Modulus Based Compaction Quality Assurance for Unbound Materials Using Lightweight Deflectometer

Abstract

Moving away from traditional density-based methods of compaction quality assurance (QA) towards modulus-based procedures using Light Weight Deflectometer (LWD) require developing practical framework to: (1) determine soil- specific LWD target modulus, and (2) evaluate LWD modulus in the field effectively. This dissertation draws upon work from two research studies, TPF-5(285) pooled fund study and pilot projects conducted by Maryland State Highway Administration to refine the two proposed QA specifications for road base, subgrade, and embankment construction. The practical method of establishing the target modulus based on LWD drops on compacted Proctor molds was proposed and evaluated. Three types of LWDs (Zorn ZFG3000, Olson LWD-01, Dynatest 3031) were utilized and their field to target modulus ratio was compared to the percent compaction as a criterion for goodness of compaction. Results confirmed the validity of procedures for the variety of geomaterials tested and suitability for practical implementation by field inspection personnel. Target modulus values, calibrated acceptance criteria, sampling method, and frequency is presented for future implementation in the state of Maryland and other state DOTs. The LWD manufacturers collaborated to facilitate the implementation by instrument design and improvement or software/application development.