Experimental Study on Compressive Behavior of FRP-Confined Expansive Rubberized Concrete

Hassanli, Reza and Youssf, Osama and Vincent, Tom and Mills, Julie E. and Manalo, Allan and Gravina, Rebecca (2020) Experimental Study on Compressive Behavior of FRP-Confined Expansive Rubberized Concrete. Journal of Composites for Construction, 24 (4):04020034. pp. 1-14. ISSN 1090-0268


Abstract

This paper presents the results of an experimental study into the behavior of rubberized concrete-filled fiber-reinforced polymer tube (CFFT) columns, where the fiber-reinforced polymer (FRP) confining layer is prestressed by using an expansive agent (EA). The study focuses on utilizing the incompressibility property of rubber in improving the strength properties of crumb rubber concrete (CRC). A total of 27 CFFT columns were tested under axial compression and the effect of rubber content, prestress level, confinement amount and curing condition was studied. Different EAs with cement replacement ratios of 0%, 7.5%, and 15% were used to examine the influence of different levels of hoop prestress on the axial compressive behavior. The influence of amount of confinement was examined with specimens prepared with either one or two layers of CFRP. The influence of the curing condition was also examined by preparing half of the one-layer specimens with steel plates confining the specimens in the axial direction during curing. Finally, both flexible and stiff molds were used to examine the influence of mold stiffness on prestress development during curing. The lateral prestress provided by the expansive agent and FRP confinement was used to mitigate the typical strength reduction associated with CRC. The positive effect of this technique is two-fold. First, the pressure produced by the expansive agent compresses the cement paste and rubber particles together, reducing porosity and increasing interaction and interface friction between the rubber particles and cement paste. Second, rubber is generally considered nearly incompressible, with a Poisson's ratio of approximately 0.5, hence as the rubber is compressed in one direction, it expands significantly in the other directions. Using rubber in unconfined and non-prestressed concrete results in strength reduction; however, the combined effects of FRP-confinement and lateral prestress on CRC can lead to significant increases in the columns' axial stiffness and strength. The stresses and strains developed during curing for the expansive mixes were found to be considerably higher in CRC compared with conventional concrete (CC), indicating that an EA is more effective in developing prestress in rubberized concrete. Moreover, the mold stiffness was found to have a noticeable influence on the compressive strength of concrete. Using stiff molds resulted in unrealistic and unsafe strength evaluation and, hence, should be avoided if expansive concrete is used, or the results should be modified to account for the effect of confinement provided by the stiff molds. It was also observed that the confinement effect in CRC was higher compared with that of CC, which is due to the incompressibility of rubber. Finally, applying confinement plates to the ends of the concrete during curing had insignificant impact on the compressive behavior.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 05 Feb 2021 05:35
Last Modified: 10 Feb 2021 05:23
Uncontrolled Keywords: Compressive strength, Rubber, Synthetic materials, Concrete, Strength of materials, Fiber reinforced polymer
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090506 Structural Engineering
09 Engineering > 0912 Materials Engineering > 091202 Composite and Hybrid Materials
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400510 Structural engineering
40 ENGINEERING > 4016 Materials engineering > 401602 Composite and hybrid materials
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280110 Expanding knowledge in engineering
Identification Number or DOI: https://doi.org/10.1061/(ASCE)CC.1943-5614.0001038
URI: http://eprints.usq.edu.au/id/eprint/41149

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