– Cold mix asphalt technology

– Cold mix asphalt technology(CMA).
There are several methods to achieve the required workability of bitumen at low temperatures, i.e. decreasing bitumen viscosity; namely by using: cut back bitumen produced from mixing the bitumen with flux oil, foamed bitumen produced from foaming process of the hot bitumen with cold water, and bitumen emulsion produced from emulsification of bitumen emulsion with water(Al-Hdabi 2014). This research study is focused on the application of cold mixtures produced using bitumen emulsion as binder. By using cold mix asphalt, energy savings of 95% compared to HMA manufacturing can be achieved .The disadvantages of cold mix asphalt are also obvious. Because water needs to evaporate from bitumen emulsion in order for the bitumen to develop adhesion with the aggregates, cold mix asphalt may need several weeks to reach its full strength (Al Nageim et al, 2012).
This may result in lower early strength and high porosity when compared with the conventional hot mix asphalt (Al-Busaltan et al, 2012; Needham, 1996; Thanaya, 2003). In addition, the moisture damage potential and the durability are of concern because of the existence of water in the mixture (Cheng, 2013; Khalid and Monney, 2009). As a result, for heavy dusty pavements cold mix asphalt has seldom been used as a structural layer (Olard et al, 2008; Partl, 2010).
The addition of ordinary Portland cement with a proportion of (1-2)% (by mass) to cold asphalt mixture significantly improves its early mechanical properties (James et al, 1996; Thanaya et al, 2009), and the fully?cured material may acquire mechanical properties comparable or even better than those of an equivalent HMA (Al-Busaltan et al, 2012; Brown and Needham, 2000; García et al, 2012).
There are many types of by-product or waste materials can be used instead of cement because they are cheaper than cement or even without cost, available, and environmentally friendly; like ground-granulated blast-furnace slag (GGBS) which is a by-product material from iron production, represented by a fine powdery material that resembles to Portland cement in its appearance