Moisture Susceptibility of a Crumb Rubber Modified Binder Containing WMA Additives Using the Surface Free Energy Approach Ayyanna Habal, S.M.ASCE 1 ; and Dharamveer Singh 2 1 Ph.D. Student, Dept. of Civil Engineering, Indian Institute of Technology Bombay, Mumbai-400 076, India. E-mail: ayyanna.habal@gmail.com 2 Assistant Professor, Dept. of Civil Engineering, Indian Institute of Technology Bombay, Mumbai-400 076, India (corresponding author). E-mail: dvsingh@iitb.ac.in Abstract: Though moisture damage potential of warm mixes have been evaluated by numerous researchers, performance of crumb rubber modified binder (CRMB) with WMA additives is still not been thoroughly investigated. The present study was undertaken to evaluate moisture damage potential of two types of aggregates (limestone and granite) with CRM binder containing three types of warm mix additives (i.e., Sasobit ® , Advera ® , Rediset ® ) using surface free energy (SFE) approach. The SFE parameters of CRM binder with and without three WMA additives were determined in the laboratory using Wilhelmy plate method. The SFE of two types of aggregates namely: granite and limestone were adopted from the literature. Thereafter, work of adhesion, work of cohesion, work of debonding, and energy ratio (ER) were calculated for a total 8 (4-binders x 2-aggregaets) combinations of aggregate-asphalt binders. The results showed that ER decreases with addition of WMA additives, indicating a poor moisture resistant of CRMB mix with WMA additives. The CRM binder with Rediset ® was found to be highly moisture resistant followed by Sasobit ® and Advera ® . In addition, moisture durability of limestone aggregates was found to be better compared to granite aggregates. INTRODUCTION Presently warm mix technology is widely used for reducing mixing and compaction temperatures of asphalt mixes. The warm mix asphalt (WMA) results in low greenhouse gas emission, energy saving, better work environment (Hurley and Prowell 2005). However, moisture performance of WMA mix is one of the major concerns (Ghabchi et al., 2013; Arbani et al., 2011; Hurley and Prowell 2005). This is mainly because of the reduced production temperature which may not be enough to dry the aggregate completely and hence a poor coating between aggregates and asphalt binder. Though many laboratory mechanical tests (tensile strength ratio, Hamburg wheel tracing) have been reported in literature to evaluate moisture damage of WMA mixes, limited study are available on use of surface free energy (SFE) method. In a study, Wei et al. (2010) evaluated the effect of commercial wax (Sasobit ® ) on PG 64-16 and PG 70-22 asphalt Geo-China 2016 GSP 262 245 © ASCE Geo-China 2016 Downloaded from ascelibrary.org by Indian Inst of Technology - Mumbai (IITM) on 07/30/16. Copyright ASCE. For personal use only; all rights reserved.