Evaluation of rapid assessment tools for determining strength characteristics of chemically stabilized unsurfaced materials

The need for rapid assessment tools as alternatives to traditional quality assurance/quality control (QA/QC) equipment has become evident over the past few years to determine the soil characteristics of stabilized, unsurfaced airstrips for military conctruction operations. These instruments must be sensitive to changes in strength properties and capable of measuring soil stiffness values well above those commonly encountered in subgrade or base course materials. The importance is apparent not only for in-theater airfields, but also for QA/QC of unbound and stabilized pavement layers. Commonly used QA/QC equipment such as the nuclear gauge is restricted by training and licensure. In this study, a stiffness gauge and a portable falling weight deflectometer were used to monitor changes in strength characteristics over time for a silty sand blend test section stabilized with type I portland cement, polymer emulsions, and combinations of both. The results were compared to values taken from unconfined compressive strength tests of the same material. The evaluation indicated the use of portable falling weight deflectometer to estimate the strength improvements of cement stabilized soils.