Study on the Deterioration of Concrete under Dry-Wet Cycle and Sulfate Attack.

Fang Liu,Tao Luo,Mengzhen Zhou,Tonghuan Zhang,Kunkun Zhang,Weiwei Ma

doi:10.3390/ma13184095

Abstract

In order to study the deterioration and mechanism of dry–wet cycles and sulfate attack on the performance of concrete in seaside and saline areas, the deterioration of compressive strength of concrete with different water cement ratios under different erosion environments (sodium sulfate soaking at room temperature and coupling of dry–wet cycling and sodium sulfate) was studied here. At the same time, ICT (industrial computed tomography) and NMR (nuclear magnetic resonance) techniques were used to analyze the internal pore structure of concrete under different erosion environments. The results show that the compressive strength under different erosion environments increases first and then decreases, and the dry–wet cycle accelerates the sulfate erosion. With the increase of dry and wet cycles, larger pores are filled with erosion products and developed into small pores in the early stage of erosion; in the later stage of erosion, the proportion of larger pores increases, and cracks occur inside the sample. In the process of sulfate soaking and erosion, the smaller pores in the concrete account for the majority. As the sulfate erosion continues, the T2 spectrum distribution curve gradually moves right, and the signal intensity of the larger pores increases.

Highlights

Concrete has become the most widely used engineering material due to its advantages of fast setting and hardening, low price, and good durability [1,2,3,4,5]
Sulfate corrosion is one of the main factors which affect the durability of concrete and the coupling between dry–wet cycles, and sulfate shows strong harm and complex mechanisms in corrosion of concrete
It is of great significance to carry out research on the deterioration of concrete under the coupling of sulfate erosion and the dry–wet cycle

Summary

Introduction

Concrete has become the most widely used engineering material due to its advantages of fast setting and hardening, low price, and good durability [1,2,3,4,5]. During the service of the concrete structure, the adverse effects of its own material defects and the complexity of the environment on the structure will result in concrete failure before the service life [6]. Pure-silane and water-based silane, were taken as treatment and applied on concrete samples for protecting from harmful saline environments by Al-Kheetan et al [9]. Sulfate corrosion is one of the main factors which affect the durability of concrete and the coupling between dry–wet cycles, and sulfate shows strong harm and complex mechanisms in corrosion of concrete. It is of great significance to carry out research on the deterioration of concrete under the coupling of sulfate erosion and the dry–wet cycle. Due to the differences in the simulated experimental environment [15,16,17,18], the selected test method [19,20,21], and the concrete mix ratio used in the test [22,23], etc., up to now, there is no unified test system

Objectives

Results

Conclusion