改性合成纤维混凝土弯曲及抗冲击试验

针对普通混凝土道面易开裂、使用寿命无法达到设计寿命的情况,在普通混凝土中加入合成聚丙烯纤维及聚丙烯腈纤维,以提高混凝土的抗弯拉开裂性能及冲击韧性。对改性合成聚丙烯纤维混凝土及聚丙烯腈纤维混凝土进行了四点弯曲试验,并采用自行设计的冲击试验装置进行了冲击试验及经冻融循环后冲击试验。试验结果表明:在几乎不影响抗压强度的情况下,长度20、40 mm的合成聚丙烯纤维可以显著提升混凝土的抗弯韧性和冲击次数,经冻融后合成聚丙烯纤维混凝土的冲击次数下降幅度明显低于普通混凝土; 在抗弯韧性及抗冲击性能方面,改性合成聚丙烯纤维改善效果最佳,聚丙烯腈纤维次之,而长度40 mm的合成聚丙烯纤维又略强于长度20 mm的合成聚丙烯纤维; 在抗弯韧性方面,掺有长度40 mm合成聚丙烯纤维混凝土相较素混凝土提升了60.09%～120.62%; 未经冻融前掺有长度40 mm合成聚丙烯纤维混凝土在冲击试验中的初裂冲击次数和破坏冲击次数均为最高,相较素混凝土分别提升了114.29%～157.14%和120%～306.67%,相较于掺有长度为20 mm合成聚丙烯纤维的混凝土分别提升了5.56%～23.53%和15.15%～35.90%,相较于掺有聚丙烯腈纤维的混凝土分别提升了5.56%～13.33%和36.36%～60.66%; 试验结果可为混凝土道面的建设提供参考依据。

Bending and Impact Test on Modified Synthetic Fiber Reinforced Concrete

Aiming at the situation that ordinary concrete pavement was easy to crack and service life cannot reach the design life, synthetic polypropylene fiber and polyacrylonitrile fiber were added to ordinary concrete to improve the flexural performance and impact toughness of concrete. Four-point bending tests were carried out on modified synthetic polypropylene fiber reinforced concrete and polyacrylonitrile fiber reinforced concrete. The impact test and the impact test after freeze-thaw cycles were carried out by a self-designed impact test device. The test results show that the synthetic polypropylene fibers with lengths of 20 mm and 40 mm can significantly improve the flexural toughness and impact times of concrete without affecting the compressive strength. The impact times of synthetic polypropylene fiber concrete after freeze-thaw are significantly lower than those of ordinary concrete. In terms of flexural toughness and impact resistance performance, the modified synthetic polypropylene fiber has the best improvement effect, followed by polyacrylonitrile fiber, and the synthetic polypropylene fiber with a length of 40 mm is slightly stronger than the synthetic polypropylene fiber with a length of 20 mm. In terms of flexural toughness, compared with plain concrete, the concrete with 40 mm synthetic polypropylene fiber increased by 60.09%-120.62%. The initial crack impact times and failure impact times of concrete mixed with synthetic polypropylene fiber with a length of 40 mm before freezing and thawing are the highest in the impact test, which are 114.29%-157.14% and 120%-306.67% higher than those of plain concrete, and 5.56%-23.53% and 15% higher than those of concrete mixed with synthetic polypropylene fiber with a length of 20 mm. The test results can provide reference for the construction of concrete pavement.