Adding steel fibres to improve shock vibration resistance of concrete

A newly developed shock vibration test method was employed to study the effects of shock vibration on steel-fibre-reinforced concrete so as to explore the possibility of improving the shock vibration resistance of concrete. In total, 21 batches of concrete with steel fibre contents ranging from 0 to 4% were cast and subjected to the shock vibration test at ages of 12 h, 1 day and 7 days. The results revealed that the effectiveness of adding steel fibres to alleviate the short-term damage caused by shock vibration (in terms of immediate reduction in ultrasonic pulse velocity) was quite low, especially for shock vibration applied at an early age. However, the effectiveness of adding steel fibres to mitigate the long-term damage caused by shock vibration (in terms of reduction in 28-day direct tensile strength) turned out to be much higher for shock vibration applied at age within 1 day than at later age. One probable reason is that, even after vibration damage had been caused, the continuing development of the steel–concrete bond while the concrete was still young could restore part of the reduced tensile strength. Finally, a new set of shock vibration control limits for steel fibre reinforced concrete was established.