This paper aims to investigate the flexural behaviour of the rubberized and hybrid rubberized reinforced concrete beams. A total of fourteen beams, 150×200 mm in cross-section with 1000 mm in length, were subject to a laboratory test over an effective span of 900 mm. The sand river aggregate was replaced by 10%, 12.5%, and 15% of crumb rubber (volume). The hybrid structure contained two double layers: 1) rubberized reinforcement concrete at the top layer of the beam and 2) reinforcement concrete at the bottom layer of the concrete beam. The static responses by the flexural test of all the beams were evaluated in terms of their fresh properties, failure patterns, total energy, flexural strength, stiffness, and ultimate deflection, modulus of rupture, strain capacity, and ductility index. The results showed that there were improvements when the hybrid beams were used in most cases such as failure pattern, ultimate load, stiffness, modulus of rupture, and stress. The rubberized concrete beams showed improvements in the strain capacity as illustrated in strain gauges and stress-strain curves, toughness, ultimate deflection, and ductility index. The findings of the study revealed an improved performance with the use of the hybrid beams. This has resulted in the implementation of innovative civil engineering applications in the engineering sustainable structures.
One of the problems experienced by reinforced concrete (RC) structures, whether a mistake at the design phase or a change in building use, is an overload. The goal of this study is to determine whether ultra-high-performance fiber-reinforced concrete (UHPFRC) is effective in repairing damaged concrete columns utilizing 30 mm thin concrete jacketing made of different steel fibers at various contents with varied aspect ratios (28, 37, and 45). Nine pieces of 500 mm long RC column specimens with a cross-sectional size of 150 mm × 150 mm were cast as part of the experimental program. By loading these columns with roughly 90% of their actual ultimate axial load capacities, damage was caused, and the columns were subsequently strengthened and rebuilt using UHPFRC jacketing materials. The results demonstrated that when steel fiber content increased, so did the mechanical qualities, such as compressive and tensile strengths. Rehab materials that contained 0.5% steel fiber recovered 138% of their maximum load-bearing capacities, while materials that contained 1.5% steel fiber recovered 164% of their original capacities, which were roughly 1.38–1.64 times that of the unjacketed reference column. Additionally, it was observed that employing steel fiber in UHPFRC contents in these approaches resulted in the ultimate displacement being improved from 2.91 to 5.53 mm at 1.5% of steel fiber content, which is an increase of almost double that of control specimens.
This current study attempts to investigate the mechanical, durability as well as rheology properties of Ultra-High Performance Concrete (UHPC) with low cement content and using coarse aggregate. The cement content used in UHPC mix in current study was 800 kg/m3. The slump flow, compressive strength, splitting tensile strength, modulus of elasticity, water absorption and water penetration tests were conducted to determine the workability, mechanical and durability properties of explored UHPC mixture. The test results show that the above properties were exceptional and comparable with other UHPC mixtures.
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