Determination of the sulphate resistance of blastfurnace slag cements using small-scale accelerated methods of test

Small-scale accelerated tests using cement paste cubes and mortar prisms have been carried out with Portland cements and blastfurnace slag cements to assess whether any of these methods could be recommended as an acceptance test for determining the sulphate resistance of cements. It is concluded that additional laboratory studies and direct comparison with longer term concrete cube test data would be necessary before any of these tests could be used as a standard sulphate resistance test method. A mortar prism test was considered to provide the best indication of cement behaviour in sulphate conditions. The three accelerated tests indicated that in general the use of ground granulated blastfurnace slag (GGBS) for up to and including class 3 sulphate conditions as recommended in Building Research Establishment Digest 250 is justified even if ordinary Portland cements (OPCs) with high C₃A and slags with high Al₂O₃ contents are used together. The performance of GGBS in more severe sulphate conditions may also be satisfactory provided that medium C₃A OPC or low Al₂O₃ slags are used.