scholarly journals Service Life Prediction and Lateral Bearing Capacity Analysis of Piles Considering Coupled Corrosion-Temperature Deterioration Processes

2021 ◽  
Vol 9 (6) ◽  
pp. 614
Author(s):  
Yue Li ◽  
Youliang Chen ◽  
Wei Shao ◽  
Juhui Zhang ◽  
Shaoming Liao ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Bearing Capacity ◽  
Chloride Concentration ◽  
Probabilistic Methods ◽  
Stiffness Degradation ◽  
Chloride Diffusion ◽  
Capacity Analysis ◽  
Chloride Diffusion Coefficient ◽  
Degradation Coefficient

High temperatures can enhance the chloride diffusion coefficient and this poses a threat to reinforced concrete (RC) piles. This study intends to propose predictive models that can evaluate the service life and lateral bearing behaviour of reinforced concrete piles subjected to marine environments and varying temperatures. The models show that temperature can accelerate the diffusion rate of chloride and increase the concentration of free chloride in concrete. The distribution law of chloride concentration is obtained by considering the ageing effect as well. Deterministic and probabilistic models are proposed to assess the time to corrosion initiation and propagation. The stiffness degradation coefficient is introduced in the analysis of the lateral bearing capacity of RC piles. The results show that high temperature can decrease the service life of piles and the life spans obtained from deterministic and probabilistic methods are similar; however, the predictions of the latter are more conservative. Temperature can enhance the current density and boost corrosion products, which leads to pile cracking. The rust appearing on the steel surface would make the stiffness degradation coefficient drop sharply. The lateral bearing capacity analysis is conducted from the perspectives of shear force, displacement and bearing moment of the piles.

scholarly journals Numerical Simulation of Non-Uniformly Distributed Corrosion in Reinforced Concrete Cross-Section

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3975
Author(s):  
Magdalena German ◽  
Jerzy Pamin
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Corrosion Current ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Initiation Phase ◽  
Chloride Corrosion ◽  
Cover Thickness

Reinforced concrete structures can be strongly damaged by chloride corrosion of reinforcement. Rust accumulated around rebars involves a volumetric expansion, causing cracking of the surrounding concrete. To simulate the corrosion progress, the initiation phase of the corrosion process is first examined, taking into account the phenomena of oxygen and chloride transport as well as the corrosion current flow. This makes it possible to estimate the mass of produced rust, whereby a corrosion level is defined. A combination of three numerical methods is used to solve the coupled problem. The example object of the research is a beam cross-section with four reinforcement bars. The proposed methodology allows one to predict evolving chloride concentration and time to reinforcement depassivation, depending on the reinforcement position and on the location of a point on the bar surface. Moreover, the dependence of the corrosion initiation time on the chloride diffusion coefficient, chloride threshold, and reinforcement cover thickness is examined.

scholarly journals Service Life Prediction of Reinforced Concrete in a Sea-Crossing Railway Bridge in Jiaozhou Bay: A Case Study

2019 ◽  
Vol 9 (17) ◽  
pp. 3570 ◽  
Author(s):  
Zhe Li ◽  
Zuquan Jin ◽  
Tiejun Zhao ◽  
Penggang Wang ◽  
Lixiao Zhao ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Reliability Index ◽  
Life Prediction ◽  
Jiaozhou Bay ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Railway Bridge ◽  
Box Girder ◽  
The Mean

Reinforced bar corrosion induced by chloride ingression is one of the most significant threats to the durability of concrete structures in marine environments. The concrete cover thickness, compressive strength, chloride diffusion coefficient, and surface defects of reinforced concrete in the Jiaozhou Bay sea-crossing railway bridge were measured. The temperature and relative humidity in the concrete and the loading applied onto the reinforced concrete were monitored. Based on the DuraCrete model, a revised model for the service life prediction of concrete structures was established, considering the effects of temperature and loading on the chloride diffusion coefficient. Further, the reliability indexes of the reinforced concrete box girder, pier, and platform, located in the marine and land sections, in relation to service lives lasting various numbers of years, were calculated. The measured and calculated results show that the mean cover thicknesses of concrete piers in the marine and land sections are 52 mm and 36 mm, respectively, and the corresponding standard deviations are 5.21 mm and 3.18 mm, respectively. The mean compressive strengths of concrete in the marine and land sections are 56 MPa and 46 MPa, respectively. The corresponding standard deviations are 2.45 MPa and 2.67 MPa, respectively. The reliability indexes of the reinforced concrete box girder and platform in the marine section, under the condition of a service life of 100 years, are 1.81 and 1.76, respectively. When the corrosion-resistant reinforced bar was used in the pier structure in the marine section, its reliability index increased to 2.01. Furthermore, the reliability index of the reinforced concrete damaged by salt fog in the land section was 1.71.

Service Life Checking Calculation of Marine Reinforced Concrete Structures Based on Monte Carlo Method

2013 ◽  
Vol 788 ◽  
pp. 663-669
Author(s):  
Gui Hong Dong ◽  
Zhi Hong Fan ◽  
Jian Bo Xiong
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Service Life ◽  
Marine Environment ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Chloride Diffusion ◽  
Distribution Model ◽  
Chloride Diffusion Coefficient ◽  
Design Life

Checking some apparent chloride diffusion coefficient of concrete in the marine environment meets the requirements of design life based on Monte Carlo method. Through the project investigations, laboratory test data, statistical analysis and to determine random distribution model of the critical chloride concentration, the surface chloride concentration ,using computer program simulation 5000 random groups critical chloride concentration, surface chloride concentration into the life value calculation model, And obtain the derived distribution of the concrete structures service life, in order to determine Compliance with the design life of concrete structures. For the concrete durability design and service life checking provide the effective analysis under the marine environment.

Ultrahigh Performance Concrete: A Potential Material for Sustainable Marine Construction in View of the Service Life

2013 ◽  
Vol 438-439 ◽  
pp. 108-112 ◽  
Author(s):  
Chun Ping Gu ◽  
Wei Sun ◽  
Li Ping Guo ◽  
Qian Nan Wang
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
High Performance ◽  
High Performance Concrete ◽  
Chloride Diffusion ◽  
Sustainable Construction ◽  
Chloride Diffusion Coefficient ◽  
Normal Concrete ◽  
Superior Mechanical Properties ◽  
Chloride Profiles

Ultrahigh performance concretes (UHPC) are promising materials for the next generation infrastructures due to their superior mechanical properties and durability. In this paper, comparison studies were conducted to show the potential of UHPC for sustainable constructions in chloride environments in view of service life. For reinforced concrete, the service life was calculated with analytical solution of Ficks second law on diffusion. And for reinforced concrete with nonlinear initial chloride profiles and depth-dependent chloride diffusion coefficient, a numerical method based on the Crank-Nicholson numerical scheme was adopted to predict the service life. The results show that the reinforced concrete structures constructed and repaired with UHPC have much longer service life than that of normal concrete (NC) and high performance concrete (HPC). It hence needs less cost for maintenance and reconstruction, which fulfills the requirements of sustainable construction.

scholarly journals Experimental Study on Effective Chloride Diffusion Coefficient of Cement Mortar by Different Electrical Accelerated Measurements

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 240
Author(s):  
Jianlan Chen ◽  
Jiandong Wang ◽  
Rui He ◽  
Huaizhu Shu ◽  
Chuanqing Fu
Keyword(s):  
Diffusion Coefficient ◽  
Cement Mortar ◽  
Early Stage ◽  
Chloride Concentration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Good Consistency ◽  
Determination Methods

This study investigated the effective chloride diffusion coefficient of cement mortar with different water-to-cement ratio (w/c) under electrical accelerated migration measurement. The cumulative chloride concentration in anode cell solution and the cumulative chloride concentration drop in the cathode cell solution was measured by RCT measurement and the results were further used to calculate the chloride diffusion coefficient by Nordtest Build 355 method and Truc method. The influence of w/c on cement mortar’s chloride coefficient was investigated and the chloride diffusion coefficient under different determination methods were compared with other researchers’ work, a good consistency between this work’s results and literatures’ results was obtained. The results indicated that the increased w/c of cement mortar samples will have a higher chloride diffusion coefficient. The cumulative chloride concentration drop in the cathode cell solution will have deviation in early stage measurement (before 60 h) which will result in overestimation of the effective chloride diffusion coefficient.

Physical and Chemical Deterioration of Reinforced Concrete Reefs in Tongyeong Reefs Coastal Waters, Korea

2008 ◽  
Vol 42 (3) ◽  
pp. 110-118 ◽  
Author(s):  
H. S. Kim ◽  
C. G. Kim ◽  
W. B. Na ◽  
J. Woo ◽  
J. K. Kim
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Dissolved Oxygen ◽  
Extreme Event ◽  
Chemical Properties ◽  
Chloride Concentration ◽  
Concrete Cover ◽  
Marine Habitat ◽  
Seawater Salinity ◽  
Physical And Chemical

As part of a marine habitat enhancement project, the physical and chemical deterioration of reinforced concrete reefs that were fully immersed in Tongyeong waters of Korea was investigated. For the investigation, marine environmental factors such as seawater, salinity, pH, dissolved oxygen, sea-bottom materials, and water depth of the targeted sites were surveyed from 1997 to 2001. Then, four reinforced concrete reefs from four different sites were recovered and tested by using various destructive and nondestructive methods. Based on the observations and test results, it was seen that the reinforced concrete reefs have sound physical and chemical properties, except for chloride concentration and its associated factors. However, because of the lack of dissolved oxygen in the targeted seawaters and its continuous supply, it is concluded that the originally designed service life will be achieved, and in fact the concrete reefs will have an even longer service life than expected. By considering an extreme event such as impact loading under installation and construction, a new minimum concrete cover depth of 40 mm is introduced into practice.

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 Influence of Pore Structure on Chloride Penetration in Cement Pastes Subject to Wetting-Drying Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Honglei Chang ◽  
Zhiwu Zuo ◽  
Mingyue Qu ◽  
Fei Wang ◽  
Zhi Ge ◽  
...  
Keyword(s):  
Pore Structure ◽  
Penetration Rate ◽  
Error Function ◽  
Chloride Concentration ◽  
Total Porosity ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Cement Pastes ◽  
The Matrix

Copious studies have discovered a phenomenon that a chloride concentration peak appears on the surface of concrete under cyclic drying-wetting environments. In such cases, the chloride diffusion coefficient (D) obtained through directly fitting the standard error function of Fick’s second law is no longer accurate. The more reliable D obtained by the method proposed by Andrade is employed in this research to investigate the influence of pore structure on chloride penetration rate of pastes. The results show that both the effective coefficient (Deff) and the apparent coefficient (Dapp) increase with total porosity, the most probable pore size, and water absorption porosity, suggesting that the increase of the three pore structure parameters accelerates chloride penetration rate under cyclic wetting-drying condition. The increase of the three parameters makes more room available and eases the difficulty for salt solution to enter the matrix and thus leads to the augmentation of chloride transporting in matrix.

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.

Sign in / Sign up

Export Citation Format

Share Document