What happens if the gradation test shows results outside the acceptable range?

When a gradation test yields results that fall outside the acceptable range, it is essential to warrant further investigation of the mixing process. The gradation of the aggregate is a critical aspect of asphalt mixture design as it affects the workability, strength, and durability of the final product. Variations in gradation can indicate potential issues such as incorrect proportions of materials, improper mixing techniques, or contamination.

Investigating the mixing process allows for identifying and correcting any underlying problems that may have contributed to the deviation in gradation. This could involve examining the calibration of equipment, ensuring that the correct materials are being used, and confirming that the mixing procedures are being followed properly. By addressing these potential issues, one can maintain the quality and performance characteristics of the asphalt mixture and ensure it meets the required specifications for construction purposes.

The other options, although they mention relevant aspects, do not encompass the comprehensive approach necessary when dealing with gradation test results. While it may indicate material usability or equipment issues, the most prudent response involves assessing the entire mixing process to prevent future discrepancies and ensure compliance with quality standards.