Highway pavements are being exposed to increasing traffic loads and severe environmental conditions, resulting in reduced service life. A lot of studies have been conducted to modify asphalt by using different materials, especially to replace the ordinary filler. Because the behaviour of the hot asphalt mix is influenced by the fillers. The use of unusual materials as fillers in asphalt mixes can help to improve the mix’s characteristics. As a result, this study uses cow dung ash materials with various replacement ratios as fillers to investigate the mechanical properties of asphalt. In the asphalt mix, a replacement percentage of limestone (0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100%) was utilized. After that, various tests were performed such as Marshall stability, Marshall flow, voids in mineral aggregate, theoretical maximum specific gravity, air voids. The results revealed a significant improvement in the asphalt mix’s behaviour, as well as an increase in the replacement percentage. According to the findings, the 50% replacement rate has the highest Marshall stability which is equal to 11.11 with a 33.5% rise and the lowest flow of 3 with a 17.83% decrease when compared to the reference mix. As a result, cow dung ash can be used as a filler to modify the mechanical properties of the asphalt mix.

For the sake of enhancing the mechanical properties and durability of asphalt concrete, many studies suggest adding different admixtures, such as waste materials in the form of filler. These admixtures have a significant influence on the performance of asphalt concrete by plying a roll in filling the voids between particles and sometimes as a cementitious material. This study aims to improve the strength of asphalt concrete by adding crushed animal bone to the mix after carbonization at a temperature of 800 Co. Seven different percentages (10, 20, 30, 40, 50, 60, and 100%) of animal bone ash as a replacement for the filler percentage were added to the optimum asphalt concrete mix. A number of tests were conducted on asphalt concrete specimens to measure Marshall stability (MS), Marshall flow value (MF), voids filled with asphalt percentages (VFA), air void percentages (VA), voids in mineral aggregate percentages (VMA), and maximum theoretical specific gravity (GMM). From the results, the maximum stability of 14.85 KN was reached when using animal bone ash of 20% as a partial replacement for the conventionally used filler (limestone). In general, there are some improvements in the physical properties of asphalt concrete with animal bone ash, which can be related to the increase in the bond between the particles of aggregates and the bitumen material. Doi: 10.28991/cej-2021-03091757 Full Text: PDF

Higher traffic loads on the wheels, increased traffic volumes, and exposure to changing weather conditions result in increasing the road stresses and strains, putting the paving layers in danger of degradation such as fatigue, stripping, cracking, and rutting. A tremendous number of studies and trials have been conducted to modify asphalt to have a longer service life, less maintenance, be cheaper, and be more environmentally friendly. Recently, nanotechnology has proven very beneficial in all industries, including asphalt. It can be used to enhance the asphalt's mechanical properties. Using nano clay in asphalt is expected to improve the mechanical properties and the service life of the asphalt. So the main objective of this study is to investigate the performance of nano clay hydrophilic bentonite in improving the physical characteristics of asphalt concrete. This study uses nano clay with various replacement ratios as fillers to the ordinary used limestone filler in asphalt concrete. The used replacement percentages were (0%, 20%, 40%, 60%, 80%, and 100). The experimental tests that were conducted in this study include Marshall Stability (MS), Marshall Flow (MF), voids in mineral aggregate (VMA), theoretical maximum specific gravity (Gmm) and air voids (AV).The results showed a noticeable enhansment in the behavior of the asphalt mix with increasing the replacement percentage by nanoclay. Also, it was found that the 60% replacement rate by nanoclay has the highest Marshall stability with an increase of 93%, also the lowest flow with a decrease of 25% compared to the control asphalt mix.

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