Using the Schleibinger Test System to Study the Restrained Drying Shrinkage Behavior of Lightweight Concrete

This paper examines the effect of different percentages of Polypropylene Fibers (PPFs) on the restrained shrinkage behavior (Schleibinger test) of Pumice Lightweight Concrete (LWC) at 0%, 0.5%, 1%, and 1.5%. The study investigates the changes in the timing for both vertical and horizontal restrained ring shrinkage tests. As shown in the experimental results, including PPF causes significant changes in the shrinkage response, especially at higher percentages. Vertical and horizontal strains display a pattern of periodic expansion and contraction at 1.5% PPF, indicating greater resistance to crack propagation due to the bridging effect of the fibers. Compared to the reference mix, fiber reinforcement alters the strain trend from primarily compressive to a balance between the cyclic responses, suggesting a delayed and more diffuse stress build-up during drying. This observation aligns with research on the microstructural role of PPF in managing the shrinkage cracking. The results show that 1.5% PPF not only decreases the early-age dimensional reduction in LWC, but also enhances the long-term dimensional stability. This behavior is crucial in applications where premature failure due to restrained shrinkage could occur. Based on these performance trends, optimized design scenarios are proposed to balance the workability and shrinkage control, which can help determine the ideal PPF content in future applications.