scholarly journals Explicitly Assessing the Durability of RC Structures Considering Spatial Variability and Correlation

2021 ◽  
Vol 6 (11) ◽  
pp. 156
Author(s):  
Cao Wang
Keyword(s):  
Spatial Variability ◽  
Structural Properties ◽  
Marine Environment ◽  
Vital Role ◽  
Concrete Cover ◽  
Chloride Diffusion ◽  
Chloride Ingress ◽  
Chloride Diffusion Coefficient ◽  
Rc Structures ◽  
Durability Design

The durability design of reinforced concrete (RC) structures that are exposed to aggressive environmental attacks (e.g., corrosion due to chloride ingress in marine environment) plays a vital role in ensuring the structural serviceability within a reference period of interest. Existing approaches for the durability design and assessment of RC structures have, for the most part, not considered the spatial distribution of corrosion-related structural properties. In this paper, a closed-form approach is developed for durability assessment of RC structures, where the structural dimension, spatial variability, and correlation of structural properties such as the concrete cover thickness and the chloride diffusion coefficient are taken into account. The corrosion and crack initiations of an emerged tube tunnel segment that was used in the Hong Kong-Zhuhai-Macau bridge project were assessed to demonstrate the applicability of the proposed approach. The accuracy of the method was verified through a comparison with Monte Carlo simulation results based on two-dimensional random field modeling. The proposed method can be used to efficiently assess the durability performance of RC structures in the marine environment and has the potential to become an efficient tool to guide the durability design of RC structures subjected to corrosion.

Production of High-Performance Composite Concrete Segment and Experimental Investigation of Materials

2010 ◽  
Vol 168-170 ◽  
pp. 1042-1045
Author(s):  
Ying Li Gao ◽  
Bao Guo Ma
Keyword(s):  
Service Life ◽  
Concrete Structure ◽  
High Performance ◽  
Concrete Cover ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Volume Deformation ◽  
Volume Stability ◽  
High Performance Composite ◽  
Structure Layer

Tunnel lining concrete segment is the most critical and important structural member of shield tunneling. This investigation designed and produced high-performance composite concrete segment (HCCS). Some key indexes that affect the properties of segment were tested, such as impermeability, volume stability, mechanical property, etc. The results indicated that the impermeability of HCCS concrete cover was excellent and the chloride diffusion coefficient decreased one order of magnitude compared to that of the ordinary segment concrete cover, while the service-life of HCCS increased more than ten-fold. The volume stability of HCCS concrete cover and concrete structure layer were good and the better compatibility in the volume deformation of the whole structure was shown. Furthermore, the mechanical properties of concrete cover and concrete structure layer met the project requirement perfectly, ensuring the higher durability and longer service-life of HCCS effectively.

scholarly journals Investigation on Durability Performance in Early Aged High-Performance Concrete Containing GGBFS and FA

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Seung-Yup Jang ◽  
Subbiah Karthick ◽  
Seung-Jun Kwon
Keyword(s):  
Diffusion Coefficient ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Corrosion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Structural Safety ◽  
Concrete Durability ◽  
Chloride Diffusion Coefficient ◽  
Rc Structures

The significance of concrete durability increases since RC (Reinforced Concrete) structures undergo degradation due to aggressive environmental conditions, which affects structural safety and serviceability. Steel corrosion is the major cause for the unexpected failure of RC structures. The main cause for the corrosion initiation is the ingress of chloride ions prevailing in the environment. Hence quantitative evaluation of chloride diffusion becomes very important to obtain a chloride diffusion coefficient and resistance to chloride ion intrusion. In the present investigation, 15 mix proportions with 3 water-to-binder ratios (0.37, 0.42, and 0.47) and 3 replacement ratios (0, 30, and 50%) were prepared for HPC (high-performance concrete) with fly-ash and ground granulated blast furnace slag. Chloride diffusion coefficient was measured under nonstationary condition. In order to evaluate the microstructure characteristics, porosity through MIP was also measured. The results of compressive strength, chloride diffusion, and porosity are compared with electrical charges. This paper deals with the results of the concrete samples exposed for only 2 months, but it is a part of the total test plan for 100 years. From the work, time-dependent diffusion coefficients in HPC and the key parameters for durability design are proposed.

Design and Impermeability of High Durability Reinforced Concrete Segment

2012 ◽  
Vol 174-177 ◽  
pp. 1199-1203
Author(s):  
Xin'gang Wang ◽  
Fang Bin Chen ◽  
Xu Na Ye ◽  
Wei Qin Zhang
Keyword(s):  
Diffusion Coefficient ◽  
Reinforced Concrete ◽  
Water Pressure ◽  
Chloride Ion ◽  
Concrete Cover ◽  
Chloride Diffusion ◽  
Shield Tunnel ◽  
Main Body ◽  
Chloride Diffusion Coefficient ◽  
High Durability

Reinforced concrete segment is the main body of structure in shield tunnel, and its durability has an important effect on shield tunnel. The durability of High Durability Reinforced Concrete Segment (abbr. HDRC Segment) was investigated by impermeability of single segment and chloride diffusion coefficient of core-drilling. HDRC Segment had high compact cover, concrete cover and high strength structural-layer. Permeable height of HDRC Segment was approximately 0.5 mm when Keeping 4 hours in the constant water pressure of 0.8 MPa, and chloride diffusion coefficient of HDRC Segment was only 4.9×10－13m2/s by NEL method. As for Water impermeability and chloride ion penetration resistance, HDRC Segment is far superior to those of conventional Reinforced Concrete Segment (abbr. conventional RC Segment). It is advantageous to increase durability of HDRC Segment and service life of tunnel engineering.

Durability Design of Tunnel Concrete Lining under Chloride Attack

2012 ◽  
Vol 594-597 ◽  
pp. 1014-1017
Author(s):  
Lu Feng Yang ◽  
Hong Bin ◽  
Yu Bo
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Concrete Lining ◽  
Chloride Diffusion Coefficient ◽  
Initial Value ◽  
Durability Design ◽  
Chloride Attack ◽  
Finite Element Formulations

Chloride induced corrosion of reinforcing steel is one of major causes of deterioration of tunnel concrete lining under chloride attack. In this paper, a finite element model for chloride ions transport in tunnel concrete lining was proposed based on the Fick’s second law of diffusion. The governing partial differential equation was solved numerically in space as a boundary-value problem and in time as an initial-value problem by means of the finite element formulations. The maximum allowable value of chloride diffusion coefficient of tunnel concrete lining with service life of 100a was achieved and some constructive suggestions for durability design of tunnel concrete lining under chloride attack were also proposed.

Sensitivity Analysis of Durability Parameters of Concrete Structures Corroded by Chloride Ions

2012 ◽  
Vol 594-597 ◽  
pp. 999-1004
Author(s):  
Li Zeng ◽  
Yuan Cheng Guo ◽  
Zhuo Zhao
Keyword(s):  
Concrete Structure ◽  
Diffusion Mechanism ◽  
Limit State ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
State Function ◽  
Chloride Diffusion Coefficient ◽  
Structural Durability ◽  
Influencing Parameters

For the pre-stressed concrete structure under marine environment，the stochastic characters of structure and environment such as concrete cover depth, initial chloride ions concentration, chloride diffusion coefficient in concrete, critical chloride ions concentration and structural surface chloride ions concentration affect the structural durability in designed service life greatly. Based on the diffusion mechanism of chloride ions, considering the durability failure character of pre-stressed concrete structure, the limit state function of durability failure is established, the sensitivity of durability influencing parameters is analyzed, and the Monte Carlo simulation is carried out based on the stochastic characters of influencing parameters, which will provide method and foundation for the structural durability design, construction and quality control of similar project.

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