Effects of Silica Fume and Temperature on Autogenous Deformation of High Performance Concrete
O. Bjontegaard and E. J. Sellevold
Appears on pages(s):
autogenous deformation; coefficient of thermal expansion; hardening phase; high-performance concrete (I-IPC); silica fume; temperature effect
High Performance Concretes (HPC) with water-to-binder (w/b) ratios of 0.40 and from 0 to 15% silica fume have been tested under 20° C isothermal conditions and under realistic (semi-adiabatic) temperature developments with maximum temperature in the range 60 to 65° C. The coefficient of thermal expansion is not very sensitive to silica fume content and its time/temperature dependence may be expressed by the maturity concept. The autogenous shrinkage is extremely temperature dependent, and, importantly, isothermal data cannot be used to predict the behavior during realistic temperature histories. The effect of silica fume (1:1 replacement of cement) is generally to increase the autogenous shrinkage; however, the increase depends strongly on the temperature history, and occurs primarily the first 2 days. Thus, the consequence for crack sensitivity is by no means obvious, and must be calculated for each particular structure.