硫酸盐侵蚀作用下低热水泥浆体退化行为研究

Deterioration Behavior of Low Heat Portland Cement Paste under Sulfate Attack

低热水泥广泛应用于水工混凝土,抗硫酸盐侵蚀是其耐久性设计的重要指标之一。采用硫酸钠溶液全浸泡试验法,对比研究了低热水泥基净浆试件与普通水泥净浆试件孔隙率、硫酸根离子分布、膨胀率、抗压强度和维氏硬度等物理、力学性能演化规律,对其侵蚀退化行为和损伤机理进行了分析。结果表明:硫酸钠溶液环境下低热水泥浆体的抗侵蚀性能优于普通硅酸盐水泥,掺入30%粉煤灰可提升其抗侵蚀能力。低热水泥浆体沿其侵蚀方向可由表及里分为损伤区、增强区、侵入区和完好区,维氏硬度指标能够较好地表征水泥石损伤时变行为。

Low heat portland cement is widely applied in hydraulic concrete,where much attention should be paid to its performance of sulfate attack.In this paper,the evolution laws of physical and mechanical properties such as porosity,sulfate ion distribution,expansion rate,compressive strength and Vickers hardness of low heat cement-based pastes were determined through the full immersion test of sodium sulfate solution,as well as the compared ordinary cement pastes.Based on which,their sulfate attack deterioration behavior and damage mechanism were also analyzed.Results show that compared with ordinary portland cement,low heat cement has better resistance to sodium sulfate attack,and adding 30%fly ash could also improve its anti-corrosion performance.The corrosion section of low heat cement paste can be divided into degraded zone,strengthened zone,ingressive zone,and sound zone from the surface to the inside.Vickers hardness could better characterize the time-varying behavior of cement paste under sulfate attack.