Systematic back-calculation protocol and prediction of resilient modulus for MEPDG. Issue Volume 19:Issued 1(2018) (2nd January 2018)

• Record Type: Journal Article
• Authors: Ng, Kam; Hellrung, Daniel; Ksaibati, Khaled; Wulff, Shaun S.
• Is Part Of: International journal of pavement engineering. Volume 19:Issued 1(2018)
• Page Start: 62
• Page End: 74
• Publication Date: 2018-01-02
• Subjects: Pavement -- MEPDG -- back-calculation -- resilient modulus -- falling weight -- deflectometer; Pavements -- Design and construction -- Periodicals; Highway engineering -- Periodicals; 625.805
• DOI: 10.1080/10298436.2016.1162303
• Languages: English
• ISSNs: 1029-8436

Abstract

Abstract: A research focusing on the characterisation of representative local material properties was conducted to facilitate the full implementation of the Mechanistic-Empirical Pavement Design Guide for roadway designs in Wyoming. As part of the test program, falling weight deflectometer deflection data were collected from 25 test sites in Wyoming for back-calculation of subgrade resilient modulus. Also, subgrade materials from these test sites were sampled for laboratory resilient modulus measurement in accordance with the AASHTO T 307. The back-calculation is a user-dependent procedure and produces a non-unique resilient modulus estimation. To alleviate this limitation, this paper focuses on the recent development of a systematic back-calculation protocol for subgrade resilient modulus using MODCOMP6 software. The protocol is intended for use on a flexible pavement with a crushed base. The proposed procedure discusses pre-analysis checks, seed modulus adjustment, pavement structure adjustment and program termination criteria. A correlation study was conducted to correct back-calculated resilient modulus to laboratory-equivalent values. The results conclude that a non-zero intercept linear regression model provides a better correlation than the widely used zero intercept linear regression model. Furthermore, better correlations are achieved when the back-calculated resilient modulus of a lower subgrade layer and resilient modulus measured at higher laboratory test sequences Nos. 11 to 15 are considered. The non-zero model based on M r test sequence No. 14 and lower subgrade layer yields the best correlation. For the zero model, a C -factor of 0.645 based on M r test sequence No. 15 and lower subgrade layer yields the best correlation.