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This paper explores the flexural behavior of carbon fiber reinforced polymer (CFRP) strengthened reinforced concrete (RC) beams. For flexural strengthening of RC beams, total ten beams were cast and tested over an effective span of 3000 mm up to failure under monotonic and cyclic loads. The beams were designed as under-reinforced concrete beams. Eight beams were strengthened with bonded CFRP fabric in single layer and two layers which are parallel to beam axis at the bottom under virgin condition and tested until failure; the remaining two beams were used as control specimens. Static and cyclic responses of all the beams were evaluated in terms of strength, stiffness, ductility ratio, energy absorption capacity factor, compositeness between CFRP fabric and concrete, and the associated failure modes. The theoretical moment-curvature relationship and the load-displacement response of the strengthened beams and control beams were predicted by using FEA software ANSYS. Comparison has been made between the numerical (ANSYS) and the experimental results. The results show that the strengthened beams exhibit increased flexural strength, enhanced flexural stiffness, and composite action until failure.

Tensile properties, deformation, and fracture behavior of a wrought nickel-base superalloy 720Li have been studied in standard solutionized and two-stage-aged condition in the temperature range of 25°C to 750°C. Effect of strain rate on tensile behavior was assessed at 25°C, 400°C, and 750°C at five strain rates that range between 10 -5 s -1 and 10 -1 s -1 . The yield strength and ultimate tensile strength of the alloy remained unaffected by temperature until about 600°C and 500°C, respectively, typical of superalloys strengthened by fine and coherent intermetallic Ni 3 Al-based precipitates. The flow stress of the alloy was found to be insensitive to the strain rates studied at 25°C and 400°C. However, at 750°C, the flow stresses showed strain rate sensitivity at strain rates <10 -3 s -1 . The strain hardening behavior at 25°C and 400°C were similar. At 750°C, stain hardening was observed only at strain rates >10 -3 s -1 , and at lower strain rates, tensile instability was seen to set in immediately after yielding. The alloy exhibited ductile dimple fracture at all the temperatures and strain rates studied. Microstructural investigations indicate that in regimes where flow stresses are insensitive to strain rate, deformation occurs through heterogeneous planar slip, whereas in strain rate sensitive regimes, thermally activated diffusion processes promote homogeneous deformation.

Currently, various types of recyclable materials are used in civil engineering applications. One of the future challenges in the civil engineering field facing sustainability and the bulk utilization of waste materials without affecting the performance of the product related to the civil engineering field. Presence of bulk amounts of disposed and demolished materials including aggregates and undecomposed recycled polymers can be recycled. The main aim of reducing environmental impact and also reduction in the cost. Present research focusing on recycled polymers as partial replacement of bitumen in addition to recycled coarse aggregate in different percentages are investigated for its feasibility used in road construction. To achieve the objectives of the current research, 6 batches of bituminous samples were prepared and each case considered three samples for repeatability. The first batch is considered as a control sample without adding Recycled Coarse Aggregates (RCA) and recycled polymer. The second batch consists of 15% partial replacement of bitumen using polymer without recycled aggregate. Remaining batches 3 to 6 were 15% partial replacement of bitumen with polymer and partial replacement of coarse aggregates using recycled coarse aggregate say 25%, 50%, 75%, and 100%. Each batch was tested by reliable and standard tests in order to determine the most efficient mix (batch). The testing methods followed in this investigation are sieve analysis test, impact test, Los Angeles test, penetration test and marshal test. The results of sieve analysis test showed that the fineness modulus value for RCA equals to 4% with uniform graded graph. The specific gravity test results showed that RCA specific gravity is 2.61 which indicates that RCA is considered as coarse grained soils. Moreover, the Impact test for RCA equals 9.3%. In addition, the result for Los Angeles for RCA value is 19.07% and comparing it with the standard and it should be less than 30% is suitable for road construction. Furthermore, penetration test results of 15% partial replacement of bitumen using polymer showed that the average value equals 58 mm compared to 63.7 mm for bitumen without polymer. Finally, the result obtained from the Marshall Stability test showed that batch 5 partial replacement of bitumen 15% using polymer and the partially replaced normal coarse aggregate 75% with RCA gives better results in all aspects. A fruitful conclusion from this study is to follow the approach of utilization of recycled coarse aggregate along with recycled polymers in road construction. Doi: 10.28991/HEF-2020-01-03-01 Full Text: PDF