Hygro-thermo-chemo-mechanical modelling of concrete at early ages and beyond. Part II: shrinkage and creep of concrete

Abstract

SUMMARYIn Part I of this paper (Int. J. Numer. Meth. Eng., in print) a mechanistic model of hygro-thermochemical performance of concrete at early ages has been introduced. Additionally, as compared to the existing models (e.g. J. Eng. Mech. (ASCE) 1995; 121(7):785-794; 1999; 125(9):1018-1027), an effect of relative humidity on cement hydration rate and associated hygro-thermal phenomena have been taken into account. Here we deal with mechanical performance of concrete at early ages and beyond, and in particular, evolution of its strength properties (aging) and deformations (shrinkage and creep strains), described by using the effective stress concept. This allow us for explanation and modelling of phenomena known from experiments, like drying creep (e.g.

Modelling of hydro-thermo-chemo-mechanical phenomena in building materials

“…The total stress tensor acting in a point of the porous medium may be split into the effective stress t ef (x,t), which accounts for stress effects due to changes in porosity, spatial variation of porosity and the deformations of the solid matrix, and a part accounting for the solid phase pressure exerted by the fluids and crystals present in pore volume, p s (x,t), [7,29,30],…”

“…The complete set of these equations, describing hydro-thermal properties of porous building materials, can be found in [18,24]. The mechanical properties, necessary for modelling stresses and strains of building materials, including creep and cracking of cement based materials, are dealt with in [7,8,30]. The relationships needed for analysis of salt transport (including osmosis in cement based materials) and precipitation in building materials are given in [11,14,15], and those necessary for modelling of calcium leaching are described in detail in [12].…”

“…[5][6][7][8][9][10][11][12][13][14][15], including also effects of water sorption hysteresis [16]. Previously this approach has been successfully applied to the numerical analysis of such difficult problems as hygro-thermo-chemical behaviour of concrete at early ages or degradation at high temperature, giving results in good agreement with experimental data, [5][6][7][8]. Here, a general approach to mathematical modelling degradation processes of building materials (including cement based materials which are particularly difficult for modelling), due to combined action of hydro-thermal, chemical and mechanical loads, is presented.…”

Age-dependent size effect and fracture characteristics of ultra-high performance concrete

“…Lackner and Mang [31] proposed a 3-D material model for the simulation of early-age cracking of concrete based on the Rankine criterion formulated in the framework of multi surface chemoplasticity. Gawin, Pesavento, and Schrefler [28,29] proposed a solidification-type early-age model and extended it to account for coupled hygro-thermo-chemo-mechanical phenomena, which was already applied to practical problems [15,14].…”

FE-Study on the Effect of Gradient Concrete on Early Constraint and Crack Risk

“…It is possible to model the complex interactions in hardening concrete using numerical material models and finite element analysis. There are already models which are capable of very detailed simulation of the behavior of the concrete [28][29][30][31][32]. These so-called "hygro-thermo-chemomechanical-models" consider moisture transport, chemical processes, temperature evolution and mechanical aspects including creep and shrinkage.…”