External sulphate attack of sprayed mortars with sulphate-resisting cement: Influence of accelerator and age of exposition

Herrera-Mesen, C.; Salvador, Renan P.; Ikumi, Tai; Cavalaro, Sérgio Henrique Pialarissi; Aguado, Antonio

doi:10.1016/j.cemconcomp.2020.103614

Cited by 21 publications

(3 citation statements)

References 34 publications

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“…Change in the compressive strength and elasticity modulus are also used as important indicators. In addition to the above-mentioned test methods, other approaches use techniques like microstructural analysis and chemical analysis (NMR, SEM/EDX; XRD and XRF) to study the formation of ettringite, gypsum and thaumasite in the pores of the attacked specimens [ 60 , 61 , 62 , 63 ]. Moreover, other techniques are used by researchers to obtain further information on the progress of ESA on cementitious materials [ 46 , 59 ].…”

Section: Overview Of the Existing Test Methodsmentioning

confidence: 99%

A Critical Review of Existing Test-Methods for External Sulfate Attack

et al. 2022

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External sulfate attack (ESA) of cementitious materials has been studied worldwide for a very long time. This physical/chemical interaction between sulfate ions and the cement hardened elements affects the long-term durability of concrete structures: cracking, spalling or strength loss of concrete structures. To study these damaging phenomena, some standardized and non-standardized accelerated aging tests are used to evaluate the performance of cements in sulfate-rich environments. However, these existing methods do not adequately predict field performance and some shortcomings or deficiencies still exist: change of degradation mechanisms when using high concentrations of sulfate, variable boundary conditions and small specimens compared to the real concrete structures. In this work, a critical review of some existing test methods and foreign national standard methods for ESA are presented, analyzed, and discussed. This results in some proposed recommendations for improving these methods to meet the needs of structure managers.

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Section: Overview Of the Existing Test Methodsmentioning

confidence: 99%

A Critical Review of Existing Test-Methods for External Sulfate Attack

et al. 2022

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“…The studies conducted on the effect of accelerators on the performance of SR-cement are rare, with [20] being one of the few. The current study aims to increase the early strength of this type of cement by adding a hardening accelerator.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Properties of Sulfate-Resisting Cement

Kammouna

2023

Eng. Technol. Appl. Sci. Res.

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Sulfate-resisting cement is used in construction works when a sulfate attack is probable. This type of cement withstands sulfates due to its low C3A content. On the other hand, the decrease in the quantity of C3A leads to a reduction in the rate of early strength development. To overcome this problem, a hardening accelerator was added to the cement mix. To estimate the effect of the accelerator on some properties of hardened cement, compressive and flexural strength, and drying shrinkage tests were carried out. Four series of cement mortar mixes were made. The hardening accelerator was not added to the control series, while it was added to the others with three different percentages (of cement mass) of 0.5, 1, and 1.5%. The results revealed that the hardening accelerator enhances the compressive strength of all mortar ages while it slightly promotes flexural strength only at early ages. It was also observed that the hardening accelerator strongly inhibits the drying shrinkage strain.

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“…In the sulfate aggressive environment, ordinary Portland cement (OPC) is often affected by sulfate erosion, which leads to material deterioration [ 17 , 18 ]. OPC contains a lot of clinkers, such as tricalcium aluminate (C 3 A) and tetra-calcium aluminoferrite (C 4 AF), which react with sulfate to form dilatant hydration products, e.g., ettringite, that have adverse effects on the stability and strength of the mortar.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sulphur-Containing Tailings Content and Curing Temperature on the Properties of M32.5 Cement Mortar

Chen

Wang

et al. 2021

Materials

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The effect of the dosage of sulphur-containing tailings (STs) and curing temperature on the properties of M32.5 cement mortar was studied in this work. An experimental study was conducted to evaluate the effects of STs with different substitution ratios (0, 10%, 20%, 30%, 40%) on the compressive strength experiment, fluidity, expansion ratio, and pore structure of M32.5 cement mortar. The results showed that the addition of STs reduced the fluidity of mortar, and the fluidity decreased with the increase of the STs dosage. The compressive strength of mortars increased at a lower substitution rate (0~20%) but decreased at a higher substitution rate (>20%). Ettringite peaks and new sulfate peaks were found by X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) observation of the microstructure showed that a large number of hydrated products, such as ettringite, formed and filled in the interstitial space, which was conducive to the development of strength. The optimal STs replacement ratio of river sand was 10%. Then, the performance of mortar at curing temperatures of 23 ± 1, 40, 60, and 80 °C was further investigated under the optimal STs replacement ratio. Under high-temperature curing conditions, the early strength of M32.5 cement mortar with STs increased greatly, but the late strength decreased gradually with the increase in curing temperature. The early strength development of the mortar mainly depended on the high speed of hydration reaction, and the late strength variation was mainly affected by hydration products and the pore size distribution. After comprehensive consideration, the optimal curing temperature of M32.5 cement mortar with STs was 40 °C.

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External sulphate attack of sprayed mortars with sulphate-resisting cement: Influence of accelerator and age of exposition

Cited by 21 publications

References 34 publications

A Critical Review of Existing Test-Methods for External Sulfate Attack

A Critical Review of Existing Test-Methods for External Sulfate Attack

Enhancing the Properties of Sulfate-Resisting Cement

Effect of Sulphur-Containing Tailings Content and Curing Temperature on the Properties of M32.5 Cement Mortar

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