A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Resistance to thaumasite sulfate attack in BaCO3-bearing cement pastes and mortars
Abstract Recent studies on the harmful effects of sulfates on OPC have shown that these salts can be immobilised by conversion to insoluble BaSO4. The response of blended OPC-BaCO3 cement to thaumasite sulfate attack is still poorly understood, however. This study explored the effect of BaCO3 on sulfate resistance in fairly high C3A (>10%) OPC mortars and pastes in the presence and absence of CaCO3. Further to the findings, due to low BaCO3 solubility at 8 °C, the temperature that favours thaumasite precipitation, neat OPC sulfate resistance was only slightly improved. Specimens, particularly mortars with 12.5% BaCO3 and no added CaCO3 (12.5B), deteriorated due to gypsum, ettringite and thaumasite precipitation, although less intensely than the samples bearing other blends. None of the BaCO3 or BaCO3 + CaCO3 blends performed better than the commercial sulfate-resistant cement used as the reference.
Highlights The potential of BaCO3 to inhibit thaumasite sulfate attack was explored. BaCO3 delayed initial silicate hydration at 25 °C. BaCO3 failed to react completely in pastes over a 6 month period. Neat OPC sulfate resistance improved only with 12.5% BaCO3 and only slightly.
Resistance to thaumasite sulfate attack in BaCO3-bearing cement pastes and mortars
Abstract Recent studies on the harmful effects of sulfates on OPC have shown that these salts can be immobilised by conversion to insoluble BaSO4. The response of blended OPC-BaCO3 cement to thaumasite sulfate attack is still poorly understood, however. This study explored the effect of BaCO3 on sulfate resistance in fairly high C3A (>10%) OPC mortars and pastes in the presence and absence of CaCO3. Further to the findings, due to low BaCO3 solubility at 8 °C, the temperature that favours thaumasite precipitation, neat OPC sulfate resistance was only slightly improved. Specimens, particularly mortars with 12.5% BaCO3 and no added CaCO3 (12.5B), deteriorated due to gypsum, ettringite and thaumasite precipitation, although less intensely than the samples bearing other blends. None of the BaCO3 or BaCO3 + CaCO3 blends performed better than the commercial sulfate-resistant cement used as the reference.
Highlights The potential of BaCO3 to inhibit thaumasite sulfate attack was explored. BaCO3 delayed initial silicate hydration at 25 °C. BaCO3 failed to react completely in pastes over a 6 month period. Neat OPC sulfate resistance improved only with 12.5% BaCO3 and only slightly.
Resistance to thaumasite sulfate attack in BaCO3-bearing cement pastes and mortars
Carmona-Quiroga, P.M. (author) / Blanco-Varela, M.T. (author)
2020-03-22
Article (Journal)
Electronic Resource
English
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Effects of Mineral Admixtures on Thaumasite Form of Sulfate Attack of Cement Mortars
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