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Articles 1 - 30 of 34
Full-Text Articles in Materials Science and Engineering
The Effects Of Curing Temperature On The Hydration Kinetics Of Plain And Fly Ash Pastes And Compressive Strength Of Corresponding Mortars With And Without Nano-Tio2 Addition., Dan Huang, Mirian Velay-Lizancos, Jan Olek
The Effects Of Curing Temperature On The Hydration Kinetics Of Plain And Fly Ash Pastes And Compressive Strength Of Corresponding Mortars With And Without Nano-Tio2 Addition., Dan Huang, Mirian Velay-Lizancos, Jan Olek
International Conference on Durability of Concrete Structures
Incorporation of fly ash in cementitious systems containing ordinary portland cement (OPC) increases their long-term strength and durability. However, replacement of cement by fly ash also reduces the heat of hydration of such systems and reduces early-age strength development. The reduced rate of strength development can increase the risk of durability problems, e.g. scaling, in cases when young concrete is exposed to low temperatures and deicing chemicals. This study investigated the potential of nano-titanium dioxide (nano-TiO2) particles to modify the hydration kinetics of fly ash pastes and compressive strength development of corresponding mortars cured under low (4°C) and …
The Degradation Of Concrete Tunnel Wall Panels: A Case Study, Christian Paglia
The Degradation Of Concrete Tunnel Wall Panels: A Case Study, Christian Paglia
International Conference on Durability of Concrete Structures
Concrete panels are often used along tunnel walls for technical and aesthetic purposes. Generally, the environment in contact with such materials is aggressive. Emission gases from the vehicles, sulphates, chlorides coming from the winter salt spreading, high temperature and humidity promote an acceleration of the deterioration phenomena. In this work 30 years old concrete panels placed along a 16 km long highway tunnel across the Alps were investigated with respect to their durability. The focus was given to the tunnel entrance zone. This region of the tunnel exhibited a critical environment with respect to the durability of the cementitious material …
Rheological Properties And Structural Build-Up Of 3d Printed Magnesium Potassium Phosphate Cement, Hui Zhi Zhao
Rheological Properties And Structural Build-Up Of 3d Printed Magnesium Potassium Phosphate Cement, Hui Zhi Zhao
International Conference on Durability of Concrete Structures
This paper focuses on the rheological properties of 3D printed magnesium potassium phosphate cements (MKPCs) with different magnesium-to-phosphate (M/P) mass ratio, MgO fineness and supplementary cementitious materials (SCMs) types. The variable shear rate tests were used to monitor the extrudability. The highest slope of the evolution of storage modulus (G') and the maximum static yield stress (Mτs) value were used as an indication of the rigidification rate. The increased M/P mass ratio, MgO fineness and SCMs addition resulted in the promoted structural build-up of 3D printed MKPCs. The consistency between the evolution of G' and Mτs with …
Mechanical Properties Of Engineering Cement-Based Materials Containing Modified Shape Memory Alloy Fiber, Song Mengfan
Mechanical Properties Of Engineering Cement-Based Materials Containing Modified Shape Memory Alloy Fiber, Song Mengfan
International Conference on Durability of Concrete Structures
在这项研究中，提出了一种 SMA 纤维的表面改性方法，以改善水泥基复合材料中纤维的界面性能。SMA 纤维涂有 SiO 2，预计会与 Ca(OH) 2反应由水泥水化形成，减少了薄弱区的可能性，并在纤维-基体界面处形成了更致密的微观结构。采用扫描电子显微镜 (SEM)、能量色散光谱 (EDS) 和红外吸收光谱 (IR) 对表面改性后的 SMA 纤维进行表征。此外，还进行了抗弯强度试验、抗压强度试验和四点弯曲试验，以评价宏观尺度上界面力学性能的增强情况。实验结果表明，包覆的 SiO 2，导致改性 SMA 纤维-水泥界面处的 CSH 凝胶量增加和孔隙率降低。改性后的SMA纤维与水泥基体之间的紧密粘附有利于建立更强的界面结合力，有利于提高抗弯强度、抗压强度、四点抗弯强度和挠度。抗弯强度、抗压强度、四点抗弯强度和挠度均在28d时显着增加。结果支持了所提出的表面改性方法适用于 SMA 纤维以提高其在工程水泥基材料中的增强效率的结论。
Super-Hydrophobic Hybrid Coatings Preparation Used By Methyltrithoxysilane (Mtes) And Tetraethylorthosilicate(Teos), Quanwei Li
International Conference on Durability of Concrete Structures
超疏水材料由于其优异的疏水自洁性能，在航空航天、海洋工程、除冰防腐等领域具有广阔的应用前景。本文采用简单的溶胶-凝胶制备超疏水涂层。 . 以甲基三乙氧基硅烷（MTES）和原硅酸四乙酯（TEOS）为前驱体，水解缩合后形成粗糙结构，1H,1H,2H,2H-全氟癸基三乙氧基硅烷（FAS）为低表面能的表面活性剂，系统研究了各自的最佳配比零件。涂层的疏水性和形貌分别通过水接触角测量、扫描电子显微镜（SEM）表征。同时，其官能团通过红外光谱表征。基于大量的实验和优化测试，
Corrosion Performance Of Embedded Steel Bar In Cl--Contaminated Limestone Calcined Clay Cement (Lc3) At Initial Stage Of Hydration, Weiwen Li, Zuhua Xu, Yaocheng Wang, Xin Wang, Feng Xing
Corrosion Performance Of Embedded Steel Bar In Cl--Contaminated Limestone Calcined Clay Cement (Lc3) At Initial Stage Of Hydration, Weiwen Li, Zuhua Xu, Yaocheng Wang, Xin Wang, Feng Xing
International Conference on Durability of Concrete Structures
Limestone Calcined Clay Cement (LC3) presents brilliant properties in binding Cl- so that the embedded steel bars are probably protected in Cl--contaminated condition, which meets the need of sea sand application. However, the corrosion performance of steel bars embedded in LC3 paste with Cl‑ is unclear, especially in early age hydration. Thus, a series of experiments were carried out to evaluate the corrosion performance of steel bars on initial and hardened stages of hydration, including concentration of OH- and Cl- in real pore solution, open circuit potential (OCP) and chemical elements of steel bars. …
Mechanical Properties And Microstructure Of High Strength Lc3 Pastes With Varying Limestone/Calcined Clay Ratios And Different Curing Conditions, Yemin Dong
International Conference on Durability of Concrete Structures
研究（抗施工蒸馏）石石和石榴石在淀粉胶系统（即0标准和低水印）下的水胶系统（即0标准和低水墨）X射线比、水量值水量-电子背基相关研究.61.25 .25.25.25.0.25.25.25.25.25.0.25.25.25.25.25.1.25.7.25.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.25.1.25.25.1.25.1.25.1.25.1.25.1.25.1 .25.1.25.1.25.1.25.1.25.1.25.0.0.0.0.0.0.0.00.0.0.1.25.1.25.1.25.1.25.1.25.0.0.0.00.0.0.0.0.0.0.0.0.0.0.0.0.0.00.0 .00.0.00.X射线比值、水量-电子显微镜相关研究测量值。早期的水泥水化程度小水的压合含煤量，降低了水泥石的。因此，需要采用合适的钙铝内容和体系以提高碳系统的性能。
Development And Properties Of Sulfate-Resistant And Corrosion-Inhibiting Admixtures, Tongwei Lu, Jie Zhang, Guisheng Cai, Linmao Wang, Xiangyang Guo
Development And Properties Of Sulfate-Resistant And Corrosion-Inhibiting Admixtures, Tongwei Lu, Jie Zhang, Guisheng Cai, Linmao Wang, Xiangyang Guo
International Conference on Durability of Concrete Structures
Sulfate and chloride-induced corrosion of concrete and steel reinforcement are the most important causes of premature failure of durability of concrete structures. To prevent damage in concrete structures, the application of sulfate-resistant and corrosion-inhibiting admixtures has proven to be an effective method. In this study, a new type of corrosion-inhibiting admixtures including organic and special inorganic components are developed and the properties of mortar mixed with them was investigated. The results show that NC-CZ series of sulfate-resistant and corrosion-inhibiting admixtures have been successfully developed. The mortar with NC-CZ has good resistance to sulfate attack, whose corrosion resistance coefficient of mortar …
Study On The Effect Of Fly Ash On The Properties Of Potassium Magnesium Phosphate Cement, Bo Pang
Study On The Effect Of Fly Ash On The Properties Of Potassium Magnesium Phosphate Cement, Bo Pang
International Conference on Durability of Concrete Structures
In this paper, the effect of fly ash on the setting time and mechanical properties of potassium magnesium phosphate cement is studied. The early hydration process of potassium magnesium phosphate cement was studied by TAM-Air, and the hydration products were analyzed by XRD. The results show that fly ash can effectively prolong the setting time and the compressive strength of the cement paste was decreased; The addition of fly ash would not change the phase composition of the hydration products of the potassium magnesium phosphate cement, which affect the hydration process, the amount of the hydration products and the degree …
Study On Hydration Properties Of Grinded Tuff-Cement Cementitious Material System, Hao Wang
Study On Hydration Properties Of Grinded Tuff-Cement Cementitious Material System, Hao Wang
International Conference on Durability of Concrete Structures
The chemical composition and microscopic morphology characteristics of grinded tuff(GT) and fly ash(FA) were compared and analyzed in the paper. The chemical bound water content and hydration heat were tested for investigating the hydration properties of grinded tuff-cement cementitious material system (GTCS) and fly ash-cement cementitious material system (FACS). The results shown that, the chemical composition of GT was similar with that of FA, however the loss on ignition of the GT was obviously higher than FA. The microstructure of the GT particles was polygonal and irregular, while the microstructure of FA particles were mostly smooth spheres. The hydrated heat …
Investigation On The Properties Of Calcium Sulfoaluminate Cement Waterproof Repair Mortar Modified With Ethylene-Vinyl Acetate Powder, Dong Dong
International Conference on Durability of Concrete Structures
本文采用乙烯-醋酸乙烯酯（EVA）粉体和CSA水泥制备了防水修复砂浆，并对其水化和性能进行了研究。结果表明，EVA粉体延长了凝固时间，提高了防水修补砂浆的流动性，使其在实际工程中更容易应用。EVA粉提高了防水修复砂浆的不渗透性，降低了吸水性。虽然EVA粉降低了防水修补砂浆的抗弯强度和抗压强度，但它仍然符合JC/T 2381-2016标准对刚性修复砂浆的要求。EVA粉体降低了防水修复砂浆的收缩率，改善了界面过渡区和拉伸粘接强度、弯曲粘接强度等粘接性能。EVA粉末抑制CSA水泥的水合作用6 h，在3 d水化年龄时抑制作用消失。
Shrinkage And Durability Of Cement Mortars With Recycled Aggregates, Wencui Yang
Shrinkage And Durability Of Cement Mortars With Recycled Aggregates, Wencui Yang
International Conference on Durability of Concrete Structures
In recent years, the rapid growth of economy and urbanization process in China resulted in the massive construction and demolition wastes (C&DW). The reutilization of C&DW as recycled aggregates (RA) fully or partially to replace natural aggregates is an effective way to solve the environmental and economic problems caused by C&DW. The properties of cement mortars could be influenced by recycled fine aggregates due to their high absorption and the quantity of fine particles. This paper presents the main results of the research to explore the effect of recycled aggregate (RA) on shrinkage and durability properties of masonry mortars. Four …
Investigation On Structural Heritability And Durability Of High Sulfate Resistance Portland Cement Mortar Modified By Aluminum Salt, Jun Xu
International Conference on Durability of Concrete Structures
The essential hydration and hardened properties of high sulfate resistance Portland cement paste/mortar were investigated with Al2(SO4)3 as admixture. Experiment results showed that that the addition of Al2(SO4)3 promoted the hydration of HSRP cement pastes, and the hydration rate accelerated with the increase of the addition amount. The mechanical properties and chloride diffusion coefficient of cement mortar were obviously improved with 0.25% Al2(SO4)3 addition . For instance, the compressive strength of AS0.25 cement mortars was 24.8% higher than AS0 samples and the chloride ion migration …
Mechanical And Thermal Insulation Properties Of Clay-Based Lightweight Concrete, Chuang Shi, Chuanlin Hu
Mechanical And Thermal Insulation Properties Of Clay-Based Lightweight Concrete, Chuang Shi, Chuanlin Hu
International Conference on Durability of Concrete Structures
建材生产和住宅采暖将消耗大量能源并排放大量CO2。在混凝土制备中，使用陶土制备具有优异隔热性能的轻质混凝土，并使用煅烧粘土代替部分波特兰水泥，可以大大降低能耗。本研究采用页岩陶土和陶砂分别作为粗骨料和细骨料制备轻质混凝土。首先，确定最佳体积砂比。然后，使用煅烧粘土和石灰石的剂量从30%，50%到70%。研究了煅烧粘土和石灰石含量对混凝土微观结构、力学性能和隔热性能的影响。结果表明，最佳体积砂比为50%。当煅烧粘土和石灰石的用量为30%时，强度在所有年龄段最高，28 d时强度可达33.6 MPa，比对照组高12%。当更换水平不断增加时，所有年龄段的实力开始下降。所制备的粘土基轻质混凝土的导热系数低至0.144 W/mK，表现出优异的保温性能。本研究制备的轻质混凝土具有较高的强度和优异的保温性能，具有良好的应用前景。
Micro-Mechanical Analysis Of Corrosion Products Formed During Long-Term Carbonation Induced Corrosion Of Steel, Marijana Serdar, Dubravka Bjegovic, Valérie L’Hostis, Stéphane Poyet, Damien Féron
Micro-Mechanical Analysis Of Corrosion Products Formed During Long-Term Carbonation Induced Corrosion Of Steel, Marijana Serdar, Dubravka Bjegovic, Valérie L’Hostis, Stéphane Poyet, Damien Féron
International Conference on Durability of Concrete Structures
During corrosion distinct types of corrosion products form, composed of different ratios of ferrous ions and oxide, hydroxides. Corrosion products have different physical and mechanical properties, mainly density, resistivity, volume and modulus of elasticity compared to iron. Knowing properties of corrosion products is indispensable for service life modelling of structures and can give valuable insight into the long-term corrosion propagation process. In this study micro-indentation method was used to evaluate mechanical properties of different layers formed during long-term carbonation induced corrosion of steel in concrete. Investigation was performed on three sets of reinforced concrete samples, that underwent corrosion during 50, …
Development Of Engineered Cementitious Composites With Conductive Inclusions For Use In Self-Sensing Applications, Benny Suryanto Dr, Danah Saraireh Ms, Steven Walls Mr, Jaehwan Kim Dr, W John Mccarter Prof
Development Of Engineered Cementitious Composites With Conductive Inclusions For Use In Self-Sensing Applications, Benny Suryanto Dr, Danah Saraireh Ms, Steven Walls Mr, Jaehwan Kim Dr, W John Mccarter Prof
International Conference on Durability of Concrete Structures
The mechanical and a.c. electrical properties of a new varietal of engineered cementitious composite (ECC) incorporating conductive inclusions are presented. Electrical measurements were undertaken over a wide frequency range while curing and when under uniaxial tensile loading to study the influence of ongoing hydration and multiple microcrack formation on the composite electrical impedance. When presented in Nyquist format, the work shows that conductive inclusions reduce the bulk resistance of the composite while enhancing its polarizability, transforming the classic, single-arc bulk response of typical cement-based materials to a two-arc response. The bulk resistance was shown to increase with time and damage, …
Mechanical And Microstructure Characteristics Of Concrete-Mixtures Designed For Durability Of Rc-Structures In Corrosive Environment, Saeid A. Alghamdi Dr., S. Ahmad, M. M. Khaled
Mechanical And Microstructure Characteristics Of Concrete-Mixtures Designed For Durability Of Rc-Structures In Corrosive Environment, Saeid A. Alghamdi Dr., S. Ahmad, M. M. Khaled
International Conference on Durability of Concrete Structures
As exposures to chloride-salts are known as prime factors causing initiation and continuity of corrosion-process of steel reinforcement bars in reinforced concrete (RC) structures, it has always been a major concern for designers considering the requirements of structural-durability for targeted-service life of RC-structures in aggressively corrosive environments typically prevalent in coastal regions. Research works previously reported by the researchers have modeled corrosion-process in terms of corrosion-current density, and it was realized that concrete-mixtures design quality and characteristics, degree of exposures to corrosive-agents such as chloride salts, and protective-concrete cover-thickness are now known beyond doubt to be determinant factors as regards …
Experimental And Numerical Investigation On The Irregularity Of Carbonation Depth Of Concrete Under Supercritical Condition, Hao Bao Masc, Min Yu Dr., Jianqiao Ye Dr., Lihua Xu Dr., Yin Chi Dr., J Ye
Experimental And Numerical Investigation On The Irregularity Of Carbonation Depth Of Concrete Under Supercritical Condition, Hao Bao Masc, Min Yu Dr., Jianqiao Ye Dr., Lihua Xu Dr., Yin Chi Dr., J Ye
International Conference on Durability of Concrete Structures
The heterogeneity of a cement-based material results in a random spatial distribution of carbonation depth, which may significantly affect the mechanical properties and durability of the material. Currently, there is a lack of both experimental and numerical investigations aiming at a statistical understanding of this important phenomenon. This paper presents both experimental and numerical supercritical carbonation test results of concrete blocks. The random fields of porosity and two-dimension random aggregate model of concrete were proposed for the simulation. The carbonation depths are measured and distributed along the carbonation boundary by the proposed rapid image processing technique, which are then statistically …
Guiding Principles In Developing The South African Approach To Durability Index Testing Of Concrete, Yunus Ballim, Mark Alexander
Guiding Principles In Developing The South African Approach To Durability Index Testing Of Concrete, Yunus Ballim, Mark Alexander
International Conference on Durability of Concrete Structures
Focused thinking on the possibility of early-age testing of concrete for long-term durability started in earnest during the late 1980’s in South Africa. Through sustained research, development and trial implementation on construction projects, three durability index (DI) tests have emerged, two of which have been adopted as national standard test methods for concrete construction, the remaining one being prepared a national standard. In this paper we review the guiding or foundational principles that directed the development of these DI tests, with a view to assessing the appropriateness and relevance of these guiding principles to modern concretes. The last 30 years …
The Effect Of Calcium Nitrate On The Hydration Of Calcium Aluminate Cement At Different Curing Temperatures, Hongxia Wang, Guizhi Diao, Guanghua Liu, H Wang, Lixiong Gao, Guangwei Liu
The Effect Of Calcium Nitrate On The Hydration Of Calcium Aluminate Cement At Different Curing Temperatures, Hongxia Wang, Guizhi Diao, Guanghua Liu, H Wang, Lixiong Gao, Guangwei Liu
International Conference on Durability of Concrete Structures
Phase conversion in calcium aluminate cements (CAC) induces significant volumetric instability; it would result in an increase in porosity and decrease in strength in CAC. In this study, calcium nitrate (CN) as a phase conversion inhibitor, the effect of CN on the hydration of CAC at different curing temperatures was studied. Xray diffraction, thermal analysis, SEM, isothermal calorimetry and the compressive strength were conducted on the CAC dosages of 0%, 5%, 10% and 15%CN cured at 20�, 30�, 40� and 50�. The results show CN can retard CAC hydration, alter the characters of the hydrates of CAC systems and avoid …
The Influence Of Waste Glass Powder On The Chloride Binding Capacity Of Fly Ash/Cement Hardened Paste, Jh Yan, Tingyu Hao
The Influence Of Waste Glass Powder On The Chloride Binding Capacity Of Fly Ash/Cement Hardened Paste, Jh Yan, Tingyu Hao
International Conference on Durability of Concrete Structures
The potential of using waste glass powder to increase the chloride binding capacity of fly ash/cement hardened paste was investigated. When only fly ash replacing cement, the chloride binding capacity was raised within 28d when the fly ash replacement level was in the range from 30-50% by mass. But at a longer age of 60 to 90d, the binding performance was increased at the replacement level of 10-30wt%. The chloride binding capacity of glass powder-fly ash-cement system was increased by adding glass powder of 2% and 4% by mass at 7d while those at larger addition and longer age reduced. …
Alkali Reactive Carbonate Rocks: Is It Alkali Silica Reaction (Asr) Or Alkali Carbonate Reaction (Acr)?, Mengesha Beyene, Rc Meininger
Alkali Reactive Carbonate Rocks: Is It Alkali Silica Reaction (Asr) Or Alkali Carbonate Reaction (Acr)?, Mengesha Beyene, Rc Meininger
International Conference on Durability of Concrete Structures
The root cause of distress in two different concrete structures made from carbonate coarse aggregates that fit the textural and compositional criteria cited for ACR was found to be caused by ASR, not ACR. Stereo-optical examination and transmitted polarized light microscopy (PLM) analysis showed that the concretes contain some dark gray, fine-grained argillaceous dolomitic coarse aggregates in which secondary white deposit filling the cracks extending from these aggregates into the paste (as well as lining air voids) is ASR gel. Back scattered electron (BSE) imaging with EDS spectra and x-ray elemental mappings, clearly confirm that the white secondary deposits consist …
Progress Of Carbonation In Chloride Contaminated Concretes, Yaocheng Wang, P. A.M. Basheer, S. Nanukuttan, Y. Bai
Progress Of Carbonation In Chloride Contaminated Concretes, Yaocheng Wang, P. A.M. Basheer, S. Nanukuttan, Y. Bai
International Conference on Durability of Concrete Structures
Concretes used in marine environment are generally under the cyclic effect of CO2 and chloride ions (Cl-). To date, the influence of carbonation on ingress of chloride ions in concretes has been widely studied; in comparison, study on the influence of Cl- on the progress of carbonation is limited. During the study, concretes were exposed to independent and combined mechanisms of carbonation and chloride ingress regimes. Profiles of apparent pH and chloride concentration were used to indicate the progress of carbonation and ingress of Cl- in concretes. From the apparent pH profile, a carbonation front …
Carbon Fiber As Anode Material For Cathodic Prevention In Cementitious Materials, Emma Qingnan Zhang, Luping Tang, Thomas Zack
Carbon Fiber As Anode Material For Cathodic Prevention In Cementitious Materials, Emma Qingnan Zhang, Luping Tang, Thomas Zack
International Conference on Durability of Concrete Structures
Cathodic prevention (CPre) technique is a promising method and has been used for the past two decades to prevent steel from corrosion in concrete structures. However, wide application of this technique has been restricted due to high costs of anode materials. In order to lower the cost and further improve this technique, carbon fiber composite anode has been introduced as an alternative anode material with affordable price and other outstanding properties. This paper presents the study of using carbon fiber mesh as anode material for long-term cathodic prevention system and the effect of accelerated current on macro- and microstructure of …
Corrosion Of Steel In Concrete And Its Prevention In Aggressive Chloride-Bearing Environments, Luca Bertolini, Maddalena Carsana, Matteo Gastaldi, Federica Lollini, Elena Redaelli
Corrosion Of Steel In Concrete And Its Prevention In Aggressive Chloride-Bearing Environments, Luca Bertolini, Maddalena Carsana, Matteo Gastaldi, Federica Lollini, Elena Redaelli
International Conference on Durability of Concrete Structures
This keynote paper deals with the durability of reinforced concrete (RC) structures exposed to aggressive environments characterized by high concentration of chloride ions, namely, marine environments or the use of de-icing salts. The mechanism of chloride-induced corrosion of steel in concrete is introduced, and its influence on the service life of RC structures is analyzed. Factors affecting the time to corrosion initiation are described with regard to both concrete properties and environmental exposure conditions. Design approaches available for achieving durability targets associated with the design service life are analyzed, focusing on studies carried out by the authors in recent years …
The Correlation Of Chloride Diffusion Coefficient And Concrete Maturity Value And Its Application In Hong Kong–Zhuhai–Macao Bridge Engineering, Pengping Li, Shengnian Wang, Jianbo Xiong, Rui Chai, Yu Yan
The Correlation Of Chloride Diffusion Coefficient And Concrete Maturity Value And Its Application In Hong Kong–Zhuhai–Macao Bridge Engineering, Pengping Li, Shengnian Wang, Jianbo Xiong, Rui Chai, Yu Yan
International Conference on Durability of Concrete Structures
The correlation of chloride diffusion coefficient and concrete maturity value within 56 days of curing was investigated by the chemically combined water content method, rapid chloride migration (RCM) test, and concrete maturity test. The experimental results showed that chloride diffusion coefficient of concretes decreased not only with increasing curing ages but also with increasing curing temperature, which can promote the hydration degree of cementitous materials. There is a significant correlation between the chloride diffusion coefficient of indoor cured specimens and the concrete maturity value when expressed as a power function (R2 = 0.976). In addition, the calculated values of …
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
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 …
On Utilization Of Elliptical Rings In Assessing Cracking Tendency Of Concrete, Xiangming Zhou, Olayinka G. Oladiran, Wei Dong
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 …
Influence Of Controlled Permeability Formwork On The Permeability Of Concrete, Wei Lin, Q. Jiang, J. Liu, J. Liu
Influence Of Controlled Permeability Formwork On The Permeability Of Concrete, Wei Lin, Q. Jiang, J. Liu, J. Liu
International Conference on Durability of Concrete Structures
Corrosion of steel reinforcement related to the intrusion of chloride ion is still the main threats to the durability of concrete structure, especially in marine environment. For the purpose of delaying the Cl− concentration at the surface of steel reinforcement reaching the critical value leading to initial corrosion, the permeability of concrete is usually improved by optimizing the concrete mixture to achieve high compatibility as well as optimized pore structure. In recent years, controlled permeability formwork (CPF) which was originally developed to obtain much smoother surface of the concrete proves to promote the service performance of the concrete by …
Characterizing The Pore Structure Of Carbonated Natural Wollastonite, Chiara Villani, Robert Spragg, Raikhan Tokpatayeva, Jan Olek, W. Jason Weiss
Characterizing The Pore Structure Of Carbonated Natural Wollastonite, Chiara Villani, Robert Spragg, Raikhan Tokpatayeva, Jan Olek, W. Jason Weiss
International Conference on Durability of Concrete Structures
This paper focuses on examining the pore structure of a cementitious paste made with a calcium silicate (wollastonite) that reacts with carbon dioxide and water to form a hardened solid. The pore structure of the hardened solid has been characterized using vapor sorption and desorption, low-temperature differential scanning calorimetry (LT-DSC), and scanning electron microscopy (SEM). The total porosity was also measured using mass measurement in oven-dry and vacuum-saturated conditions. Evidence exists that support the hypothesis that the solid has two main pore sizes: large macropores (>10 nm) appear to form between the initial calcium silicate particles and small micropores …