Comparative Assessment of Tensile and Shear Behavior of Cold, Warm and Hot Mix Asphalt Concrete

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The environment awareness of toxic gases emissions during the production, transportation, and construction of hot mix asphalt concrete (HMAC) have led to the development of Warm, half warm, and cold mix asphalt concrete. Such development of alternative mixtures is considered as sustainable materials in asphalt concrete paving process. The temperature reduction in the mixing of binder during production, handling, and compaction of the mix results in saving energy, reduction of emissions and significant reduction in production costs. Warm and Cold mixtures technology is considered as more environmentally friendly option to prepare asphalt by adding the binder in the form of an emulsion. Very limited laboratory and practical experience are available in Iraq for these mixtures. However, no trial section was constructed yet which considers such sustainable techniques. Until recent time there were even no technical specifications giving rules for design and use of these warm and cold mixtures. In this investigation, asphalt concrete mixtures usually used for wearing course have been prepared in the laboratory using the traditional hot mix and the sustainable alternatives of warm and cold mix techniques. Emulsified asphalt was implemented as a binder in case of warm and cold mixtures. Specimens were subjected to indirect tensile strength and double punching shear strength determination at 25°C. It was concluded that lower bulk density for cold mix was obtained as compared to hot and warm mixtures. The tensile strength of warm mix and Cold mix are lower by (82.8 and 93.1) % than that of hot mix. The punching shear strength of cold mix is lower by 50 % than that of warm or hot mix.