掺合料混凝土干缩开裂的Cl^-扩散系数实验  

The Study on Chloride-Ion-Diffusion-Coefficient of Drying Shrinkage Crack of Concrete Mixed Admixture

作　　者：张巨松[1] 邓嫔[1] 宋东升 张微[1] 韩自博[1] 彭丙杰[1] 

机构地区：[1]沈阳建筑大学材料科学与工程学院,辽宁沈阳110168 [2]沈阳市泰丰特种混凝土有限公司,辽宁沈阳110002

出　　处：《沈阳建筑大学学报（自然科学版）》2010年第1期129-134,共6页Journal of Shenyang Jianzhu University：Natural Science

基　　金：建设部科技攻关项目(2007-k4-19);沈阳地铁混凝土攻关项目(sw06-08-30)

摘　　要：目的研究不同矿物掺合料及硫酸钠对混凝土干缩开裂的影响,以降低混凝土早期干缩和避免出现早期干缩裂缝.方法根据NEL法采用自制装置,用电导率仪测试不同养护条件下混凝土的电导率,并转化成Cl-扩散系数,利用不同养护条件下扩散系数差值来反映混凝土早期干缩开裂程度.结果粉煤灰、矿粉掺量分别低于10%、20%时,Cl-扩散系数差值低于基准混凝土的差值,且随掺量的增加而增加;粉煤灰混凝土Cl-扩散系数差值在7d前上升趋势较明显;掺入Na2SO4后,Cl-扩散系数差值随龄期的增加而明显增加.结论低掺量矿物掺合料对混凝土的抗干缩开裂有利,且随着掺量的增加而降低,粉煤灰混凝土的干缩开裂主要发生在早期;掺硫酸钠后矿物掺合料对混凝土的抗干缩开裂不利.To decrease concrete early drying shrinkage and avoid early during shrinkage crack appearing, this paper studies the effect of different mineral admixtures and sodium sulfate on the drying shrinkage crack of concrete. According to the NEL method, the self-control equipment is applied to test the electric conductivity rate of concrete under different protecting conditions with the electric conductivity rate instrumentation, and convert the electric conductivity rate into the chloride-ion-diffusion-coefficient, then the chloride-ion-diffusion-coefficient dissimilarity of different protecting conditions is used to reflect the degree of the drying shrinkage crack of concrete in early days. When the fly-ash quantity is under 10% and the pulverized slag quantity is under 20%, the chloride-ion-diffusion-coefficient dissimilarity is lower than the basic concrete, and it increases along with the increase of the mineral admixtures quantity;Tbe chloride-ion-diffusion-coefficient dissimilarity of fly-ash concrete rises significantly before 7 days;The chloride-ion-diffusion-coefficient dissimilarity increases along with the increase of hydrated period after adding the sodium sulfate. When the mineral admixtures quantity is low under this experiment condition, it is beneficial to resist drying shrinkage crack of concrete, but it decreases as the mineral admixtures quantity increases, and the fly-ash drying shrinkage crack of concrete mainly appears in early hydrated period;The mineral admixtures is disadvantageous to resist drying shrinkage crack of concrete after adding the sodium sulfate.

关 键 词：粉煤灰 矿粉 硫酸钠 Cl-扩散系数 干缩开裂 

分 类 号：TU528.32[建筑科学—建筑技术科学]