Soundness Test
The soundness test is performed in the laboratory to determine the extent of weathering of aggregates for road works. It helps in assessing the resistance of the aggregates to disintegration due to weathering.

Procedure:
The soundness test is conducted according to the ASTM C88 standard. The following steps are involved in the test:

1. Sample Preparation: A representative sample of the aggregate is taken and washed to remove any dust or fines. The sample is then dried in an oven at a temperature of 105°C to 110°C until it attains a constant weight.

2. Sulfate Solution: A 3% solution of sodium sulfate (Na2SO4) is prepared by dissolving the required amount of sodium sulfate in distilled water.

3. Test Specimens: The dried aggregate sample is divided into two portions. Each portion is weighed to the nearest gram and placed in separate containers.

4. Immersion: The containers with the aggregate samples are filled with the sulfate solution and covered tightly. The samples are then immersed in a water bath at a temperature of 25°C to 30°C for a specified duration.

5. Drying: After the specified immersion period, the samples are removed from the solution, drained, and placed in an oven at a temperature of 110°C to 115°C until they attain a constant weight.

6. Weighing: The dried samples are weighed to the nearest gram. The loss in weight is calculated and expressed as a percentage of the original weight of the sample.

Interpretation:
The extent of weathering or disintegration of the aggregates is determined based on the loss in weight. If the loss in weight is within the specified limits, the aggregates are considered sound. However, if the loss in weight exceeds the specified limits, it indicates a higher susceptibility to weathering and the aggregates may not be suitable for road works.

Advantages of Soundness Test:
- It provides a quantitative measure of the resistance of aggregates to disintegration due to weathering.
- It helps in selecting durable aggregates for road construction, which can withstand the effects of weathering and maintain their integrity over time.

Limitations of Soundness Test:
- The test does not consider other properties of aggregates such as strength and toughness, which are also important for road works.
- The test results may vary depending on the type and composition of the aggregate.

Overall, the soundness test is a crucial laboratory test in determining the extent of weathering of aggregates for road works. It helps in ensuring the durability and long-term performance of road pavements by selecting appropriate aggregates.