应用复合材料力学理论和有孔介质力学(Poromechanics)理论建立了一个描述硬化硅酸盐水泥浆体弹性模量的细观力学模型,将硬化水泥浆体从不同尺度上划分为4个层次,即C-S-H凝胶、水泥水化产物、水泥浆体骨架和水泥浆体,分别应用不同的细观...应用复合材料力学理论和有孔介质力学(Poromechanics)理论建立了一个描述硬化硅酸盐水泥浆体弹性模量的细观力学模型,将硬化水泥浆体从不同尺度上划分为4个层次,即C-S-H凝胶、水泥水化产物、水泥浆体骨架和水泥浆体,分别应用不同的细观力学模型予以描述:将C-S-H视为饱和的有孔介质;应用Mori-Tanaka模型描述水泥水化产物的弹性性质;应用三相模型(Three-phase model)模拟水泥浆体骨架的有效弹性模量;最后,再次应用Mori-Tanaka模型和有孔介质理论,计算水泥浆体的排水和不排水弹性模量(Drained and undrainedelastic moduli)。该模型所需要的参数为水泥浆体各个组成部分的自身弹性性质,使用方便。通过预测文献中的实测结果,证明了该模型的有效性。展开更多
The microstructural evolution of C-（A）-S-H gel in Portland cement pastes immersed in pure water and 5.0 wt% Na2SO4 solution for different ages was comparatively investigated, by means of ^（29） Si NMR spectroscopy,...The microstructural evolution of C-（A）-S-H gel in Portland cement pastes immersed in pure water and 5.0 wt% Na2SO4 solution for different ages was comparatively investigated, by means of ^（29） Si NMR spectroscopy, and SEM-EDS analysis. Additionally, molecular dynamics simulation was performed to study the aluminum coordination status and interaction of sulfate ions in C-（A）-S-H gel. The results showed significant changes in the microstructural evolution of C-（A）-S-H gel in Portland cement paste. Sulfate attack has decalcifying and dealuminizing effect on C-（A）-S-H gel which is evident from increase in mean chain length（MCL） and decrease in Ca/Si ＆ Al[4]/Si ratios of C-（A）-S-H gel. Additionally, Molecular dynamics simulation proves that Al[4] substituted in silicate chains of C-（A）-S-H gel is thermodynamically metastable, which may explain its migration from the silicate chains and transformation to Al[6], thus lowering the Al[4]/Si ratio of C-（A）-S-H gel. SO4^（2-）ions can carry the interfacial Ca^（2＋） ions into the pore solution by the diffusion-absorption-desorption process, which unravels the mechanism of sulfate attack on C-（A）-S-H gel.展开更多
文摘应用复合材料力学理论和有孔介质力学(Poromechanics)理论建立了一个描述硬化硅酸盐水泥浆体弹性模量的细观力学模型,将硬化水泥浆体从不同尺度上划分为4个层次,即C-S-H凝胶、水泥水化产物、水泥浆体骨架和水泥浆体,分别应用不同的细观力学模型予以描述:将C-S-H视为饱和的有孔介质;应用Mori-Tanaka模型描述水泥水化产物的弹性性质;应用三相模型(Three-phase model)模拟水泥浆体骨架的有效弹性模量;最后,再次应用Mori-Tanaka模型和有孔介质理论,计算水泥浆体的排水和不排水弹性模量(Drained and undrainedelastic moduli)。该模型所需要的参数为水泥浆体各个组成部分的自身弹性性质,使用方便。通过预测文献中的实测结果,证明了该模型的有效性。
基金Funded by National Natural Science Foundation of China(Nos.51778513,51578004,51608004)the Major State Basic Research Development Program of China("973"Program)(No.2015CB655101)
文摘The microstructural evolution of C-（A）-S-H gel in Portland cement pastes immersed in pure water and 5.0 wt% Na2SO4 solution for different ages was comparatively investigated, by means of ^（29） Si NMR spectroscopy, and SEM-EDS analysis. Additionally, molecular dynamics simulation was performed to study the aluminum coordination status and interaction of sulfate ions in C-（A）-S-H gel. The results showed significant changes in the microstructural evolution of C-（A）-S-H gel in Portland cement paste. Sulfate attack has decalcifying and dealuminizing effect on C-（A）-S-H gel which is evident from increase in mean chain length（MCL） and decrease in Ca/Si ＆ Al[4]/Si ratios of C-（A）-S-H gel. Additionally, Molecular dynamics simulation proves that Al[4] substituted in silicate chains of C-（A）-S-H gel is thermodynamically metastable, which may explain its migration from the silicate chains and transformation to Al[6], thus lowering the Al[4]/Si ratio of C-（A）-S-H gel. SO4^（2-）ions can carry the interfacial Ca^（2＋） ions into the pore solution by the diffusion-absorption-desorption process, which unravels the mechanism of sulfate attack on C-（A）-S-H gel.
