Influence of Cement Composition on Expansions Observed in Standard and Modified ASTM C1260 Test Procedures (05-2460) - MP-22**
Prasada Rao Rangaraju, Clemson University
Ketan Ramakant Sompura, Clemson University

This paper presents the results of a lab study conducted to determine the influence of cement composition on the expansions observed in standard and modified ASTM C 1260 tests. Also, the effectiveness of selected mitigation measures for alkali-silica reactivity using a modified ASTM C 1260 test was studied. Two different cements with substantially different alkali levels were used in combination with a Class F fly ash and a Class C fly ash. Results obtained from testing 89 different sources of fine aggregate were analyzed. The results from this study indicate that cement composition has a distinct influence on the expansion levels observed in the ASTM C 1260 study. For a majority of aggregates tested in this study (88%), the use of a specific cement, that is low in its alkali content, resulted in higher expansion than a cement that had relatively higher alkali content, regardless of the level of reactivity of the aggregate in the standard ASTM C 1260 tests. Class F fly ash was found to be more effective compared to Class C fly ash in reducing the expansions in the modified ASTM C 1260 tests. However, the cement used in the mixture influenced the percent reduction in expansion offered by both Class F fly ash and Class C fly ash. The use of low-alkali cement with Class F and Class C fly ashes yielded larger reductions in percent expansion in the modified ASTM C 1260 test. Keywords: ASTM C 1260 test, alkali-silica reaction, ASR, fly ash, mitigation measures