چكيده به لاتين
HMAs are one the most principal structures to be performed on road surfaes which are consistently exposed to different kinds of degradation reasons. To propose novel approaches in order to diminish asphalt degradations and damages and so to prolong its lifetime is of importance to the society of road engineers to a large extent. Traffic loadings and weather changes are two of the major reasons which damage the HMA.The concentration of this study is the effect of aerobic microorganisms on a HMA in terms of disintegrating its structure and accelerating the asphalt damages, such as cracking or weathering. Besides, the interaction between clay and carbonaceous nanoparticles with asphalt damages has been studied and analysed, as a fruitful proposed solution to reduce the HMA damages. In this study, three different types of HMAs, in some of which nanoclay and carbon nanotubes have been used, were produced by Marshall Method in Iran University Of Science and Technology and one type of aged HMA were also gathered from there for rest of the studies. Then HMA specimens were sent to microbiology laboratory of Shahid Beheshti University Of Medical Sciences for a bacterial diagnosis about bacillus and pseudomonas exixtence. The first action was to produce asphalt suspension and then the bacteria culture process was operated in common culture environments, such as Nutrient Agar and Mueller Hinton Agar and then were kept in incubator to reach the optimum growth for one day in 37oC. Eventually, the effect of nanoparticles on the bacterias were tested and analysed by the MIC technique with micro-dilution broth method. The vital points that were observed, briefly, are that a lot of bacteria colonies were found inside the aged specimens and it can be deduced that existence of bacteria in structures such as HMA which includes bitumen as substrate can be one important probable reason to damage the asphalt rather than the reasons which have been illuminated, previously, for the road engineers. Besides, the specimens with clay and carbonaceous nanoparticles in their structure were rarely found to include any kind of bacillus or pseudomonas. The suggested amounts of nanoparticles in this study to be counted enough were 2 percent for carbon nanotubes and 4 percent for nanoclay after the MIC technique was operated. This project showed that combining the nanoparticles of clay and carbon can lead to the HMA durability increase and economic expenses reduce in urban plannings and road engineering.
Keywords: Asphalt, Nanoclay, Nanocarbon, Bacteria, Damage
