EXPERIMENTAL STUDY ON ANTI-CORROSION OF CORN STRAW AND ITS EFFECT IN SILT IMPROVEMENT

Due to the characteristics of low cohension and poor water stability, the silt using in the civil engineering is limited. Corn straw can have high tensile strength and is known as a good natural and enviromental protection fiber. This paper examines the reinforcement effect of the corn straw after preservation treatment in silt. It applies the antiseptic treatment to corn straw. It proposes a new concept of utilizing corn straw to reinforce soil. A series of tests are conducted to verify this idea. Fristly the tensile strength of corn straw is tested and the straw barks without stem node is selected to be samples because of its higher strength. Then the samples are soaked into the Kathan, Sodium diacetate and Polyvinyl alcohol solutions individually for some time. Their tensile strength are tested to compared their antiseptic ability. Test results show that the straw which soaked in the three antiseptic solutions and after waterlogged have higher tensile strength than that of natural straw. The antiseptic effect of polyvinyl alcohol is the best. The sample at 12 weeks after the treatment with polyvinyl alcohol has the tensile strength of about 160% of the nature straw. Microscope photographs and weighing test are carried out on the samples soaked into the polyvinyl alcoho. The results show that the straw can reach saturation after three days of immersion. The corn straw antiseptically treated with polyvinyl alcohol is then added into the silt and the triaxial tests are tested for the compacted silt samples. The strength increasing of silt reinforced with corn straw is mainly embodied in the cohesion. The increase is about 100% as much as pure soil, which contribute to water stability of silt; the curves of stress-strain relationship of reinforced soil come to exhibit a hardening character, which is different to the softening character of pure soil. The failure mode of reinforced soil is comparatively complete, which is different to shear failure modes of pure soil. These kind of phenomena show that the ability of silt to resist the external load is improved by corn straw fiber.