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The effect of various reinforcements on the ablative composites has been discussed in this paper. The ability of phenolic resin to reside a char layer at high temperatures is the main reason to select it as a matrix. Analysis of the physical ablation process of a composite and low thermal conductivity of zirconium oxide is performed to produce Resole/carbon fabrics composites coated with a thin film of zirconium at the back side of the specimens. Different materials, such as carbon fabrics, glass fabrics, and also silica and zirconium powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconium. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 8.35 Mw/m2 at approximately 3000°C was used. It was found from ablation test that the erosion rates of the Resole/carbon fabric specimens are 20% lower than that of the other specimens. Additionally the high insulation index of the Resole/carbon fabrics coated with zirconium, indicates that these composites are the best ablative materials in the present study. SEM observations show that the thermo mechanical and thermo physical erosion effects are the most important factors that influence the ablation process. The proper adhesion between reinforcements and matrix is important to achieve improved ablative properties.

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The effect of various reinforcements on the ablative composites has been discussed in this paper. The ability of phenolic resin to reside a char layer at high temperatures is the main reason to select it as a matrix. Analysis of the physical ablation process of a composite and low thermal conductivity of zirconium oxide is performed to produce Resole/carbon fabrics composites coated with a thin film of zirconium at the back side of the specimens. Different materials, such as carbon fabrics, glass fabrics, and also silica and zirconium powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconium. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 8.35 Mw/m2 at approximately 3000°C was used. It was found from ablation test that the erosion rates of the Resole/carbon fabric specimens are 20% lower than that of the other specimens. Additionally the high insulation index of the Resole/carbon fabrics coated with zirconium, indicates that these composites are the best ablative materials in the present study. SEM observations show that the thermo mechanical and thermo physical erosion effects are the most important factors that influence the ablation process. The proper adhesion between reinforcements and matrix is important to achieve improved ablative properties.

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This experimental study is intended to evaluate the effectiveness of a Near Surface Mounted (NSM) technique using bars made of carbon fabrics (BMCF) for shear strengthening of RC beams. To delay the onset of BMCF debonding, a new anchorage is also developed and tested. When the amount of NSM FRP in shear strengthening of RC beams is low, the shear failure is likely to be due to debonding of individual FRP rod and in this case improved bond properties as well as proper anchoring of the FRP rods are likely to delay the failure of the beam. In this project an innovative bars made of carbon fabrics is produced by wrapping an FRP sheet around a wooden rod. BMCF provide a larger perimeter to cross sectional area ratio with respect to conventional FRP rods for the same amount of FRP used, providing potentially higher bond strength. In addition, the circular shape of BMCF is not only convenient for production but also suitable for NSM shear strengthening as noted by previous researchers. Another key advantage of introducing the BMCF is that it allows the incorporation of a novel anchor system that can be used to improve the performance of NSM BMCF reinforcement for shear strengthening of RC beams in applications with low FRP percentage. A distinguished benefit of the proposed anchor system is that it only requires the access to the beam sides for installation. This means that the proposed anchorage system can be conveniently applied to RC beams whose top and/or bottom face is inaccessible. A set of six shear deficient beam specimens were designed. All specimens had the same internal reinforcement arrangements. They were 200 mm wide, 250 mm high and 1650 mm long. One half of each beam was designed to be weak in shear as the test shear span while the other half was designed as the strong shear span. Only the test shear span was strengthened in shear with NSM BMCF with or without proposed end anchorages. The amount of steel shear reinforcement in the two sides was designed to ensure that shear failure would occur in the test span. All beams were simply supported at the ends and tested under a concentrated monotonic load applied at the mid-span. Test results presented in this paper have confirmed that the use of BMCF is an effective technique for improving the shear capacity of RC beams. The increase in the shear capacity was between 25 to 30% for beams strengthened with simple BMCF, and ranged between 41% and 48% for beams strengthened with anchored BMCF, compared with the reference beam. Beams strengthened with BMCF with end anchors exhibited excessive flexural cracking at their mid spans. The use of the end anchors also significantly enhanced the maximum strain in the BMCF. The load–deflection response of beams is presented, in addition to selected strain measurements. Performance and the failure modes of the test beams are studied and discussed.