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.

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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