Extensive Modeling of Peculiar Hydration in Fine Micro-Pore Structures Applicable to Integrated Thermodynamic Analysis for Portland Cement

Koji Kinomura,Tetsuya Ishida

doi:10.3390/app9102137

Koji Kinomura, Tetsuya Ishida

Open Access

https://doi.org/10.3390/app9102137

Copy DOI

Journal: Applied sciences	Publication Date: May 24, 2019
Citations: 2	License type: CC BY 4.0

Affiliation: Taisei (Japan), The University of Tokyo

Abstract

Although applications of low water-to-cement ratio mixtures to practical structures have been increasing to enhance seismic resistance and long-term durability in recent years, it was experimentally observed that such a mixture causes peculiar hydration under long-term normal or high temperature curing. On the other hand, excessive hydration was revealed in the analysis using the original model, compared with the experiment in such an environment, because un-hydrated cement particles and existing condensed water reacted more significantly in the model. This study aims to enhance the integrated multiscale thermodynamic analysis, which is able to predict structural behavior in various conditions in a unified approach, by incorporating recent technical evolutions for its reverification and extending the original model to resolve the above peculiar concerns. Hence, the extensive modeling of continuous hydration considering spatial condensed water in fine micro-pore structures was proposed. Further, coupling of the integrated analysis with the extensive model was conducted, providing good agreement with time-dependent deformation experiments at different temperatures. Eventually, the validity and practical benefit of this study were demonstrated.

Highlights

Hydration occurs as soon as cement comes into contact with water to form micro-pore structures while precipitating hydration products
The Concrete Laboratory of the University of Tokyo has been developing an integrated microphysics and macro-structural analysis system to predict the overall behavior of a reinforced concrete (RC) structure in various conditions in a unified approach for its entire service life [1]. This integrated system synthesizes the following two systems: one simulating micro-pore structures and thermodynamic states in multiscale pores based on physical chemistry, considering hydration and environmental actions [2], and the other relating to structural mechanics modeling to estimate non-linear dynamic macroscopic behavior of a RC structure, even if including damage, under mechanical actions [3]
As underestimate of cumulative mass loss in the analysis suggests over-consumption of condensed variousdue thermodynamic states estimatedinbased on the basic components areprogress transferred water to the excessive hydration the original model

Summary

Introduction

Hydration occurs as soon as cement comes into contact with water to form micro-pore structures while precipitating hydration products. The Concrete Laboratory of the University of Tokyo has been developing an integrated microphysics and macro-structural analysis system to predict the overall behavior of a RC structure in various conditions in a unified approach for its entire service life [1]. This integrated system synthesizes the following two systems: one simulating micro-pore structures and thermodynamic states in multiscale pores based on physical chemistry, considering hydration and environmental actions [2], and the other relating to structural mechanics modeling to estimate non-linear dynamic macroscopic behavior of a RC structure, even if including damage, under mechanical actions [3]. They are generally referred to as DuCOM (Durability of COncrete Model) and COM3, respectively [1,4]

Objectives

Discussion

Conclusion