电脉冲下矿物掺合料对砂浆硫酸盐侵蚀的影响

通过对掺与不掺矿物掺合料的水泥砂浆分别在电脉冲和浸泡条件下进行外观和强度比较,研究了电脉冲作用下矿物掺合料对水泥砂浆硫酸盐侵蚀的影响,并利用扫描电镜和能谱仪对试件内部进行了微观结构分析.试验结果表明:电脉冲加速了外部SO_4~(2-)向砂浆内部迁移,SO_4~(2-)与水泥水化产物反应生成大量钙矾石,使得试件短时间内出现明显的开裂、脱落以及强度损失;矿物掺合料改善了砂浆的抗硫酸盐侵蚀性能,掺量越高改善效果越明显,然而在电脉冲作用下掺矿物掺合料的砂浆仍受到明显的硫酸盐侵蚀.可见,电脉冲加速了硫酸盐侵蚀,这为快速评价水泥基材料的抗硫酸盐侵蚀性能提供了新的思路.

Effect of Mineral Admixtures on Sulfate Attack for Mortars Subjected to Electrical Pulse

The effect of mineral admixtures on sulfate attack for mortars subjected to electrical pulse was investigated by the appearance observation and strength measurement on the mortars with and without mineral admixtures under electrical pulse and immersion. The microstructures of the damaged specimens were analyzed by using scanning electron microscopy and energy dispersive spectrometer. The results showed that electrical pulse accelerated the penetration of the external sulfate ions into the mortars, and the sulfates then reacted with the cement hydration products to form massive ettringites. As a consequence, the specimens displayed significant cracking and spalling as well as strength reduction within a short period. Mineral admixtures improve the sulfate resistance performance of the mortars, and the improvement is increased with the increase of the amount of the admixtures. However, the mortars blended with mineral admixtures were still subjected to the dramatic sulfate corrosion under electrical pulse. The above findings indicate electrical pulse the accelerated sulfate attack, and also provide a new idea in rapidly evaluating the sulfate resistance of cement-based materials.