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Experimental investigation on concrete overlaid with textile reinforced mortar: Influences of mix, temperature

《结构与土木工程前沿(英文)》 2023年 第17卷 第2期   页码 271-283 doi: 10.1007/s11709-022-0896-z

摘要: Textile reinforced mortar is widely used as an overlay for the repair, rehabilitation, and retrofitting of concrete structures. Recently, textile reinforced concrete has been identified as a suitable lining material for improving the durability of existing concrete structures. In this study, we developed a textile-reinforced mortar mix using river sand and evaluated the different characteristics of the textile-reinforced mortar under various exposure conditions. Studies were carried out in two phases. In the first phase, the pullout strength, temperature resistance, water absorption, and compressive and bending strength values of three different textile-reinforced mortar mixes with a single type of textile reinforcement were investigated. In the second phase, the chemical resistance of the mix that showed the best performance in the abovementioned tests was examined for use as an overlay for a concrete substrate. Investigations were performed on three different thicknesses of the textile reinforced mortar overlaid on concrete specimens that were subjected to acidic and alkaline environments. The flexural responses and degradations of the textile reinforced mortar overlaid specimens were examined by performing bending tests. The experimental findings indicated the feasibility of using textile reinforced mortar as an overlay for durable concrete construction practices.

关键词: textile reinforced mortar     bending tests     acid and alkaline environment     concrete overlay    

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 110-122 doi: 10.1007/s11709-018-0476-4

摘要: Asphalt concrete (AC) overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing pavements. The strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement material. This study was conducted to analyze the influence of anisotropy, modulus gradient properties, and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays, as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA). The mechanical behaviors of the AC overlay were numerically obtained using the three-dimensional finite element method with the aid of ABAQUS a commercial program. Variations in the AC overlay’s modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients method. Comparing the mechanical behavior in terms of surface deflection, stress, and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC overlay. In addition, the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore, future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.

关键词: asphalt concrete overlay     anisotropy     temperature gradients     modulus gradients     finite element simulation     sensitivity analysis    

Optimization of polyurethane-bonded thin overlay mixture designation for airport pavement

Xianrui LI; Ling XU; Qidi ZONG; Fu JIANG; Xinyao YU; Jun WANG; Feipeng XIAO

《结构与土木工程前沿(英文)》 2022年 第16卷 第8期   页码 947-961 doi: 10.1007/s11709-022-0836-y

摘要: This research explored the application potential of PUM thin-overlay technology on airport rapid maintenance. The rapid curing process of polyurethane binder determines the limited time window for mixing and construction of polyurethane-bonded mixture (PUM), which presents significant difference with hot-mix asphalt (HMA) technology. Therefore, this research investigated and optimized the mix design of PUM for airport thin-overlay technology based on its thermosetting characteristics. First, limestone and basalt were comprehensively compared as an aggregate for PUM. Then, the effects of molding and curing conditions were studied in terms of mixing time, molding method, molding parameters and curing temperature. Statistical analysis was also conducted to evaluate the effects of gradation and particle size on PUM performances based on gray relational analysis (GRA), thus determining the key particle size to control PUM performances. Finally, the internal structural details of PUM were captured by X-ray CT scan test. The results demonstrated that it only took 12 hours to reach 75% of maximum strength at a curing temperature of 50 °C, indicating an efficient curing process and in turn allowing short traffic delay. The internal structural details of PUM presented distribution of tiny pores with few connective voids, guaranteeing waterproof property and high strength.

关键词: polyurethane-bonded mixture     mix design optimization     airport pavement     thin overlay     gray relational analysis    

面向高性能计算的自部署运行环境 Research Articles

邵明天,卢凯,张文喆

《信息与电子工程前沿(英文)》 2022年 第23卷 第6期   页码 845-857 doi: 10.1631/FITEE.2100016

摘要:

传统高性能计算系统提供了标准的预置环境来支持科学计算。然而,高性能计算的发展需要为越来越多应用提供支持,如人工智能、大数据等。标准的预设环境已无法满足这些多样化的要求。如果用户仍然在高性能计算系统上运行这些新兴应用程序,他们需要手动维护应用程序的特定依赖项(库、环境变量等),这增加了用户的开发和部署负担。此外,多用户模式也带来用户之间的隐私问题。像Docker和Singularity这样的容器可以封装作业的执行环境,但是在高度定制的高性能计算系统中,Docker和Singularity的跨环境应用部署是受限的。容器镜像的引入也给系统管理员增加了维护负担。针对上述问题,本文提出一种适用于高性能计算的自部署执行环境(SDEE)。SDEE结合了传统虚拟化和现代容器的优点,为用户提供了一个独立、可定制的环境(类似于虚拟机)。该用户是此环境中的根用户。用户开发和调试应用程序,并在此环境中部署其特殊的依赖项,然后可以通过传统高性能计算系统的作业管理系统,直接将作业加载到计算节点。作业及其依赖项将被自动分析、打包、部署和执行。该过程实现了透明、快速的作业部署,不仅减轻了用户负担,而且保护了用户隐私。实验表明,SDEE引入的开销可忽略不计,比Docker和Singularity都要低。

关键词: 运行环境;高性能计算;轻量化;隔离;Overlay    

Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要: Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词: slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

《结构与土木工程前沿(英文)》   页码 935-947 doi: 10.1007/s11709-023-0964-z

摘要: Extrudability is one of the most critical factors when designing three-dimensional printable foam concrete. The extrusion process likely affects the foam stability which necessitates the investigation into surfactant properties particularly for concrete mixes with high foam contents. Although many studies have been conducted on traditional foam concrete in this context, studies on three-dimensional printed foam concrete are scarce. To address this research gap, the effects of surfactant characteristics on the stability, extrudability, and buildability of three-dimensional printed foam concrete mixes with two design densities (1000 and 1300 kg/m3) using two different surfactants and stabilizers (synthetic-based sodium lauryl sulfate stabilized with carboxymethyl cellulose sodium salt, and natural-based hingot surfactant stabilized with xanthan gum) were investigated in this study. Fresh density tests were conducted before and after the extrusion to determine stability of the foam concrete. The results were then correlated with surfactant qualities, such as viscosity and surface tension, to understand the importance of key parameters in three-dimensional printing of foam concrete. Based on the experimental results, surfactant solu1tion with viscosity exceeding 5 mPa·s and surface tension lower than 31 mN/m was recommended to yield stable three-dimensional printable foam concrete mixes. Nevertheless, the volume of foam in the mix significantly affected the printability characteristics. Unlike traditional foam concrete, the variation in the stabilizer concentration and density of concrete were found to have insignificant effect on the fresh-state-characteristics (slump, slump flow, and static yield stress) and air void microstructure of the stable mixes.

关键词: foam concrete     3D printable concrete     stability     rheology     air void microstructure    

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0955-0

摘要: This paper proposes an innovative column composed of a core column (including both reinforced concrete (RC) and plain concrete (PC) columns) and a prefabricated textile-reinforced fine concrete (TRC) shell. To study the confinement properties of TRC shells on this novel type of concrete column, 20 circular specimens, including 12 PC columns and 8 RC columns, were prepared for axial compressive tests. Four key parameters, including the column size, reinforcing ratio of the carbon textile, concrete strength, and stirrup spacing, were evaluated. The results indicated that the compressive properties of the columns were improved by increasing the reinforcing ratio of the textile layers. In the case of TRC-confined PC columns, the maximum improvement in the peak load was 56.3%, and for TRC-confined RC columns, the maximum improvement was 60.2%. Based on the test results, an analytical model that can be used to calculate the stress–strain curves of prefabricated TRC shell-confined concrete columns has been proposed. The calculated curves predicted by the proposed model agreed well with the test results.

关键词: textile-reinforced fine concrete     prefabricated shell     confined concrete column     confinement properties     stress–strain relationship    

Computational modeling of fracture in concrete: A review

Luthfi Muhammad Mauludin, Chahmi Oucif

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 586-598 doi: 10.1007/s11709-020-0573-z

摘要: This paper presents a review of fracture modeling of concrete. The complex material, such as concrete, has been widely used in construction industries and become trending issue in the last decades. Based on comprehensive literature review, there are two main approaches considered to-date of concrete fracture modeling, such as macroscopic and micromechanical models. The purpose of this review is to provide insight comparison from different techniques in modeling of fracture in concrete which are available. In the first section, an overview of fracture modeling in general is highlighted. Two different approaches both of macroscopic and micromechanical models will be reviewed. As heterogeneity of concrete material is major concern in micromechanical-based concrete modeling, one section will discuss this approach. Finally, the summary from all of reviewed techniques will be pointed out before the future perspective is given.

关键词: concrete fracture     macroscopic     micromechanical     heterogeneity    

Experimental study on shear behavior of prestressed reactive powder concrete I-girders

Hui ZHENG, Zhi FANG, Bin CHEN

《结构与土木工程前沿(英文)》 2019年 第13卷 第3期   页码 618-627 doi: 10.1007/s11709-018-0500-8

摘要: As a new generation of concrete, RPC(Reactive Powder Concrete) has attracted great research attention for its ultra-high strength and high durability. In the present paper, experimental results from tests on eight prestressed RPC I-section girders failing in shear are reported herein. The beams with RPC of 120 MPa in compression were designed to assess the ability to carry shear stress in thin webbed prestressed beams with stirrups. The test variables were the level of prestressing, shear span-depth ratio ( / ) and stirrup ratio. Shear deformation, shear capacity and crack pattern were experimentally investigated in detail. With regard to the shear resistance of the test beams, the predictions from three standards (AFGC, JSCE and SIA) on the design of UHPC structures were compared with the experimental result suggesting that the experimental strength is almost always higher than predicted. RPC, as a new concrete, was different from normal concrete and fiber reinforced concrete. Further study should be needed to develop an analytical method and computation model for shear strength of RPC beams.

关键词: prestressed concrete     RPC(Reactive Powder Concrete)     concrete beams     shear strength     experimental study    

Influence of steel corrosion on axial and eccentric compression behavior of coral aggregate concrete

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1415-1425 doi: 10.1007/s11709-021-0786-9

摘要: To study the behavior of coral aggregate concrete (CAC) column under axial and eccentric compression, the compression behavior of CAC column with different types of steel and initial eccentricity (ei) were tested, and the deformation behavior and ultimate bearing capacity (Nu) were studied. The results showed that as the ei increases, the Nu of CAC column decreases nonlinearly. Besides, the steel corrosion in CAC column is severe, which reduces the steel section and steel strength, and decreases the Nu of CAC column. The durability of CAC structures can be improved by using new organic coated steel. Considering the influence of steel corrosion and interfacial bond deterioration, the calculation models of Nu under axial and eccentric compression were presented.

关键词: coral aggregate concrete column     axial compression     eccentric compression     steel corrosion     calculation model    

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Mohammed FARUQI, Mohammed Sheroz KHAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 81-91 doi: 10.1007/s11709-018-0468-4

摘要: Fiber reinforced polymer(FRP) have unique advantages like high strength to weight ratio, excellent corrosion resistance, improving deformability and cost effectiveness. These advantages have gained wide acceptance in civil engineering applications. FRP tendons for prestressing applications are emerging as one of the most promising technologies in the civil engineering industry. However, the behavior of such members under the influence of elevated temperatures is still unknown. The knowledge and application of this could lead to a cost effective and practical considerations in fire safety design. Therefore, this study examines the deflection behavior of the carbon fiber reinforced polymer(CFRP) prestressed concrete beam at elevated temperatures. In this article, an analytical model is developed which integrates the temperature dependent changes of effective modulus of FRP in predicting the deflection behavior of CFRP prestressed concrete beams within the range of practical temperatures. This model is compared with a finite element mode (FEM) of a simply supported concrete beam prestressed with CFRP subjected to practical elevated temperatures. In addition, comparison is also made with an indirect reference to the real behavior of the material. The results of the model correlated reasonably with the finite element model and the real behavior. Finally, a practical application is provided.

关键词: FRP     CFRP     concrete     elevated temperatures     deflections     prestress    

Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiber-reinforced concrete

《结构与土木工程前沿(英文)》 2023年 第17卷 第3期   页码 411-428 doi: 10.1007/s11709-023-0928-3

摘要: In this study, ultrahigh-performance fiber-reinforced concrete (UHPFRC) used in a type B70 concrete sleeper is investigated experimentally and parametrically. The main parameters investigated are the steel fiber volume fractions (0%, 0.5%, 1%, and 1.5%). Under European standards, 35 UHPFRC sleepers are subjected to static bending tests at the center and rail seat sections, and the screw on the fastening system is pulled out. The first cracking load, failure load, failure mode, crack propagation, load–deflection curve, load–crack width, and failure load from these tests are measured and compared with those of a control sleeper manufactured using normal concrete C50. The accuracy of the parametric study is verified experimentally. Subsequently, the results of the study are applied to UHPFRC sleepers with different concrete volumes to investigate the effects of the properties of UHPFRC on their performance. Experimental and parametric study results show that the behavior of UHPFRC sleepers improves significantly when the amount of steel fiber in the mix is increased. Sleepers manufactured using UHPFRC with a steel fiber volume fraction of 1% and a concrete volume less than 25% that of standard sleeper B70 can be used under the same loads and requirements, which contributes positively to the cost and surrounding environment.

关键词: pre-stressed concrete sleeper     ultrahigh performance fiber-reinforced concrete     pull-out test     static bending test     steel fiber     aspect ratio     volume fraction    

Compressive behavior and microstructure of concrete mixed with natural seawater and sea sand

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1347-1357 doi: 10.1007/s11709-021-0780-2

摘要: Noncorrosive reinforcement materials facilitate producing structural concrete with seawater and sea sand. This study investigated the properties of seawater and sea sand concrete (SSC), considering the curing age (3, 7, 14, 21, 28, 60, and 150 d) and strength grade (C30, C40, and C60). The compressive behavior of SSC was obtained by compressive tests and digital image correction (DIC) technique. Scanning electron microscope (SEM) and X-ray powder diffraction (XRD) methods were applied to understand the microstructure and hydration products of cement in SSC. Results revealed a 30% decrease in compressive strength for C30 and C40 SSC from 60 to 150 d, and a less than 5% decrease for C60 from 28 to 150 d. DIC results revealed significant cracking and crushing from 80% to 100% of compressive strength. SEM images showed a more compact microstructure in higher strength SSC. XRD patterns identified Friedel’s salt phase due to the chlorides brought by seawater and sea sand. The findings in this study can provide more insights into the microstructure of SSC along with its short- and long-term compressive behavior.

关键词: seawater and sea sand concrete     compressive strength     strain field     microstructure     hydration products    

In-situ condition monitoring of reinforced concrete structures

Sanjeev Kumar VERMA,Sudhir Singh BHADAURIA,Saleem AKHTAR

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 420-437 doi: 10.1007/s11709-016-0336-z

摘要: Performance of concrete structures is significantly influenced and governed by its durability and resistance to environmental or exposure conditions, apart from its physical strength. It can be monitored, evaluated and predicted through modeling of physical deterioration mechanisms, performance characteristics and parameters and condition monitoring of in situ concrete structures. One such study has been conducted using Non-destructive testing equipment in the city of Bhopal and around located in India. Some selected parameters influencing durability of reinforced concrete (RC) structures such as concrete cover, carbonation depth, chloride concentration, half cell potential and compressive strength have been measured, for establishing correlation among various parameters and age of structures. Effects of concrete cover and compressive strength over the variation of chloride content with time are also investigated.

关键词: concrete     carbonation     chloride     corrosion     monitoring     models    

Crack detection for wading-concrete structures using water irrigation and electric heating

《结构与土木工程前沿(英文)》 2023年 第17卷 第3期   页码 368-377 doi: 10.1007/s11709-022-0926-x

摘要: Cracking in wading-concrete structures has a worse impact on structural safety compared with conventional concrete structures. The accurate and timely monitoring of crack development plays a significant role in the safety of wading-concrete engineering. The heat-transfer rate near a crack is related to the flow velocity of the fluid in the crack. Based on this, a novel crack-identification method for underwater concrete structures is presented. This method uses water irrigation to generate seepage at the interface of a crack; then, the heat-dissipation rate in the crack area will increase because of the convective heat-transfer effect near the crack. Crack information can be identified by monitoring the cooling law and leakage flow near cracks. The proposed mobile crack-monitoring system consists of a heating system, temperature-measurement system, and irrigation system. A series of tests was conducted on a reinforced-concrete beam using this system. The crack-discrimination index ψ was defined, according to the subsection characteristics of the heat-source cooling curve. The effects of the crack width, leakage flow, and relative positions of the heat source and crack on ψ were studied. The results showed that the distribution characteristics of ψ along the monitoring line could accurately locate the crack, but not quantify the crack width. However, the leakage flow is sensitive to the crack width and can be used to identify it.

关键词: structural health monitoring     underwater concrete structure     fiber Bragg grating     crack detection     temperature tracer method    

标题 作者 时间 类型 操作

Experimental investigation on concrete overlaid with textile reinforced mortar: Influences of mix, temperature

期刊论文

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

期刊论文

Optimization of polyurethane-bonded thin overlay mixture designation for airport pavement

Xianrui LI; Ling XU; Qidi ZONG; Fu JIANG; Xinyao YU; Jun WANG; Feipeng XIAO

期刊论文

面向高性能计算的自部署运行环境

邵明天,卢凯,张文喆

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

期刊论文

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

期刊论文

Computational modeling of fracture in concrete: A review

Luthfi Muhammad Mauludin, Chahmi Oucif

期刊论文

Experimental study on shear behavior of prestressed reactive powder concrete I-girders

Hui ZHENG, Zhi FANG, Bin CHEN

期刊论文

Influence of steel corrosion on axial and eccentric compression behavior of coral aggregate concrete

期刊论文

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Mohammed FARUQI, Mohammed Sheroz KHAN

期刊论文

Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiber-reinforced concrete

期刊论文

Compressive behavior and microstructure of concrete mixed with natural seawater and sea sand

期刊论文

In-situ condition monitoring of reinforced concrete structures

Sanjeev Kumar VERMA,Sudhir Singh BHADAURIA,Saleem AKHTAR

期刊论文

Crack detection for wading-concrete structures using water irrigation and electric heating

期刊论文