12 research outputs found
Performance of fire-damaged concrete beams strengthened with NSM laminates embedded in cement-based and epoxy adhesives
No full textThis thesis is concerned with the suitability and effectiveness of the CFRP NSM laminate strengthening system to repair concrete after exposure to high temperature. The thesis begins with the assessment of the mechanical properties of concrete at various temperature exposure levels. The study is then extended to prisms damaged by heating and subsequently repaired with NSM CFRP strips using epoxy and cement-based adhesive. The main purpose is to investigate the effect of high temperature on the flexural behaviour of beams, and repair of RC beams damaged by elevated temperature using NSM CFRP embedded with a bonding agent. Based on experimental results of specimens damaged by heating and subsequently repaired with CFRP laminates using epoxy and cement-based adhesives, finite element models (FEAs) were developed, using ATENA-GiD software to simulate the behavior of both unheated and heat-damaged RC beams strengthened with NSM laminates embedded in epoxy and cement-based adhesives
Experimental Investigation on High Performance Green Concrete (HPGC) Produced with Iron Filings
No full textThe acronym "HPGC" refers to "high performance green concrete." This breakthrough is significant because it moves the industry closer to its goal of replacing concrete with eco-friendly alternatives that claim superior mechanical qualities, thereby making concrete a more sustainable building material. When working with metal, a fine powdery dust known as "iron filings" is inevitably created. The purpose of this study was to evaluate the usefulness of iron filings as a fine aggregate in building projects. An experiment was conducted to examine the mechanical iron filings' effects on concrete's characteristics utilised as a supplement to sand. Using a range of sand replacement percentages (0% (control mix), 10% (treatment mix), 20% (treatment mix), and 30% (treatment mix)), the compressive, split-tensile, and flexural strengths of 35 concrete specimens consist of cubes, cylinders, and prisms were tested after 28 days of treatment in water. The findings indicated that the mechanical qualities of HPGC were enhanced when iron filings were used in place of sand, but that the concrete's slump value and workability were diminished. Therefore, only 30% of the sand (fine particles) should be substituted by weight with iron filings in the concrete mix, depending on the desired strength attribute. In this case, the concrete's compressive strength is increased by 13.2%, split-tensile strength by 21.1%, and flexural strength by 49.88%, all by replacing 30% of the sand (fine particles) with iron filings. Therefore, employing iron filings in concrete will help with recycling and waste reduction
Modelling of NSM CFRP strips embedded in concrete after exposure to elevated temperature using epoxy adhesives
No full text
Performance of heat-damaged partially-insulated RC beams strengthened with NSM CFRP strips and epoxy adhesive
No full textExperimental and numerical study of strengthening of heat-damaged RC beams using NSM CFRP strips
No full textBond Behavior between NSM CFRP Strips and Concrete Exposed to Elevated Temperature Using Cement-Based and Epoxy Adhesives
No full textThe flexural response of hybrid beams strengthened with fiber polymer rebars
No full textThe current study aimed to examine the value of applying the hybridization approach to study the flexural behavior of hybrid reinforced concrete beams including two different concrete types: normal strength concrete and reactive powder concrete. In addition, carbon fiber-reinforced polymer bars and glass fiber-reinforced polymer bars were bonded in the tension face of the hybrid RC beams utilizing the near-surface-mounted technique. Eight simply supported reinforced concrete beams were tested. The hybridization technique enhanced the flexural behavior and increased the first crack and ultimate loads. Furthermore, the hybrid beams are stiffer than that of a normal beam, and it became even stiffer as the reactive powder concrete layer thickness increased. The hybrid beams that were strengthened with carbon fiber-reinforced polymer bars displayed higher load capacity by about 20% more than those strengthened with glass fiber-reinforced polymer bars
Revolutionizing Recycled Aggregate Concrete: A Dual Approach Using HCl Treatment and Silica Fume
No full textDebris from building and demolition projects, as well as the shortage of natural resources, have become more pressing issues on a global scale in recent times. Even though concrete, the utmost adaptable building material, is a vital factor in the development of the infrastructural and industrial sectors, it has been claimed that it is not an environmentally friendly material due to its potential for profound environmental influence beyond its use and critical resource-consumption nature. Nevertheless, it will continue to be the dominant building material utilized globally. The present research aims to investigate the synergistic effects of the treatment of recycled concrete aggregate (RCA) by hydrochloric acid (HCl) and the replacement of cement by silica fume (SF) on the mechanical properties of produced concrete. Four groups of concrete mixes were prepared: (1) untreated recycled concrete aggregate (URCA), (2) HCl-treated recycled concrete aggregate (TRCA), (3) URCA with SF replacement, and (4) TRCA with SF replacement. The HCl treatment was applied at four molarities (0.2M, 0.4M, 0.6M, and 0.8M), while SF was used to replace cement by weight at four ratios (5%, 10%, 15%, and 20%). The results were evaluated in terms of the 7, 14, and 28-day compressive strength. The findings indicated that TRCA mixes significantly outperformed URCA mixes in terms of the mechanical properties, namely the 28-day compressive strength, in which the optimal mix was that with 100% TRCA by 0.4M HCl combined with 5% SF replacement. The results also demonstrated that 0.6M HCl treatment significantly enhanced the quality of RCA by removing weakly adhered mortar, leading to a nearly 21% rise in the 28-day compressive strength compared to URCA with complete replacement. Indeed, adding further SF enhanced the performance, as using 75% of TRCA+10% SF achieved the highest compressive strength of 38.7 MPa at 28 days, equalling around 25% improvement over the URCA with the same replacing level. Doi: 10.28991/CEJ-2025-011-05-08 Full Text: PD
Efficacy of Plastic Waste Strips Towards Enhancement of Shear Capacity of Reinforced Concrete Beams
No full textThe amount of plastic waste produced worldwide has been steadily rising. Manufacturing processes, service industries, and municipal solid waste produce a significant amount of waste plastic. One common construction and industrial waste that could be employed as shear reinforcement in concrete beams for specified purposes is the plastic waste strips, since they have relatively high tensile strength. Such plastic strips are used to tie clay bricks, floor finishing tiles, walkway finishing blocks, curbstones, and so on in different industrial products. This study examines an approach that uses plastic waste strips in place of conventional stirrups to enhance the shear performance of reinforced concrete (RC) beams. A set of shear tests was performed on carefully constructed 150 mm width × 225 mm depth × 1400 mm length beam specimens to evaluate failure mechanisms, modes of failure, crack patterns, and shear strength. All beams have the same flexural requirements, so they were ensured to fail by exceeding their shear strength under the applied load. This study examined five concrete beams that were reinforced internally using plastic waste strips in the shear region, as well as one control beam. The tested beams were reinforced using various strip spacings and configurations. The results of the tests indicated that increasing the plastic waste strips improved the concrete section shear strength. As the number of plastic strips in the section increases, the distance between each strip is drastically reduced, increasing the shear capacity of the beam. The experimental results indicate that the beam with six vertical plastic waste strips in its section has a 75% higher shear strength capacity than the reference beam without any transverse reinforcement. In addition, shear resistance is higher in the beam with plastic strips at 45° and 135° inclined angles than in the beam with vertical plastic strips in the same amount of plastic strips. Based on these findings, reinforced concrete beams can be utilized for specific purposes by employing plastic waste strips as transverse reinforcement to resist internal shear forces
