Research On A New Cemeatitious Composites Of High Toughness And High Damping

Ultra high toughness cementitious composites is a new, outstanding fiber reinforced cement-based composites which is invented in recent years. This material’s superior toughness, unique multiple cracking characteristics, strain hardening properties, extensive product range and outstanding environmental protection, all of these significantly improve the seismic performance of concrete structures and flexural properties, that helps the structures achieving the goal of energy consumption by themselves, and with a good sense of sustainable development.This paper introduced the preparation of PVA-ECC process, and taked fiber content, water/cement ratio, silane coupling agent, the influence of fiber length as starting point,to study mechanical properties and damping properties of PVA-ECC, and the specific contents were illustrated:(1)By reading literature to determine the initial mix of PVA-ECC, and by the test of the fiber dispersion, mechanical properties and damping performance, constantly adjusting the mix, finally maked out a new cementitious composites which has characteristics of high toughness and high damping.(2) To improve the dispersion in the fiber in cement matrix, this paper added the substrate surface active agent, and the results show that the it can help to improve the dispersion of fibers in the matrix.(3) This paper taked four-point bending test research of PVA-ECC, and explored its ability of bending deformation. The results show that:in the matrix mixed with PVA fiber can obviously increase its strength and toughness, and the more dosage of pva fiber,the effect is better; improve the water-binder ratio can increase the toughness of the material but can reduce the strength; through the toughness index, the fiber surface with silane coupling agent can increase the toughness and the strength; the toughness of the fibre length of PVA-ECC also has certain influence, and long fiber effect is better; and appeares in the process of multiple cracking characteristics and strain hardening properties.(4) This paper taked the axial tensile test of PVA-ECC, the test results show that the increase of fiber content, improve the water/cement ratio, adding silane coupling agent and fiber length to diameter ratio can increase the ductility of the material, and the maximum tensile strain can be 2.8%;the tensile elastic modulus of PVA-ECC is lower than the pure matrix which shows that its stiffness is less and toughness is bigger, and through its deformation to release more energy.(5) This paper taked the damping ratio test of PVA-ECC, and summarized several main way of energy consumption. The test results show that increasing the fibre content, improving water/cement ratio, adding silane coupling agent can improve the damping performance of materials, and the maximum damping ratio can be 7.5%.