SAP内养生水泥混凝土综述

分析了超吸水性聚合物(SAP)的材料性能和SAP内养生混凝土配合比设计的关键参数，提出了内养生混凝土组成设计方法；从SAP吸释水行为和内养生混凝土水化特征角度，探讨了SAP内养生混凝土水分传输机制，综述了SAP内养生混凝土的收缩阻裂性能、力学性能和耐久性能；通过界面过渡区特征、水化产物和孔结构特征，探究了SAP内养生混凝土性能增强机理；总结了SAP内养生混凝土国内外工程应用情况，并展望了其未来的研究方向和应用前景。分析结果表明:SAP内养生原理为其本身的吸释水特性，但因SAP性能的差异和混凝土配合比等因素的不同，内养生水泥混凝土的各项性能有一定的差异性；SAP在渗透压和离子浓度的驱动下及时释水，补充混凝土内部水分丧失，降低早期水化热，并提升后期水化程度；SAP内养生混凝土的各项性能均受到其粒径、掺量和额外引水量的影响，在各参数均合适的条件下，SAP能够有效抑制混凝土的自收缩和干燥收缩，并增强混凝土的力学性能；SAP能够促进水化反应，生成更多的水化产物，填充混凝土的孔隙，增强混凝土的密实性，细化孔结构，切断连通孔隙，从而改善混凝土的抗冻、抗渗等耐久性能；SAP的再溶胀能力可阻塞混凝土裂缝，生成的CaCO₃等水化产物可使混凝土裂缝自愈合；SAP内养生作用能够增强水泥石与集料之间的黏结性，减少甚至消除界面过渡区微裂缝，提高界面过渡区强度；SAP内养生水泥混凝土在桥梁桥面整体化层、横隔梁、湿接缝、桥墩及隧道二次衬砌等部位已成功应用，抗裂效果优良。 

Review on cement concrete internally cured by SAP

The material properties of a superabsorbent polymer (SAP) were analyzed. Key parameters of mix ratio designs for SAP internally curing concrete were evaluated. A design method for internally cured concrete was developed. The water transmission mechanism of SAP internally curing concrete was investigated from the perspective of the water absorption and water release behavior of the SAP and the hydration characteristics of concrete. The shrinkage and crack resistance, mechanical properties, and durability of SAP internally curing concrete were examined. Its performance enhancement mechanism was explored by considering the characteristics of the interfacial transition zone, hydration products, and pore structure. The engineering applications of SAP internally curing concrete at home and abroad, as well as future research directions and application prospects, were identified. Analysis results show that the principle of SAP internally curing concrete relies on its water absorption and release characteristics. However, there is some variability in the performance of internally cured cement concrete because of the differences in SAP performance and concrete mix ratio and other factors. SAP, as a result of osmotic pressure and ionic concentration, is able to release water over time to replenish the loss of water inside the concrete, reduce the early heat of hydration, and enhance the later hydration. The properties of SAP internally curing concrete are affected by its particle size and admixture amount, and additional water quantity. SAP can effectively suppress the self-shrinkage and drying shrinkage and enhance the mechanical properties of concrete when all the parameters are suitable. SAP can also promote the hydration reaction, generate more hydration products, fill pores of concrete, enhance the compactness of concrete, refine the pore structure, and break off the connected pores, thereby improving the durability of concrete, including its frost resistance and impermeability. The reswelling ability of SAP can block concrete cracks and generate hydration products, such as CaCO₃, to enable concrete to self-heal. The curing effects of SAP can enhance the adhesion between cement stones and aggregates, reduce or even eliminate the microcracks in the interfacial transition zone, and improve the strength of the interfacial transition zone. The SAP internally curing concrete can be successfully applied to bridge deck integrative layers, cross diaphragms, wet joints, bridge piers, tunnel secondary linings, etc. with an excellent anti-cracking effect. 46 figs, 137 refs.