Backfill that isn't sufficiently compacted can subside, leading to pavement failure. Even with the best efforts by a field crew, it is impossible to tell whether the backfill has been compacted to its maximum density without the use of sophisticated instruments and/or expensive laboratory tests. Foster-Miller developed the Soil Compaction Meter to measure the density of the compacted backfill in typical utility pavement cuts and lower the risk of pavement failure due to backfill subsidence. The measurement is easy to make and also minimizes the number of callbacks to repair subsidence problems.

The system consists of a hand-held, battery powered, electronic device and an inexpensive disk-shaped disposable sensor. The low-cost sensor uses a polymer-based piezoelectric element which is bonded to the inside top surface of the sensor case. A single sensor is placed at the bottom of each excavation.  As each soil lift is compacted, signals from the sensor are interpreted by the microprocessor contained within the meter. When soil density is maximized (for a given soil type, compaction tool and lift height), the meter will signal the operator to "STOP" the tamping operation and proceed to the next soil lift. After the backfilling is completed, the sensor wire is disconnected, leaving the sensor at the bottom of the excavation for minimal disruption to the backfilling process.

After developing the technology, Foster-Miller transferred commercialization, and Soil Compaction Meters are available for purchase from M-B-W in Slinger, WI.

Return to Overview

Printable Version