Electrical Response Of Mortar Saturated With Nacl Solutions Under Freeze–Thaw Cycles,
2016
Hokkaido University
Electrical Response Of Mortar Saturated With Nacl Solutions Under Freeze–Thaw Cycles, Yi Wang, Fuyuan Gong, Tamon Ueda, Dawei Zhang
International Conference on Durability of Concrete Structures
This paper presents the test results of electrical response of mortar saturated with sodium chloride (NaCl) solutions under freeze–thaw cycles (FTCs). To quantitatively evaluate the salt frost damage of mortar based on its electrical response, mesoscale samples are prepared to assure the uniform pore solution concentration. The reduction of electrical resistivity shows the same tendency with elastic modulus, but with less degree. The investigation shows that electrical resistivity of mortar decreases with temperature and the phase changes can be observed based on their relationship. The freezing and thawing points decreasing with increment of solution concentration can be found, but their …
Basic Examination On Assessing Mechanical Properties Of Concrete That Has Suffered Combined Deterioration From Fatigue And Frost Damage,
2016
Civil Engineering Research Institute for Cold Region
Basic Examination On Assessing Mechanical Properties Of Concrete That Has Suffered Combined Deterioration From Fatigue And Frost Damage, Hiroshi Hayashida, Yasuhiko Sato, Tamon Ueda
International Conference on Durability of Concrete Structures
An examination including an evaluation of mechanical properties of concrete that had suffered combined deterioration from fatigue and frost damage was done using cylindrical specimens. The order of deterioration and degree of deterioration of the specimens were used as variables. The examination clarified that certain mechanical properties of concrete that had undergone combined deterioration were able to be evaluated by measuring the propagation speed of ultrasonic waves. The decrease in the elastic modulus and the ultrasonic velocity that accompanies the increase in the number of freeze–thaw cycles was smaller in the specimens that experienced fatigue first and then frost damage …
The Effect Of Nano-Sio2 Dispersed Methods On Mechanical Properties Of Cement Mortar,
2016
University of Jinan & Shandong Provincial Key Laboratory of Preparation and Measurement of Building Material
The Effect Of Nano-Sio2 Dispersed Methods On Mechanical Properties Of Cement Mortar, Mingle Liu, Zonghui Zhou, Xiuzhi Zhang, Xiangzi Yang, Xin Cheng
International Conference on Durability of Concrete Structures
Nano-SiO2 is added to the cement by using different dispersion methods, through the macroscopic mechanical properties to characterize its dispersion in the cement, it can be used to explore the best experimental process. The results show that the compressive strength of cement samples with different dispersion methods is different. When the physical dispersion method is used, the intensity is not improved, but the ultrasonic dispersion method is the smallest, and the dispersion of nano-SiO2 is -9.11%. When the surfactant is used as dispersant, the dispersion of nano-SiO2 by Naphthalene water reducer is the best, and the compressive …
Effect Of Nano-Sio2 Content On The Setting Time And Mechanical Properties Of Tricalcium Silicate,
2016
University of Jinan
Effect Of Nano-Sio2 Content On The Setting Time And Mechanical Properties Of Tricalcium Silicate, Zhenhai Xu, Zonghui Zhou, Xin Cheng
International Conference on Durability of Concrete Structures
Using analytically pure calcium carbonate and silica as raw materials, high purity tricalcium silicate (C3S) is prepared by solid-state reaction. The tricalcium silicate was sintered at a temperature of 1550°C with the heat preservation time of 6 h. The final sample needs three times of calcination circles. Ultrasonic cleaning machine was used to disperse the water and different amount of nano-SiO2 (0, 1, 2, and 3 wt%) for 5 min, then mixed with C3S, and formed into standard blocks. The setting time and compressive strength of each age (1, 3, 7, and 28 days) was …
Effects Of Nano-Caco3 On The Properties Of Cement Paste: Hardening Process And Shrinkage At Different Humidity Levels,
2016
University of Jinan
Effects Of Nano-Caco3 On The Properties Of Cement Paste: Hardening Process And Shrinkage At Different Humidity Levels, Yamei Cai, Pengkun Hou, Zonghui Zhou, Xin Cheng
International Conference on Durability of Concrete Structures
The hardening process and volume stability of cement pastes with and without nano-CaCO3 (NC) were studied through investigations on the setting time and shrinkage. Results showed that NC shortened the setting time of cement paste: the initial setting time decreased by 3.9 and 11.1% when 1 and 3% NC were added, and the finial setting times were shortened by 6.2 and 15.2%, respectively. The shrinkage of cement paste was compensated by NC, and the effect was more obvious as more NC was added into the cement paste. Although the shrinkage decreased at the lower relative humidity, the degree of …
Effect Of Bfrp Grid On Crack Propagation Of Reinforced Concrete Beam With Thick-Cover Concrete,
2016
Dalian University of Technology
Effect Of Bfrp Grid On Crack Propagation Of Reinforced Concrete Beam With Thick-Cover Concrete, Li-Juan Cheng, Hua-Nan He
International Conference on Durability of Concrete Structures
For the purpose of solving the problem of large crack width in concrete beam with thick cover, BFRP grid is added to the concrete cover to control the crack development and to improve the distribution status of cracks. In this paper, the bending tests under four-point loading are adopted to investigate cracking properties of reinforced concrete beams with thick cover, in which BFRP grid is added. During test cracking load, crack width and the number of crack were recorded, which will be analysed later. Test results show that crack development of reinforced concrete beam with thick cover can be effectively …
Effect Of Pet Wrapping On Shear Performance Of Corroded Reinforced Concrete Columns,
2016
Zhejiang University
Effect Of Pet Wrapping On Shear Performance Of Corroded Reinforced Concrete Columns, Dawei Zhang, Yuxi Zhao, Weiliang Jin, Tamon Ueda
International Conference on Durability of Concrete Structures
In this paper, an experimental study is presented on the influence of PET warping on shear performance, such as diagonal shear cracking load, peak load, and energy dissipation of RC columns with stirrup corrosion before strengthening. The experimental program involved an electrochemical process to accelerate the migration of chlorides from an external electrolyte into the tested columns, a wetting–drying cycle process with a controlled current to speed up the corrosion of the stirrup in the tested columns, the strengthening of corroded columns with PET warping, and a pseudostatic test to determine the shear capacity of the tested beams. The shear …
Effect Of Cured Time On Creep Of Lightweight Aggregate Concrete,
2016
Shenzhen University
Effect Of Cured Time On Creep Of Lightweight Aggregate Concrete, Hongzhi Cui, Haibin Yang, Xiaoxiao Xu, Zitao Lin, Tommy Yiu Lo
International Conference on Durability of Concrete Structures
Creep and shrinkage are such properties that will occur in concrete when they are under load and exposed to surrounding. Since this property will cause deformation which may decrease the design strength of the concrete, it is necessary to do have more knowledge on this phenomenon. So, we will study the effect of creep on 7 and 14 days of cured time of specimens which sealed or unsealed will be considered, respectively. The specimens have shown how the concrete strains when they are under sustained load with time. Besides, the sealed specimens have shown how the basic creep is different …
Application Of Raman Spectroscopy For Tracing The Status Of Silica Fume In Cementitious Materials,
2016
University College London
Application Of Raman Spectroscopy For Tracing The Status Of Silica Fume In Cementitious Materials, Yanfei Yue, Yun Bai, Jing Jing Wang
International Conference on Durability of Concrete Structures
Silica fume (SF) is an important component for manufacturing high performance concrete (HPC), owing to its superb pozzolanic reactivity and physical filling effects. However, application of SF in concrete may cause potential hazards issues. Although using SF in slurry form can somehow reduce the potential biotoxicity, the long-term stability and status of the SF particles within cementitious materials is still uncertain. In the current study, attempts were made to use Raman spectroscopy as an innovative alternative technique for tracing and identifying the status of SF both in its original SF slurry and in a 6-month-old hydrated cement paste. Light-optical microscope …
Delayed Ettringite Formation In Fly Ash Concrete Under Moist Curing Conditions,
2016
Nanjing Tech University
Delayed Ettringite Formation In Fly Ash Concrete Under Moist Curing Conditions, Zhuqing Yu, Jian Ma, Hu Shi, Xiaodong Shen, Guang Ye
International Conference on Durability of Concrete Structures
During the hydration of cement, tricalcium aluminate (C3A) reacts with gypsum and forms ettringite (AFt). Once all gypsum is consumed, ettringite can further react with remaining C3A and form monosulfate (AFm) at 1–2 days. Normally, at early ages, ettringite all transfers to AFm phase. After several months or years, ettringite can form again if a new source of sulfate becomes available in the pore solution of the paste, viz. delayed ettringite formation. In previous study, it was found that delayed ettringite forms in Portland cement concrete when the concrete samples were cured under moist conditions, …
Study On The Disposition Of Water In Fly Ash-Based Geopolymers Using Atr–Ir,
2016
Shenzhen University
Study On The Disposition Of Water In Fly Ash-Based Geopolymers Using Atr–Ir, Jian Liu, Yuan Fang, Obada Kayali
International Conference on Durability of Concrete Structures
This paper addresses the question of whether the main product of low calcium fly ash-based geopolymer is a hydrate, namely, sodium aluminosilicate hydrate (N-A-S-H). The answer to this question is important for understanding geopolymer characteristics. One of these is its fire resistance. In this study, fly ash-based geopolymers were synthesized using the combination of Na2CO3 and Ca(OH)2. Samples were cured at ambient temperature for 7 days, then placed in the oven at 105°C for 24 h, and then calcined at 1050°C for 48 h. IR was used to examine the produced geopolymers at each stage …
Micromechanical Modeling For Material Design Of Durable Infrastructural Materials: The Influence Of Aggregate And Matrix Modification On Elastic Behavior Of Mortars,
2016
Arizona State University
Micromechanical Modeling For Material Design Of Durable Infrastructural Materials: The Influence Of Aggregate And Matrix Modification On Elastic Behavior Of Mortars, Sumanta Das, Amit Maroli, Narayanan Neithalath
International Conference on Durability of Concrete Structures
This paper reports the fundamental difference in microstress distributions in traditional hardened cement paste with quartz inclusions and a cement paste with lightweight aggregate (LWA) inclusions using microstructurebased numerical simulation involving finite element method with periodic boundary conditions. Variation of relative stress distributions under varying component material properties and varying microstructural features in both the systems is elucidated for a comprehensive understanding. The presented microstructure-based numerical technique accurately captures the stress concentrations inside microheterogeneous systems, which is otherwise not detectible using analytical homogenization schemes. Numerical simulations reveal that strengthening and stiffening of matrix and interfacial transition zone (ITZ) with silica …
Research On Concrete Durability Improving For Existing Island-Building And Its Application,
2016
Zhejiang University
Research On Concrete Durability Improving For Existing Island-Building And Its Application, Mao Jianghong, Zhu Yaofeng, Xu Fangyuan, Jin Weiliang, Xu Yidong, Chen Xu
International Conference on Durability of Concrete Structures
China’s coastal cities contain a large number of islands with abundant human activities, in which buildings are in a typical marine corrosion environment and the corrosion of reinforced concrete structures is very prominent. This paper makes research work on two aspects: (1) the durability assessment and durability improvement after a thorough investigation of the architecture of Xiangtan County, Ningbo city, on an island and (2) the application research of the bidirectional electromigration rehabilitation (BIEM) technology to enhance the durability of existing island building life. This paper designs a set of BIEM equipment based on solar power supply and develops a …
Chloride Penetration In Surface-Treated Concrete In Natural And Accelerated Environments,
2016
Institute of Structural Engineering, Zhejiang University
Chloride Penetration In Surface-Treated Concrete In Natural And Accelerated Environments, Jianfeng Dong, Yuxi Zhao, Shaoliang Pu, Ming Ji
International Conference on Durability of Concrete Structures
This study investigated the chloride penetration of surface-treated concrete in natural and accelerated environments. A part of a real concrete port, including the beams and the columns, was investigated. Concrete specimens cast together with the concrete port were transported to the lab and subjected to wetting and drying cycles for accelerating the ingression of chloride ion. Chloride concentration of the specimens in the lab and the components in situ was tested. The results show that the surface treatments obviously slow down the chloride penetration into the concrete in both lab and in situ. The chloride penetration in situ is …
Hierarchical Life-Cycle Design Of Concrete Structures,
2016
Zhejiang University
Hierarchical Life-Cycle Design Of Concrete Structures, Zhujun Wang, Jin Weiliang, Ju Chen
International Conference on Durability of Concrete Structures
Concrete structures’ service life lasts decades. In order to deal with all the probable degradations and deteriorations in the whole life span, the concept of concrete structures’ Life-Cycle Design was introduced into China in the 1980s. However, until this day, Life-Cycle Design is still more of a concept to most structure designers and engineers, rather than a practical method. This paper provides a hierarchical method for concrete structures’ Life-Cycle Design, in which the design process is divided into five levels. Safety should be the fundamental requirements for all concrete structures, so as to guarantee a reliable quality. For structures located …
Study Of Water Permeability Of Lightweight Concrete,
2016
Shenzhen University
Study Of Water Permeability Of Lightweight Concrete, Xiaoxiao Xu, Haibin Yang, Hongzhi Cui, Zitao Lin, Tommy Yiu Lo
International Conference on Durability of Concrete Structures
The relationship between water permeability and different levels of the tested layers from the top surface to the bottom surface of the lightweight concrete specimens is determined in this study. It is beneficial to develop the design criteria for a durable lightweight concrete. The water permeability coefficient K of the samples was determined by water permeability test using GWT. It is found that the water permeability coefficient K of the three layers in each set of samples tends to decrease as the level of the tested from the top surface increase. Larger Rebound Number and higher density in the bottom …
Influence Of Sio2@Pmhs On The Water Absorption Of Cement Mortar As A Surface Treatment Agent,
2016
University of Jinan
Influence Of Sio2@Pmhs On The Water Absorption Of Cement Mortar As A Surface Treatment Agent, Ran Li, Pengkun Hou, Zonghui Zhou, Xin Cheng
International Conference on Durability of Concrete Structures
In this paper, the core–shell structured SiO2@PMHS hybrid nanoparticles were synthesized with tetraethoxysilane (TEOS) and polymethylhydrosiloxane (PMHS). And SiO2@PMHS core–shell nanoparticles were first used as a surface treatment agent for cement-based materials. The influence of SiO2@PMHS nanoparticles on the water absorption of hardened cement mortar with water-to-cement ratio of 0.6 was investigated. Results showed that the water absorption of cement mortar treated with SiO2@PMHS nanoparticles was decreased by 93.47% in comparison to the control sample.
Edge Detection Of Concrete Mesostructure Based On Dis Operator,
2016
Institute of Structural Engineering, Zhejiang University, Hangzhou, China
Edge Detection Of Concrete Mesostructure Based On Dis Operator, Bin Feng, Zicheng Xu, Jin Xia, Shijie Jin, Weiliang Jin
International Conference on Durability of Concrete Structures
Aggregate edge detection is the basis of creating concrete mesoscale model, which is applied to analyze concrete mesoscale characteristics. A concrete digital image edge detection method using DIS operator is presented in this paper. Mean filter, multi-scale filter, and Gaussian filter are compared on the effect of concrete image noise reduction. Based on the result, Gaussian filter is the most optimum method to reduce image noise and remain aggregate edge distinct. Sobel operator, Laplacian operator, and DIS operator are applied respectively to detect the aggregate edge on Gaussian filter processed images. Based on the experiment, DIS operator outperforms other two …
Influence Of The Surface Treatment Of Hardened Cement Mortar With Colloidal Nano-Silica And Teos,
2016
University of Jinan
Influence Of The Surface Treatment Of Hardened Cement Mortar With Colloidal Nano-Silica And Teos, Pengkun Hou, Xin Cheng, Zonghui Zhou
International Conference on Durability of Concrete Structures
Two types of silicate material, tetraethoxysilane (TEOS) and colloidal nanoSiO2 (CNS), were applied for surface treatment of hardened cement mortar by exploring their filling and pozzolanic reactivity to make the surface compacter. Results showed that the water adsorption coefficient, the water vapor transmission rate, and the water penetration depth were reduced when CNS and TEOS were applied onto the surface of hardened cement mortar, and TEOS exhibits a superior effect on surface treatment, making the mass-transport rate and extent smaller than CNS does.
Performance Of Concrete Patch Repairs: From A Durability Point Of View,
2016
University of Liverpool
Performance Of Concrete Patch Repairs: From A Durability Point Of View, Choorackal Avirachan Eldho, Ominda Nanayakkar, Jun Xia, Steve Jones
International Conference on Durability of Concrete Structures
Chloride contamination in reinforced concrete leads to the corrosion of steel bars. Concrete patch repairs are widely practiced as a remedial measure for the mitigation of such corrosion in reinforced concrete structures. The performance of the patch repairs was studied by various researchers in the past. The structural and material aspects of patch repairs have received more attention than the electrochemical consequences of patch repairs in past studies. But electrochemical changes could be the underlying cause for the failure of many patch repairs. This paper reviews the performance of patch repairs from a durability point of view. It covers the …
