Experimental Research on the Fracture Behavior of Internally Cured Roller Compacted Concrete Pavement by Superabsorbent Polymer

In highway construction projects, the supply of water for external curing often encounters challenges that can lead to reduced concrete quality. This study investigates the effects of superabsorbent polymers (SAP) as internal curing agents on the workability, mechanical properties, and fracture characteristics of roller compacted concrete pavements (RCCPs) under various curing regimes and SAP contents. The research examines the influence of the crack-to-depth ratio and loading rate on fracture toughness (K Ic ) and fracture energy (G f ). The incorporation of SAP enhanced workability by decreasing the modified Vebe time as a result of increased water content in the cement. Compressive strength tests indicated that higher SAP content generally reduced strength at 28 days; however, specimens with 0.2% SAP and 3 days of external curing exhibited comparable strength to the reference sample, with only a 6.7% reduction. Splitting tensile strength tests showed a downward trend with increased SAP content. Moreover, the indirect tensile strength of all samples ranged from 2 to 4 MPa, which is typically suitable for RCCP applications. K Ic and G f decreased with an increasing crack-to-depth ratio but improved with higher loading rates. The study concludes that internal curing with 0.2% SAP and 3 days of external curing can enhance fracture resistance while maintaining acceptable compressive and tensile strengths, suggesting a potential reduction in water consumption.