Identification of Fracture Characteristics of Cement-Stabilized Macadam with Super-Absorbent Polymer Based on Acoustic Emission

Super-absorbent polymer (SAP) is recognized as one of the most promising internal curing materials because of its outstanding internal curing performance. It has been shown to mitigate self-shrinkage and crack propagation in cement-based materials significantly. Building on this premise, the study employs two distinct particle sizes of SAP to formulate cement-stabilized macadam (CSM). It investigates the mechanical strength and drying shrinkage properties of SAP-CSM and observes the micro-morphology of the cement-based materials influenced by SAP. Additionally, acoustic emission (AE) equipment was used to explore the cracking behavior of CSM during the splitting test. The results indicate that the addition of SAP promotes cement hydration and reduces porosity, thereby enhancing the mechanical properties of CSM and retarding its drying shrinkage. In the splitting tests, the CSM specimens primarily exhibited tensile cracking, and the introduction of SAP did not alter the failure mode of the mixture. The specimens with added SAP showed reduced crack widths, lower cumulative ring counts, and more dispersed amplitude and peak frequency data, suggesting that the inclusion of SAP has a certain inhibitory effect on crack propagation. In a comparison of the two particle sizes of SAP, SAPA demonstrated a better crack suppression effect on CSM. This study provides new insights into early cracking in CSM, contributing to healthy and sustainable road construction.