Engineering Commons^™

Evaluation Of The Chloride Ions Penetration Into Concrete Structure With The Surface Penetrants Served In Cold Marine Environment For 20 Years, Yanhua Kuang, Yuki Sakoi Associate Professor, Naoto Takashima Postgraduate, Minoru Aba Professor, Yoichi Tsukinaga Professor,

International Conference on Durability of Concrete Structures

The intrusion of chloride ions in concrete served in the marine environment is the leading cause of corrosion of steel bars. This paper examined the result of a long-term survey on the actual structure (the Tomakomai breakwater) treated with a set of penetrants partly. The survey was conducted twice, in the 12th and 20th years after construction.

The results showed that the penetrants could effectively reduce the penetration of chloride ions into concrete. After using the penetrants, the calculated surface chloride ion concentration was decreased by 5.04%/72.18% (the 12th year/the 20th year). As the service years increase, surface chloride ion …

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 …

End Effect Of Corroded Steel Bar In Concrete Specimen During Corrosion Test By Galvanostatic Method, Peng Zhao, Gang Xu, Qing Wang, Xuan Wang

International Conference on Durability of Concrete Structures

The galvanostatic method is a commonly used accelerated corrosion method in studying the durability of concrete structures caused by steel corrosion. If this method is not adequately controlled, the ends of steel bars will be corroded seriously (this phenomenon is called end effect), which is not common in natural corrosion. How to effectively control the end effect during electrified corrosion is helpful to make the characteristics of electrified corrosion more similar to that of natural corrosion. In this paper, experimental and electromagnetic numerical simulation methods are used to study the influence of cathode and corrosion medium coverage area along the …

Investigation Of Chloride Transportation Mechanism In Reinforced Concrete Specimen Subjected To Eccentric Compression, Yong Dong Yan

International Conference on Durability of Concrete Structures

In order to deal with the chloride ion transportation mechanism in eccentric compressive concrete pier and column in marine environment, stress distribution in the section of eccentric compressive concrete specimen was analyzed firstly, relationship between chloride diffusion coefficient and stress level was developed according to porosity varying under different loads, at last a model of chloride diffusion coefficient under varying stress level was developed. Conversion-diffusion equation in COMSOL Multiphysics was used in this paper to calculate the chloride ion transportation process. Three test beams with different mixture were cast and then loaded to different stress level. After that, all of …

Finite Element Modeling Of Thermal Effect On Airport Slabs, Chuanyue Shen

International Conference on Durability of Concrete Structures

A sub-ground tunnel connecting two concourses of a terminal at Chicago O’Hare International Airport suffered from water leakage. The airport engineers suspected that the problem was caused by high stresses impinging on the tunnel structure by the pavement sections above the tunnel, acting to damage joints and waterproofing membranes that should have prevented such leakage. To provide a fundamental solution to this problem while minimizing the interference with airport operation, a repair strategy needs to be determined based on a clear understanding of the root cause. A preliminary field inspection confirmed that the concrete pavement slabs moved significantly when ambient …

Application Of Multi-Environmental Time Similarity Theory Based On Relative Information (Ri-Mets) Theory In Durability Of Concrete Structures In Marine Chloride Environment, Zhang Kai

International Conference on Durability of Concrete Structures

The Multi-environmental time similarity (METS) method is a testing method that establishes the similarity relationship between the indoor test environment and the on-site environment to evaluate the durability and predict service life of the proposed or under-constructed concrete structure. Based on the METS theory, a similarity ratio of chloride ion concentration and diffusion coefficient between the indoor accelerated environment and the on-site natural environment was established. Then the relative information entropy was introduced into the Multi-Environmental Time Similarity based on Relative Information (RI-METS) theory to consider the time variability of the diffusion coefficient and the surface chloride ion mass fraction. …

Durability Assessment Of Repairing Vertical Cracks In Concrete Using Microbially Induced Calcium Carbonate Precipitation Technique, Chunhua Lu

International Conference on Durability of Concrete Structures

No abstract provided.

End Effect Of Corroded Steel Bar In Concrete Specimen During Corrosion Test By Galvanostatic Method, Peng Zhao, Gang Xu, Qing Wang, Xuan Wang

International Conference on Durability of Concrete Structures

Corrosion of steel bars is the main durability problem of concrete structures, which seriously endangers the safety and service life of reinforced concrete (RC) structures. When studying such problems, the electrifying corrosion method is often used to obtain corroded components. How to effectively control the corrosion area of steel bars is the key to improve the applicability of the corrosion method. In this paper, experimental and electromagnetic numerical simulation methods are used to study the influence of cathode and corrosion medium coverage area along the longitudinal direction on the corrosion area of steel bar before concrete protective layer corrosion cracking. …

Ultra- Ductile Waterborne Epoxy-Concrete Composite Repair Material, Bo Pang, Zuquan Jin, Yunsheng Zhang, Xiaoyun Song

International Conference on Durability of Concrete Structures

With the extension of service time, the building structure is in urgent need of repair and reinforcement due to its deterioration in safety and durability with the years. Normal cement concrete exposes shortcomings such as high brittleness and low flexural-tensile strength for which fails to meet the requirement of construction repairing. In this paper, a novel waterborne epoxy-concrete composite repair material (WECM) was prepared by using self-synthesized water-based epoxy resin based on the molecular structure-activity relationship. The key flexural and tensile performance parameters of WECM were accurately obtained.

Effects Of Organic Corrosion Inhibitors On The Performance Of Repair Mortars, Ominda Nanayakkara Dr.

International Conference on Durability of Concrete Structures

Reinforced concrete (RC) structures are severely degraded due to the corrosion of the embedded reinforcing steel, and hence, the upgrading of RC structures is essential. Repairing mortar is widely used to improve durability and strengthen structures; however, further repairing might be required considering the extended life of the structure. The use of inhibitors to protect the reinforcement from corrosion has become of great interest. Therefore, it is vital to study the potential of using corrosion inhibitors in a newly repaired system.

This study investigated the performance of a commercially available polymer-modified mortar with migrating and admixed corrosion inhibitors. The study …

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. …

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。

Influence Of Biological Sulfuric Acid On Corrosion Mechanism Of Alkali-Activated Cement Concrete, 季 韬 教授

International Conference on Durability of Concrete Structures

生物硫酸对碱活化水泥混凝土腐蚀机理的影响

丁方硕、韬骥、潘伟杰

福州大学土木工程系

抽象的

讨论了不同浓度的生物硫酸对碱活化水泥混凝土（AACC）腐蚀的影响，并以化学硫酸为参考。AACC的质量和抗压强度、孔溶液的pH曲线和Ca ²⁺对其释放进行了研究，并通过 ESEM-EDS 和 XRD 揭示了 AACC 的腐蚀机理。结果表明，在不同浓度的化学硫酸和生物硫酸作用下，AACC的腐蚀产物主要是石膏。随着硫酸浓度的增加，AACC的失重率增加，AACC的抗压强度降低。石膏阻碍化学硫酸进入混凝土。然而，石膏为细菌提供了生存环境，细菌很容易渗透到混凝土中，加速了AACC的破坏。与化学硫酸相比，生物硫酸增加了AACC的质量损失率和抗压强度。

参考

荣H，Wu，C.，Ma，G.，Zheng，X.，和Liu，Z，2021。污水环境下混凝土微生物腐蚀研究进展。中国陶瓷学会学报，49（5）：988-999。

Scholz, F., 1997。微生物影响的材料腐蚀：科学和工程方面。固态电化学杂志，1（2）：181-181。

谢毅，林，X.，吉，T.，2019。普通硅酸盐混凝土与碱活化混凝土在生物硫酸侵蚀下的耐腐蚀机理比较。建筑和建筑材料，228（20）：1-12。

Frost Resistance And Pore Structure Properties Of Mortar Containing Air Entraining Agent Combined With Superabsorbent Polymer, Yanqun Xu, Qiang Yuan

International Conference on Durability of Concrete Structures

The air entraining effect of air entraining agent (AEA) is deeply affected by environment, which will further influence its function of improving frost resistance. To solve this problem, a strategy of using AEA combined with superabsorbent polymer(SAP) to improve the frost resistance of mortar was proposed in this study. Mass loss and relative dynamic elastic modulus of mortar were used to characterize frost resistance of mortar. Air void density, spacing factor, air void distribution and air content were measured to analyze its pore structure properties. The results verify that the combined use of AEA and SAP can improve the frost …

The Transportation Of Corrosion Products In Cementitious Material Under Chloride-Rich Environment, Yuzhou Wang

International Conference on Durability of Concrete Structures

Corrosion products, forming on steel bar in cementitious material, can lead to concrete cracking. Clear the transportation of corrosion products is of great significance to predict corrosion-induced structural deterioration. This study investigates the corrosion products in steel-reinforced concrete specimen. By Raman spectroscopy and SEM method, the chemical constituents and micromorphology of corrosion products at steel-concrete interface as well as those inside the pore of cement paste are investigated. The proportion of corrosion products filling into the cement paste is determined by EDTA titration method. The results reveal that corrosion products diffuse in forms of ion in solution under chloride-rich environment, …

Research On Water Absorption And Frost Resistance Of Concrete Coated With Different Impregnating Agents For Ballastless Track Structure, Xin Ge, Yanbin Tan, Xiaowei Wang, Yongjiang Xie, Qinfei Li, Linxiang Li, Lu Yang, Zhongwei Feng

International Conference on Durability of Concrete Structures

In consideration of performance requirement of ballastless track concrete in cold regions of China, 3 types of commercially available impregnating agents were employed to research their effect on water absorption and frozen resistance of concrete, containing silanes, potassium silicate and osmotic curing agent. The results presented that coating silanes was the most effective on the reduction of water absorption among all employed impregnating agents, because of the most significant character change of concrete surface from hydrophilicity to hydrophobicity which could be proved by the contact angle test of concrete. The promotion on frozen resistance of concrete was not as significant …

Study On Corrosion Resistance Of Portland Cement-Calcium Sulphoaluminate Cement Binary System In A Sodium Chloride Environment, Shilin Song, Tao Xing, Yu Zhang, Jianzheng Wang, Xiaodong Shen, Ying Ma

International Conference on Durability of Concrete Structures

Portland cement is widely used in civil engineering. However, Portland cement-based materials are easy to be corroded by seawater in marine environment. Many research show the corrosion resistance of Portland cement mortar can be improved by add appropriate amount of mineral admixture.Sulphoaluminate cement have high strength and good corrosion seawater resistance. However, the short setting time and high hydration heat of sulphoaluminate cement limit its application in civil engineering.Portland cement-sulphoaluminate cement (PC-CSA) not only have high strength and corrosion resistance but also long setting time.In this work, the sulphoaluminate cement was used to partially replace Portland cement. The replacement level …

Damage Evaluation Of Full-Scale Rc Slab By Ultrasonic Tomography, Hiroshi Hayashida, Tamon Ueda

International Conference on Durability of Concrete Structures

There have been reports of road bridges that deteriorated after their RC slabs had been repaired. The insufficient removal of damaged materials is said to be the cause of such post-repair deterioration. Consequently, there is a call for a survey method that can detect deteriorated materials of bridges with high accuracy. Towards the development of such a method, this report focuses on ultrasonic tomography, because it can detect damage to the RC slabs of road bridges over relatively large areas. We examined the applicability of ultrasonic tomography to a method of assessing the RC slab damage by a test that …

Integrated Sensor Network For Monitoring Steel Corrosion In Concrete Structures, José Enrique Ramón-Zamora, José Manuel Gandia-Romero, Román Bataller, Ana Martínez-Ibernón, Isabel Gasch, Juan Soto

International Conference on Durability of Concrete Structures

The developed Integrated Sensor Network (ISN) allows a non-destructive monitoring of the rebar condition at different parts of the structure. The corrosion sensor allows the accurate determination of the corrosion rate (µm/year). Moreover, additional sensors are integrated in order to detect relevant changes in the concrete electrochemical condition.

The ISN has been published as an international invention patent (reference number WO 2016/177929 A1). The system is based on an economic, simple, reliable and durable technology, which makes its implementation viable on new and repaired reinforced concrete structures (RCS). Therefore, it is also possible monitoring non-accessible parts such as deep foundations …

Similarity Analysis Of Rebar Corrosion Under Different Electrochemical Accelerated Method, Chuanqing Fu, J Chen, X Jin, H Ye, Jun Zhu

International Conference on Durability of Concrete Structures

The concrete cover cracking caused by non-uniform corrosion of reinforcing bar is one of the most important reason for structure service performance degradation. The most widely used electrochemical accelerated corrosion methods include external and internal electrode methods. The reinforcement are used as anode in both methods. The different between two methods is the position of auxiliary. In external electrode method, the auxiliary is set outside the specimen, including three methods, i.e. samples whole/part submerged in saline, samples wrapped by sponge and steel mesh. The electrochemical mechanism of these four accelerated method were analyzed by using the FE software COMSOL. According …

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, …

An Experimental Study Of Concrete Resistivity And The Effects Of Electrode Configuration And Current Frequency On Measurement, Hayder Oleiwi, Yu Wang, Nan Xiang, Levingshan Augusthus-Nelson, Xianyi Chen, Igor Shabalin

International Conference on Durability of Concrete Structures

Electrical resistivity, a measurable parameter of the state of concrete, plays an important role in the assessment of reinforced concrete structures. An experimental study using two-electrode method has been conducted to evaluate the resistivity of Portland cement concrete. Internal and external electrodes were varied in order to understand effect of the electrodes configuration, where carbon fibre (CF) sheets were employed as the internal electrodes and CF and copper sheets were used as external electrodes. Furthermore, frequency of applied current was varied from low to high, to identify the most suitable frequency that can be utilized for stable and reliable results. …

Will Blended-Cement Systems With Similar Chloride Penetration Potentials Resist Similarly To Corrosion?, William Wilson, Vincent Labattaglia, Arezki Tagnit-Hamou, Luca Sorelli

International Conference on Durability of Concrete Structures

The capacity of concrete to prevent chloride ions penetration represents a key durability factor for steelreinforced structures exposed to de-icing salts and/or marine environments. Although blended-cement systems are commonly characterized with accelerated chloride penetration tests developed for Portlandcement concrete (e.g. the ASTM C1202 method), their microstructures and pore solutions are very different. This study aims to illustrate how the full potential of blended-cement systems to resist chloride ingress (and thus, chloride-induced corrosion) may not be justly disclosed by these accelerated tests using electrical current, even when tested after three months of curing. A Portland-cement-only mortar and five binary blended-cement mortars …

An Investigation On Moisture And Water Absorption In Cement Paste With Electrical Resistance Method, Manami Mizoguchi, Tatsuya Kitagawa, Totsawat Daungwilailuk, Yuko Ogawa, Kenji Kawai

International Conference on Durability of Concrete Structures

Moisture in concrete is one of main factors related to degradation and deterioration of concrete structure, and there are various moisture transport phenomena in concrete such as drying and absorbing. There are a lot of previous studies on the drying process of concrete to clarify the mechanisms of creep as well as shrinkage. However, few studies have been reported on the process of water absorption and moisture absorption although carbonation and chloride attack are strongly related to moisture and water absorbing. It is necessary to investigate moisture transfer in concrete in detail. This study investigated the moisture transfer in moisture …

Pore Characteristics And Computed Permeability Of Pastes Subject To Freeze-Thaw Cycles At Very Early Ages By X-Ray Ct, Ya Wei, Zehong Wu, Xiang Gao

International Conference on Durability of Concrete Structures

Freeze-thaw cycling can damage microstructure of concrete and reduce the service life of concrete structures. This is especially detrimental for concrete subject to freeze-thaw cycles at very early-ages, such as within the first few days after constructions. Typical low and high water-to-cement (w/c) ratio pastes are investigated experimentally and numerically in this study. The pastes are subject to freeze-thaw cycles at the age of 1, and 7 days and then sealed-cured to the age of 45 days. The pore size distribution is measured and quantified by X-ray computer tomography (CT) with high resolution. The permeability of the corresponding pastes is …

Investigation Of Microstructure Of Cementitious Materials Exposed To High Temperature By Non-Destructive Integrated Ct-Xrd Method, Takuya Mikami, H Takahashi, T Sugiyama

International Conference on Durability of Concrete Structures

Severe accident occurred in 2011 at the Fukushima Daiichi nuclear power plant and it can be assumed that the concrete building was exposed to high temperatures environment for a long time due to loss of the cooling function of the nuclear reactor. In order to prepare for the best scenario in the decommission plan, it should be first needed to clarify and evaluate the level of damage and deterioration of the contaminated concrete. To solve this problem, experiments were conducted for cementitious materials with the maximum temperature of 400 or 1000 degrees Celsius with durations of up to 2 hours. …

Influence Of Pore Structure On Relative Chloride Diffusion Coefficient In Unsaturated Cementitious Materials, Yong Zhang, Guang Ye

International Conference on Durability of Concrete Structures

Chloride-induced corrosion of reinforcement in concrete structures is a serious issue in engineering practice. This paper investigates the influence of pore structure on the relative chloride diffusion coefficient Drc in unsaturated cementitious materials. The effects of various pore features, including porosity, pore size, and pore connectivity, on the continuity of water-filled pores in unsaturated porous systems are analyzed based on the Kelvin law and water desorption process. In the experimental program, different cementitious materials (OPC, slag, fly ash, and limestone powder) were used to prepare paste and mortar samples. The Drc of the mortar samples (one year old) at various …

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, …

Diagnosis On Expansion Of Heat-Cured Precast Concrete Blocks Due To Delayed Ettringite Formation In Japan, Yuichiro Kawabata

International Conference on Durability of Concrete Structures

Delayed ettringite formation (DEF) in concrete causes internal swelling, which reduces the mechanical properties of concrete and can lead to issues with concrete structures due to potentially large expansive deformation. In order to address the issues of DEF-affected structures, proper assessment of the structures affected is important. However, petrographic diagnosis of concrete affected by DEF remains a controversial issue. In this paper, as case studies, diagnosis on precast concrete blocks suspected of experiencing DEF was carried out. The concrete blocks were made of white Portland cement, limestone gravel, and limestone sand mixed with copper slag. The blocks were excessively heat-cured …

Rehabilitation Of Low Rise Rcc Structure Along 9m High Retaining Wall, Aniruddha Nakhawa Er, Vivek Deshmukh Dr

International Conference on Durability of Concrete Structures

Mumbai is the financial, commercial and entertainment capital of India, facing bigger challenges in accommodating its over growing population day by day. The Mumbai City has population of 18.4 million over its 634 km2 area, ie. Almost 350 ft2/person. This enormous rise in population density has restricted the development to expand vertically. This also, results in growth of major slums, which is almost 62% of the population dwelling in slums. Subsequently, the authorities is in need of a large scaled Slum Sanitation Program, which utilize the scarcely available land for construction of Community Toilet Blocks with involvement of NGO’s and …