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Several types of highway pavement have been adopted by various highway agencies, and each type has both advantages and disadvantages. Estimations of the life cycle cost and environmental impacts of pavement types have thus become major components of roadway planning, as the economic and environmental sustainability of pavements depends on both the project characteristics and the maintenance programme applied during the pavement life span. This article focuses on making a comparison of environmental impact in terms of Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) of two arterial streets in Al-Diwaniyah city centre. The first street utilises flexible pavement, while the second street is constructed with composite pavement layers, with a Hot Mix Asphalt (HMA) wearing layer implemented over a Portland Concrete Cement (PCC) pavement. The comparison between the streets was conducted using Athena Pavement LCA software, and the resulting analysis clarified the impact of pavement type, construction process and maintenance conditions on the environment in each case, taking into in consideration all related parameters such as material, construction processes, and the maintenance and rehabilitation programmes applied to the pavements during their life cycle. The results showed that the environmental impact in terms of gas emissions for the street implemented with flexible pavement was 48% higher than that of street implemented with a composite structure; further, the initial cost for the flexible structure was 17% higher that of pavement constructed with composite PCC and HMA. The LCCA for the street with flexible pavement was also 78% higher than that of composite structure due to the additional maintenance activities required during its service life.

The current research focuses on investigating the effect of using reclaimed asphalt pavement (RAP) on performance of hot mix asphalt (HMA) prepared with polymer modified bitumen (PMB) binder. This PMB used for the first time with HMA contained RAP. The mechanical properties and performance of HMA were assessed using several standard tests including Marshall, indirect tensile strength, creep compliance, and wheel track test. The RAP replacement was conducted up to 70% of total aggregate in HMA with an increment of 10%. The results of investigation showed, that the use of PMB binder prepared by addition novolac (phenol formaldehyde solid resin) and hexamine to conventional bitumen, significantly improved the performance of HMA contained RAP. Also, the optimum percentage of RAP replacement was found to be 50% of total aggregate in HMA. For this level of replacement, the rut depth reduced up to 38% of its original value.