What is the minimum size requirement for the base plate of a sand cone?

The minimum size requirement for the base plate of a sand cone is determined to ensure stability and effective functionality during the test. Choosing a base plate that is 3 inches larger than the funnel guarantees that the cone-shaped funnel can be adequately supported while also ensuring that any soil that may be displaced has enough area to form a transition into the surrounding material. This size provides a stable platform that can accommodate varying conditions in the field, preventing any interference with the test results which might arise from an improperly sized base.

A base plate that is smaller than this minimum size could lead to inaccurate results due to instability during testing, as it may not completely support the funnel or might allow for soil or sand to escape outside of the designated area, thus impacting the measurement of the density of the sand used in the test. Hence, adhering to this specified size is critical for achieving reliable and valid results in soil density testing.