Quantification of moisture sensitivity of warm mix asphalt using image analysis technique Meor Othman Hamzah a, * , Muhammad Rafiq Kakar a , Sayed Abulhasan Quadri b , Jan Valentin c a School of Civil Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia b Collaborative Microelectronic Design Excellence Centre (CEDEC), Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia c Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic article info Article history: Received 16 August 2013 Received in revised form 27 December 2013 Accepted 27 December 2013 Available online 4 January 2014 Keywords: Direct tension Moisture susceptibility Cecabase Adhesion failure abstract Warm Mix Asphalt (WMA) is susceptible to moisture damage owing to its lower production temperature. Moisture can cause adhesion failure, hence stripping of asphalt binder from aggregates. This paper proposes a new method based on image analysis to estimate the adhesion failure due to moisture on fractured conditioned asphalt surfaces. A novel approach is used to identify the adhesion failure sus- ceptibility due to moisture damage related to its mechanical strength in direct tension. The percent area failure due to adhesion is quantified more precisely via image analysis technique after the specimens were fractured in direct tension. The specimens under observation were evaluated for dry, 1 Freeze Thaw (F-T) cycle and 3 F-T cycles before being fractured by direct tensile force. The Environment for Visualizing Images (ENVI) Version 4.0 image analysis software tool was used to evaluate the extent of adhesion failure. The results from the image analysis showed that adhesion failure increased with the number of F- T cycles and mixtures prepared using PG-76 binder exhibited lower adhesion failure compared to PG-64 binder. The method enabled evaluation of adhesive failure of mixtures prepared using different binders and levels of laboratory moisture conditioning. This shows that the image analysis method can be used to quantify adhesive failure of warm mix asphalt and is a better alternative to the conventional method of visualization using the naked eye. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Warm mix asphalt has been conceptualized to produce asphalt pavement material at lower temperature (100e140  C) without compromising its performance (Ameri et al., 2013). The major component of pavement construction is the amount of energy consumed that significantly contributes to the total cost (Hamzah et al., 2010). Warm and half-warm mix asphalt is very popular nowadays because of its comparable performance to that of hot mix asphalt (Rubio et al., 2012a,b). The lower production and compac- tion temperature brings many potential benefits. This includes environmental benefits, lower plant emissions and fumes, up to 40% reduction in CO2, paving benefits, improved workability and compaction efficiency. The other benefits include longer haul distance, quicker turnover to traffic due to shorter cooling time, production benefits, increased Reclaimed Asphalt Pavement (RAP) content and location of plant site in urban areas (Rubio et al., 2012a,b). In the context of sustainable pavements, research has been done on the use of recycled demolition wastes, recycled asphalt, crushed brick (Poon and Chan, 2007), crushed glass (Grubb et al., 2006) recycled concrete in the pavement base, subbase and asphalt wearing courses. In road maintenance and rehabilitation, recycled pavement material has become a viable substitute. Some of the benefits obtained are the preservation of the resources and environment by reusing waste pavement materials (Taha et al., 2002). The use of RAP materials yields substantial savings in the overall costs of pavement construction (Hoyos et al., 2011). Simi- larly, in pavements subbase layer, the use of crushed brick (Arulrajah et al., 2011) and recycled glass when blended with other recycled aggregates, enhances the pavement subbase performance (Ali et al., 2011). According to Miliutenko et al. (2013), the use of hot-in-place asphalt recycling slightly reduces the greenhouse gas emissions and cumulative energy demand than hot-in-plant * Corresponding author. Tel.: þ60 4 5996210; fax: þ60 4 5941009. E-mail addresses: cemeor@eng.usm.my, cemeor@gmail.com, cemeor@yahoo. com (M.O. Hamzah). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro 0959-6526/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jclepro.2013.12.072 Journal of Cleaner Production 68 (2014) 200e208