THE COMBINED USE OF FLY ASH AND LITHIUM NITRATE FOR CONTROLLING EXPANSION DUE TO ALKALI-SILICA REACTION

This paper presents preliminary data from a comprehensive research program investigating the efficacy of combinations of fly ash and lithium compounds for preventing damaging expansion due to alkali-silica reaction in concrete. The data presented include results from mortar bar expansion tests using two highly reactive aggregates from New Mexico and Pyrex glass (i.e. ASTM C 227 and C 441), and from a modified version of the accelerated mortar bar test (ASTM C 1260). Cements were blended to give a range of alkali levels and fly ashes from six different sources were selected to provide a range of chemical compositions. Lithium was added to mortars in the form of a 30% lithium nitrate solution. The data indicate that the beneficial effects of lithium and fly ash are cumulative when the materials are combined and, in some cases, there is a synergistic effect.