Experimental Study On Flexural Behavior Of Reinforced Concrete Beams Strengthened With Textile Reinforced Concrete

Textile Reinforced Concrete(TRC) is a new type of composite materials,which mainly refers to using alkali-resistant fibers(such as carbon fiber,aramid fiber, AR-glass fiber) fabrics to reinforce the high-performance fine aggregate concrete (mortar).TRC strengthening technology is a new method to strengthen the concrete structure,and this technology has more advantages in simple construction,wide-spread application,corrosion resistance and plasticity that steel unmatched with.TRC can be made into thin-layer structures,because non-metallic fabrics do not corrode in the concrete,which almost have no effect on weight and sectional dimension of the old structure when strengthening concrete structure.Compared with the FRP strengtheing technique,TRC strengthening technique uses cement-based inorganic material for interface adhesive between new and old concrete,which makes it better compatibility, co-ordination and mutual permeability between strengtheing layer and the old concrete structure,and it has advantage in better anti-aging,high temperature resistance, durability,good economic.Therefore,it is a new type of strengthening technique with higher value of theoretical research and market development prospects.Interface bonding properties of TRC strengthened concrete members and flexural performance of TRC strengthened RC beams are experimental investigated and theoretical analyzed in this article.The specific research works are as follows:(1) Based on the double-shear model,the shear experiment research on TRC strengthening layer and the old concrete columns are performed in this paper.The effects of different interfacial techniques on the shear properties,i.e.artificial chiseling and reinforced bar planting,are investigated,and the influence law of different roughness and ratio of planting reinforced bar on the interface shear strength are studied. The experimental results show that the bonding behaviour between TRC sheet and old concrete are improved prominently by the above two different interfacial techniques. The shear strength of specimens increases greatly when the technique of artificial chiseling is used,and the range of 2.0-4.0mm is recommended as the best average sand-pouring depth.Furthermore,reinforced bar planting can also improve the shear strength and ductility of the specimens,but the ratio of improvement is subject to anti-splitting capacity of TRC strengthening layer.(2)Flexural performance study on 10 RC beams strengthened with TRC and two reference beams are presented.Two main change parameters are considered in test beams:the number of textile layers using in TRC and the anchorage system of strengthening layer in bond zone.The effects on failure characteristics,mechanics performance of bending resistance and crack development of strengthened beams are analyzed.The experimental results show that,TRC strengthening layer can effectively improve the flexural bearing capacity of RC beams,and the more textile layers increase, the higher improving rate increase with non-linear proportion relationship.The stiffness of strengthened beams is enhanced,and its limit deformation is reduced,but the strengthened beams still have good ductility;TRC strengthening layer can effectively inhibit the development of cracks,so that the crack form of strengthened beams has "thin and dense" characteristics;TRC strengthening layer can cooperate with the old concrete members well and the required anchorage length for flexural strengthening is relatively short.(3) On the basis of experimental research and analysis,the cracking load calculation formula and the limit flexural capacity calculation formula in different flexural failure mode are derived.The calculated results with formulas recommended in this article close to the experimental values,they may supply with the reference in actual design of strengthening works.(4) Finally,the construction technology on using TRC for strengthening is presented in this article according to engineering application practice.Based on the reaserch on flexural behavior of RC beams strengthened with TRC, not only the research directions of TRC are expanded in domestic,but also some reliable references and basis are provided for studying and developing the strengthening technique of TRC further.Therefore,it has important practical significance for popularizing and applying this strengthening technique.