Numerical Simulation of Heat and Mass Transport during Hydration of Portland Cement Mortar in Semi-adiabatic and Steam Curing Conditions

Published

October 22, 2015

Author(s)

Emilio Hernandez-Bautista, Dale P. Bentz, Sadoth Sandoval-Torres, Prisciiano Cano Barrita

Abstract

The mass and heat transport during steam curing of concrete has a bearing on both the mechanical and durability properties. Therefore, it is essential to take into account the temperature evolution and the moisture distribution to prevent premature damage to the material. A model that describes hydration and heat and mass transport in Portland cement mortar was developed. The hydration reactions are described by a maturity function that uses the equivalent age concept, thereby describing the change in the degree of hydration based on the time-temperature history. These equations are coupled to a heat and mass balance. The thermal conductivity and specific heat of mortar with water-to-cement mass ratio (w/c) of 0.30 was measured during hydration, using the Transient Plane Source method. Furthermore, the parameters used in the maturity equation and the activation energy were obtained by isothermal calorimetry conducted at 23 ºC and 38 ºC. Steam curing and semi-adiabatic experiments were carried out to obtain the evolution of temperature, final moisture content and degree of hydration at the end of the process. Magnetic resonance imaging measurements were undertaken to nondestructively monitor changes in evaporable water distribution. Three specimen geometries were simulated and the results were compared with those obtained experimentally. The results indicate that the maturity model adequately describes the evolution of heat and the degree of hydration during the curing conditions evaluated. The experimental and simulated temperature evolution had maximum residual values of 2.5 oC and 5°C for semi-adiabatic and steam curing conditions, respectively. The model predicts the evaporable water distribution obtained by magnetic resonance imaging, but showing a deviation in the first 5 h, especially at the surface where some evaporation of water occurs.

Citation

Cement and Concrete Composites

Pub Type

Journals

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https://doi.org/10.1016/j.cemconcomp.2015.10.014

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Keywords

Accelerated curing, cement-based materials, moisture distribution, exothermic reaction, isothermal calorimetry, nuclear magnetic resonance

Citation

Hernandez-Bautista, E. , Bentz, D. , Sandoval-Torres, S. and Cano Barrita, P. (2015), Numerical Simulation of Heat and Mass Transport during Hydration of Portland Cement Mortar in Semi-adiabatic and Steam Curing Conditions, Cement and Concrete Composites, [online], https://doi.org/10.1016/j.cemconcomp.2015.10.014, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917749 (Accessed April 25, 2024)