TY - JOUR ID - 2721 TI - Precision of elastic modulus estimation using back-calculation and independent variables based models in comparison to experimental data JO - Amirkabir Journal of Civil Engineering JA - CEEJ LA - en SN - 2588-297X AU - Kheradmandi, N. AU - Modarres, A. AD - Department of Civil Engineering, Babol Noshirvani University of Technology, Mazandaran, Iran Y1 - 2019 PY - 2019 VL - 51 IS - 2 SP - 267 EP - 284 KW - Falling weight deflectometer KW - Pavement layers KW - modulus KW - Back-calculation KW - Deflection basin parameters KW - Surface modulus DO - 10.22060/ceej.2017.13392.5400 N2 - Pavement condition assessment requires structural evaluation that can be achieved using Falling Weight Deflectometer (FWD). This paper focused attention to the FWD results. The main objective of this research is to present a new method to estimate the pavement layers elastic modulus and to investigate its precision considering the experimental test results. To this end, several sections in Shush-Andimeshk and Semnan-Damghan highways were evaluated by ground penetrating radar (GPR) for estimating the layer thickness and falling weight deflectometer test at different load levels for estimating the elastic moduli of pavement layers. At the same sections, some cores were extracted and tested to measure the elastic modulus using the indirect tensile and dynamic triaxial methods for bound and unbound layers, respectively. The FWD data were analyzed by ELMOD6.0 software as a conventional back-calculation method. Furthermore, a new method was proposed by implementing a code using BASIC programming language and the obtained results were compared with those from ELMOD6.0 and experimental results. Based on these investigations the proposed method could precisely estimate the experimental moduli. Some models were present to estimate laboratory modulus (assumed as real modulus) considering the back-calculated modulus. In addition to back-calculation based models, models were developed based on the independent variables such as surface curvature index (SCI) and base damage index (BDI). Using the latter models, the layer modulus can be estimated without using the complicated back-calculation analysis methods. The final part of this research related to the validation of developed models. Validation of these models showed that they were sufficiently reliable to predict the real elastic moduli. UR - https://ceej.aut.ac.ir/article_2721.html L1 - https://ceej.aut.ac.ir/article_2721_3e5aaebd431f9eb4eaf376b08d846ddf.pdf ER -