Analysis on Potential Alkali Reactivity of the Aggregate and its Inhibiting Method in Dam Concrete of a Hydro Project

摘要

The aim of this paper is to systematically investigate the alkali activity of the aggregate selected from a stockyard, and examine its supression method, before pouring roller compacted concrete into the hydro project in Lechang gorge. Samples of natural sand, sandstone and limestone will be analysed through comprehensive petrographic method and accelerate mortar bar method. The results showed that natural sand is the aggregate without activity; sandstone core contains some wave shape with extinction characteristics of deformation quartz, because of active alkali-aggregate and the harm expansion of mortar, which is the aggregate with potentially harmful alkali-silicate reaction; wave shape and elastic deformation of the alkali in limestone are also the harmful element in concrete. The addition of level 1 and level 2 fly ash both has the ability to inhibit the reaction between alkali and silicate, and can control expansion rate of sandstone under 0.1 %.