Modeling Strains of Concrete Induced by Delayed Ettringite Formation in Variable Hygro-Thermal Conditions

Delayed 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.