Direct Coal Liquefaction Residue (DCLR), accounting for 30% by mass of total coals, is a main byproduct inevitably produced in direct coal to oil liquefaction(DCOL). DCLR possesses high amounts of ashes, sulfurs, carbons and calorific value and composed of heavy oil, asphaltene   preasphaltenes, and tetrahydrofuran insoluble. The heavy oil and asphaltene is about 30%~50% by mass of DCLR [14]. Efficient utilization of DCLR could reduce environmental pollution and make a huge influence on thermal and economical efficiency of DCOL processes. Therefore, how to reuse DCLR is a big problem to DCOL processes.  

Since the 1970s, how to reuse DCLR has started to be investigated. Lytle et al. found that during DCOL process a high amount of DCLR was produced and further studied the characteristics of DCLR [5]. Khare and Suganom et al. presented basic structure and pyrolysis property of DCLR [67]. Tanaka et al. proved the molecular structure of DCLR is same as that of raw coal [8].

In summary, it is generally considered that DCLR could be reused as a asphalt modifier, intermediate asphalts, etc. However, most researches were focused on the effect of adding DLCR on asphalts, however the properties of asphalt mortar and asphalt mixtures were not studied. Based on the mortar theory, it is well known that asphalt mixture is a dispersion system with multilevel space network structure. Especially, asphalt mortar plays a most important role in performance of asphalt mixture. The composition and filler/asphalt ratio of asphalt mortar determine the high and low temperature performance  of asphalt mixture [9]. When the filler/asphalt ratio is too small, the free asphalts are  too much and the binding strength between asphalts with coarse or fine aggregates are weak. While the filler/asphalt ratio is too big, free asphalts are totally absorbed by mineral fillers. Asphalt mortar becomes brittle and stiff without enough asphalt as a medium. The binding strength between asphalts with coarse or fine aggregates are also weak. Only with an appropriate filler/asphalt ratio, the optimal binding strength of asphalt mortar can be obtained [10].

Direct Coal Liquefaction Residue (DCLR) is a main byproduct inevitablyproduced in direct coal to oil liquefaction(DCOL), accounting for 30% of the totalcoal by weight. Composed of heavy oil, asphaltene preasphaltenes, andtetrahydrofuran insoluble, DCLR possesses high amounts of ashes, sulfurs,carbons, and calorific value, of which the heavy oil and asphaltene takes about30%~50% by weight^[14]. Efficient utilization of DCLRcould reduce environmental pollution and make a huge influence on thethermal and economical efficiency of DCOLprocesses. Therefore, how to reuse DCLR is an importantissue to DCOL processes.

Since the 1970s, how to reuse DCLR has started tobe investigated. Lytle et al.found that during DCOL process a high amount of DCLRwas produced and they further studied the characteristics of DCLR^[5].Khare andSuganom et al.presented the basic structure and pyrolysis propertyof DCLR^[67]. Tanaka et al.proved the molecularstructure of raw coal in DCLR ^[8].

In summary, it is generallyconsidered that DCLR could be reused as an asphalt modifier, intermediateasphalts, etc. Most researches werefocused on the effect of adding DLCR on asphalts, not on the properties ofasphalt mortar and asphalt mixtures. Based on the mortar theory, itis well known that asphalt mixture is a dispersion system with a multilevelspace network structure, in which asphalt mortarplays a most important role in the performance of asphalt mixture. Thecomposition and filler/asphalt ratio of asphalt mortar determine the high/low temperature performanceof asphalt mixture^[9]. When thefiller/asphalt ratiois too small, the free asphalts are toomuch and the binding between asphalts with coarse or fine aggregatesis weak. While the filler/asphalt ratio istoo big, the free asphalts are totally absorbed by mineral fillersand asphalt mortar becomesbrittle and stiff due to lack of asphalt as a medium and consequently thebinding becomes weak. Only with an appropriate filler/asphalt ratio, theoptimal binding strength of asphalt mortar can be obtained ^[10].