A new testing configuration for shrinkage cracking of shotcrete and fiber reinforced shotcrete

Shotcrete and fiber reinforced shotcrete are commonly employed to produce layers or linings with large surface area versus volume ratios. Restrained shrinkage cracking is hence an important concern. The common test set-up used for shrinkage cracking of concrete, with a ring specimen cast around a stiff steel form, is not applicable to shotcrete. A new testing configuration, consisting of a shotcrete specimen bonded to a steel I-section and angles, is therefore proposed. In this investigation, a finite element analysis was first performed to identify member sizes that provide a good compromise between the effectiveness of constraint and weight of steel members. Restrained shrinkage tests using this new configuration were performed for plain and fiber reinforced shotcrete. Despite the simplifying assumptions in the finite element analysis, the predicted degree of restraint is in reasonable agreement with test results. From the results, the proposed set-up is shown to be a practical and viable approach for investigating the shrinkage cracking behavior of shotcrete and fiber reinforced shotcrete.