Alkali-silica reaction and pore solution composition in mortars in sea water

The promotion of expansion of mortars containing a reactive aggregate in 1N NaCl solution at 38 degrees C was attributed to a rise of OH- ion concentration in the pore solution in the mortars. However, it is ambiguous whether the promotion of expansion of mortars in sea water at a room temperature can be explained in the same way as in NaCl solution at an elevated temperature. This study aims at pursuing the expansion behavior of mortars containing a reactive aggregate relating it to their pore solution composition and the extent of alkali-silica reaction occurring within reactive grains. The alkali-silica reaction in mortars in sea water and 0.51N NaCl solution at 20 degrees C appears to progress differently from that in mortars in 1N NaCl solution at an elevated temperature of 38 degrees C. The promotion of expansion of mortars in sea water at 20 degrees C was found to be responsible for an effect of Cl- ions on the alkali-silica reaction at early stages of immersion. Only when OH- ion concentration in the pore solution was relatively high, NaCl and sea water could accelerate the alkali-silica reaction in mortars at 20 degrees C. Copyright (C) 1996 Elsevier Science Ltd