Effect of Silica Fume on the Heat of Hydration of High-Performance Concrete
E. H. Kadri and R. Duval
Appears on pages(s):
cement; high-performance concrete; hydration heat; poz-zolanic;
silica fume; superplasticizer
The objective of the study was to evaluate the influence of silica fume on the rate of heat liberation and the accumulated heat in high-performance concretes. Portland cement was replaced by silica fume in amounts from 10 % to 30 % in concretes with water-binder ratios varying between 0.25 to 0.45. A superplasticizer was used to maintain a fluid consistency. The heat of hydration was followed continuously by a semi-adiabatic calorimetric method for 10 days at 20°C. The calorimetric study indicates that the hydration is modified by the presence of silica fume. In the early stages, the silica fume shows a high activity and accelerates the hydration rate compared with the control concrete. The fine silica fume particles provide nucleation sites for hydrate growth. Then the pozzolanic activity takes over and increases the heat of hydration. A substitution of portland cement by 10 % silica fume produces greater cumulative heat of hydration compared with the control concrete.