دانلود رایگان مقاله تاثیر الیاف بازالت جمع شدگی پلاستیکی آزاد و محدود

1. Introduction

Chopped basalt fibre is a relatively new concrete reinforcing material, with excellent mechanical properties and an environmentally friendly manufacturing process. The majority of research into basalt fibre reinforced concrete has focused on its mechanical properties [1e3]. In these studies, the results do not suggest the fibres are particularly effective in enhancing the post-cracking response of the concrete, which is one of the most significant benefits of fibre reinforcement [4]. Previous research has also indicated basalt fibres without any protective coating suffer from a lack of long-term durability in the alkaline environment of concrete [5,6]. Until this problem is resolved, a useful application of the fibre in its current state of development could be in enhancing the durability of concrete by preventing early-age cracking due to plastic shrinkage. It seems probable the fibres could be effective in this regard before any potential degradation negates their benefit.

4. Conclusions

The results presented in this paper suggest basalt fibres are effective in mitigating the detrimental effects of plastic shrinkage by reducing the magnitude of the shrinkage strain, and by restricting the growth of cracks if they do occur. As the w/c ratio decreases, it is the latter mechanism that becomes more prominent. However, related literature suggests that high-modulus fibres like basalt have a more severe impact to workability than lowmodulus fibres. Therefore, the application of basalt fibres for early-age crack control is likely best suited for general-use concrete, where the w/c ratio is often high enough that the fibres will not require additional measures (and cost) to restore workability. Moreover, they will be more efficient in this scenario due to the ability to simultaneously reduce the shrinkage strain and restrict crack growth. An example of such a mix can be found in a previous study, in which it was shown the addition of basalt filament dispersion fibres did not have a significant effect on the workability of regular-strength concrete (30e35 MPa compressive strength) with a w/c ratio of 0.5 until a dosage of approximately 0.46% by volume [2].