Revised Rebound Hammer and Pull-Out Test Strength Curves for Fiber-Reinforced Concrete

Rebound hammer tests and postinstalled pull-out tests are commonly used for evaluating the compressive strength of ordinary concrete, and the strength of concrete is estimated by strength curves. However, using these strength curves to predict the compressive strength of carbon fiber-reinforced concrete (CFRC), polypropylene fiber-reinforced concrete (PFRC), and carbon-polypropylene hybrid fiber-reinforced concrete (HFRC) may lead to considerable uncertainties. Therefore, this study revises the strength curves derived from rebound hammer tests and postinstalled pull-out tests for ordinary concrete. 480 specimens of fiber-reinforced concrete (FRC) of six strength grades are examined. Standard cube compressive strength tests are used as a reference, and the results of various regression models are compared. The linear model is determined as the most accurate model for postinstalled pull-out tests, whereas the power model is the most accurate for rebound hammer tests. The proposed strength curves have important applications for FRC engineering of the postinstalled pull-out tests and rebound hammer tests.

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