Modeling of chloride penetration in concrete structures under freeze-thaw cycles

2019 ◽  
Vol 38 (1) ◽  
pp. 127-147 ◽  
Author(s):  
H’mida Hamidane ◽  
Ayman Ababneh ◽  
Ali Messabhia ◽  
Yunping Xi
Keyword(s):  
Finite Element ◽  
Temperature Variation ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Life Assessment ◽  
Chloride Diffusion ◽  
Chloride Ingress ◽  
Variable Boundary ◽  
Content Type ◽  
Freeze Thaw

Purpose The purpose of this paper is to develop a method for predicting the chloride ingress into concrete structures, with an emphasis on the low temperature range where freeze-thaw cycles may cause damage. Design/methodology/approach The different phenomena that contribute to the rate and amount of transported chlorides into concrete, i.e., heat transfer, moisture transport and chloride diffusion are modeled using a two-dimensional nonlinear time dependent finite element method. In modeling the chloride transport, a modified version of Fick’s second law is used, in which processes of diffusion and convection due to water movement are taken into account. Besides, the effect of freeze-thaw cycles is directly incorporated in the governing equation and linked to temperature variation using a coupling term that is determined in this study. The proposed finite element model and its associated program are capable of handling pertinent material nonlinearities and variable boundary conditions that simulate real exposure situations. Findings The numerical performance of the model was examined through few examples to investigate its ability to simulate chloride penetration under freeze-thaw cycles and its sensitivity to factors controlling freeze-thaw damage. It was also proved that yearly temperature variation models to be used in service life assessment should take into account its cyclic nature to obtain realistic predictions. Originality/value The model proved promising and suitable for chloride penetration in cold climates.

scholarly journals Limitations of sorptivity and water permeability for the estimation of the chloride penetration rate in concrete regarding the accomplishment of prescriptive design for durability in the marine environment

2018 ◽  
Vol 8 (3) ◽  
pp. 301-316
Author(s):  
Yury A Villagrán Zaccardi ◽  
María E Sosa ◽  
Ángel A Di Maio
Keyword(s):  
Marine Environment ◽  
Diffusion Rate ◽  
Penetration Rate ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Capillary Absorption ◽  
Chloride Ingress ◽  
Water Penetration ◽  
Conventional Concrete

This paper presents an analysis of experimental data from conventional concrete regarding sorptivity and penetrability under pressure comparing these parameters to chloride diffusion rate determined in the laboratory and in actual marine environment. Prescriptions for durability assurance of reinforced concrete structures is based on the qualitative characterization of transport properties. For the specific case of the marine environment, it is required to assess the resistance of concrete to chloride ingress. The results show the limitations of both parameters as prescriptive indexes, with capillary absorption rate showing some advantages over water penetration under pressure.

scholarly journals Perpendicular-to-crack chloride ingress in cracked and autonomously healed concrete

2018 ◽  
Vol 199 ◽  
pp. 02011
Author(s):  
Bjorn Van Belleghem ◽  
Philip Van den Heede ◽  
Kim Van Tittelboom ◽  
Nele De Belie
Keyword(s):  
Concrete Structures ◽  
Chloride Ions ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Crack Healing ◽  
Crack Location ◽  
Spray Method ◽  
Surface Visualization ◽  
Chloride Profiles ◽  
Concrete Matrix

Cracks in reinforced concrete structures exposed to a marine environment or de-icing salts can cause major durability issues due do accelerated ingress of chloride ions. In this study, the influence of autonomous crack healing by means of encapsulated polyurethane on the chloride ingress perpendicular to cracks was evaluated. This was done quantitatively by determining perpendicular-to-crack chloride profiles by means of profile grinding followed by potentiometric titration and qualitatively through visualization of the chloride penetration front by means of the AgNO3 spray method. The resulting chloride profiles showed that the healing mechanism was able to reduce the chloride concentrations in the direct vicinity of the crack to a large extent and to reduce the perpendicular-to-crack chloride penetration, especially further away from the exposed surface. Visualization of the chloride penetration front showed some variation in crack healing. For some healed samples almost no additional chloride ingress was found compared to uncracked samples, others showed a slightly enhanced ingress at the crack location but less perpendicular-to-crack chloride penetration compared to untreated cracked samples. Generally, the reduced amount of chlorides present in the concrete matrix due to crack healing will enhance the durability and service life of concrete structures.

A fictitious crack XFEM with two new solution algorithms for cohesive crack growth modeling in concrete structures

2015 ◽  
Vol 32 (2) ◽  
pp. 473-497 ◽  
Author(s):  
Xiaodong Zhang ◽  
Tinh Quoc Bui
Keyword(s):  
Finite Element ◽  
Nonlinear System ◽  
Crack Growth ◽  
Concrete Structures ◽  
Research Paper ◽  
Cohesive Crack ◽  
Multiple Cracks ◽  
System Of Equations ◽  
Nonlinear System Of Equations ◽  
Content Type

Purpose – The purpose of this paper is to achieve numerical simulation of cohesive crack growth in concrete structures. Design/methodology/approach – The extended finite element method (XFEM) using four-node quadrilateral element associated with the fictitious cohesive crack model is used. A mixed-mode traction-separation law is assumed for the cohesive crack in the fracture process zone (FPZ). Enrichments are considered for both partly and fully cracked elements, and it thus makes the evolution of crack to any location inside the element possible. In all. two new solution procedures based on Newton-Raphson method, which differ from the approach suggested by Zi and Belytschko (2003), are presented to solve the nonlinear system of equations. The present formulation results in a symmetric tangent matrix, conveniently in finite element implementation and programming. Findings – The inconvenience in solving the inversion of an unsymmetrical Jacobian matrix encountered in the existing approach is avoided. Numerical results evidently confirm the accuracy of the proposed approach. It is concluded that the developed XFEM approach is especially suitable in simulating cohesive crack growth in concrete structures. Research limitations/implications – Multiple cracks and crack growth in reinforced concretes should be considered in further studies. Practical implications – The research paper presents a very useful and accurate numerical method for engineering application problems that has ability to numerically simulate the cohesive crack growth of concrete structures. Originality/value – The research paper provides a new numerical approach using two new solution procedures in solving nonlinear system of equations for cohesive crack growth in concrete structures that is very convenient in programming and implementation.

Influence of Boundary and Initial Condition on Durability of Concrete Structures Exposed to Chloride Environment

2012 ◽  
Vol 166-169 ◽  
pp. 1946-1953
Author(s):  
Xin Gang Zhou ◽  
Fang Zhao
Keyword(s):  
Service Life ◽  
Initial Conditions ◽  
Error Function ◽  
Concrete Structures ◽  
Life Time ◽  
Chloride Penetration ◽  
Analytical Models ◽  
Chloride Ingress ◽  
Chloride Environment ◽  
Penetration Profile

According to investigations of apparent surface chloride contents and chloride penetration profile of concrete structures exposed to chloride environment, the influences of boundary and initial conditions, geometry parameters such as the geometry dimension and section shape, etc. were discussed. Based on the Fick’s second law of diffusion and different boundary and initial conditions, different analytical models to predict the chloride penetration profile in concrete structural members with different boundary and initial conditions were derived. Some calculations examples were made using those analytical models. Computational results show that the boundary and initial conditions have remarkable influences on chloride penetration profile and service life time of concrete structures. Using prevailing error-function solution model based on the semi-infinite assumption of chloride ingress, the prediction of service life time of concrete structures are over evaluated, in particular for the steel reinforcement in corner of the section. Some modify coefficients should be taken into consideration, concerning the influences of boundary and initial conditions.

Research on resistance degradation and reliability of pre-stressed concrete structures in freeze-thaw zone

2018 ◽  
Vol 9 (4) ◽  
pp. 442-454
Author(s):  
Jinliang Liu ◽  
Yanmin Jia ◽  
Guanhua Zhang ◽  
Jiawei Wang
Keyword(s):  
Service Life ◽  
Structural Reliability ◽  
Concrete Structures ◽  
Calculation Model ◽  
Time Dependent ◽  
Content Type ◽  
Freeze Thaw ◽  
Remaining Service Life ◽  
Resistance Degradation ◽  
Thaw Zone

Purpose In the freeze-thaw zone, the pre-stressed concrete of bridge structure will be damaged by freezing-thawing, the bearing capacity of structure will decrease and the safety will be affected. The purpose of this paper is to establish the time-dependent resistance degradation model of structure in the freeze-thaw zone, and analysis the structural reliability and remaining service life in different freeze-thaw zones. Design/methodology/approach First, according to the theory of structural design, a calculation model of the resistance of pre-stressed concrete structures in f freeze-thaw zone is established. Second, the time-dependent resistance model was verified by the test beam bending failure test results done by the research group, which has been in service for 20 years in freeze-thaw zone. Third, using JC algorithm in MATLAB to calculate the index on the reliability of pre-stressed concrete structure in frozen thawed zones, forecasting the s remaining service life of structure. Findings First, the calculation model of the resistance of pre-stressed concrete structures in freeze-thaw zone is accurate and it has excellent applicability. Second, the structural resistance deterioration time in Wet-Warm-Frozen Zone is the earliest. Third, once the pre-stressed reinforcement rusts, the structural reliability index will reach limit value quickly. Finally, the remaining service life of structure meets the designed expectation value only in a few of freeze-thaw zones in China. Originality/value The research will provide a reference for the design on the durability of a pre-stressed concrete structure in the freeze-thaw zone. In order to verify the security of pre-stressed concrete structures in the freeze-thaw zone, engineers can use the model presented in this paper for durability checking, it has an important significance.

Stochastic Finite Element Based Reliability Analysis of Concrete Structures in Marine Environment

2012 ◽  
Vol 193-194 ◽  
pp. 831-838
Author(s):  
Bin Hong ◽  
Lu Feng Yang ◽  
Zheng Chen ◽  
Qing Ming Jiang ◽  
Chun Yan Hu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Marine Environment ◽  
Concrete Structures ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Stochastic Finite Element Method ◽  
Stochastic Finite Element ◽  
Average Theory ◽  
Element Method

The stochastic model of chloride diffusion is the foundation of evaluating concrete structures’ reliability in marine environment. In this paper, the random field of chloride diffusion coefficient was described as a group of random variables by local average theory. The chloride distribution matrix, diffusion matrix and nodal concentration vector were expanded by using the Taylor series. The stochastic finite element method was developed, and the mean and standard deviation of the chloride distribution concentration were yielded by the presented method. A numerical example demonstrated the high precision of the stochastic finite element method presented, and the service life of concrete structures could be predicted by the method.

scholarly journals Reliability algorithms applied to reinforced concrete structures durability assessment

2012 ◽  
Vol 5 (4) ◽  
pp. 440-450 ◽  
Author(s):  
C. G. Nogueira ◽  
E. D. Leonel ◽  
H. B. Coda
Keyword(s):  
Reinforced Concrete ◽  
Diffusion Process ◽  
Concrete Structures ◽  
Threshold Level ◽  
Concrete Cover ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Reinforced Concrete Structures ◽  
Reliability Method ◽  
Corrosion Time

This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to ions chloride penetration. Structural durability is an important criterion which must be evaluated in every type of structure, especially when these structures are constructed in aggressive atmospheres. Considering reinforced concrete members, chloride diffusion process is widely used to evaluate the durability. Therefore, at modelling this phenomenon, corrosion of reinforcements can be better estimated and prevented. These processes begin when a threshold level of chlorides concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in the literature, deterministic approaches fail to predict accurately the corrosion time initiation due to the inherently randomness observed in this process. In this regard, the durability can be more realistically represented using probabilistic approaches. A probabilistic analysis of ions chloride penetration is presented in this paper. The ions chloride penetration is simulated using the Fick's second law of diffusion. This law represents the chloride diffusion process, considering time dependent effects. The probability of failure is calculated using Monte Carlo simulation and the First Order Reliability Method (FORM) with a direct coupling approach. Some examples are considered in order to study these phenomena and a simplified method is proposed to determine optimal values for concrete cover.

scholarly journals A Thermo-Hygro-Coupled Model for Chloride Penetration in Concrete Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Nattapong Damrongwiriyanupap ◽  
Suchart Limkatanyu ◽  
Yunping Xi
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Chloride Penetration ◽  
Heat Diffusion ◽  
Chloride Diffusion ◽  
Actual Condition ◽  
Reinforced Concrete Structures ◽  
Coupled Transport ◽  
Governing Equations

Corrosion damage due to chloride attack is one of the most concerning issues for long term durability of reinforced concrete structures. By developing the reliable mathematical model of chloride penetration into concrete structures, it can help structural engineers and management agencies with predicting the service life of reinforced concrete structures in order to effectively schedule the maintenance, repair, and rehabilitation program. This paper presents a theoretical and computational model for chloride diffusion in concrete structures. The governing equations are taking into account the coupled transport process of chloride ions, moisture, and temperature. This represents the actual condition of concrete structures which are always found in nonsaturated and nonisothermal conditions. The fully coupled effects among chloride, moisture, and heat diffusion are considered and included in the model. The coupling parameters evaluated based on the available material models and test data are proposed and explicitly incorporated in the governing equations. The numerical analysis of coupled transport equations is performed using the finite element method. The model is validated by comparing the numerical results against the available experimental data and a good agreement is observed.

Finite element method for solving asphalt mixture problem

2019 ◽  
Vol 10 (4) ◽  
pp. 569-579
Author(s):  
Wang Lijun ◽  
Li Qingbo
Keyword(s):  
Finite Element ◽  
Uniaxial Compression ◽  
Asphalt Mixture ◽  
Element Model ◽  
True Stress ◽  
Bending Test ◽  
Uniaxial Compression Test ◽  
Content Type ◽  
Freeze Thaw ◽  
Material Resources

Purpose Asphalt mixture is widely used in road engineering, and its performance research is particularly important. But the study of asphalt mixture performance needs a lot of tests, such as bending test, splitting test and so on. It also needs a lot of time and material resources. The purpose of this paper is to obtain test results through finite element numerical simulation, and show that this saves a lot of manpower and material resources. Design/methodology/approach The mechanical parameters of the material are obtained through uniaxial compression tests. The true stress and plastic strain are calculated according to nominal stress and nominal strain. A constitutive model is established. Then a finite element model of asphalt mixture is established. The numerical simulation and performance study of asphalt mixture bending test is carried out. At the same time, according to the above method, the asphalt mixture is subjected to freeze-thaw cycles and ultraviolet aging, and the mechanical parameters are obtained by a uniaxial compression test. A numerical model is established to simulate the bending characteristics of asphalt mixture after freeze-thaw cycles and ultraviolet aging. Findings A uniaxial compression test of the asphalt mixture is conducted to obtain nominal stress and nominal strain. The true stress and plastic strain are calculated and the elastic modulus is established with Poisson’s ratio as the elastic part, and the true stress and plastic strain as the plastic part. The model is constructed, the finite element model is established and the bending test is numerically simulated. The verified trend is consistent, and the method is feasible. According to the above method, the concrete is subjected to freeze-thaw cycle and ultraviolet aging, and the finite element model is established by using uniaxial compression test to obtain parameters. The bending test is simulated and the verification method is feasible. With the increase of the number of freeze-thaw cycles and the increase of UV aging time, the maximum bending strain of SBS modified asphalt mixture and matrix asphalt mixture is decreased .The low-temperature performance of SBS modified asphalt mixture is better than that of matrix asphalt mixture. Originality/value A method of simulating asphalt mixture test by finite element method numerical simulation is established. By using this method, the performance of asphalt mixture is studied, which saves a lot of manpower and material resources. At the same time, this method can be used to study the characteristics of asphalt mixture under complex conditions.

Sign in / Sign up

Export Citation Format

Share Document