从纳米水化硅酸钙到水泥净浆弹性性能多尺度递推模型

Multiscale Upscaling Model for Elastic Properties from Calcium Silicate Hydrate Nanoparticle to Cement Paste

混凝土具有多尺度结构特征,其力学性能受到不同水化产物组分及微观结构的影响。基于分子动力学方法、化学计量法和均质化方法,建立了从纳米尺度水化硅酸钙(C-S-H)到水泥净浆弹性性能多尺度递推模型,其计算结果与实验数据吻合较好。基于该模型的计算结果可得:C-S-H凝胶中44%的孔隙率致使其体积模量、剪切模量和杨氏模量分别降低了约66%、53%和55%。当水灰比从0.3变化至0.5时,水泥净浆的体积模量、剪切模量和杨氏模量分别降低了约39%、30%和32%;LD C-S-H和毛细孔的体积分数分别增大了13%和20%。水化产物中C-S-H的体积分数越大,或水泥熟料中硅酸三钙的质量分数越大,水泥净浆的弹性参数越大。该模型为水泥基材料微观调控提供了指导。

Concrete has multiscale structure and its mechanical properties are affected by different hydration products and microstructure.Based on molecular dynamics,stoichiometry and homogenization method,a multiscale upscaling model of elastic properties fromcalcium silicate hydrate(C-S-H)nanoparticle to cement paste was proposed.And the calculated results are in good agreement with the experimental data.Based on the model,it was found that the 44%porosity of C-S-H gel reduced the bulk modulus,shear modulus and Young’s modulus by about 66%,53%and 55%,respectively.When the water/cement ratio changed from 0.3 to 0.5,the bulk modulus,shear modulus and Young’s modulus of the cement paste decreased by about 39%,30%and 32%,respectively.And the volume fraction of LD C-S-H and capillary pores increased by 13%and 20%,respectively.The greater the volume fraction of C-S-H in hydration products or the mass fraction of tricalcium silicate in cement clinker,the greater the elastic parameters of cement paste.The model provided guidance for microcontrol of cement-based materials.