Why is it important to dry aggregate to constant mass?

Drying aggregate to constant mass is vital because it allows for the accurate measurement of moisture content. When aggregates are used in concrete mixtures, the moisture content can significantly affect the water-to-cement ratio, which is crucial for achieving the desired strength and durability of the concrete. If the aggregates contain excess moisture and this is not accounted for, it can lead to an incorrect proportion of water being added to the mix, ultimately compromising the quality of the final product. By drying the aggregates until they reach a constant mass, testers can obtain a reliable measure of their moisture content, ensuring that the correct amounts of all components are used in the concrete mix. This process is essential for producing concrete that meets specified performance criteria and for maintaining the consistency of the mixture in various batches.