The effect of curing temperatures on the development of mechanical properties of fresh and hardened high-strength silica fume mixtures: A maturity approach

The primary purpose of this research was to assess the applicability of the maturity approach to describe temperature effects on setting and hardening of high-strength concrete mixtures incorporating silica fume and superplasticizer. The influence of these admixtures on the setting behavior was also studied. Setting times, and compressive strength and modulus of elasticity development with time at different curing temperatures were measured for a high-strength mixture.;The setting period was monitored by the penetration resistance of freshly cast mortar, with silica fume and superplasticizer being added in various proportions. Silica fume was found to shorten initial set times, while superplasticizer was found to delay initial set. Different apparent activation energies were estimated for the time period before initial set, depending on mixture proportions. However, a unique apparent activation energy was obtained during the setting period regardless of the admixture content in the mixture.;The hardening period was monitored by compressive strength and modulus of elasticity development of concrete specimens of a single mixture proportion. An exponential, a hyperbolic, and a parabolic-hyperbolic strength-age relationship were investigated. The hyperbolic strength-age relationship was observed to better describe strength-gain development, while the parabolic-hyperbolic modulus of elasticity-age relationship better described the modulus of elasticity development with time.;This research indicates that the maturity approach can be applied to high-strength concrete mixtures during the entire time period starting with mixing procedures and ending with mature, hardened concrete. Different apparent activation energies, though, should be estimated for the different stages of setting and hardening to allow the most accurate application of the maturity approach.;A maturity function based on the Arrhenius equation of the rate of chemical reactions was investigated with apparent activation energies for cement hydration being estimated at different stages of cement hydration. Equivalent ages at the times of initial and final set, and during compressive strength and modulus of elasticity gain were calculated.