Abstract
Research on the utilization of recycled concrete in civil engineering applications is gaining popularity world-wide due to the increased efforts to promote preservation of the environment and sustainable development. Recycled concrete is, however, presently still limited to nonstructural applications. This is due to the poor mechanical properties of recycled concrete, which make it difficult to cope with complex mechanical environments. Therefore, an experimental work is presented to investigate the mechanical behaviour of recycled concrete, focusing on the cube, flexural, and uniaxial compressive mechanical properties of steel-polyvinyl alcohol fibre-doped specimens. The test results showed that the compressive strength and the flexural strength of the recycled concrete increased by 6.0% and 55.2%, respectively, when steel fibre was single-incorporated. The cubic compressive strength of the recycled concrete decreased by 14.1% when polyvinyl alcohol fibre was single-incorporated, but there was a 47.9% increase in the flexural strength of recycled concrete. Based on these tests, the elastic modulus, the Poisson’s ratio, and the uniaxial compression toughness were digitised to derive mathematical expressions that provided a theoretical understanding of the mechanical properties of steel-polyvinyl alcohol fibre-reinforced recycled concrete. Moreover, combining the characteristics of the uniaxial compressive stress–strain curve of fibre-reinforced recycled concrete, an equation for the uniaxial compressive stress–strain curve of recycled concrete associated with the fibre characteristic value was established, which agreed well with the test results.
Highlights
Hybrid fibre-reinforced concrete (HFRC) is a mixture of two or more fibres mixed into the concrete matrix to form a new composite material that can achieve different fibres to complement each other’s strengths and advantages
Banthia [1], Qian [2], and Li [3] mixed steel and polypropylene fibre into concrete in different proportions to carry out mechanical properties tests, and the results showed that mixing different fibres into concrete could significantly improve the compressive and flexural strengths
Mehran [4] mixed steel fibre, polypropylene fibre, and glass fibre into concrete and carried out a semicircular bending test (SCB), which showed that the hybrid fibre enhanced the ductility and load-bearing capacity of the concrete, with the glass fibre enhancing the ductility of the concrete and the steel fibre improving the energy absorption capacity of the concrete
Summary
Hybrid fibre-reinforced concrete (HFRC) is a mixture of two or more fibres mixed into the concrete matrix to form a new composite material that can achieve different fibres to complement each other’s strengths and advantages. Basalt fibre is made from basalt stone molten at 1450–1500 ◦ C and drawn at high speed through a platinum–rhodium alloy drawing funnel It has high strength and has a variety of excellent properties such as electrical insulation, corrosion resistance, and high temperature resistance. Banthia [1], Qian [2], and Li [3] mixed steel and polypropylene fibre into concrete in different proportions to carry out mechanical properties tests, and the results showed that mixing different fibres into concrete could significantly improve the compressive and flexural strengths. Vishaul [5] chose to mix alkali-resistant glass fibre and coconut bark fibre into concrete to study the effect of hybrid fibre on the mechanical properties of concrete, and the test results showed that hybrid fibre can enhance the compressive strength and tensile strength of concrete; the impact resistance had improved. Based on the above research, it has been shown that HFRC has incomparable advantages over single-fibre-reinforced concrete, and it improves the mechanical properties of concrete in many aspects and multiple dimensions
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