EVALUATION OF PORTLAND FLYASH CEMENT AS A PREVENTIVE AGAINST ALKALI-SILICA REACTION

It has been shown that the use of a portland flyash cement delays the onset of alkali-silica expansion of a structure which is in contact with an external alkali source. However, due to an early termination of expansion measurement no definite conclusion could be drawn as to the effect of portland flyash cement on the ultimate expansion capacity. This shortcoming has been amended in the investigation presented below. In this investigation mortar bars, made with a highly reactive and a medium reactive sand and each of a portland flyash cement and a low alkali sulphate resistant portland cement, were tested by the saturated nacl solution bath method. Expansion measurements were carried out up to 48 weeks. The results show that compared to the low alkali sulphate resistant portland cement the use of portland flyash cement significantly reduced alkali-silica expansion of mortar bars made with both high and medium reactive sand types. For the covering abstract see IRRD 812060.