DTU Concrete Prism Test Method DTU CPT: An Assessment of a “New” Accelerated Test Method for Alkali Silica Reactions in Concrete for Both Fast Reactive and Slow Reactive Coarse Aggregates

The newly developed ‘DTU concrete prism test method’ (DTU CPT) ‘Accelerated test method for alkali silica reaction in concrete’ is based on the NORDTEST method NT BUILD 295 ‘Sand-alkali-silica reactivity accelerated test’. The changes from NT BUILD 295 in DTU CPT primary concerns test specimen size, aggregate size and expansion limit. The DTU CPT can be used for ASR-reactivity assessment of a single coarse aggregate or a combination in the range (4–16 mm) hence the method can reproduce representative results for concrete. The method applies concrete prisms of size 75 × 75 × 285 mm in saturated NaCl solution at 50 ℃ up to 52 weeks.

The paper shows measurement results by use of DTU CPT for seven coarse aggregates, both fast reactive and slow reactive aggregates, in relation with two innocuous reference aggregates. The results from DTU CPT tests are compared with results from ASTM C 1293 tests. The results from the test show that DTU CPT seems to be useful for assessing both fast and slow coarse reactive aggregate types, seemingly also for aggregates with pessimum behaviour.