Durability of concrete exposed to sulfate attack under flexural loading and drying–wetting cycles

Gao, Jianming; Yu, Zhenxin; Song, Luguang; Wang, Tingxiu; Sun, Wei

doi:10.1016/j.conbuildmat.2012.05.033

Cited by 132 publications

(57 citation statements)

References 12 publications

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“…As a result, the strength decreased in the late stages of the specimen immersion in the Na2SO4 solution. These results agreed with those of Wang et al [21,22].…”

Section: Compressive Strength Test Resultssupporting

confidence: 83%

Self-Curing Concrete under Sulfate Attack

Bashandy

2016

Archives of Civil Engineering

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1Self-curing concrete SC is a concrete type that can be cured without using any external curing regimes. Tt can perform by several methods such as using lightweight aggregate or chemical agents. In this research chemical curing agent is used to produce SC. This paper reports the resuJts of a research study conducted to evaluate the effect of su I fates on the performance of se! f-curing concrete compared Io ord in ary concrete. Samples are immersed in sodium sui fate Na2S04 sol uti on of 4% concentration. Results are measured in terms of compressive strength, tensile strength, flexural strength and mass loss. It was found that the rate of strength loss is noticed at ordinary concrete compared to SC concrete. Sulfate resistance is improved when using self-curing concrete. This improvement appears to be dependent on using a chemical curing agent.

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“…As a result, the strength decreased in the late stages of the specimen immersion in the Na2SO4 solution. These results agreed with those of Wang et al [21,22].…”

Section: Compressive Strength Test Resultssupporting

confidence: 83%

Self-Curing Concrete under Sulfate Attack

Bashandy

2016

Archives of Civil Engineering

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“…The methodology of evaluation of the process of attack by sulfates with a proposal of acceleration of the process through cycles of wetting and drying has already been used by other authors such as Gao et al [2], Gong et al [26], Jiang and Niu [27] and Capraro et al [28].…”

Section: Testing Proceduresmentioning

confidence: 99%

“…The concrete structure degradation-mechanisms, attacked internally by sulphates, are caused primarily by the sulphide mineral oxidation phenomenon, which generates expansion and the appearance of cracks, due to the stress caused by crystallization of the new by-products with superior volume to the original [1][2][3]. Additionally, the products generated by this phenomenon react with the compounds of the hydrated cement, aluminate tri-calcium (C 3 A), calcium silicate hydrate (CSH) and calcium hydroxide (Ca (OH) 2 ), forming new products [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…1), ferrous sulphate (FeSO 4 ) and sulphuric acid (H 2 SO 4 ), are water soluble and capable of reacting with hydrated compounds, making possible an internal attack [10]. The main products formed due to the deleterious reactions, between the compounds resulting from the pyrite oxidation process and hydrated compounds of the cement paste, are ettringite (3CaOÁAl 2 [1,2,[4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, the products generated by this phenomenon react with the compounds of the hydrated cement, aluminate tri-calcium (C 3 A), calcium silicate hydrate (CSH) and calcium hydroxide (Ca (OH) 2 ), forming new products [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Internal attack by sulphates in cement pastes and mortars dosed with different levels of pyrite

et al. 2017

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This study aims to investigate cementitious compound behaviour at early stages (up to 168 days), primarily when dosed with different levels of pyrite. To accomplish this, a study was conducted with cement pastes and mortars contaminated by sulphide. For the cement pastes, four contaminant levels were adopted: with one as a reference value (0%), two as cited by the standards, and one value greater than the set standards. In the mortars, two series were studied, one without contamination and the other with use of an aggregate contaminated naturally by pyrite. Pozzolanic cement was used (65% Portland cement CPV ? 35% fly ash) and the materials were submerged in curing compounds for 28 days.Subsequently, the samples were subjected to two exposure conditions: 1-a wet-dry cycle and 2-immersion in aqueous solution with aeration. To identify the products formed by pyrite oxidation, and the subsequent by-product-based reactions, and cement hydrates, scanning electron microscopy with elemental analysis was used. For the analysis of the mechanical properties, strength tests were performed to test axial compression and tensile strength in bending. Furthermore, monitoring of the dimensional variation in prisms (2.5 9 2.5 9 28.5) cm 3 was performed. In conclusion, we determined that at the exposure times tested, there were signs of sulphide oxidation in the contaminated compounds. It was proven that the higher the degree of pyrite contamination, the higher the relative expansion of the series, which was confirmed by the formation of expansive products identified in the scanning electron microscopy.

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A Wiener degradation process with drift‐based approach of determining target reliability index of concrete structures

Zhang

Liang

Niu

et al. 2022

Quality & Reliability Eng

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In this paper, a novel approach is proposed to determine target reliability index based on modeling performance degradation of concrete structures as a stochastic process. First, the Wiener process with drift is used to simulate the degradation process of relative dynamic elastic modulus of concrete, and the drift coefficient and diffusion coefficient of Wiener process are estimated according to the experimental data of degradation of relative dynamic elastic modulus. Then, based on the relations between concrete compressive strength, dynamic elastic modulus, and relative dynamic elastic modulus, the relationship between compressive strength and the amount of degradation of relative dynamic elastic modulus are deduced, and then, the statistical parameters of concrete compressive strength under different service time can be calculated.Finally, based on the established limit state equation of flexural capacity of the weak section and the statistical parameters of compressive strength at different times, the reliability index of a structure under different service life is calculated. On the other hand, according to the drift Wiener process model of relative dynamic elastic modulus degradation of concrete, the time-varying failure probability of structural durability degradation is calculated based on the first-passage failure probability formula of drift Wiener process. Taking a concrete plant structure as an example, the time-varying reliability index calculated based on the limit state equation and the time-varying failure probability obtained based on the first-passage failure probability analysis of drift Wiener process are compared, and then the recommended values of target reliability index of structural bearing capacity are comprehensively determined.

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Durability of concrete exposed to sulfate attack under flexural loading and drying–wetting cycles

Cited by 132 publications

References 12 publications

Self-Curing Concrete under Sulfate Attack

Self-Curing Concrete under Sulfate Attack

Internal attack by sulphates in cement pastes and mortars dosed with different levels of pyrite

A Wiener degradation process with drift‐based approach of determining target reliability index of concrete structures

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