The external jacketing method using cement-based matrices and textile reinforcement has gained popularity for the enhancement of strength and ductility characteristics of reinforced concrete members. In this study, glass fiber–reinforced mortar (GFRM) with or without basalt textile reinforcement was used for external jacketing of low-strength concrete prisms. An innovative spraying method was used during the application of the cement-based matrix to the specimen’s surface. Investigations were carried out on a large number of concrete prisms with five different cross-sectional geometries (circular, square, and rectangular, with cross-sectional aspect ratios of 1.5, 2, and 3). At the end of the tests, it was shown that the proposed retrofit methodology is effective for the enhancement of performance of low-strength concrete members. The spraying technique is practical and feasible, particularly for the cases in which access to the structural members that are destined to be retrofitted is limited. Furthermore, a simple analytical approach based on the effectively confined concrete area concept is also presented for predicting the peak strength and the ultimate strains of the retrofitted specimens.
11 October 2016 in Bulletin of Earthquake Engineering
The proposed study combines sprayed glass fiber-reinforced mortar and basalt textile-reinforcement to harness the favorable properties of each component to obtain a composite material that can be used for strengthening of existing structures. This includes crack resistance and a bridging effect of glass fiber-reinforced mortar and the strength provided by the basalt mesh. In terms of weight, mortars containing two different glass fiber ratios (3.5% and 5%) were designed, and tensile and flexural tests were conducted on these mortar configurations. Moreover, the tensile and flexural tests were performed on the composite configurations containing one, two, and three layers of basalt fiber textile reinforcement in addition to 3.5% glass fiber. Maximum stress, cracked and uncracked modulus of elasticity, failure mode, and average tensile stress curve results were compared to determine each system’s mechanical parameters. When the glass fiber content increased from 3.5% to 5%, the composite system without basalt textiles’ tensile behavior slightly improved. The increase in tensile strength of composite configurations with one, two, and three layers of basalt textile reinforcement was 28%, 21%, and 49%, respectively. As the number of basalt textile reinforcements increased, the slope of the hardening part of the curve after cracking clearly increased. Parallel to the tensile tests, four-point bending tests showed that the composite’s flexural strength and deformation capacities increase as the number of basalt textile reinforcement layers increase from one to two.
The mechanical performance of laminated panels manufactured from beech (Fagus orientalis) wood was enhanced by reinforcement with aramid fibers. Specimens were organized into three primary groups: (i) a solid (control) group, (ii) laminated groups composed of two and three layers without aramid reinforcement, and (iii) laminated groups incorporating one or two layers of aramid fiber reinforcement. Results of compressive strength tests revealed that both laminated and aramid-reinforced laminated specimens exhibited improved performance compared to the control group. Static bending strength was improved by lamination alone, and inclusion of aramid reinforcement in the lamination interface gave further enhancement. Lamination by itself did not yield a statistically significant improvement in the modulus of elasticity in static bending. A significant increase in the modulus of elasticity was observed only when aramid fibers were embedded in the lamination interface. Moreover, dynamic bending strength was substantially improved by the incorporation of aramid reinforcement into the laminated structure. The enhancement ratios were 63.4% for two-layer laminates with one aramid layer and 123.5% for three-layer laminates with two aramid layers. These findings indicate that aramid fiber reinforcement is an effective strategy for improving the mechanical performance of laminated wood composites.