Analysis of Service Life of Surface Coated-Concrete Structures Considering Climate Change and Chloride Ingress

2020 ◽  
Vol 842 ◽  
pp. 299-305
Author(s):  
Xiao Yong Wang
Keyword(s):  
Climate Change ◽  
Service Life ◽  
Surface Coating ◽  
Concrete Structures ◽  
Parameter Analysis ◽  
Chloride Ingress ◽  
Arrhenius Law ◽  
Chloride Diffusivity ◽  
Chloride Profile ◽  
Marine Concrete

Mortar surface coating is widely used as a finishing material to extend the service life and improve chloride ingression resistance of marine concrete structures. This study proposes a model for estimating the service life of surface-coated marine concrete considering climate change. First, the increase of chloride diffusivity due to climate change is considered using Arrhenius’ law. A two-layered chloride ingress model is used to analyze chloride profile. The probability-based approach is used to find the service life of concrete structures. Second, parameter analysis is performed considering the effects of various factors on service life. The influences of thickness and chloride diffusivity of the coating and substrate concrete on service life are highlighted. The reduction of service life due to climate change is clarified based on the regression of results of parameter analysis. For marine concrete with 50 years’ service life, 6% service life reduction occurs because of climate change.

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.

Achieving Concrete Durability in Chloride Exposures

2016 ◽  
Vol 711 ◽  
pp. 607-614 ◽  
Author(s):  
R. Douglas Hooton
Keyword(s):  
Service Life ◽  
Predictive Models ◽  
Performance Test ◽  
Concrete Structures ◽  
Test Methods ◽  
Transport Processes ◽  
Chloride Ingress ◽  
Concrete Durability ◽  
Life Predictions ◽  
Construction Defects

Obtaining durability in concrete structures over a long service life in chloride exposures requires knowledge of the concrete properties, relevant transport processes, depths of cover as well as minimization of cracking and construction defects. For example, imperfect curing can result in depth-dependent effects of the concrete cover’s resistance to chloride ingress. Several service life models with various levels of sophistication exist for prediction of time-to-corrosion of concrete structures exposed to chlorides. The model inputs have uncertainty associated with them such as boundary conditions (level of saturation and temperature), cover depths, diffusion coefficients, time-dependent changes, and rates of buildup of chlorides at the surface. The performance test methods used to obtain predictive model inputs as well as how models handle these properties have a dramatic impact on predicted service lives. Very few models deal with the influence of cracks or the fact that concrete in the cover zone will almost certainly have a higher diffusion coefficient than the bulk concrete as the result of imperfect curing or compaction. While many models account for variability in input properties, they will never be able to account for extremes in construction defects. Therefore, to ensure the reliability of service life predictions and to attain a concrete structure that achieves its predicted potential, designers, contractors and suppliers need to work together, using proper inspection, to ensure proper detailing, minimize defects, and adopt adequate, yet achievable, curing procedures. As well, concrete structures are often exposed to other destructive elements in addition to chlorides (eg. freezing or ASR) and this adds another level of complexity since regardless of cause, cracks will accelerate the ingress of chlorides. These issues are discussed along with the need to use performance-based specifications together with predictive models.

scholarly journals Durability design of concrete structures, Part 1: Analysis fundamentals

2009 ◽  
Vol 7 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Radomir Folic
Keyword(s):  
Service Life ◽  
Limit State ◽  
Natural Extension ◽  
Concrete Structures ◽  
International Committee ◽  
Chloride Ingress ◽  
Freezing And Thawing ◽  
Model Code ◽  
Design Service Life ◽  
Present Design

Concrete structures (CS) are designed so that they can satisfy requirements regarding safety, serviceability, durability and aesthetics throughout their design service life. Present design procedures regarding CS required by national or international codes and standards such as Model Code Euro International Committee of Concrete (1993) now Federation Internationale du Beton (FIB), Eurocodes, ACI, RILEM, etc. are predominantly based on strength principles and limit state formulation. The durability aspect is a natural extension of the classical resistance verification where deterioration effects are normally neglected. The reliability is assessed through the given performance that must be delivered within the design service life, the so-called performance-based design. This approach can be adopted for a performance based on service life design. In the recent years design is related to durability through the analysis of carbonation, resistance to chloride ingress, improved freezing and thawing resistance, etc. The review of literature and some recommendations are presented referring to the design of structures aiming to attain greater durability of CS. The accent is put on the theory of reliability, failure probability and service life probability. The basics of this analysis are given through the principles of performances and service life, and deterministic and scholastic methods using the lifetime safety factor.

scholarly journals Approaches for Modelling the Residual Service Life of Marine Concrete Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Amir Rahimi ◽  
Christoph Gehlen ◽  
Thorsten Reschke ◽  
Andreas Westendarp
Keyword(s):  
Service Life ◽  
General Procedure ◽  
Concrete Structures ◽  
Chloride Diffusion ◽  
Residual Service Life ◽  
Chloride Ingress ◽  
Repair Material ◽  
Layer System ◽  
Exposure Test ◽  
Residual Service

This paper deals with the service life design of existing reinforced concrete structures in a marine environment. The general procedure of condition assessment for estimating the residual service life of structures before a repair measure is illustrated. For assessment of the residual service life of structures which have undergone a repair measure a simplified mathematical model of chloride diffusion in a 2-layer system is presented. Preliminary probabilistic calculations demonstrate the effect of various conditions on the residual service life. First studies of the chloride diffusion in a 2-layer system have been conducted using the finite element method. Results of a long-term exposure test are presented to illustrate the performance of two different repair materials. The distribution of residual chlorides after application of a repair material is being studied in laboratory investigations. The residual chlorides migrate from the concrete layer into the new layer immediately after the repair material has been applied to the concrete member. The content and gradient of residual chlorides, along with the thickness and the chloride ingress resistance of both the remaining and the new layer of cover, will determine the residual service life of the repaired structures.

Diffusivity Resistance of Concrete Systems in Chloride Rich Environment for Corrosion Protection of Embedded Steel Bars

2013 ◽  
Vol 831 ◽  
pp. 3-8
Author(s):  
Suad Khalid Al-Bahar ◽  
Safaa M. Abdul Salam ◽  
Adel M. Husain
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Steel Reinforcement ◽  
Mineral Admixtures ◽  
Chloride Ingress ◽  
Corrosion Initiation ◽  
Chloride Ion Penetration ◽  
Ion Penetration

Improving concrete performance and minimizing corrosion-induced deterioration of reinforced concrete structures are mandated Building Codes Practices and Specifications in arid regions such as the Arabian Gulf. Concrete structures resist corrosion due to the passivating properties of the hydrated cement around the steel reinforcement created by the high alkaline environment within the composite structure (pH > 12). However, the presence of chloride ions in the pore structure of the concrete destroys this passivating layer, which makes the steel reinforcement vulnerable to chloride-induced corrosion attack that accelerates degradation and deterioration of concrete structures. Corrosion activities-related tests such as Time-to-Corrosion Initiation (Modified ASTM G-109)6, and Corrosion Rate Test (Lollipop Test), can be effectively used to monitor the behavior of corrosion development, while chloride ingress characteristics tests such as Electrical Indication of Concretes Ability to Resist Chloride Ion Penetration ASTM C-1202-91)7, and the Resistance of Concrete to Chloride Ion Penetration (AASHTO T 259-80)8, are applied to evaluate the rate at which chloride ions can diffuse through concrete to onset the time-to-corrosion initiation, which will impact the structure service life and compromise its sustainability. Efforts have been made by scientists to develop mathematical simulation models that predict the service life of the structure based on Ficks Second Law for semi-finite diffusion of chloride ions, concentrated at different concrete depths. The study concluded that mineral admixtures have contributed to the enhancement of concrete performance and its resistance to chloride diffusivity, as well when in combination with corrosion-inhibiting admixture such as calcium nitrite.

Sign in / Sign up

Export Citation Format

Share Document