Mineralogical evolution of Portland cement blended with silica nanoparticles and its effect on mechanical strength

Mineralogical analysis on pastes of Spanish Portland cement Type I, blended with nanosilica was carried out by conventional and high-resolution thermogravimetric analysis (TG-HRTG) and X-ray diffraction (XRD) in order to determine the quantity of the different mineralogical phases obtained during the hydration process. Simultaneously, mortars with the same materials and replacement ratio were made in order to assess their compressive strength for up to 28 days of curing time. In this paper, the rate and quantity of each one of the main constituent phases of the cement during its hydration process (C-S-H, portlandite, stratlingite, etc.) were determined. A correlation between the quantity of C-S-H and the development of compressive strength was established. Additionally, the pozzolanic activity of nanosilica was evaluated by quantifying the fixation of calcium hydroxide and its impact on the development of the compressive strength. (C) 2012 Elsevier Ltd. All rights reserved.