Mark J. Farrow, P.E.
One of the most significant costs for construction projects at sites underlain by expansive clays is associated with building pad preparation. Injection stabilization is not always the most cost effective alternative for all sites. When deep building excavations are required to remove expansive clay, the largest expenses associated with building pad construction are the costs of purchasing and transporting select fill materials to the site and transporting the excavated clay spoil off-site. Through a conscientious Quality Control program, it is possible to rework and recompact on-site clay soils in moisture controlled lifts above their optimum moisture content with the assurance that the clay soils will not cause excessive upward slab movements. This paper presents a simple Quality Control program that involves the use of hand penetrometer tests during field testing operations along with nuclear density testing. Similar correlations are developed during Proctor compaction testing in the CME Laboratory prior to earthwork operations. In this way, a high level of confidence is achieved in assuring that reliable field results are being obtained.