自密实混凝土抗冻性研究进展

Research Progress on Frost Resistance of Self-compacting Concrete

本文总结了混凝土冻融破坏机理,综述了矿物掺合料、化学外加剂、集料种类和纤维等对自密实混凝土抗冻性能的影响规律和改性机理。矿物掺合料和化学外加剂通过改变自密实混凝土拌合物的工作性和含气量,降低了硬化混凝土孔隙率和微孔间距。粗细骨料的孔隙性、力学性能、变形性能和颗粒组成影响了自密实混凝土拌合物的流动性和体系中水分的赋存状态,改变了硬化混凝土的孔结构和孔隙的连通性。纤维通过微引气作用和桥接阻裂效应,抑制了冻融过程中毛细孔压力所引起的裂纹的产生与扩展。本文阐述了自密实混凝土研究应用中存在的问题并提出了改善自密实混凝土抗冻性的途径。

The freeze-thaw damage mechanism of concrete was summarized,and the influence and modification mechanisms of mineral admixtures,chemical admixtures,aggregate types and fibers on the freezeresistance performances of self-compacting concrete(SCC)were reviewed.Mineral admixtures and chemical admixtures reduce the porosity and microporous spacing of hardened SCC by changing the workability and air content of its mixture.The porosity,mechanical properties,deformation properties and particle composition of coarse and fine aggregates affect the fluidity of mixes and the state of water residence in the system,changing the pore structure and pore connectivity of hardened SCC.The fibers retard the generation and expansion of cracks caused by capillary pressure during freezing and thawing through micro-air-entraining and bridging and crack-blocking effects.The problems and development prospects in the research and application of SCC were further elaborated,and the ways to improve the frost resistance of self-compacting concrete were proposed.