Local structure and Ca/Si ratio in C-S-H gels from hydration of blends of tricalcium silicate and silica fume

At the microscale, C-S-H gels from alite, or neat Portland cements, has a Ca/Si ratio close to 1.80. nanoscale, is described by defective tobermorite structure which allows maximum 1.40. There no agreement in location of extra 0.40 mol Ca(OH)2 at nanoscale. Atomistic modelling studies reported species within interlayer space. Other works point toward fine intermixing and nanoportlandite. Here, we have prepared series alite blended with silica fume studied pastes several techniques including synchrotron pair distribution function (PDF). In employed conditions, gel formed pozzolanic reaction nearly same local than primary gel. Furthermore, differential PDF points excess having compatible few-layer thick nanoparticles stretched along c-axis.