This paper aimed to explore the performance of concrete with iron tailings sand modified by polypropylene fibers under aggressive environment. Three kinds of concrete (ordinary concrete, concrete with iron tailings sand (ITS), and concrete with ITS modified by polypropylene fibers) were exposed to drying-wetting cycles in 5% Na₂SO₄ solution for 28, 56, 84, 112, and 140 days. The performance, such as pores distribution, crack width, corrosion products, mass variation, expansion variation, compressive strength, flexural strength, and the diffusion of sulfate ion were measured at regular time intervals during the whole exposure period to describe the associated evolution laws. The results show that, in the process of the corrosion of sodium sulfate solution, the formation of gypsum and ettringite (AFT) has an important impact on the harmful pores (>0.1 μm), cracks, mass variation, expansion variation, compressive strength, and flexural strength of the three concrete. Polypropylene fibers can refine the pores development and inhabit the crack development of the concrete with ITS, further alleviating the rate of sulfate ion attack on concrete and the rate of increase of corrosion products, so that the mass variation, the expansion variation, and the reduction of compressive strength and flexural strength can be limited effectively. Furthermore, in the concrete with ITS modified by 0.1% polypropylene fibers, the content of sulfate ions diffused is always the lowest.

中文翻译：

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侵蚀环境下聚丙烯纤维改性铁尾矿砂的混凝土性能。

本文旨在探讨在侵蚀性环境下用聚丙烯纤维改性的铁尾矿砂混凝土的性能。在5％Na ₂ SO ₄中将三种混凝土（普通混凝土，含铁尾矿砂（ITS）的混凝土以及由聚丙烯纤维改性的ITS混凝土）进行干湿循环解决28、56、84、112和140天。在整个暴露时间段内定期测量孔分布，裂纹宽度，腐蚀产物，质量变化，膨胀变化，抗压强度，弯曲强度和硫酸根离子扩散等性能，以描述相关的演化规律。结果表明，在硫酸钠溶液的腐蚀过程中，石膏和钙矾石（AFT）的形成对有害孔（>  0.1μm），三种混凝土的裂缝，质量变化，膨胀变化，抗压强度和抗弯强度。聚丙烯纤维可利用ITS细化混凝土的孔洞发展和裂纹发展，进一步减轻硫酸根离子对混凝土的侵蚀速度和腐蚀产物的增加速度，从而使质量变化，膨胀变化和减少。可以有效地限制抗压强度和抗弯强度。此外，在ITS用0.1％聚丙烯纤维改性的混凝土中，扩散的硫酸根离子含量始终是最低的。