Effect of Slate Powder on Alkali Activity of Slate Aggregate

In order to study the effect of manufactured-sand's feature on the alkali activity of slate aggregate, refer to the accelerated mortar bar test in the "Standard for Constructional Quality Acceptance of Railway Concrete Engineering" TB 10424-2010. The text has studied the expansion of the specimens that are made from slate aggregate with different powder contents or different particle size distribution. The results show that: When the content of powder in slate aggregate is less than 10%, the powder dose not have adverse effects on the expansion of specimens, and when the powder content is 15% to 20%, the expansion has downward trend. Slate powder is an active powder. It can not suppress the alkali-aggregate reaction of slate aggregate, but it can reduce the expansion of specimens. Particle size has influence on the expansion of specimens. The most unfavorable particle size of slate aggregate for the alkali activity is 0.16 similar to 0.315(mm).