TESTING NATURAL SANDS FOR ALKALI-REACTIVITY WITH THE ASTM C1260 MORTAR-BAR EXPANSION METHOD

The effect of different portland cements on the alkali expansivity of five italian natural sands of known held performance was investigated using the ASTM C1260 mortar-bar expansion method. The alkali reactivit y of these sands was also evaluated according to the petrographic exam ination, infrared spectroscopy technique, ASTM C227 expansion method, ASTM C289 and AFNOR P18-589 chemical tests. The expansivity of the san ds in the ASTM C1260 test is significantly affected by both the native alkali content and the specific surface area of the portland cement w hile it is virtually unaffected by its mineralogical composition. For all the sands there is good agreement between the diagnoses of the AST M C1260 and the other test methods, except ASTM C227, only when a port land cement with a Blaine surface area of 500 m(2)/kg and a native alk ali content of 1.13-1.15% Na2Oeq is used in the ASTM C1260 test.