Okazu

POUNDING ROCKS AND DIGGING HOLES

I recently had the opportunity to watch the paving contractor reseal our church’s parking lot and driveways, bringing back memories of a stint I did with an Airport Engineering firm spanning 10 years. The firm’s owner had an outstanding reputation in the long history of this type of work. The core of his work was designing, contract managing and materials testing the construction of airport run-ways, taxiways and aircraft parking aprons.

One of the important jobs that I had was to test in our “lab” the suitability of materials to be used by the contractor. The equipment I used was all manual and considered very old. I would gather a sample of base rock (aggregate to be used under the asphalt layer), place it in a steel mold and pond away. This pounding simulated the action of a steel drum roller that you see on road projects. We would then test the compaction of this effort and if OK, the contractor was allowed to proceed.

In the field during the actual construction, I would have to test the compaction of the base course before the layer of asphalt was laid. While the contractor’s technician used a “nuclear gage” I would have to get on my hands and knees and dig a hole about 6 inches wide and 8 inches deep, sort of like an inverted dunce cap. I would then fill the hole with special sand. Each hole took about 25 minutes to complete. This procedure was designed to test the compaction of the base course.

Then came the asphalt. As the loaded asphalt trucks arrived, I would randomly gather a bucketful of the hot material, run to my makeshift “lab,” place the hot material (285 degrees) in molds and start pounding away. This action again simulated a steel drum roller working the asphalt and would determine how well the material could be compacted.

Some of the contractor’s field testers were amazed that I was still using testing methods developed decades ago, but as the saying goes, “If it ain’t broke don’t fix it.” Actually, although time consuming, these methods were accurate and withstood the test of time. I learned a lot in those 10 years and was surprised the company lo longer uses these methods — it outsources all lab an field testing to specialty companies.