What preparation should be done to sand before using it in the sand cone method?

To ensure accuracy and consistency in the sand cone method, the sand used must be in a specific condition. It is essential that the sand is dried and reaches an air-dried state before conducting the test. This preparation is critical because moisture content in the sand can lead to inaccurate measurements of density when calculating the moisture density relationship. If the sand is not dried, it may contain excess water that can affect the volume occupied by the sand and, consequently, the calculations of soil density.

A state of air-dried sand ensures that any influence from moisture is eliminated, resulting in reliable test results that reflect the soil's true condition. This preparation step is a standard practice in soil testing to maintain the integrity of the data collected.