Abstract
Aiming at the prominent problem of short durability life of concrete in saline soil area and the shortcomings of indoor accelerated test, an outdoor field exposure test was designed. The concrete specimens were semiburied in the Tianshui area with salinized soil characteristics, and nondestructive testing was conducted every 180d (days). The durability evaluation parameters and mechanical performance indexes were selected for macroscopic analysis, and the corrosion mechanism was analyzed by using the SEM image and the XRD phase. The Birnbaum-Saunders model based on physical failure and probability statistics was used for life prediction. The results show that there are rod-shaped and chip-shaped crystals growing from the surface of the gel and the internal holes in the exposed end and the embedded end of the concrete. However, the damage and deterioration of the buried end are more serious than those of the exposed end. The corrosion products mainly included ettringite, gypsum, calcium carbonate, sodium sulfate hydrate, carbosilite, and Friedel’s salt. The reliability life curve based on the Birnbaum-Saunders model can describe the whole process of exposed concrete from damage accumulation to failure. In addition, the dynamic modulus degradation index is more sensitive to concrete durability damage, and the life obtained by the Birnbaum-Saunders model is shorter than the quality degradation index. The life obtained by this degradation index is taken as the life of the concrete exposed in the saline soil site, and the concrete life of C30, C40, and C50 is about 3340d, 3930d, and 4360d, respectively.
Highlights
In the actual service environment, concrete is affected by various erosion factors, and its durability continues to decline
Aiming at the current durability test of structural concrete materials, researchers mostly carry out indoor accelerated tests based on corrosion factors to simulate the one-sided and deficiencies caused by the damage and deterioration of concrete in the actual service environment. is paper proposes an outdoor field exposure concrete durability test program. e concrete specimens were placed in the saline soil environment in the northwest of China and subjected to the combined effects of climate and environment; the degradation data were collected after a certain period of exposure
Evaluation Index of Concrete Durability. e size of the specimen was 100 × 100 × 400 mm prism, and three test blocks of each strength level were used as a group
Summary
In the actual service environment, concrete is affected by various erosion factors, and its durability continues to decline. Due to the long period of outdoor durability tests and data collection difficulty, the current research on the corrosion degradation mechanism and erosion degradation analysis of concrete is mainly based on indoor tests It mainly considers the main damage factors of structural concrete materials in a certain corrosive environment, designs the accelerated stress level on this basis to obtain the degradation process of structural concrete materials in a relatively short period [8, 9], and explores the damage mechanism [10, 11] to propose the ways and methods to improve the durability [12, 13]. The concrete was exposed in the saline soil area, carried out outdoor durability tests, selected the B–S distribution model for modeling, and predict the durability life of concrete in the northwest saline soil area
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