Circular geopolymer concrete columns with composite rebars

Robertson, Matthew (2015) Circular geopolymer concrete columns with composite rebars. [USQ Project]

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Reinforced concrete (RC) is one of the most popular construction materials. Columns are critical to the safety as well as the performance of the structure. RC columns traditionally use Portland cement as a main ingredient for the cement as well as using steel bars and stirrups for reinforcement. One major problem encountered by RC columns is the corrosion of the reinforcement cages, which can result in deterioration of the concrete, loss of serviceability as well as, in extreme cases, brittle failure of the entire structure. This has resulted in the search for a product that will not corrode but still has similar behaviour. This search lead to the trial of glass fibre reinforced polymer (GFRP) material, which is made from high strength glass fibres surrounded by polymer matrices and shaped in the form of bars, tubes and grids.

Another major problem is the issue of global warming. There is major concern over the amount of C O2 released by Portland cement. Due to modern day societies being extremely environmentally conscientious, an alternative product is needed to reduce this. This has resulted in the product which is known as geopolymer cement. Geopolymer concrete has been used in many projects around the world, and has been found to have the same strength as concrete.

To test these two promising materials, six specimens were created, with the parameters of spacing between transverse reinforcement and type of transverse reinforcement varied. Each specimen was then tested through the application of axial loading with the internal longitudinal, internal transverse and external concrete strain recorded.

The obtained resulted stated that both GFRP hoop and spiral ties are effective in pro- viding confinement to a GFRP reinforced geopolymer column. The results also show that the spiral ties are slightly more effective, due to having a higher ultimate load, ductility as well as confinement efficiency. These findings are why it is recommended that the spiral ties be used if GFRP reinforced geopolymer concrete is to be used within the construction industry. This study differs from other studies as the effect of the longitudinal GFRP bars on the behaviour of the specimen has been included. It was calculated that the longitudinal bars resulted in an increase in strength between 6-9% of the entire specimen. This contribution from the longitudinal bars is not quite as much as the contribution of steel reinforcement (12%) however, are still significant enough to avoid being neglected. A theoretical analysis was also performed to find an accurate equation to predict the axial capacity of the specimens. It was found that the equation 5.5 shown in this report was the most accurate from existing literature. This equation does not result in an accurate prediction of the capacity of the specimens. This was due to the strength reduction factor (α1) used being calculated for ordinary Portland cement concrete. An accurate prediction can be obtained if a strength reduction factor of 0.91 is used.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Civil Engineering with Honours project
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Manalo, Allan
Date Deposited: 31 May 2016 00:34
Last Modified: 31 May 2016 00:34
Uncontrolled Keywords: geopolymer, composite rebars, reinforced concrete, glass fibre
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090599 Civil Engineering not elsewhere classified
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400599 Civil engineering not elsewhere classified

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