Sulfate resistance of Portland-limestone cements in combination with supplementary cementitious materials
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ORIGINAL ARTICLE
Sulfate resistance of Portland-limestone cements in combination with supplementary cementitious materials Amir Mohammad Ramezanianpour R. Douglas Hooton
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Received: 29 June 2012 / Accepted: 28 September 2012 / Published online: 9 October 2012 Ó RILEM 2012
Abstract In this study, the sulfate resistance of five different high-C3A Portland and Portland-limestone cements and their combinations with 30–50 % slag were examined at both 5 and 23 °C according to CSA A3004-C8 (similar to ASTM C1012). Also, XRD was used to identify the phases formed after sulfate attack. It was found that in 23 °C exposure, while 100 % cement mixes deteriorated due to conventional ettringite-based sulfate attack, partially replacing the cements with 30 or 50 % slag was effective in making the mixes highly sulfate-resistant. At 5 °C, all of the 100 % cement mortar bars expanded more than the test limits and eventually completely disintegrated due to the formation of thaumasite. Partially replacing cement with 30 % slag was only effective in controlling the deterioration for Portland cements but not Portland-limestone cements. However, all the Portland-limestone cements with 50 % slag were resistant to the thaumasite form of sulfate attack after 2 years. Keywords Portland-limestone cements Sulfate resistance Thaumasite Slag Sustainability
A. M. Ramezanianpour (&) R. D. Hooton Department of Civil Engineering, University of Toronto, 35 St. George St, Toronto, ON M5S 1A4, Canada e-mail: [email protected] R. D. Hooton e-mail: [email protected]
1 Introduction Portland-limestone cements (PLC) have been used in practice for a considerable period of time in several countries. Perhaps the main advantage of producing PLC is its contribution to sustainable development. By intergrinding limestone with cement clinker and calcium sulfate, the amount of clinker required to produce cement decreases. This results in a substantial energy savings in the production of cement as the consumption of natural raw materials and the fuel needed for production of clinker is reduced. Moreover, it contributes to sustainable development due to the reduction in greenhouse gas emissions, mostly CO2 and NOx, involved in the pyroprocessing of clinker. On this basis, the future world production of PLC is expected to increase. Nevertheless, it should be noted that all the aforementioned benefits can only be achieved provided that PLC has similar performance characteristics to Portland cement, and has no adverse effects on the properties of concrete. One of the major concerns regarding the use of PLC is their resistance to sulfate attack, especially at lower temperatures. Several researchers have studied the sulfate resistance of PLC or combinations of Portland cements with limestone filler [1, 2, 4–10, 12, 14, 15, 17–24]. A review on these studies suggests that the literature is conflicting with respect to use of PLC in sulfate exposure [13]. Moreover, data on the performance of PLC when used in conjunction with SCMs is lim
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