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Title: Advanced Calibration of Historic Apparent Moisture Diffusivity Models for Mortar

Author(s): Milena Rangelov, Somayeh Nassiri, Deviyani Gurung, and Timothy Ginn

Publication: Materials Journal

Volume: 117

Issue: 2

Appears on pages(s): 65-74

Keywords: diffusion; moisture transfer; shrinkage; transport properties

Date: 3/1/2020

Abstract:
Models are available to estimate the apparent moisture diffusivity (Da) of cement-based materials (CbMs) for internal relative humidity (h) prediction; however, these models include multiple nonunique shape parameters and are therefore impossible to manually calibrate. A common workaround is to use typical values, which are mostly outdated and inadequate for contemporary CbMs. This study presents an integrated procedure in which a finite difference inverse solution of Fick’s second law is linked with an advanced calibration software to identify and optimize the critical parameters of two widely used Da models. The observation dataset was h-profiles collected in mortar prisms from seven mixtures exposed to one-dimensional drying. Using the integrated method, the models’ parameters were optimized to fit the observation dataset. The impact of water-cement ratio and fly ash content on Da was established. Further, the critical parameters in both models were identified and correlated to different aspects of the pore system.




  

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