Experiments and numerical analysis of cold-recycled asphalt mixture modified with desulfurization gypsum additive

Abstract

The purpose of this study is to find and evaluate the optimal mixing ratio of Cold Recycled Asphalt Mixtures (CRAM) with Desulfurized Gypsum (DG) mineral additives that satisfies the newly revised quality standard of the pavement in South Korea, and to evaluate their mechanical behavior. The optimal content of inorganic materials for CRAM is determined by the evaluation of the indirect tensile strength tests by DG contents. The performance evaluation of mixture for the common mixture type for the asphalt base course (Black Base course, hereafter BB course) and two types of developed CRAM with DG(w/DG) was conducted through Dynamic modulus. 3D FEA (Finite Element Analysis) of asphalt pavement applying the dynamic modulus through the experiments was performed in order to compare the behavior of the typical BB course and CRAM course for the alternative. When 7% of DG mineral additive is mixed into CRAM, it was found that the newly changed standard was satisfied. For CRAM 7%, since inorganic materials were mixed and the impact of temperature in the overall binder was relatively low, the stiffness change in the high-temperature region was less sensitive than in BB. As a result of the finite element analysis, the horizontal and vertical strain of the pavement using 0% CRAM and 7% CRAM as the substrate was 1.6 to 3.5 times greater than that of the pavement using BB. Based on the results of the experiment and 3D FE analysis, it is concluded that the thickness of the CRAM w/DG course should be designed and constructed to be thicker for the same performance as the BB course.