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Full-Text Articles in Engineering

Durability Assessment Of Concrete Structures In Hzm Sea Link Project For Design Life Of 120 Years, Kefei Li, Q. W. Li, Q. M. Zhang, Z. H. Fan, L. H. Yang Jul 2014

Durability Assessment Of Concrete Structures In Hzm Sea Link Project For Design Life Of 120 Years, Kefei Li, Q. W. Li, Q. M. Zhang, Z. H. Fan, L. H. Yang

International Conference on Durability of Concrete Structures

This article presents the durability assessment of the concrete structures in the ongoing Hong Kong–Zhuhai–Macao (HZM) sea link project for a design service life of 120 years. During the preliminary study phase, the durability design of concrete structures has been performed by a model-based method with a partial factor scheme for chloride-induced corrosion process. On the basis of the actual design options adopted in the detailed design phase, the durability assessment of concrete structures is performed for the achieved durability and reliability levels. For this purpose, the durability assessment retains the same model for chloride-induced corrosion as in the preliminary …

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Effect Of Drying Rate On Shrinkage Of Alkali-Activated Slag Cements, Hailong Ye, Christopher Cartwright, Farshad Rajabipour, Aleksandra Radlińska Jul 2014

Effect Of Drying Rate On Shrinkage Of Alkali-Activated Slag Cements, Hailong Ye, Christopher Cartwright, Farshad Rajabipour, Aleksandra Radlińska

International Conference on Durability of Concrete Structures

The volumetric instability of alkali-activated slag (AAS) binders has raised concerns and impeded the acceptance of this Portland cement-free material. The objective of this article is to characterize the influence of drying rate on drying shrinkage behavior of AAS mortars to better understand the mechanisms responsible for its large shrinkage deformation. A series of four AAS mortar mixtures with varying activator composition, as well as a reference Portland cement mortar, was cast and dried at different relative humidities, that is, 30, 50, 70, and 85% RH. Drying took place inside nitrogen-purged environmental chambers for the purpose of eliminating the contribution …

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Using Modified Mortar-Bar Test Method To Access The Effects Of Deicers On Expansion Of Mortars With And Without Reactive Aggregates, Yi-Cheng Chiu, Jan Olek Jul 2014

Using Modified Mortar-Bar Test Method To Access The Effects Of Deicers On Expansion Of Mortars With And Without Reactive Aggregates, Yi-Cheng Chiu, Jan Olek

International Conference on Durability of Concrete Structures

The influence of deicing chemicals on alkali reactivity of aggregates is still an area of active research. The potential alkali reactivity of aggregates is often tested using the ASTM C1260 method. This research used the modified ASTM C1260 to test the potential alkali reactivity of aggregates. The modification included replacing the standard 1N sodium hydroxide (NaOH) used in ASTM C1260 with eutectic concentrations of the three common chloridebased deicing chemicals: sodium chloride (NaCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2). The results showed that the mortar bars with reactive aggregate (Jobe sand) stored in NaCl solution …

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Performance Evaluation Of Sugarcane Bagasse Ash-Based Cement For Durable Concrete, A. Bahurudeen, Manu Santhanam Jul 2014

Performance Evaluation Of Sugarcane Bagasse Ash-Based Cement For Durable Concrete, A. Bahurudeen, Manu Santhanam

International Conference on Durability of Concrete Structures

Sugarcane bagasse ash (SCBA) is obtained as a by-product from cogeneration combustion boilers in sugar industries. Bagasse ash is mainly composed of reactive silica and can be used as pozzolanic material in concrete. Previous studies have reported that the utilization of SCBA as pozzolanic material in concrete can significantly improve its performance. A comprehensive investigation of durability performance of bagasse ash in concrete is not available in existing literature. In all previous studies, raw bagasse ash was ground to cement fineness and directly used in the concrete for the performance evaluation, without suitable characterization. Development of SCBA-based Portland pozzolana cement …

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Influence Of Fly Ash On Surface Chloride Concentration Under Shallow Immersion Condition, Jun Liu, Xiaodong Wang, Feng Xing, Ningxu Han Jul 2014

Influence Of Fly Ash On Surface Chloride Concentration Under Shallow Immersion Condition, Jun Liu, Xiaodong Wang, Feng Xing, Ningxu Han

International Conference on Durability of Concrete Structures

In this paper, the influence of fly ash content on concrete surface chloride concentration was investigated through periodical tests of surface chloride concentration of concrete by immersing three kinds of concrete specimens in 5.0 wt.% sodium chloride solution. One kind of specimen is common concrete without fly ash, whereas the other two kinds of specimens are mixed with fly ash. The results show that the surface chloride ion concentration ranges from 0.295 to 0.777 wt.% for the immersed concrete samples in this study; in the initial stage of immersion, the concrete surface chloride ion concentration is affected by added fly …

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The Analysis Of The Internal Forces In Strengthened Old Concrete Bridge Subject To Vehicular Load By Transforming Simply Supported Into Continuous System, Huanan He, Lijuan Xin Jul 2014

The Analysis Of The Internal Forces In Strengthened Old Concrete Bridge Subject To Vehicular Load By Transforming Simply Supported Into Continuous System, Huanan He, Lijuan Xin

International Conference on Durability of Concrete Structures

In the past half century, large numbers of simply supported bridges were constructed in China; however, with the passing of years and the increase in the volume of transport, many of the bridges are out of normal service level and even gradually lose their bearing capacity due to overload or environmental influence. Therefore, some strengthening works have to be carried out in order for these old bridges to work well. Among the common strengthening methods, an efficient way to transform a simply supported into a continuous system is widely used in simply supported bridges with small or medium span. After …

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Effects Of Stirrups On Bond Behavior Between Concrete And Corroded Steel Bars, Hongwei Lin, Yuxi Zhao, Ming Sun Jul 2014

Effects Of Stirrups On Bond Behavior Between Concrete And Corroded Steel Bars, Hongwei Lin, Yuxi Zhao, Ming Sun

International Conference on Durability of Concrete Structures

Steel corrosion leads to the deterioration of bond between concrete and steel bars. The serviceability and ultimate strength of concrete elements within RC structures are hence affected. Many researchers have studied the bond behavior of corroded steel bars. However, very few studies have investigated the effects of confinements on the degradation of bond strength. The present paper proposed a new kind of beam specimen based on which the effects of stirrups on degradation of bond were investigated. The test results proved that stirrups can effectively increase the bond strength between concrete and corroded steel bars.

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Saturation Of Air Entrained Voids And Its Implication On The Transport Of Ionic Species In Concrete, Yiwen Bu, Jason Weiss Jul 2014

Saturation Of Air Entrained Voids And Its Implication On The Transport Of Ionic Species In Concrete, Yiwen Bu, Jason Weiss

International Conference on Durability of Concrete Structures

Air entrainment is commonly used to improve the durability of concrete materials exposed to freezing and thawing. While the influence of air voids on freeze/thaw damage and salt scaling is frequently studied, the influence of entrained air voids on ionic transport has been studied less frequently. Since ionic transport in concrete materials relies on pore fluid as the medium of conduction, only saturated or partially saturated air voids participate in the transport processes. This paper discusses the conditions under which air voids could become saturated. Specifically, the saturation condition of entrained air voids in laboratory tests and in service is …

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Visualization And Quantification Of Solute Diffusivity In Cracked Concrete By X-Ray Ct, Michael Henry, T. Sugiyama, I. S. Darma Jul 2014

Visualization And Quantification Of Solute Diffusivity In Cracked Concrete By X-Ray Ct, Michael Henry, T. Sugiyama, I. S. Darma

International Conference on Durability of Concrete Structures

This paper explores the usage of microfocus X-ray computed tomography (CT) for visualization and quantification of diffusion phenomena in cracked concrete. Mortar specimens of varying shapes (prismatic and cylindrical), crack types (artificial and splitting tensile), and binder compositions (OPC and fly ash) were prepared. Cesium carbonate (Cs2CO3) was used as a tracer in the diffusion test because it has high X-ray absorption due to its high atomic number and thus contrasts with mortar and air voids in the CT images. Image processing and analysis was carried out to visualize and quantify the diffusion behavior in 3D …

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Effect Of Blast Furnace Slag Powder And Fly Ash On Durability Of Concrete Mixed With Seawater, Nobuaki Otsuki, Takahiro Nishida, Chang Yi, Tomohiro Nagata, Hiroki Ohara Jul 2014

Effect Of Blast Furnace Slag Powder And Fly Ash On Durability Of Concrete Mixed With Seawater, Nobuaki Otsuki, Takahiro Nishida, Chang Yi, Tomohiro Nagata, Hiroki Ohara

International Conference on Durability of Concrete Structures

According to the report of the United Nations, it is said that two-third of world population would be influenced by water shortage before 2050. To use fresh water effectively, the usage of seawater in concrete industry seems imperative. However, the usage of seawater as concrete material is prohibited in almost all the standards or specifications around the world. In this article, the usage of seawater as a material of concrete based on the results of experimental works and deterioration prediction was discussed. Especially, the effects of by-products such as blast furnace slag or fly ash on the durability of concrete …

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Surface Treatment Of Cement-Based Materials With Nanosio2, Pengkun Hou, Xin Cheng, Jueshi Qian, Surendra P. Shah Jul 2014

Surface Treatment Of Cement-Based Materials With Nanosio2, Pengkun Hou, Xin Cheng, Jueshi Qian, Surendra P. Shah

International Conference on Durability of Concrete Structures

A dense surface structure of cement-based material is favorable for its resistance to the impacts of environment. In this work, effectiveness and mechanisms of the surface treatment of cement-based materials with nanoSiO2 of different states, that is, colloidal nanoSiO2 (CNS) and the in situ formed nanoSiO2 gel through the hydrolysis of its precursor of tetraethoxysilane (TEOS), by brushing and soaking techniques, were investigated. Results showed that both CNS and TEOS are capable of reducing the liquid and gaseous transport properties of hardened cement-based materials, although at a different extent. It revealed that the pozzolanic reactivity and the …

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Research On Embedded Sensors For Concrete Health Monitoring Based On Ultrasonic Testing, Shifeng Huang, Mimi Li, Yuesheng Xu, Dongyu Xu, Xinchun Xie, Xin Cheng Jul 2014

Research On Embedded Sensors For Concrete Health Monitoring Based On Ultrasonic Testing, Shifeng Huang, Mimi Li, Yuesheng Xu, Dongyu Xu, Xinchun Xie, Xin Cheng

International Conference on Durability of Concrete Structures

In this article, embedded ultrasonic sensors were prepared using 1–3-type piezoelectric composite and piezoelectric ceramic as the piezoelectric elements, respectively. The frequency bandwidth of the novel embedded ultrasonic sensors was investigated. To obtain the relationship between the receiving ultrasonic velocity and compressive strength, as well as their response signals to crack damage, the sensors were fabricated and embedded into the cement mortar before testing. The results demonstrated that the piezoelectric composite sensor had wider frequency bandwidth than the piezoelectric ceramic sensor. The compressive strength and ultrasonic velocity had a positive linear relationship, with a correlation coefficient of 0.9216. The head …

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Finite Volume Numerical Analysis Of The Thermal Property Of Cellular Concrete Based On Two And Three Dimensional X-Ray Computerized Tomography Images, She Wei, Yang Yonggan, Xie Deqing, Zhang Yunsheng Jul 2014

Finite Volume Numerical Analysis Of The Thermal Property Of Cellular Concrete Based On Two And Three Dimensional X-Ray Computerized Tomography Images, She Wei, Yang Yonggan, Xie Deqing, Zhang Yunsheng

International Conference on Durability of Concrete Structures

Cellular concrete is one kind of lightweight concrete, which are widely used in thermal insulation engineering project. In this study, a three dimensional (2D and 3D) finite-volume-based models was developed for analyzing the heat transfer mechanisms through the porous structures of cellular concretes under steady-state heat transfer condition and also for investigating the differences between 2D and 3D modeling results. 2D and 3D reconstructed pore networks were generated from the microstructural information measured by a 3D image captured by X-ray computerized tomography (X-CT). In addition, the 3D-computed value of the effective thermal conductivity was found to be in better agreement …

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Review Of Microbially Induced Corrosion And Comments On Needs Related To Testing Procedures, Mitchell House, W. J. Weiss Jul 2014

Review Of Microbially Induced Corrosion And Comments On Needs Related To Testing Procedures, Mitchell House, W. J. Weiss

International Conference on Durability of Concrete Structures

Concrete is the most widely used material for the construction of the wastewater collection, storage, and treatment infrastructure. The chemical and physical characteristics of hydrated Portland cement may make it susceptible to degradation under highly acidic conditions. As a result, some concrete wastewater infrastructure may be susceptible to a multistage degradation process known as microbially induced corrosion (MIC). MIC begins with the production of aqueous hydrogen sulfide (H2S(aq)) by anaerobic sulfate-reducing bacteria present below the waterline. H2S(aq) partitions to the gas phase where it is oxidized to sulfuric acid by the aerobic sulfur-oxidizing bacteria Thiobacillus that resides on concrete surfaces …

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Behavior Of Steel–Concrete Composite Beams With Corroded Shear Studs Under Negative Bending Moment, Ju Chen, A. Jiang, W. Jin Jul 2014

Behavior Of Steel–Concrete Composite Beams With Corroded Shear Studs Under Negative Bending Moment, Ju Chen, A. Jiang, W. Jin

International Conference on Durability of Concrete Structures

The behavior of corroded steel–concrete composite beams under hogging moment was studied by experimental investigation and theoretical analysis. A total of eight specimens, six of which had corroded shear studs, were tested. The corrosion rate of studs ranged from 0 to approximately 50%. The constant-current accelerated corrosion method was adopted to accelerate the corrosion process. The loading test results indicated that the bending capacity of the corroded beams decreased slightly with increasing corrosion ratio of the studs. The corroded beams also exhibited an obvious decrease in bending rigid stiffness and increase in the slip between the steel beam and the …

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Experimental Study On Water Absorption By Concrete Damaged By Uniaxial Loading, Licheng C. Wang Jul 2014

Experimental Study On Water Absorption By Concrete Damaged By Uniaxial Loading, Licheng C. Wang

International Conference on Durability of Concrete Structures

Cracking of concrete, which may be induced by several mechanisms, such as shrinkage, thermal effect, and loading, plays an important role in the deterioration of reinforced concrete structures because they provide additional pathways for water and aggressive agents, for example, chlorides, to penetrate into concrete. To well understand the transport properties of cracked/damaged concrete is essential for predicting its long-term durability. In general, water acts as the medium for agents to move into concrete, and water penetration by capillary absorption is more common for the real concrete structures since concrete is rarely saturated. As a result, absorption of water is …

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Numerical Simulation Of The Early Age Three-Dimensional Microstructure Development Of Cement Pastes, Yunsheng Zhang, Zhiyong Liu, Wei Sun Jul 2014

Numerical Simulation Of The Early Age Three-Dimensional Microstructure Development Of Cement Pastes, Yunsheng Zhang, Zhiyong Liu, Wei Sun

International Conference on Durability of Concrete Structures

The formation process of microstructure in cement pastes was first simulated with a numerical model CEMHYD3D. The influence of water-to-cement ratio and particles size on heat release and degree of hydration were then investigated. In addition, the mass of CH and C–S–H phases simulated have been verified by measuring values by thermogravimetry–differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD)-Rietveld analysis. The evolutions of solids phase percolation and capillary pores de-percolation were also identified by means of a three-dimensional (3D) numerical model. The results show that the simulated values are in good agreement with the available experimental data, indicating a good …

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Study On Variable Action Value Standard For Harbor Infrastructures, Xiaoping Zhong, Qianyi Zhao, Weiliang Jin Jul 2014

Study On Variable Action Value Standard For Harbor Infrastructures, Xiaoping Zhong, Qianyi Zhao, Weiliang Jin

International Conference on Durability of Concrete Structures

To meet with different levels of requirements from proprietors and users and to offer a basis for variable action value to the designers, associated with the standards, this dissertation studied the value standard of load effect and environmental effect. For load effect, on the foundation of analyzing variable load effect model, we used equal exceeding probability principle to calculate the load adjustment coefficient for the cargo loading in harbor and river port under different designing service life. For environmental effect, according to the ranks of marine chloride environment in standards GB/T 50476-2008, after analyzing and comparing the research achievements on …

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Application Of Nanomechanical Methods In Investigation Of C–S–H Gel/Cement Grain Interface, Jing Xu, David J. Corr, Surendra P. Shah Jul 2014

Application Of Nanomechanical Methods In Investigation Of C–S–H Gel/Cement Grain Interface, Jing Xu, David J. Corr, Surendra P. Shah

International Conference on Durability of Concrete Structures

Investigation on the mechanical properties of cement-based materials at micron and submicron scales is important for understanding the overall performance, particularly of high-performance concrete (HPC). Due to low water-tocement ratio of HPC, a large amount of unhydrated cement grains remain in matrix, and a significant impact of the interface between C–S–H gel and cement grains on concrete behavior could be expected. Recent progress in experimental nanomechanics opens new access to nanoengineering of cement-based composites. In this paper, nanoindentation and viscoelastic modulus mapping were used to study the interfacial properties. The interface width measured by modulus mapping was around 200 nm …

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On Utilization Of Elliptical Rings In Assessing Cracking Tendency Of Concrete, Xiangming Zhou, Olayinka G. Oladiran, Wei Dong Jul 2014

On Utilization Of Elliptical Rings In Assessing Cracking Tendency Of Concrete, Xiangming Zhou, Olayinka G. Oladiran, Wei Dong

International Conference on Durability of Concrete Structures

A new experimental method by utilizing elliptical rings to replace circular rings recommended by ASTM and AASHTO was explored for assessing cracking potential of concrete and other cement-based materials under restrained condition. A series of thin and thick elliptical concrete rings were tested alongside circular ones until cracking. Cracking age, position, and propagation were carefully examined. It is found that thin elliptical rings with appropriate geometry can initiate cracks quicker than circular ones, which is desirable for accelerating the ring test. However, thick elliptical rings seem not to exhibit a desirable geometry effect of accelerating ring test compared with circular …

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Revised Model Of Chloride Diffusion In Concrete Bridge By Considering Complex Action Of Load And Chloride Binding Capacity, Yiqiang Xiang, Dongmei Guo Jul 2014

Revised Model Of Chloride Diffusion In Concrete Bridge By Considering Complex Action Of Load And Chloride Binding Capacity, Yiqiang Xiang, Dongmei Guo

International Conference on Durability of Concrete Structures

Coastal concrete bridges will suffer from deterioration of RC structural performance and resistance attenuation because of the chloride penetration and other environment factors. This article discusses current different chloride diffusion models and puts forward the revised model of chloride diffusion in concrete bridge by considering the complex action of load influence and chloride-binding capacity. Comparison of numerical predicted values and relative experimental tests show the presented chloride diffusion model to be more accurate. It provides a theoretical basis for the performance assessment and accurate prediction of the remaining life of highway concrete bridges.

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Effect Of Aggregate Gradation With Fuller Distribution On Properties Of Sulfoaluminate Cement Concrete, Chenchen Gong, Jie Zhang, Shoude Wang, Wen Zong, Lingchao Lu Jul 2014

Effect Of Aggregate Gradation With Fuller Distribution On Properties Of Sulfoaluminate Cement Concrete, Chenchen Gong, Jie Zhang, Shoude Wang, Wen Zong, Lingchao Lu

International Conference on Durability of Concrete Structures

Aggregate, the main ingredient of concrete, has a great effect on mechanical property and durability of concrete. Sulfoaluminate cement has lots of special properties such as high early-age compressive strength, fast hydration and setting rate, and hydration with slight swelling. But effect of aggregate gradation with Fuller distribution on properties of sulfoaluminate cement concrete was seldom studied. Hence, in this paper, experimental investigations on mechanical property and durability of sulfoaluminate cement concrete with aggregate gradations according to Fuller distribution were presented. Fuller distribution of aggregates was beneficial to the close packing of aggregates, and the packing density was changed by …

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Effect Of Transverse Crack On Chloride Penetration Into Concrete Subjected To Drying–Wetting Cycles, Chunhua Lu, Y. Gao, R. G. Liu Jul 2014

Effect Of Transverse Crack On Chloride Penetration Into Concrete Subjected To Drying–Wetting Cycles, Chunhua Lu, Y. Gao, R. G. Liu

International Conference on Durability of Concrete Structures

In this paper, several transversely cracked RC beams, self-anchored in a three-point bending mode, were prepared and subjected to NaCl solution drying–wetting cycles. Based on two experimental results obtained after 15 and 30 cycles, respectively, the profiles of free chloride concentration at different sections of sound and cracked concretes were presented and analyzed. The depth of surface convection zone in cracked concretes subject to chloride drying–wetting cycles is about 10–20 mm, which may increase gradually with the increasing of crack width. Then, it can be found that the speed of chloride penetration in concrete will be increased by cracks. Based …

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Preparation And Properties Of Alkali-Activated Ground-Granulated Blast Furnace Slag Thermal Storage Concrete, Linnu Lu, Bing Ping, Yongjia He, Qingjun Ding, Fazhou Wang, Hang Zhu Jul 2014

Preparation And Properties Of Alkali-Activated Ground-Granulated Blast Furnace Slag Thermal Storage Concrete, Linnu Lu, Bing Ping, Yongjia He, Qingjun Ding, Fazhou Wang, Hang Zhu

International Conference on Durability of Concrete Structures

Thermal storage concrete is prepared by using alkali-activated ground-granulated blast furnace slag as cementitious material. To improve thermal conductivity, graphite aggregate is used to replace part of the coarse aggregate, and, furthermore, polypropylene fiber is added to improve the heat resistance performance of the concrete. The compressive strength of concrete specimens before and after heating (up to 450 °C) was tested, and, furthermore, scanning electron microscopy was used to investigate the structure alteration due to heating. Results showed that the partial replacement of coarse aggregate by graphite block could obviously improve the thermal conductivity of the thermal storage concrete. At …

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Surface And Uniaxial Electrical Measurements On Layered Cementitious Composites Having Cylindrical And Prismatic Geometries, Robert Spragg, Scott Z. Jones, Chiara Villani, Kenneth A. Snyder, Dale P. Bentz, Amire Poursaee, Jason Weiss Jul 2014

Surface And Uniaxial Electrical Measurements On Layered Cementitious Composites Having Cylindrical And Prismatic Geometries, Robert Spragg, Scott Z. Jones, Chiara Villani, Kenneth A. Snyder, Dale P. Bentz, Amire Poursaee, Jason Weiss

International Conference on Durability of Concrete Structures

Electrical measurements are becoming a common method to assess the transport properties of concrete. For a saturated homogenous system, the surface resistance and the uniaxial resistance measurements provide equivalent measures of resistivity once geometry is appropriately taken into account. However, cementitious systems are not always homogenous. This article compares bulk and surface resistance measurements in cementitious materials intentionally composed of layered materials (i.e., layers with different resistivities). For this study, layered systems were composed of paste and mortar layers, representing the heterogeneity that can exist in the surface layers of field applications as a result of differences in moisture content, …

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Experimental Research On Corrosion-Induced Cracking Monitoring Based On Optical Fiber Sensor, Mao Jianghong, Jin Weiliang, Xiong Yanjun, Wang Qi, Yong He, Zhang Jun Jul 2014

Experimental Research On Corrosion-Induced Cracking Monitoring Based On Optical Fiber Sensor, Mao Jianghong, Jin Weiliang, Xiong Yanjun, Wang Qi, Yong He, Zhang Jun

International Conference on Durability of Concrete Structures

Corrosion-induced cracking is a widely existent issue for coastal infrastructure, which leads to its advanced failure. The monitoring of corrosion-induced cracking is an important means of evaluating its influence on structure normal use and safe operation. However, traditional sensors such as strain gage are unsuitable to embed into concrete and to record long-term strain of concrete caused by steel bar corrosion. The optical fiber sensor, Brillouin Optical Time Domain Analysis (BOTDA) can effectively avoid the undetected phenomenon existing in point-wise test method, and it has the characteristic of automated monitoring. The optical fiber sensor is also electrical insulation and anti-electromagnetic …

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Probabilistic Estimation Of Corrosion Propagation Period For Prestressed Concrete Structures Exposed To Chlorides, Radhakrishna G. Pillai, Jayachandran Karuppanasamy Jul 2014

Probabilistic Estimation Of Corrosion Propagation Period For Prestressed Concrete Structures Exposed To Chlorides, Radhakrishna G. Pillai, Jayachandran Karuppanasamy

International Conference on Durability of Concrete Structures

The overall service life of concrete structures can be divided into corrosion initiation and corrosion propagation phases. The durations of these two phases depend on the chloride threshold (Clth) and corrosion rate (icorr), respectively, of the embedded steel reinforcement. Quantitative information on Clth and icorr of conventional steel reinforcement are available in literature. Now‑a‑days, the use of prestressed concrete elements are rapidly increasing and there is a dire need for estimating their service life. Quantitative information on the Clth and icorr of prestressing steel are required for this estimation. However, very limited …

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Numerical Simulation Method For Fracture Effect Of Corroded Steel Strand Under Tension, Fumin Li, Yaxu Qu, Yu Zhao, Rong Lu Jul 2014

Numerical Simulation Method For Fracture Effect Of Corroded Steel Strand Under Tension, Fumin Li, Yaxu Qu, Yu Zhao, Rong Lu

International Conference on Durability of Concrete Structures

Steel strand presents characteristic pitting corrosion in chloride environment, which leads PC structures to a serious structural failure even with light presentational corrosion. So it is necessary to analyze the fracture effect of steel strand caused by pitting corrosion. The theoretical analyses are difficult for the presence of complicated threedimension pits, so numerical method becomes a feasible choice. A numerical simulation method for fracture effect of corroded steel strand under tension by the ANSYS software is introduced in this paper, which contains mainly four issues such as fracture criterion, constitutive relation, geometrical models, and simplified mechanical models. The Mises strain …

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Nondestructive Integrated Ct-Xrd Method For Research On Hydrated Cement System, Takafumi Sugiyama, T. Hitomi, K. Kajiwara Jul 2014

Nondestructive Integrated Ct-Xrd Method For Research On Hydrated Cement System, Takafumi Sugiyama, T. Hitomi, K. Kajiwara

International Conference on Durability of Concrete Structures

A nondestructive integrated CT-XRD method has been developed and used to study hydrated cement system. In this research, a beam line (BL) at the third-generation synchrotron radiation facility, SPring-8, in Japan, was used. First, X-ray computed tomography (CT) was employed to obtain three-dimensional (3D) images and select a region of interest (ROI) in a given plane section of the hardened cement paste. Then, X-ray diffraction analysis (XRD) was conducted on the specified region. These operations were implemented in situ without the removal of specimen from the stage inside the BL. The hardened cement paste was precracked and then leached by …

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Prediction Of Corrosion-Induced Crack Width Of Corroded Reinforced Concrete Structures, Jin Xia, Wei-Liang Jin Jul 2014

Prediction Of Corrosion-Induced Crack Width Of Corroded Reinforced Concrete Structures, Jin Xia, Wei-Liang Jin

International Conference on Durability of Concrete Structures

This paper presents an experimental investigation on the crack width induced by the corrosion of reinforcing steel bars in concrete. Reinforcing steel bars with different diameters were corroded using an accelerated test in three types of concrete members, including 24 beams with corroded stirrup and 20 beams with corroded longitudinal reinforcing steel bars. The corrosion patterns and rusts characteristics of the corroded steel bars were examined and compared with those observed in real RC structures. According to the experimental result, the corrosioninduced crack width were analyzed and showed a linear relationship with the corrosion loss of reinforcing steel bar. Finally, …

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