Evaluation of the Alkali-Silica Reactivity of Sands from the Yarlung Tsangpo River in Qinghai-Tibet Plateau by Chinese Autoclave Method

The use of non-reactive aggregate is the most reliable measure for avoiding alkali aggregate reaction (AAR) in concrete. Rapid and reliable identification of the distribution of alkali-reactive aggregate in an area is important for the construction and long-term service of concrete infrastructures. In present study, about 100 river sand samples distributed over 2100-km-long of the Yarlung Tsangpo River in Qinghai-Tibet Plateau were collected, and their alkali-silica reactivity as well as the type and source of reactive constituent of expansive sample were examined by petrographic analysis and Chinese autoclave method. Results show that 13% of these sands are reactive, and the main reactive constituent are microcrystalline quartz and acid volcanics. Based on expansion measurement, petrography quantification and geological mapping, a map showing the distribution of the alkali-silica reactivity of sands in drainage basin of Yarlung Tsangpo River is established.