Effects of cyclic seawater exposure on the mechanical performance and chloride penetration of calcium sulfoaluminate concrete

Tang, Xudong; Xu, Qiang; Qian, Kun; Ruan, Shaoqin; Lian, Songsong; Zhan, Shulin

doi:10.1016/j.conbuildmat.2021.124139

Cited by 30 publications

(7 citation statements)

References 41 publications

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“…The porosity of the surface of CSA concrete increases gradually due to the marine drying–wetting cycles, whereby CO 2 in the atmosphere reacts with ettringite to produce calcite, AH 3, and gypsum. The carbonization process causes a decrease in alkalinity within the concrete pore solution, which reduces the stability of ettringite and leads to its conversion into AFm and gypsum [ 39 , 40 ]. Furthermore, the sand and gravel in seawater continuously scour the concrete surface in the tidal zone, reducing the bonding strength between aggregate particles and cement paste, which can result in the formation of pores.…”

Section: Discussionmentioning

confidence: 99%

Mechanical Performance and Chloride Penetration of Calcium Sulfoaluminate Concrete in Marine Tidal Zone

Tang

Zhan

et al. 2023

Materials

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The enhancement of the durability of sulfoaluminate cement (CSA) in marine environments is of great importance. To this end, an investigation was carried out involving the placement of CSA concrete in the tidal zone of Zhairuoshan Island, Zhoushan, China, and subjected to a 20-month marine tidal exposure test. The comparison was made with ordinary Portland cement (OPC) concrete to evaluate the effectiveness of the former. The test findings indicate that the compressive strength of both types of concrete is reduced by seawater dry-wet cycling, and the porosity of the surface concrete is increased. However, the compressive strength of CSA concrete is observed to be more stable under long-term drying–wetting cycles. When the ettringite in the CSA surface concrete is decomposed due to carbonization and alkalinity reduction, its products will react with Ca2+ and SO42− in seawater to regenerate ettringite to fill in the concrete pores, making the concrete strength more stable and hindering chlorine penetration. Furthermore, CSA concrete exhibits a higher capillary absorption capacity than OPC concrete, which results in chloride accumulation on its surface. However, the diffusion capacity of chloride in CSA concrete is significantly lower than that in OPC concrete.

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Section: Discussionmentioning

confidence: 99%

Mechanical Performance and Chloride Penetration of Calcium Sulfoaluminate Concrete in Marine Tidal Zone

Tang

Zhan

et al. 2023

Materials

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“…In this section, the stability parameters of ettringite‐accelerated binders composed of CAC–PC–C$ and CSA–PC–C$ are discussed in terms of carbonation and sulfate attack. Interactions of ettringite with calcium and sulfate ions in seawater are an area for further research 180 …”

Section: Other Factors Influencing Stabilitymentioning

confidence: 99%

“…Interactions of ettringite with calcium and sulfate ions in seawater are an area for further research. 180…”

Section: Other Factors Influencing Stabilitymentioning

confidence: 99%

A critical review of the role of ettringite in binders composed of CAC–PC–C$ and CSA–PC–C$

2023

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Ettringite-accelerated binders composed of CAC-PC-C$ (calcium aluminate cement-Portland cement-calcium sulfate) and CSA-PC-C$ (calcium sulfoaluminate cement-Portland cement-calcium sulfate) have been used widely for indoor applications, such as self-leveling floor screeds, underlayment, and tile adhesives owing to their rapid setting, early strength gain, and shrinkage compensation properties. These properties also make these binders appealing candidates for outdoor rapid repair (e.g., highways, bridge decks, and airfield pavements). However, a central question remains: Does ettringite remain stable in outdoor exposure conditions? If so, which factors will contribute positively/negatively to the long-term stability of ettringite in these systems? To address these questions, this critical review presents the current state of knowledge regarding the hydration of ternary binders composed of CAC-PC-C$ and CSA-PC-C$ with respect to ettringite formation and the factors affecting the stability of ettringite thereafter. The purpose of this review paper is to synthesize and analyze current research regarding conditions that promote or deter ettringite stability, establish what information is missing, unclear, or contradictory, and identify remaining research needs to address the identified knowledge gaps.

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“…1 shows that samples were removed from the oven as soon as the rate of mass loss had decayed to help prevent ettringite dehydration. The resulting duration of two days at 60ºC is a method that has previously been used in literature for CSA samples prior to porosimetry [4]. However, it is acknowledged that the drying at 60ºC could result in lower moisture loss and lower porosity measurements than conventional drying process at 105ºC.…”

Section: Physical Propertiesmentioning

confidence: 99%

“…Electrical resistivity is emerging as a preferred indicator for transport properties [2]. Evaluating the transport properties of ettringite binders is especially important since chloride binding products like Friedel's salt have not been observed in laboratory studies of calcium sulfoaluminate (CSA) systems [3,4]. However, the efficacy of these methods has mainly been studied in ordinary portland cement (OPC) systems and studies have found discrepancies between the electrical properties of ettringite systems and actual rebar corrosion tests in mixtures produced with ettringite binders.…”

Section: Introductionmentioning

confidence: 99%

Factors Influencing the Electrical Properties of Ettringite Binders as Repair Materials

Tuinukuafe

Noor²,

Ideker³

et al. 2022

MATEC Web Conf.

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Ettringite binders are increasingly being used as rapid-repair materials to extend the service-life of reinforced concrete where rebar corrosion has caused deterioration and spalling. The transport properties of these ettringite binders are important in assessing the longevity of such repairs. This study demonstrates how the electrical properties of such binders can be interpreted to obtain meaningful results related to the transport properties. In addition to the pore solution chemistry, the degree of saturation in calcium sulfoaluminate (CSA) cement was found to be an important factor in the electrical properties since ettringite binders can have greater self-desiccation at earlier ages than ordinary portland cement (OPC). After one day of hydration, the electrical properties suggested that the CSA containing mixtures had greater pore network connectivity than the OPC mixture and this can be attributed to the varying phase compositions. Thermodynamic modelling confirmed a high amount of ettringite formation in the CSA system and a lower capillary water and capillary porosity associated with this. The lower internal relative humidity of ettringite binders should be considered when using electrical measurements to evaluate their transport properties since it increases the total electrical resistivity.

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Effects of cyclic seawater exposure on the mechanical performance and chloride penetration of calcium sulfoaluminate concrete

Cited by 30 publications

References 41 publications

Mechanical Performance and Chloride Penetration of Calcium Sulfoaluminate Concrete in Marine Tidal Zone

Mechanical Performance and Chloride Penetration of Calcium Sulfoaluminate Concrete in Marine Tidal Zone

A critical review of the role of ettringite in binders composed of CAC–PC–C$ and CSA–PC–C$

Factors Influencing the Electrical Properties of Ettringite Binders as Repair Materials

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