福島県環境創造センター
Fukushima Environmant Creation Center

The results from concrete prism test with alkali wrapping (AW-CPT) show complex ASR expansion behaviour that is dependent on temperature and alkali content. In this study, concrete prisms were made with two types of aggregate i.e. rapid expansive andesite containing opal/cristobalite and chert containing chalcedony and cryptocrystalline quartz. ASR was accelerated by increasing the exposure temperature up to 60 ºC and alkali content to 5.5 kg/m3. An image analysis method was developed to quantify the alkali-silica gel content by treating the samples with uranyl acetate and measuring the emitted fluorescence with a high sensitive camera. Procedures for sample preparation, treatment and imaging were optimized. The results showed that alkali-silica gel inside reactive aggregates may exude out around the reacting aggregate and onto the surface of polished section. A general correlation was observed between the measured ASR gel amount and expansion.