Author ORCID Identifier
0000-0003-4067-5953
Document Type
Dissertation
Date of Award
5-31-2023
Degree Name
Doctor of Philosophy in Civil Engineering - (Ph.D.)
Department
Civil and Environmental Engineering
First Advisor
Matthew J. Bandelt
Second Advisor
Matthew P. Adams
Third Advisor
Jay N. Meegoda
Fourth Advisor
Methi Wecharatana
Fifth Advisor
Shawn Alexander Chester
Abstract
Durability challenges of reinforced concrete materials can shorten the service life and increase the carbon footprint of civil infrastructure systems. Novel alternative materials, such as high-performance fiber reinforced cementitious composites (HPFRCCs) and recycled aggregate concrete (RAC), offer an alternative to tradi-tional concrete materials by increasing the service life of infrastructure or reducing raw material consumption, thereby reducing the life-cycle carbon footprint. Due, in part, to a lack of robust numerical tools, predicting the durability response of these emerging cementitious materials has been insufficiently addressed. A time-dependent multi-physics modeling framework is proposed and adopted to investigate the chloride induced deterioration mechanisms of conventional and novel reinforced concrete structures. Three different concrete types are studied: ultra-high performance concrete (UHPC), traditional concrete subjected to mechanical loading conditions and wet and dry cycles, and reinforced RAC.
The proposed framework is applied to investigate the durability behavior of an ultra-high performance concrete (UHPC), one type of HPFRCC. A series of two-dimensional numerical simulations are carried out to study the electrochemical-mechanical coupling effects on deterioration mechanisms of reinforced UHPC beams subjected to service loading conditions and chloride attack. Service loads that induced cracking and rust expansion that caused deformations are considered in the finite element models. Material transport properties such as chloride and oxygen penetration parameters are updated based on cracking conditions. The results indicate that UHPC has superior durability characteristics compared to traditional reinforced concrete, with minimal loss in yield load capacity and negligible increase in UHPC damage. The effect of oxygen supply on the corrosion performance of UHPC is also explored, showing that the corrosion rate is limited due to depleted oxygen at the steel UHPC interface. The simulation results are verified against experimental trends on the corrosion performance of reinforced UHPC specimens.
The next study aims to analyze the effects of crack widths and varying levels of chloride exposure on the chloride penetration and corrosion performance of reinforced concrete beams using the proposed time-dependent multi-physics simulation approach. Finite element models are simulated in three dimensions, incorporating load induced cracking. Different chloride exposure concentrations and crack widths are considered. The material transport properties, such as chloride and oxygen diffusion parameters, are updated in each time step based on the wet and dry conditions and the development of damage. The simulation results show that larger crack widths lead to increased chloride concentration and corrosion propagation is faster at higher chloride ponding concentrations. The effects of wet and dry cycles on corrosion performance are also examined. This computational framework provides an efficient way to analyze the deterioration processes of reinforced concrete infrastructure under various loading and exposure conditions, which can be used for service life assessment of such structures.
A two-dimensional five-phase meso-scale time-dependent analysis is conducted to investigate the effects of chloride transport on the corrosion induced damage of reinforced RAC. The simulations incorporate the material properties of the aggregates, adhered mortar (AM) to the aggregates, old and new interfacial transition zones (ITZs), and cementitious matrix. The results show that the presence of more AM leads to quicker corrosion initiation and more corrosion product accumulation, resulting in more severe cracking. However, chloride distributions are less sensitive to chloride diffusion coefficients when the AM is in a very low range. The effects of aggregate shape and orientation on corrosion-induced cracking are also investigated. The chloride profiles at specific evaluated locations depend on the geometric characteristics of AM distributions and surface chloride conditions. The findings provide insights into the mechanisms of service life deterioration in reinforced RAC structures.
The time-dependent multi-physics simulation framework presented in this study provides a robust method to analyze deterioration processes and evaluate service life performance of reinforced concrete infrastructure. Moreover, the proposed modeling framework can be extended to various structural types and loading and exposure conditions.
Recommended Citation
Fan, Jin, "Multi-physics numerical simulation of corrosion and service life evaluation of novel reinforced concrete systems" (2023). Dissertations. 1927.
https://digitalcommons.njit.edu/dissertations/1927
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