Effect of Test Procedures on the Assessment of the Sulfate Resistance of Slag Cements
J. P. H. Frearson and D. D. Higgins
Appears on pages(s):
aggregates; blast furnace slag; compacting; curing; expansion; mortars (material); slags; sulfate resistance; tests; water-cement ratio; Materials Research
Various accelerated test methods have been proposed for the assessment of sulfate resistance of cements. A majority of these methods measure the expansion of mortar prisms in sulfate solution. Differences in test procedure can have a significant effect on the expansion observed and may possible affect the ranking of cement types. The different performance in sulfate solutions of cements containing different slag percentages and water- cement ratios and the lesser influence of different slag alumina contents have been reported previously. This paper summarizes data from various test works which demonstrate the effect on expansion of variations in the following test parameters: aggregate- cement ratio (at constant water-cement ratio), specimen shape, initial curing period, specimen compaction, initial curing deficiencies, early carbonation, concentration of sulfate solution, and type of sulfate solution. The first three of these parameters had comparatively little influence on expansion; the remainder had more significant influences on expansion. Sieving mortar for test specimens from production concrete provided a useful and comparable method of assessment. The test programs were principally concerned with slag cement blends, but as any test method had to be applicable to all types of cement, a number of sulfate-resisting portland cements were tested. The wide range of expansion characteristics suggest that a "typical" control SRPC may not be easily defined.