Laboratory and Field Testing

Sand replacement density

Sand replacement density (SRD) tests are used to measure the in-situ density of natural or compacted soils using sand pouring cylinders. The in-situ density is typically used for highway or pavement design purposes to estimate the relative density of base course or subgrade materials.

The test can be carried out using either a small or large sand pouring cylinder. Unless otherwise specified the large pouring cylinder method is ordinarily used. The tests are typically undertaken at ground level or the prepared formation level. In some circumstances the test may be carried out in shallow trial pits or trenches excavated up to around 1m deep. If the side walls of the excavation are prevented from collapse either by digging a safe angle or by shoring with timber or support systems.

A cylindrical flat bottomed hole is excavated from the surface, approximately 200mm deep by 200mm diameter. All material excavated is carefully saved in a moisture retaining container, and weighed. Sand of a known density is poured into the hole using a calibrated cylinder. From the weight of sand taken to fill the hole, the volume of the hole is determined. The bulk density is calculated and after determining the moisture content, the dry density and air voids can be established.