Decreasing Thermal Cracking on Asphalt Pavement by Nano Calcium Carbonate (CCN) Modified Bitumen

Thermal cracking is one of the serious damage of asphalt pavements that occurs in cold areas. Thermal stress extend with decreasing temperature in the surface layer of asphalt when it reaches to critical value cracks occur. In recent years Nano materials commonly use to improve performance in bitumen. In this paper, Nano calcium carbonate (CCN) have been used to improve performance characteristics of bitumen at low temperature. For this purpose the bending beam remoter BBR test is carried out on unmodified and CCN-modified bitumen samples. CCN is added to control the bitumen at contents of 4% and 6% by the weight of bitumen and BBR test is done at -6 oC and -12 oC temperatures. BBR use to measure stiffness of bitumen at low temperature. The results showed that using CCN in bitumen samples cause to improvement on performance characteristics of bitumen at low temperatures particularly at -12 oC in comparison with unmodified bitumen samples. The results of BBR on samples modified with CCN is compared with previous research show on modified asphalt binder with Nano clay that the effect of CCN is better on performance characteristics of bitumen compared with Nano clay at low temperature.