Experimental Study on Durability of Hybrid Fiber-Reinforced Concrete in Deep Alluvium Frozen Shaft Lining

Zhishu Yao,Xianwen Huang,Ping Zhang,Yu Fang

doi:10.3390/cryst11070725

Zhishu Yao, Xianwen Huang + Show 2 more

Open Access

https://doi.org/10.3390/cryst11070725

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Journal: Crystals	Publication Date: Jun 23, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Anhui University of Science and Technology

Abstract

This article proposes hybrid fiber-reinforced concrete (HFRC) mixed with polyvinyl alcohol fiber (PVA) and polypropylene steel fiber (FST) as a wall construction material to improve the bearing capacity and durability of frozen shaft lining structures in deep alluvium. According to the stress characteristics and engineering environment of the frozen shaft lining, the strength, impermeability, freeze–thaw damage, and corrosion resistance are taken as the evaluation and control indexes. The C60 concrete commonly used in freezing shaft lining is selected as the reference group. Compared to the reference group, the test results show that the compressive strength of HFRC is similar to that of the reference concrete, but its splitting tensile strength and flexural strength are higher; according to the strength test, the optimum mixed content of 1.092 kg/m3 PVA and 5 kg/m3 FST are obtained. According to the impermeability test results, the mixing of PVA and FST can improve the impermeability resistance of concrete. For the freeze–thaw cycle test results, the mixing of PVA and FST can improve the frost resistance of concrete; based on the 120 days sulfate corrosion test, the mixing of PVA and FST will improve the corrosion resistance of concrete.

Highlights

IntroductionWith the increase in the depth of the well construction, the thickness of the inner and outer sidewalls of the deep alluvium shaft is greatly increased, the hydration heat generated during the pouring of the shaft is high, and the environmental temperature varies greatly during construction, so the high-strength concrete of the shaft lining produces temperature cracks [11]
Under the design strength of C60, the compressive strength of the hybrid fiber group was the same as that of the reference group, with an increase of −5.5~3.0%, while the splitting tensile strength and flexural strength were significantly higher than those of the reference group, with a maximum increase of 32.4% and 25.6%, respectively
According to the impermeability test results, the average impermeability height and relative permeability coefficient of the hybrid fiber concrete were reduced by 31.7%

Summary

Introduction

With the increase in the depth of the well construction, the thickness of the inner and outer sidewalls of the deep alluvium shaft is greatly increased, the hydration heat generated during the pouring of the shaft is high, and the environmental temperature varies greatly during construction, so the high-strength concrete of the shaft lining produces temperature cracks [11]. In the method of shaft sinking by freezing in deep alluvium, the freezing pressure on the outer wall of the shaft is obviously unevenly distributed, due to the uneven distribution of the saline flow at the freezing hole deviation, which is extremely adverse to the force on the shaft lining and can cause the tensile failure of the high-strength concrete [12,13].

Results

Discussion

Conclusion