دانلود رایگان مقاله نرم افزار نظارت بر خود بتن آسفالتی رسانا تحت تغییر شکل کششی غیر مستقیم

ABSTRACT

Conductive asphalt concrete has excellent self-monitoring abilities for internal damage and attractive application prospects. By studying the resistance and strain changes under indirect tensile deformation, three distinct stages of output resistivity changes are observed during the destruction of the specimen. In the initial loading stages, contact between the mixture particles tightens because the specimen under loading forms a more conductive path, and the resistivity decreases significantly. In the second stage, asphalt concrete deforms smoothly; small changes in the interior of the asphalt concrete also correspond to small changes in resistivity. In the final stage, because of the progressive development of cracks in asphalt concrete, the specimens are destroyed, and the conductive paths are also seriously damaged, significantly increasing resistivity. This change in the resistivity value exceeds 50%. Conductive asphalt concrete also has a good self-monitoring ability regarding the strain caused by the applied stress. The unit strain corresponding to changes in resistivity is greater when graphite content is lower. CT (Computer Tomography)identification can confirm that changes in resistivity are caused by material changes in the interior due to fatigue failure. The decrease or increase in resistivity is the result of a decrease or increase in the internal porosity of the material.

4. Conclusions

Conductive asphalt concrete with a suitable amount of graphite powder and carbon fibre can effectively diagnose its own strain during the loading process and resulting damage. (1) The resistivity changes are a negative pressure resistance effect in which resistivity decreases as the load increases and back to the initial state after unloading. Although the variation of the absolute value of each cycle in resistivity may not be consistent because of the influence of noise and changes in the structure, the changes in the resistivity of frequency and load frequency are equal, demonstrating that the resistivity of each cycle changes in response. (2) Conductive asphalt concrete has excellent self-monitoring capabilities of internal damage, and there are three distinct stages of resistivity changes during the destruction process of the specimen. In the initial stages of loading, the contact between the mixture becomes tighter because the conductive asphalt concrete specimen is subjected to loads, forming a more conductive path, and the resistivity decreases sharply. In the second stage, asphalt concrete is deformed smoothly. In this process, small changes in the internal structure of the asphalt concrete result in small changes in resistivity. In the final stage, the progressive development of cracks in asphalt concrete leads to the complete destruction of the specimen. Conductive paths are seriously damaged, resulting in a sharp increase in resistivity; the change in resistivity exceeds 50%. (3) The resistivity change is related to internal carrier concentration. Resistivity is inversely proportional to carrier concentration. The smart mechanism is due to changes in the carrier concentration per unit volume. (4) CT identification can confirm that resistivity change is caused by material changes in the internal structure of the process of fatigue failure. The decrease or increase in resistivity is the result of the decrease or increase of internal porosity.