Spherical Indentation Creep Behavior with Local Depth Deformation Analysis of Self-Compacting Concrete: Influence of Water-to-Binder Ratio

This study investigates the creep behavior of self-compacting concrete (SCC) under indentation loading, a relatively underexplored area compared with traditional loading conditions. The main objective is to elucidate the creep characteristics of five SCC mixtures, differentiated by varying water-to-binder (w/b) ratios while maintaining identical base formulations. Through instrumented indentation, the research evaluates the impact of the water-to-binder ratio, compressive strength, and type of concrete on creep behavior. The experimental methodology involved applying a constant indentation load of 2,000 N to samples after 28 days of curing, under controlled conditions of 20°C±2°C and 50%±5% relative humidity, with a loading duration of 1,000 s. The main results revealed that the SCCs exhibit a higher creep capacity than normal vibrated concrete (NVC) with equivalent compressive strength, with notable differences in terms of total creep depth and relative creep depth, particularly pronounced for medium-strength concrete (C37) and less so for high-strength concrete (C54). More specifically, the SCCs showed increases of 14.43% and 3.94% in total creep depth and relative creep depth for C37, and 5.76% and 4.75% for C54, compared with NVC. Moreover, after 1,000 s, the creep coefficients of the SCC were found to be slightly higher than those of the NVC, with differences of approximately 8.9% and 32.59% for C37 and 9.06% and 11.54% for C54 in terms of total creep. The study highlights the complexity of the creep behavior of the SCC, emphasizing the need to further explore their performance under various loading conditions. This research provides valuable insights into the mechanical properties of SCC, paving the way for a deeper exploration of their performance in different loading conditions.