硫酸钙晶须水泥砂浆力学性能及增强机理

(1.西安科技大学 建筑与土木工程学院,陕西 西安 710054; 2.中北工程设计咨询有限公司,陕西 西安 710068)

水泥砂浆; 硫酸钙晶须; 力学强度; 物理性能; 增强机理

Mechanical properties and strengthening mechanism of cement mortar with calcium sulfate whiskers
LI Wen-bo 1,LI Hai-bin 1,ZHAO Gui-juan 1,WANG Guang-hui 2

(1.CCollege of Civil and Architectural Engineering,Xi'an University of Science and Technology,Xi'an 710054,China; 2.Zhongbei Engineering Design Consulting Co.,Ltd.,Xi'an 710068,China)

cement mortar; CaSO4whiskers; mechanical properties; physical properties; enhancement mechanism

DOI: 10.13800/j.cnki.xakjdxxb.2020.0306

备注

针对水泥砂浆使用环境的多样性要求,结合硫酸钙晶须的自身特点,为实现增强与增韧的目的 ,采用外掺法将硫酸钙晶须加入水泥砂浆,通过实验研究了2%,4%,6%和8%(质量百分数)掺量的硫酸钙晶须对水泥砂浆物理性能和力学性能的影响,提出了水泥砂浆工作性能最好,力学强度最优时的硫酸钙晶须掺量及水灰比,并通过微观试验分析了硫酸钙晶须水泥砂浆的强度增强机理。实验结果表明:水泥砂浆的凝结时间随硫酸钙晶须掺量的增大先延长后缩短,当硫酸钙晶须掺量为4%时,水泥砂浆的凝结时间最长; 当水灰比为0.5,硫酸钙晶须掺量为6%时,水泥砂浆的抗折抗压强度增强效果最佳; 硫酸钙晶须可以缓解水泥砂浆内部裂缝尖端的应力集中,阻碍裂纹发展,晶须与水泥基体界面的桥接效应,实现了整体的增强和增韧。

In view of the various requirements of the environment of cement mortar,and the characteristics of calcium sulfate whiskers,the external admixture method is used to add calcium sulfate whiskers to the cement mortar,in order to achieve the purpose of strengthening and toughening.Through experiments, the effects of calcium sulfate whiskers with 2%,4%,6% and 8%(mass percent)on the physical properties and mechanical properties of cement mortar have been analyzed.The calcium sulfate whisker's content and water cement ratio when cement mortar has the best working performance and the mechanical strength is optimal.The strength enhancement mechanism is analyzed by microscopic test.The experimental results show that the setting time of cement mortar is prolonged first and then shortened with the increase of calcium sulfate whisker content.When the content of calcium sulfate whisker is 4%,the cement mortar has the longest setting time; when the water-cement ratio is 0.5,the content of calcium sulfate whisker is 6%,and the cement mortar has the best effect of strengthening the flexural and compressive strength; the calcium sulfate whisker can alleviate the stress concentration at the crack tip of the cement mortar,and hinder the crack development.The bridging effectbetween the whisker and the cement matrix achieves overall reinforcement and toughening.