Estimating the mechanical properties of hydrating blended cementitious materials: An investigation based on micromechanics

Abstract

The hydration model of Parrot & Killoh (1984) [1] has been extended to blended cements and coupled to a micromechanical scheme similar to that of Pichler & Hellmich (2011) [2] to estimate the Young modulus and the compressive strength of cementitious materials as a function of time. A finite aspect ratio of 7 is introduced to describe the shape of the hydrates and improve the estimate of the early age strength by the micromechanical scheme. Furthermore, accounting for the stress fluctuations in the cement paste partly explains the fact that the compressive strength of a concrete can be lower than that of its cement paste. Finally, the estimated physical properties are compared to numerous experimental measurements from the literature and new experimental measurements on blended cement pastes featuring significant weight fractions of limestone filler, fly ash or silica fume. It is shown that the present model slightly overestimates the dilution effect.

Effect of nano-silica particles on the hydration, the rheology and the strength development of a blended cement paste

“…The hydration model for blended cements proposed in [25] is extended to NS particles. Asis, the model provides an estimate of the advance of the various chemical reactions occurring in the cement paste.…”

“…The equation above can easily be extended to ternary blend by accounting for there weight fraction and an equivalent Blaine specific surface. For instance, the equivalent specific surface for silica fumes was set to 2000m 2 /kg in [25]. The experimental tests performed in the sequel are expected to provide an estimate for the equivalent Blaine specific surface for NS particles.…”

“…Nevertheless, these figures are very sensitive to the prices of materials and the present study is limited to isothermal conditions at 20°C while precast and thick concrete structures experience a rise of the internal temperature. The hydration model [25]…”

“…Temperatures during semi-adiabatic calorimetry tests are estimated by using the hydration model[25].…”

Micromechanical Multiscale Modeling of ITZ-Driven Failure of Recycled Concrete: Effects of Composition and Maturity on the Material Strength

“…Mean field homogenization-based micromechanical models are, up to this point, not able to incorporate non-homogeneous interface damage given the lack of analytical solutions of the corresponding matrix-inclusion problem-such solutions are currently only available for two-dimensional circular inclusions [48]. As an alternative, the proposed model and several of its predecessors [21,30,49], do quantify the ultimate strength of mortars and concretes based on elastic stresses obtained from micromechanics concentration relations referring to non-damaged microstructures. The question whether the such-obtained elastic microstresses allow for reasonable strength approximations can only be answered by comparing model predictions to independent experiments.…”