A critical review on the properties of natural fibre reinforced concrete composites subjected to impact loading

To gain a complete grasp of the dynamic properties and the engineering application potential of natural fibre reinforced concrete (NFRC), the recent research progress on the mechanical properties of NFRC composites subjected to impact loadings is reviewed in this study. A brief introduction of various natural fibres and their applications in construction engineering was first addressed. Then, the impact experimental test methods and instrumentation on NFRC are introduced. The comprehensive impact performance of concrete reinforced with various types of natural fibres is summarised in terms of load conditions, fibre type, fibre volume, fibre length, matrix strength, strain rate sensitivity and damage pattern. By comparing the impact resistance properties of different fibre types of NFRCs, the potential being applied as impact-resistant materials/structures in the field of building structural dynamics are discussed. Furthermore, the impact resistance of natural fibre and man-made fibre reinforced concrete is compared and discussed. Lastly, the main challenges and future research directions for NFRC are prospected and conclusions are summarised. Based on the current studies, it is recommended that the optimum fibre content range is between is 0.3-3% for different type of NFRC. The optimal length of coir fibre is suggested to be 20-75 mm. There is no recommended length for other fibre reinforced concrete. After considering the data, analysis, and debate that have been examined, it is very beneficial to provide relatively complete information database for the impact resistance of NFRC, and can provide some quantitative evaluation basis and suggestions for the further application of NFRC.