Study on the Regulation of Early-Age Deformation Characteristics of High-Strength Coral Sand Grouting Materials

Coral sand grouting materials can effectively meet the new development requirements of remote island and reef engineering projects, demonstrating significant application value. However, its early-age shrinkage deformation may compromise structural stability. To effectively regulate this early shrinkage behavior, this study investigated the influence of varying dosages of early strength agent (ES), plastic expansive agent (PEA), and post-hardening expansive agent (HP-CSA) on the complete vertical expansion rate curve of coral sand grouting materials during 0-48 h, while comparatively examining the combined effects of composite expansive agents on early autogenous shrinkage and drying shrinkage characteristics. The results show that during 0-48 h, ES and composite expansive agents can precisely control the activation window of PEA, enabling controllable development of ultra-early vertical expansion in the grouting material, with increased HP-CSA dosage accelerating the progression of the complete vertical expansion rate curve. From 2 to 28 days, the coral sand grouting materials exhibit continuous shrinkage development. An appropriate combination of PEA and HP-CSA effectively synergizes to regulate shrinkage deformation. The drying shrinkage significantly correlates with the water loss rate. Within the scope of this study, when the dosages of ES, PEA, and HP-CSA are 1%, 0.06%, and 4%, respectively, the performance of coral sand grouting materials is relatively good.