Elsevier

Cement and Concrete Research

Volume 32, Issue 12, December 2002, Pages 1859-1864
Cement and Concrete Research

Effect of chloride salt, freeze–thaw cycling and externally applied load on the performance of the concrete

https://doi.org/10.1016/S0008-8846(02)00769-XGet rights and content

Abstract

The effect of sodium chloride solution, freeze–thaw cycling and externally applied load on the performance of concrete was experimentally investigated. The results show that the concrete specimens subjected to freeze–thaw cycling scaled more severely in chloride salt solution than those in water, and weight losses of the specimens tested in chloride salt solution were twice as much as those tested in water. However, dynamic modulus of elasticity of the concrete specimens decreased more slowly in chloride salt solution than in water due to the decline in the freezing point of the chloride salt solution compared with water. It is also shown that the performance deterioration in the concrete subjected to multidamaging processes was significantly accelerated. The larger the stress ratios, the fewer freeze–thaw cycles the concrete could bear. When steel fiber is incorporated, performance degradation in the steel fiber-reinforced concrete exposed to the multidamaging processes could be considerably retarded.

Introduction

The evaluation of durability and service life for concrete structures is quite important and complicated, and it has been discussed in previous papers [1], [2], [3], [4], [5]. Performance deterioration caused by a monodamaging process, such as freeze–thaw cycling, is not consistent with the real conditions to which concrete structures are actually exposed. It has been found that the deterioration of concrete could be accelerated when subjected to dual-damaging processes, e.g., simultaneously subjected to both external loading and freeze–thaw cycling [6], [7]. Moreover, deterioration of concrete becomes more severe when subjected to multidamaging processes, e.g., simultaneously exposed to external load, freeze–thaw cycling, chloride or sulphate attack and so on. In this paper, the concrete with different strength levels when exposed to mono-, dual- and multidamaging processes was investigated, and the improvement from steel fiber to resist against the performance degradation in concrete was discussed as well.

Section snippets

Materials

The 525# R(II) Portland cement, river sand with fineness modulus 2.36, coarse aggregate of crushed basalt stone with maximum size of 10 mm, XP-II superplasticizer, steel fibers with length of 20 mm and aspect ratio of 40, respectively, were used in the test. The proportions of the various concrete mixes with three strength levels are given in Table 1.

Test methods

Tests of concrete specimens (40×40×160 mm) subjected to freeze–thaw cycling or to externally applied load in water or in a NaCl solution (3.5% by

Effect of NaCl solution on the frost resistance of the concrete

There is much difference in frost resistance of the concrete specimens between that tested in fresh water and in the chloride solution. Concrete with good frost resistance often scaled severely in a NaCl solution when subjected to freeze–thaw cycling, the weight losses of concrete specimens reaching failure threshold earlier in a NaCl solution than in water. Fig. 1a and b gives the weight losses of the plain concrete (C40NPC, C60NPC and C80NPC) subjected to freeze–thaw cycling in water or in a

Conclusions

Severe surface scaling occurred when the plain concrete was subjected to freeze–thaw cycling in a 3.5% NaCl solution, in which the weight losses of the concrete were larger than those in water. Due to the decline of the freezing point of the salt solution, the ultimate freeze–thaw cycles of the concrete in a NaCl solution were about 20% higher than those of the concrete exposed to the freeze–thaw cycling in water, while the losses in the dynamic modulus of elasticity of the former were fewer

Acknowledgements

The authors thank the key program from the National Natural Science Foundation of China, Grant No. 59938170, for the financial support. Jiangsu Research Institute of Building Science, which supported the experimental work, was greatly acknowledged as well.

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