FBGC and steel reinforcement (10 MPa). The results also indicated that the increase in the fly ash content in the FBGC significantly increased the bond strength between the FBGC and steel reinforcement. The bond strength of the FBGC responded differently to changes in the Na2SiO3/NaOH ratio in the alkaline activator corresponding to the use of different fly ash.
Highlights
Geopolymer concrete is developing as an environmentally friendly alternative to PortlandCement Concrete (PCC)
The results showed that the Fly Ash-Based Geopolymer Concrete (FBGC) that was mixed with Gladstone (GL) fly ash exhibited the highest average bond strength between the FBGC and steel reinforcement (25 MPa)
That was mixed with BW fly ash showed the lowest bond strength between the FBGC and steel reinforcement where the average bond strength was 10.3 MPa
Summary
Geopolymer concrete is developing as an environmentally friendly alternative to Portland. The use of fly ash (by-products of coal combustion in power stations) in producing geopolymer concrete is gaining more interest by many researchers across the world. This is because the fly ash is one of the cheapest aluminosilicate materials which is rich in silica (SiO2 40%-70% by weight) and alumina (Al2O3 15%-30% by weight) [2, 3]. The existing studies did not investigate the effect of using different fly ash sources (different characteristics) and different mix proportion on the bond strength between the FBGC and steel reinforcement. The present study examines the effect of different fly ash sources (five different Australian fly ash sources) and different mix proportion of the FBGC (three different fly ash contents and three different weight ratios of Na2SiO3/NaOH) on the bond strength between the FBGC and steel reinforcement
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