# Rheological Performance of Bio-Char Modified Asphal with Different Particle Sizes  
[PERSON]  
1 School of Highway, Chang'an University, South Erhuan Middle Section, Xi'an 710064, China; [EMAIL_ADDRESS]  
2 Department of Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA; [EMAIL_ADDRESS]  
3 Faculty of Engineering, China University of Geosciences, Wuhan 430074, China  
4  
[PERSON]  
2 Department of Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA; [EMAIL_ADDRESS]  
[PERSON]  
2 Department of Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA; [EMAIL_ADDRESS]  
[PERSON]  
1 School of Highway, Chang'an University, South Erhuan Middle Section, Xi'an 710064, China; [EMAIL_ADDRESS]  
1 School of Highway, Chang'an University, South Erhuan Middle Section, Xi'an 710064, China; ranzhang@mtu. of a few hours. Typical yields at high-temperature conditions include 60% bio-oil, 20% bio-char and 20% gases. In contrast, a higher yield of bio-char can be produced through slow pyrolysis, nearly a 50% yield [14]. The majority of studies on bio-char have been focused on its ability to act as an amendment for soil, to increase the soil productivity and to enhance the nutrient cycling and plant growth [15; 16; 17; 18]. However, according to studies in recent years, it has been found that in some cases, the crop productivity cannot be increased and could even decrease because of the sorption of pesticides and water [19]. The use of bio-char in soil has a negative impact on the environment. It can lead to a detrimental impact on Greenhouse Gas (GHG) levels and the environment [20]. Bio-char can act as a sink of soil pollutants. Various toxic substances can be retained by bio-char through sorption or physicochemical reactions. Moreover, bio-char is difficult to be separated again from the soil, after its inactivation [19; 21]. Currently, as one of the biomass pyrolysis waste by-products, bio-oil can get efficient use as a biofuel [11; 22; 23; 24]. Along with bio-oil, bio-char is also produced as another byproduct, and if it cannot be used appropriately, and is instead randomly stacked, the bio-char in the air will also be a health risk for humans [25]. It is likely that bio-char can be used as a modifier for asphalt modification, to reduce environmental impacts and human health concerns. Meanwhile, carbon-based materials, such as carbon fiber, graphite, and carbon black, have been successfully applied in asphalt modification. With the addition of carbon fiber, the high-temperature properties and putting resistance of asphalt binder, as well as the alleviation of the aging and oxidation processes, were improved [26; 27]. Moreover, the fatigue life could be increased with the action of carbon nano-fiber [28]. The combination filler of graphite and carbon fiber improved the electrical property and the mechanical performance of asphalt concrete [29]. Carbon black could also be used to increase the anti-aging property, high-temperature performance and thermal conductivity of asphalt binder [30]. In addition, there has been a limited number of studies, over the past few years, about the application of bio-char as a construction and building material. A 1 wt% bio-char generated from food waste was found to increase the impermeability of mortar [31]. A pulp and paper mill sludge bio-char, with a content of 0.1% of total volume, was found to improve the mechanical strength of conventional concrete [32]. A 10 wt% swine manure bio-char decreases the temperature susceptibility and shear susceptibility of asphalt binder [33]. A 10 wt% switchgrass bio-char also significantly reduces the temperature susceptibility of asphalt binder and increases the moisture, cracking and rutting resistance of asphalt mixture [34; 35].