دانلود رایگان مقاله خصلت خم شکاف در R / FRC با استفاده از تجزیه و تحلیل تصویر

ABSTRACT

In this study, experiments were conducted to induce bending cracks of specific surface crack width to reinforced concrete beams made of plain concrete (RC) and reinforced concrete beams made of fibre reinforced concrete (R/FRC). After injecting and impregnating the cracks with dyed epoxy resin, image processing and analysis were employed to investigate the internal crack morphology. Several crack features including crack width (accumulated, effective and maximum), branching and tortuosity were defined and quantified. The results showed that in addition to arrested crack development, the presence of fibres yielded a distinctive change in the internal crack pattern, including increased branching and tortuosity, both of which have positive implications regarding concrete permeation. Likewise, specimens with fibres exhibited reduced maximum individual crack widths near the rebar, potentially increasing the ability of autogenous crack healing and reducing the risk of corrosion initiation.

5. Conclusions

In this study, an experimental investigation has been carried out to characterise bending cracks in reinforced concrete beams and the influence of fibre reinforcement has been assessed. The modified three point bending test setup based on the standard test used to characterise the flexural strength of fibre reinforced concrete mixes proved to be an effective way of studying internal cracks in reinforced concrete beams. The low viscosity (0.1 Pa • s) resin used was fluid enough to penetrate and fill the cracks and after hardening and curing, cracks were effectively prevented from closing.Digital microscopy and image processing were found suitable for this purpose. The high resolution images taken at 20× magnification (2.7 lm/pixel) provided an accurate description of the crack morphology at the sections studied. These images could also be used as a modelling framework for the fracture of concrete and FRC. The algorithm implemented in this study based on the arc-length concept was capable of successfully determining the crack width perpendicular to the local direction of propagation along the whole crack path, as well as in the presence of multiple cracks. This fact permitted us to quantitatively determine several crack features even when the cracks significantly deviated from the global direction of propagation.