Sodium Soundness test measures an aggregate’ss resistance to disintegration by weathering and freeze thaw cycles. The primary soundness test involves continuously submerging aggregate in a solution of sodium or magnesium sulfate. The process makes salt crystals form in the aggregates pores that are meant to simulate ice crystal formation.
The test typically consists of placing sample in solution for 18 hours, removing it and drying it, then repeating approximately 5 times. The sample is then washed and dried. The loss in weight is determined for each sieve size resulting in a complete loss weighted average. Loss ranges are typically in the 10-20% range for 5 cycles. Similar soundness tests are done by actual freeze thaw techniques