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Sodium Sulfate Soundness Test assesses the durability of aggregates by subjecting them to five cycles of immersion in sodium sulfate solution and drying. Samples are immersed for 17 hours, drained, dried at 230°F, and cooled. After the cycles, samples are washed to remove sodium sulfate and dried again. Finally, the samples are sieved, and the mass of retained particles is recorded. This test simulates natural weathering to determine aggregate durability.