关键词: 凝灰岩骨料, 碱活性, 混凝土棱柱体法, 矿物掺合料, 龄期

Abstract: Tuff aggregate contains a large amount of amorphous volcanic glass, and its alkali activity may be characterized by strong reaction and long duration. The expansion law of tuff alkali aggregate reaction under different dosage of fly ash and slag powder was studied by using concrete prism method of prolonged age. The effect of curing age and mineral admixture on tuff alkali aggregate reaction was analyzed to determine the effective inhibiting dosage of fly ash and slag powder and evaluate its inhibiting effect. The results showed that the expansion rate of tuff prism specimens increased first and then decreased during 2.5 years, the expansion rate increased rapidly in the first 1 year, reached its maximum value in 1.5~1.75 years, and then decreased. The maximum expansion rate of tuff prism specimens in 2.5 years was higher than that in 1 year. In practical engineering, it can be considered to prolong the testing period of prism specimens or to increase the expansion rate in 1 year. The corresponding admixtures can reasonably inhibit the content of alkali aggregate. The inhibiting effect of fly ash was higher than that of slag powder, increasing the content of admixtures can improve the inhibiting effect of alkali aggregate reaction in a long period of time. The research results can provide reference for the detection and inhibition of alkali activity of tuff aggregate.

Key words: tuff, alkali activity, concrete prism method, mineral admixture, curing age