Repeated Drop-Weight Impact Tests on RPC Containing Hybrid Fibers

Abstract

The impact resistance of micro-steel fiber-reinforced and hybrid fiber-reinforced reactive powder concrete is investigated in this study. Six groups of specimens were prepared with 2.5% volumetric contents of different combinations of fibers. For this purpose, micro-steel fibers with 6 and 15 mm length in addition to polypropylene fibers were used. Each group includes 12 identical specimens. The impact tests were conducted using the repeated drop-weight impact test of ACI 544-2R. However, higher drop-height (700 mm) and drop-weight (10 kg) were adopted to accelerate the failure and reduce the effort required to crack the specimens. The test results showed that the use of only 15 mm micro-steel fiber led to much higher impact resistance than other micro-steel fiber combinations. The recorded number of blows for the group with SF15 was 247, while those of SF6 and combined SF6 and SF15 were 127 and 112, respectively. The replacement of 0.5% of micro-steel fiber by 0.5% of PP fiber was found to reduce the impact resistance regardless of the type or combination of the used micro-steel fiber.