Early Shrinkage Performance of UHPC via Non-contact Testing

This study aims to systematically investigate the early-age shrinkage performance of Ultra-High Performance Concrete (UHPC) using a non-contact testing technique based on eddy current sensors. Different proportions of UHPC with varying POM fiber contents were utilized, and the shrinkage of UHPC specimens was periodically measured using eddy current sensors, followed by the analysis of shrinkage rate curves. The research findings reveal that with the increase in POM fiber content, the early-age shrinkage of UHPC gradually decreases, reaching a stable state when the POM fiber content reaches 24 kg/m³, with a 3-day shrinkage of 0.29 mm and an estimated shrinkage of 5.89 mm per 10 meters. Additionally, a clear pattern of shrinkage behavior is observed, with the highest shrinkage rate occurring within the first 18 hours after casting. Furthermore, comparative analysis between UHPC and ordinary concrete shrinkage performance indicates that under certain POM fiber contents, the shrinkage of both materials tends to be consistent. This study provides significant insights for the design and engineering application of UHPC materials.