Nebraska LTAP
Date of this Version
2019
Document Type
Article
Citation
Halsey, L. and Heyen, W. (2019). "Evaluation of Nebraska’s Aggregate Reactivity by the Miniature Concrete Prism Test Method – AASHTO T380" NDOT Research Report.
Abstract
The evaluation of nine different aggregates shows the viability of the T380 test method as an alternative to the standard C1293 test method. The T380 assesses the Alkali-Silica Reaction potential of aggregates with the same reliability as C1293 and correlates well with the C1293 test method. Results are obtained within 56 days by T380 compared to 365 days required by C1293. The T380 method at 56 days appears to characterize the aggregate reactivity similarly to C1293 for all the aggregates evaluated in this study. Therefore, T380 will be part of the Department test method for approval of interground/blended cements along with the ASTM C1567-Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate. The Department has changed the specification for approving IP or IT cements to allow the use of T380 after the Department has completed the test method C1567. Per the specification, the mortar bars shall not exceed 0.10% expansion at 28 days while performing C1567. If the expansion is greater than 0.10% at 28 days while performing C1567, then the interground/blended cements shall be tested in accordance with AASHTO T380 using fine aggregate from an approved Platte River Valley and/or Elkhorn River aggregate source with an expansion not greater than 0.02% at 56 days.