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纤维混凝土较普通混凝土具有更加优异的阻裂、增强和增韧效果,能更好地满足现代混凝土工程设施的要求。作者以高强、高弹模、低密度的捻制超高分子量聚乙烯(UHMWPE)纤维作为增强体,试验研究一种新型纤维混凝土的准静态力学性能。通过改进制备流程,研制C70等级的4种纤维体积掺量纤维混凝土,通过劈裂抗拉、立方体抗压和棱柱体轴心压缩试验,研究纤维掺量对混凝土强度和变形性能的影响。最后,试验结果与未处理UHMWPE纤维混凝土及聚丙烯纤维混凝土进行对比。结果表明:改进的制备工艺提高了纤维在混凝土中的分散均匀性,改善了混凝土的和易性;纤维使混凝土试件破坏时保持了良好的整体性,避免了大量碎块的脱落;UHMWPE纤维显著提高了混凝土劈裂抗拉强度,当纤维掺量为0.3%~1.0%时,强度提高率为47.2%~78.6%;纤维对混凝土单轴抗压强度作用不明显,但极大改善了残余抗压强度;压缩峰值应变及泊松比随纤维掺量增加而增大,弹性模量则相反,压缩韧性指数ηc15.5为素混凝土的1.40倍~2.53倍;捻制UHMWPE纤维较其他两种纤维更加显著地改善了混凝土的劈裂抗拉强度,并对单轴抗压强度有一定的增强效果。
Compared with ordinary concrete, fiber reinforced concrete has more excellent resistance to cracking, strengthening and toughening, which can better meet the requirements of modern concrete engineering facilities. The author studied the quasi-static mechanical properties of a new kind of fiber reinforced concrete by using UHMWPE fibers with high strength, high elastic modulus and low density as reinforcements. Through improving the preparation process, four kinds of fiber volume fraction fiber concrete with C70 grade were developed. The influence of fiber content on the strength and deformation performance of concrete was studied by splitting tension, cube compression and prism axial compression test. Finally, the test results are compared with untreated UHMWPE fiber-reinforced concrete and polypropylene fiber reinforced concrete. The results show that the improved preparation process improves the uniformity of fiber dispersion in concrete and improves the workability of concrete. The fiber keeps the integrity of the concrete specimen and avoids the shedding of a large number of fragments. The UHMWPE fiber The splitting tensile strength of concrete was significantly increased. When the fiber content was 0.3% ~ 1.0%, the strength increasing rate was 47.2% ~ 78.6%. The effect of fiber on the uniaxial compressive strength of concrete was not obvious, but the residual Compressive strength, compressive peak strain and Poisson’s ratio increase with the increase of fiber content, but the modulus of elasticity is the opposite, the compressive toughness index ηc15.5 is 1.40 times to 2.53 times that of plain concrete; twisting UHMWPE fiber than the other two Fibers more significantly improve the splitting tensile strength of concrete, and the uniaxial compressive strength of a certain degree of enhancement.