Volume 2, Issue 1 (January 2005)
ASTM C 88 Test on Soundness of Aggregate Using Sodium Sulfate or Magnesium Sulfate: A Study of the Mechanisms of Damage
In this study, the mechanisms of damage to aggregate particles by sodium sulfate and magnesium sulfate solutions were investigated. By using glass and aluminum containers to represent aggregate pore space and confining walls, test results showed that during soaking cycles crystal growth occurred that applied some bearing pressure on the container. This bearing pressure, however, was secondary to more damaging pressure that occurred during the oven drying cycles. During soaking cycles, mirabilite (Na2·SO4 10H2O) applied bearing pressures up to about 0.6 MPa. During oven drying cycles, thenardite applied bearing pressures up to about 2.0 MPa. Magnesium sulfate salts produced bearing pressures about the same magnitude as that of the sodium sulfate salts.