Efficient Methodology for Processing and Using Lightweight Deflectometer Data for On-Site Quality Control of Cement-Bitumen Treated Materials

Full-depth reclamation with hydraulic and/or bituminous binders, also known as cement-bitumen treated materials (CBTM), is a cost-effective and eco-friendly road rehabilitation method, as it fully utilizes existing materials. The mechanical behavior of stabilized materials changes over time due to curing, which is crucial for long-term performance. Then, in situ quality control (QC) strategies are necessary. This chapter proposes and investigates a methodology for processing and using Lightweight Deflectometer (LWD) experimental data to assess CBTM properties at different locations and curing times. Multiple data processing and three calculation methods for modulus values are introduced: (1) the surface modulus obtained by Love’s solution using only one deflection (ES1); (2) the surface modulus obtained by BackCAP, a backcalculation software based on Finite Element Method, using three deflections (ES3), considering the pavement as composed as one single semi-infinite layer; and (3) the elastic modulus of the two distinct materials (ECBTM and Esubgrade), backcalculated using three deflections. Results show that BackCAP provides reliable elastic modulus values. Comparisons between surface modulus (ES) and the moduli set (ECBTM and Esubgrade) demonstrate the third method effectively assesses each material’s contribution to pavement stiffness, which is important in evaluating the CBTM layer. The research concludes that LWD is an efficient QC tool for CBTM and using backcalculated elastic moduli for the separated layers provides better data than the surface modulus for monitoring material evolution over curing time.