scholarly journals Birnbaum-Saunders Durability Life Prediction Model of Site-Exposed Concrete in the Saline Soil Area

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Chenggong Lu ◽  
Zhiqiang Wei ◽  
Hongxia Qiao ◽  
Theogene Hakuzweyezu ◽  
Kan Li
Keyword(s):  
Life Prediction ◽  
Mechanical Performance ◽  
Saline Soil ◽  
Corrosion Mechanism ◽  
Concrete Durability ◽  
Degradation Index ◽  
Field Exposure ◽  
Exposure Test ◽  
Sem Image ◽  
Soil Area

Aiming at the prominent problem of short durability life of concrete in saline soil area and the shortcomings of indoor accelerated test, an outdoor field exposure test was designed. The concrete specimens were semiburied in the Tianshui area with salinized soil characteristics, and nondestructive testing was conducted every 180d (days). The durability evaluation parameters and mechanical performance indexes were selected for macroscopic analysis, and the corrosion mechanism was analyzed by using the SEM image and the XRD phase. The Birnbaum-Saunders model based on physical failure and probability statistics was used for life prediction. The results show that there are rod-shaped and chip-shaped crystals growing from the surface of the gel and the internal holes in the exposed end and the embedded end of the concrete. However, the damage and deterioration of the buried end are more serious than those of the exposed end. The corrosion products mainly included ettringite, gypsum, calcium carbonate, sodium sulfate hydrate, carbosilite, and Friedel’s salt. The reliability life curve based on the Birnbaum-Saunders model can describe the whole process of exposed concrete from damage accumulation to failure. In addition, the dynamic modulus degradation index is more sensitive to concrete durability damage, and the life obtained by the Birnbaum-Saunders model is shorter than the quality degradation index. The life obtained by this degradation index is taken as the life of the concrete exposed in the saline soil site, and the concrete life of C30, C40, and C50 is about 3340d, 3930d, and 4360d, respectively.

scholarly journals Service Life Prediction of Shaft Sidewall Exposed to Sulfate Environment

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Wei He ◽  
Xia Meng ◽  
Ji-hui Zhao
Keyword(s):  
Life Prediction ◽  
Laboratory Tests ◽  
Residual Life ◽  
Underground Water ◽  
Corrosion Mechanism ◽  
Research Subject ◽  
High Concentration ◽  
Degradation Model ◽  
Immersion Corrosion ◽  
Different Parts

Under the influence of underground water with high concentration of sulfate, several vertical shafts in the Huang-Huai region are seriously corroded but have varying degradation degrees in different parts. Taking the auxiliary shaft of Lin-Huan coal mine as the research subject, the mechanism of this phenomenon was studied. Then, wet-dry alternated and immersion corrosion tests were carried out, and it was found that only the dry-wet alternated accelerate test is representative of the corrosion mechanism that cause the corrosion in the shaft. However, it will cost much time and money for the laboratory test to reach the same degradation depth. To solve this problem, combining with field and laboratory tests, a modified theoretical degradation model was developed to evaluate the residual life of the corroded sidewall. The results indicate that the residual life of the shaft sidewall is 25 years, and the damaged parts have no need for an immediate reinforcement.

scholarly journals Nitric acid and particulate matter measurements at Athens, Greece, in connection with corrosion studies

2009 ◽  
Vol 9 (21) ◽  
pp. 8309-8316 ◽  
Author(s):  
C. Tzanis ◽  
C. Varotsos ◽  
M. Ferm ◽  
J. Christodoulakis ◽  
M. N. Assimakopoulos ◽  
...  
Keyword(s):  
Test Site ◽  
Water Soluble ◽  
Passive Samplers ◽  
Field Exposure ◽  
Exposure Test ◽  
Corrosion Studies ◽  
Long Time ◽  
The University ◽  
The Vertical Distribution ◽  
The Eu

Abstract. For a long time, scientists have been concerned about the effects of air pollution on materials and especially on the monuments of the cultural heritage. The EU funded a project, entitled MULTI-ASSESS, to determine these effects and to develop dose-response functions appropriate for the new multi-pollutant environment. The University of Athens participated in this effort as a targeted field exposure test site. In the present paper, the measurements of the passive samplers, which were exposed during the same period with the samples for corrosion studies, at the Athens station, are presented. The results have shown that only 16.5% of the deposited mass was water soluble. The vertical distribution of passive particle collectors has led to the conclusion that the height of maximum deposition of each ion is different. In addition, a variation of the water-soluble mass to total deposited mass between 8% and 31% was observed.

scholarly journals Durability and service life prediction for concrete structures – developments and challenges

2018 ◽  
Vol 149 ◽  
pp. 01006 ◽  
Author(s):  
Mark G Alexander
Keyword(s):  
Service Life ◽  
Life Prediction ◽  
Concrete Structures ◽  
Performance Testing ◽  
Integrated Approach ◽  
Service Life Prediction ◽  
Site Quality ◽  
Concrete Durability ◽  
Durability Prediction ◽  
Service Life Modelling

The paper reviews developments in service life prediction for concrete structures. It indicates the difficulties inherent in rational service life design, in view of the multiple factors and variabilities involved in the process. The paper also emphasises the advantages of performance-based approaches to durability prediction, and considers performance testing, which is critical to achieving intended service life. Such approaches allow service life modelling, which the current prescriptive approaches do not. The concept of ‘durability indicators’ is covered, with a practical example showing how this can be used to improve concrete durability in construction. The paper also stresses the importance of an ‘integrated approach’ to durability specifications, performance-based predictions, and site quality control.

10-Year Experience With T23(2.25Cr-1.6W) and T122(12Cr-0.4Mo-2W) in a Power Boiler

2004 ◽  
Vol 127 (2) ◽  
pp. 190-196 ◽  
Author(s):  
N. Komai ◽  
F. Masuyama ◽  
M. Igarashi
Keyword(s):  
Growth Rate ◽  
Pressure Vessels ◽  
Steam Oxidation ◽  
Steel Tubes ◽  
Remarkable Change ◽  
Field Exposure ◽  
Exposure Test ◽  
Power Boiler ◽  
Oxidation Behaviors ◽  
Oxidation Scale

Tungsten strengthened ferritic steels, 2.25Cr-1.6W-V-Nb and 12Cr-0.4Mo-2W-V-Nb-Cu have been developed and approved by the ASME Boiler and Pressure Vessels Code Committee for use in Section I construction, designated as T23 and T122, respectively. A field exposure test installing both steel tubes in service along with comparative materials in the tertiary superheater and secondary reheater of a 156MW utility power boiler has been conducted since April 1993. The tubes were removed to confirm their material properties and corrosion/steam oxidation behaviors after 1-year, 3-year, 6-year, and 10-year periods of service. The tensile and creep rupture strengths of both steels showed no remarkable change during service. Examination of steam oxidation scale on the inner surface of the tubes indicated that the scale growth rate of T122 was extremely small following 1-year service. The growth rate and morphology of steam oxidation scale is discussed, as compared with conventional materials.

scholarly journals DIFFERENT BEHAVIORS OF ZINC RICH PAINT AGAINST CORROSION IN ATMOSPHERIC ZONE AND TIDAL ZONE OF INDUSTRIAL PORT ENVIRONMENT

2018 ◽  
Vol 55 (5B) ◽  
pp. 194 ◽  
Author(s):  
Vinh Dat Vuong
Keyword(s):  
High Temperature ◽  
Steel Substrate ◽  
Constructional Steel ◽  
Tidal Zone ◽  
Field Exposure ◽  
Exposure Test ◽  
Environmental Conditioning ◽  
Time Of Wetness

A study on zinc rich paint (ZRP) and its behaviors of protecting JIS SS400 constructional steel against impacts of industrial port environment at Phu My port (Ba Ria - Vung Tau Province, Vietnam) was started in January 2014. After three years of investigation, thickness of ZRP decreased slowly and the reduction reached to 38 µm and 31 µm in atmospheric and tidal zone, respectively. Moreover, in accelerated environmental conditioning tests, separation and failures of ZRP from steel substrate were responsible for blistering. By comparison of field exposure test and accelerating test, growth of blistering on ZRP is caused by high temperature and time of wetness.

Life Prediction for Anticorrosive Coatings on Steel Bridges

CORROSION ◽  
10.5006/3504 ◽  
2020 ◽  
Vol 76 (8) ◽  
pp. 773-785
Author(s):  
Zehui Zhang ◽  
Jin Wu ◽  
Tian Su ◽  
Xiangkun Mo ◽  
Huachao Deng ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Prediction Model ◽  
Life Prediction ◽  
Test Site ◽  
Steel Bridge ◽  
Exposure Test ◽  
Anticorrosive Coatings ◽  
Natural Exposure ◽  
Stress Coefficient ◽  
Life Prediction Model

This paper presents the results of the effects of tensile stress and corrosion environment on the performances of epoxy (EP) coating systems and fluorocarbon (FC) coating systems on steel bridge by accelerated exposure test. Gloss, color characteristic parameter, and blistering area were selected to be aging indexes of anticorrosive coatings. Four different stress levels were applied on coated steel panel specimens by using a three-point bend loading, and the stress coefficient is proposed in this paper. The results showed that coating corroded more severely in seawater than in freshwater. The tensile stress may accelerate the degradation of the coating. The degree of corrosion damage of the coatings increased with the increase of stress levels. Natural exposure tests of EP and FC coating systems were performed at Sanya test site and Qingdao test site in China, respectively. The correlation between natural exposure test and accelerated exposure test is presented by the acceleration coefficient. A life prediction model of anticorrosive coatings on steel bridge is proposed. The stress coefficient was presented in the life prediction model. The stress coefficient increases with the increase of stress applied on coatings. The proposed life prediction model can provide an important basis for quantitatively describing the failure of anticorrosive coatings and predicting the life of anticorrosive coatings on steel bridges.

Detection of Voids in Carbon/Epoxy Laminates and Their Influence on Mechanical Properties

2017 ◽  
Vol 25 (5) ◽  
pp. 371-380 ◽  
Author(s):  
Luca Di Landro ◽  
Aurelio Montalto ◽  
Paolo Bettini ◽  
Stefania Guerra ◽  
Fabrizio Montagnoli ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Mechanical Performance ◽  
Thermal Analyses ◽  
Void Content ◽  
Processing Conditions ◽  
Micro Computed Tomography ◽  
Sem Image ◽  
Beam Shear ◽  
Mechanical Performances ◽  
Curing Cycle

Defects, such as voids and delaminations, may significantly reduce the mechanical performance of components made of composite laminates. Distributed voids and porosity are generated during composite processing and are influenced by prepreg characteristics as well as by curing cycle parameters. On the basis of rheological and thermal analyses, as well as observations of laminates produced by different processing conditions, curing pressure appears the most influent factor affecting the void content. This work compares different methods for void analysis and quantitative evaluation (ultrasonic scan, micro-computed tomography, acid digestion, SEM image analysis) evidencing their applicative limitations. Carbon/epoxy laminates were produced in autoclave or oven by vacuum bag technique, using different processing conditions, so that void contents ranging from 0% to 7% volume were obtained. Effects of porosity over laminates mechanical performances are analysed. The results of tensile and compressive tests are discussed, considering the effect that different curing cycles have over void content as well as over fibre/resin fraction. Interlaminar strength, as measured by short beam shear tests, which is a matrix-dominated property, exhibits a reduction of failure strength up to 25% in laminates with the highest void content, compared to laminates with no porosity.

scholarly journals Remaining useful life prediction for power-shift steering transmission based on fusion of multiple oil spectra

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878420 ◽  
Author(s):  
Shu-Fa Yan ◽  
Biao Ma ◽  
Chang-Song Zheng
Keyword(s):  
Life Prediction ◽  
Health Management ◽  
Principal Component ◽  
Remaining Useful Life ◽  
Cumulative Distribution ◽  
Kernel Principal Component Analysis ◽  
Degradation Index ◽  
Life Estimation ◽  
Power Shift ◽  
Useful Life

Remaining useful life prediction is a critical issue to fault diagnosis and health management of power-shift steering transmission. Power-shift steering transmission wear, which leads to the increase of wear particles and severe wear afterwards, is a slow degradation process, which can be monitored by oil spectral analysis, but the actual degree of the power-shift steering transmission degradation is often difficult to evaluate. The main purpose of this article is to provide a more accurate remaining useful life prediction methodology for power-shift steering transmission compared to relying solely on an individual spectral oil data. Our methodology includes multiple degradation data fusion, degradation index construction, degradation modelling and remaining useful life estimation procedures. First, the robust kernel principal component analysis is used to reduce the data dimension, and the state space model is utilized to construct the wear degradation index. Then, the Wiener process–based degradation model is established based on the constructed degradation index, and the explicit formulas for several important quantities for remaining useful life estimation such as the probability density function and cumulative distribution function are derived. Finally, a case study is presented to demonstrate the applicability of the proposed methodology. The results show that the proposed remaining useful life prediction methodology can objectively describe the power-shift steering transmission degradation law, and the predicted remaining useful life has been extended as 65 Mh (38.2%) compared with specified maintenance interval. This will reduce the maintenance times of power-shift steering transmission life cycle and finally save the maintenance costs.

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