超细微粉对水泥胶砂抗硫酸盐侵蚀的影响

研究了不同细度超细微粉掺合料对水泥胶砂在硫酸钠溶液全浸泡和干湿循环条件下抗侵蚀性能的影响,测试试件在(20±2)℃的3%Na2SO4溶液浸泡后的强度变化情况,从胶砂抗折强度的发展规律入手,结合抗蚀系数对胶砂抗硫酸盐侵蚀性能进行评价,并对两种侵蚀条件下胶砂抗硫酸盐侵蚀的性能进行了比较分析.结果表明:在全浸泡条件下胶砂抗折强度随掺入微粉比表面积变化规律为:550 m2/kg>450 m2/kg>310 m2/kg>空白组,超细微粉掺合料的加入明显的提高了水泥胶砂的抗折强度;在干湿循环条件下掺入超细微粉水泥胶砂抗折强度28 d前变化规律为:450 m2/kg>空白组>550 m2/kg>310 m2/kg;28 d后为强度下降阶段,掺入超细微粉掺合料各组强度下降速度均超过空白组,超细微粉掺合料的加入对于提高水泥胶砂在干湿循环条件下的抗折强度的效果不明显,特别后期加剧了强度下降.

Effect of ultrafine powder on sulfate resistance of cement sand

The effects of ultrafine powder admixtures with different fineness on the resistance of cement mortar to sulfate erosion under the conditions of full soaking in sodium sulfate solution and dry and wet cycling were studied.The strength changes of the specimens after soaking in 3%Na2SO4 solution at(20±2)℃were tested.Based on the development rule of the flexural strength of cemented sand,combined with the corrosion resistance coefficient,the corrosion resistance of cement sand to sulfate was evaluated,and the resistance to sulfate erosion of cement sand under two kinds of erosion conditions was compared and analyzed.The results show that the variation of the flexural strength of the mortar with the specific surface area of the micropowder under the condition of full immersion is 550 m2/kg>450 m2/kg>310 m2/kg>blank group.Under dry and wet conditions,the flexural strength of cement bonded sand mixed with ultra-fine powder was 28 d before age,and the change rule was 450 m2/kg>blank group>550 m2/kg>310 m2/kg.But the decrease rate of strength in each group was higher than that in blank group at the later stage of strength decline.The addition of ultrafine powder admixture has no obvious effect on improving the flexural strength of cement mortar under dry and wet cycling conditions,especially in the late stage,which intensifies the decrease of strength.The addition of ultrafine powder admixture can obviously improve the sulfate corrosion resistance of cemented sand.