Abstract
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.
Highlights
How to address and utilize iron tailings sand (ITS) has become an important topic [1,2,3]
A series of tests have been carried out for ordinary concrete, concrete with ITS, and concrete with ITS modified by polypropylene fibers under the condition of drying-wetting cycles in 5%Na2SO4 solution to analyze whether polypropylene fibers can improve the performance of concrete with ITS. is research provides a new way to modify the properties of concrete with ITS
Specimen Casting. 150 mm × 150 mm × 150 mm cubic specimens were used to test the pores distribution, crack width, corrosion products, mass variation, expansion variation, compressive strength, and diffusion of sulfate ions. 150 mm × 150 mm × 550 mm prism specimens were used to test the flexural strength. e mixing process details are shown as follows: (1) dry fine aggregates and cement are added into the mixer, the mixer is started for 2 min, and at the same time, the polypropylene fibers are dispersed into the running mixer slowly by hand to ensure uniform distribution. (3) e tap water and superplasticizer are poured into the mixer, and the mixer is run for 2 min
Summary
Erefore, improving the performance of concrete with iron tailings sand under aggressive environment, such as saline soils and salt lake areas, is an urgent problem to be solved. To make the concrete with iron tailings sand have a good performance under aggressive environment, some scholars have conducted corresponding research on controlling the content of ITS. A series of tests have been carried out for ordinary concrete, concrete with ITS, and concrete with ITS modified by polypropylene fibers under the condition of drying-wetting cycles in 5%Na2SO4 solution to analyze whether polypropylene fibers can improve the performance of concrete with ITS. Tests on the pores distribution, crack width, corrosion products, mass variation, expansion variation, compressive strength, flexural strength, and the diffusion of sulfate ions of the concrete under the condition of drying-wetting cycles in 5% Na2SO4 solution are carried out
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