硫酸盐腐蚀对混杂纤维混凝土弯曲韧性的影响研究

Effect of Sulfate Corrosion on Flexural Toughness of Hybrid Fiber Reinforced Concrete

为了研究混杂纤维混凝土经硫酸盐腐蚀后的弯曲性能,首先对不同掺量的聚乙烯纤维(PE)与聚丙烯粗合成纤维(HPP)混凝土进行了硫酸盐干湿循环腐蚀和长期浸泡腐蚀试验,然后以三分点弯曲试验为基础,结合美国ASTMC1018和奥地利ORS评价方法,对比分析了混杂纤维混凝土在硫酸盐腐蚀前后其弯曲韧性变化及最佳纤维掺量。结果表明,纤维的掺入使得混凝土的破坏类型发生了变化,破坏时的最大荷载和挠度均明显增大,混凝土I_5、I_(10)、I_(20)、R_(5,10)和R_(10,20)显著提高,韧性水平也明显高于普通混凝土;在硫酸盐腐蚀作用后不同纤维掺量的混凝土其弯曲韧性均出现了不同程度的下降,其中干湿循环腐蚀条件下比长期浸泡腐蚀条件下的混凝土的弯曲韧性受损更为严重;聚乙烯纤维(PE)与聚丙烯粗合成纤维(HPP)掺量为0.8%~1.2%的混凝土在经受450 d长期浸泡腐蚀作用后的I_5、I_(10)与R_(5,10)值分别提高了32.2%、19.6%和6.8%,具有良好的耐硫酸盐腐蚀性能和弯曲韧性。

In order to study the flexural properties of hybrid fiber reinforced concrete after sulfate corrosion,the sulfate dry-wet cycle corrosion and long-term immersion corrosion tests were carried out to study the effect of different content of polyethylene fibers（ PE） and polypropylene crude synthetic fiber（ HPP） concrete. Then,based on the three-point bending test,the flexural toughness of mixed fiber concrete before and after sulfate corrosion and the optimum fiber content were compared with ASTMC1018 of USA and ORS of Austrian standard. The results show that the failure mode of concrete is changed by the incorporation of fiber,the maximum load and deflection of the concrete are obviously increased,the I5、I（10）、I（20）、R（5,10） and R（10,20） of concrete are obviously improved,and the toughness level is also obviously higher ordinary concrete. The flexural toughness of the concrete with different fiber content in the presence of sulfate has been damaged to varying degrees. The flexural toughness of the concrete under the wet and dry cycle corrosion condition is more serious than that under the long-term immersion corrosioncondition. When the content of polyethylene（ PE） and polypropylene crude synthetic fiber（ HPP） is between 0. 8% and 1. 2%,the concrete exhibits good corrosion resistance and flexural toughness,after 450 d long immersion corrosion, I5、I（10）and R（5,10） are increased by 32. 2%,19. 6% and 6. 8%respectively.