A Large-Capacity Batch Filling Water Balloon Apparatus for Deep In-situ Density Tests
A large-capacity water balloon aparatus has been developed specifically for measuring the in-situ density of compacted high-way trench backfill. In operation water is expelled from a calibrated 6-L reservoir to displace a rubber membrane. A dual-valve system enables larger volumes to be measured by repeated filling of the reservoir. The apparatus is simple, robust, and inexpensive, and has been used to measure hole volumes up to 30 L, with depths up to 0.8 m. It is much smaller and more easily handled that previous medium capacity apparatuses. Proving trials have shown that the apparatus can reliably determine hole volumes to an accuracy of +0/-0.6%, which is a significant improvement over the performance of the standard small volume equipment.