160,457 research outputs found
Modeling Strains of Concrete Induced by Delayed Ettringite Formation in Variable Hygro-Thermal Conditions
No full textDelayed Ettringite Formation is a type of chemical degradation of moist concrete exposed at early ages to heating up to temperature of about 70-80°C. The material deterioration is caused by expanding phases produced by the ettringite reaction. A phenomenological, rate-type model of the DEF strains, considering effect of the temperature and duration of heat-treatment of concrete at early ages, and the evolution of ambient temperature and relative humidity, on the development of strains is introduced into the mathematical model of heat and moisture transport in deformable porous media. The model equations are solved numerically by means of finite element, finite difference and Newton-Raphson methods. The computer code was developed and used for the model validation by comparing its' results with the published experimental data
Modelling strains of concrete exposed to alkali-silica reaction in variable hygro-thermal conditions
No full textA mathematical model of combined action of hygro-thermal, chemical and mechanical loads is proposed to describe chemical degradation of concrete due to ASR. The model is based on mechanics of multiphase reactive porous media. The mass-,
energy- and momentum balance equations, as well as constitutive and physical relationships necessary for modelling the ASR in variable environmental conditions, are presented. A method for their numerical solution with the finite element and finite differences methods is described. The proposed mathematical model is validated by comparing the simulation results with some published experimental data concerning hygro-thermal processes and ASR expansion of concrete specimens in different hygro-thermal conditions, both constant and variable in time
Modeling chemical degradation of cement based materials with mechanics of multiphase porous media
No full textEffect of variable hygro-thermal conditions on chemical degradation of concrete structures due to alkali-silica reaction
No full textModelling degradation of concrete structures due to alkali-silica reaction in variable hygro-thermal conditions
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Prediction for the acoustic performance of a floating floor: Novel probabilistic approach considering materials Gaussian uncertainties
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Numerical modelling of concrete degradation due to alkali - silica reaction in variable hygro-thermal conditions
No full textModelling of concrete degradation due to alkali - silica reaction in variable hygro-thermal conditions
No full textDurability of cement based materials in normal and chemically aggressive environment has been an important subject of research in recent two decades. Several mathematical models have been developed for predicting the service life of concrete structures. Different chemical degradation processes are considered, including also those due to the Alkali - Silica Reaction (ASR). Most of the models describing the latter process are based on a phenomenological approach. Here a mechanistic-type approach to mathematical modelling of chemical degradation of concrete, based on mechanics of multiphase porous media, due to combined action of hygro-thermal, chemical and mechanical loads, is presented. Then the model has been applied to the concrete degradation due to ASR reaction and the sensitivity analysis of the model for variations of some selected material parameters, has been performed
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