Effect of Cyclic Freeze-Thaw on Dynamic Impact Resistance of Fiber-Reinforced Concrete

It is investigated how the content of basalt fiber with a diameter of 23 mu m influences specific energy intensity of failure in concrete D2000 and in light heat-reflecting concrete D1000. The mechanisms of alternating temperature effects on dynamic impact resistance of fiber-reinforced concrete are determined. After 12 cycles (freezing temperature -50 +/- 2 degrees C), the energy cost of failure in the samples of concrete D2000 at the fiber volume ratio of 2.7% totals 1962 J/m(2), which is 3.6 times higher than the energy intensity of failure in the samples of non-reinforced concrete. It is found that concrete with a porous absorbing aggregate made of expanded vermiculite possesses higher dynamic impact resistibility than high-density concrete. The energy intensity of failure was 5038 J/m(2) in vermiculite-containing heat-reflecting concrete and 2326 J/m(2) in fine-grain concrete D2000. The failure energy intensity in vermiculite-containing non-reinforced concrete after three freeze-thaw cycles drops by 71%, from 5038 to 1473 J/m(2). At the fiber volume ratio of 2.4%, the energy intensity of failure in fiber-reinforced concrete decreases by 9%, to 4608 J/m(2). These results can help increase the impact resistibility of shotcrete lining, including situations after the adverse effect of cyclic freeze-and-thaw.