Engineering Commons^™

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 …

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 …

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 …

Using Long-Term Outdoor Exposure Data To Benchmark Accelerated Durability Test Methods, R. Hooton

International Conference on Durability of Concrete Structures

Many performance-based durability test methods adopted in various national and international standards were developed decades ago based on short-term evaluations. Most durability tests use various methods to accelerate reactions in order to obtain results in a reasonably short period of time. Then pass/fail criteria are set for these tests in standard specifications. However, the acceleration techniques used maybe overly severe, and preclude the use of concrete materials and mix designs that perform perfectly well in the field. The inclusion of long-term field tests or outdoor exposure tests can be used to verify the appropriateness of both the test methods and …

Sustainable Concrete With Seawater And Corrosion Resistant Reinforcement: Results Of Monitoring Of Corrosion Behaviour, Elena Redaelli, Maddalena Carsana, Federica Lollini, Matteo Gastaldi, Forood Torabian Isfahani

International Conference on Durability of Concrete Structures

The use of seawater for mixing concrete for reinforced concrete structures is prohibited, since it can promote steel corrosion. However, the use of seawater would contribute to decrease the environmental impact of concrete, in particular in those regions of the world where potable water is a precious resource. The project SEACON-INFRAVATION between University of Miami and Politecnico di Milano, with various industrial partners, aims at investigating the use of seawater for the construction of sustainable and durable reinforced concrete structures and infrastructures. Within the project, that included a vast campaign of laboratory tests, also two demo projects – one in …

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 …

Performance Of Concrete Made With A Calcined Clay – Limestone-Portland Cement Exposed To Natural Conditions, Fernando Martirena, Ernesto Díaz, Dayran Rocha, Hamed Maraghechi, Karen Louise Scrivener

International Conference on Durability of Concrete Structures

This work presents the results of an investigation carried out to assess durability of concrete made with a calcined clay- limestone-Portland cement with 47% of clinker, hereafter named LC3, produced during an industrial trial in 2013. LC3 was used to cast concrete blocks and later expose them at a natural location at the northern coast of Cuba. Reference concrete was cast with Cuban Portland cement having 88% of clinker. Throughout three years (2015, 2016, 2017) concrete cores were systematically taken and the specimens were subjected to a testing program that included Formation factor, chloride profiling, surface resistivity, air permeability and …

Polymer Binder, Impact On The Pull-Out Force Of Macro Fibers In Sprayed Concrete, Klaus Bonin, Christina Neumaier

International Conference on Durability of Concrete Structures

Macro-fibers have been used in sprayed concrete for many years now, particularly to prevent cracks from developing in the concrete due to deformation energy. These fibers can be made of steel or plastics and are provided for the Application. The type of fiber to be used is selected based on the building project’s requirements. Usually, the fibers are added to the sprayed concrete in the standard application’s mixture, regardless of whether the concrete is wet or dry (fiber-reinforced concrete or FRC). FRC’s functional principle is to mechanically anchor the steel or polymer fibers in the dense matrix of the binder …

The Synergistic Effect Of Nano-Silica With Slag On Frost Resistance Of Concrete, Yuan Lianwang, Zhou Zonghui, P Du, X Cheng, P Hou, L Zhang, Q Li

International Conference on Durability of Concrete Structures

The frost resistance of concrete is one of the most important factors for its durability. Supplementary cementitious materials could effectively improve the frost resistance of concrete. On this basis, the synergistic effect of nano-silica (NS) with slag on the frost resistance of concrete is better than the single, which was investigated. Nano-silica and slag were employed as a partial substitute of cement. The effect of these on the related indexes, including the mass loss, relative dynamic elastic modulus and porosity of concrete were measured after specified number of freeze and thaw cycles. Results show that the frost resistance of nano-silica …

Using Of Proper Pavement Material For The Intersections With Slow-Moving Traffic, Bekim Selimi

UBT International Conference

Use of proper pavement material for some of intersections need special attention by road designers. At Camp Bondsteel-Kosovo on 2002 were built four road intersections using the concrete as pavement material. Heavy and slow-moving trucks that are turning or accelerating exposed these intersections to some of the highest stress level. After some years this intresections start deteriorating on their surface due to friction. The concrete pavements did not survive this period of usage and after eight years were removed and replaced with asphalt pavements. After more than seven years, the asphalt has shown minor distress but is still in good …

Reducing The Porosity And Sealing Cracks By Using Crystalline Admixture In Conventional Concrete, Visar Krelani, Liberato Ferrara

UBT International Conference

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the wellfunctioning of the entire structure. The use of a crystalline admixture during the …

Prediction Of Punching Shear Capacity Of Two-Ways Frp Reinforced Concrete Slabs, Ilker Fatih Kara, Besian Sinani

UBT International Conference

An innovative solution to the corrosion problem is the use of fiber-reinforced polymer (FRP) as an alternative reinforcing material in concrete structures. In addition to the non corrodible nature of FRP materials, they also have a high strength-to-weight ratio that makes them attractive as reinforcement for concrete structures. Extensive research programs have been carried out to investigate the flexural behavior of concrete members reinforced with FRP reinforcement. On the other hand, the shear behavior of concrete members, especially punching shear of two-way slabs, reinforced with FRP bars has not yet been fully explored. The existing provisions for punching of slabs …

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 …

Aggregate Shape Effect On Multicomponent Ionic Electromigration In Concrete, Qing-Feng Liu, Long-Yuan Li, Jian Yang

International Conference on Durability of Concrete Structures

This paper presents a numerical study on the mechanism of chloride migration in concrete. Unlike most of existing work, this study utilises multicomponent ionic transport models to reflect the influence of ionic interactions by coupling both mass conservation and Poisson’s equations. A series of 2-D, 3-phase models with different shapes and volume fractions of aggregates are developed to simulate the chloride migration test. Through a comparatively overall numerical exploration that considers external voltage, ionic interactions, heterogeneous nature, ITZ, and ionic binding, some important features about multispecies coupling and aggregate shape effect, which have not been properly reported from existing concrete …

Reducing The Porosity And Sealing Cracks By Using Crystalline Admixture In Conventional Concrete, Visar Krelani, Liberato Ferrara

UBT International Conference

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the well-functioning of the entire structure. The use of a crystalline admixture during the …

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

International Conference on Durability of Concrete Structures

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

Application Of Neural Network For Concrete Carbonation Depth Prediction, Daming Luo, Ditao Niu, Zhenping Dong

International Conference on Durability of Concrete Structures

Concrete carbonation is one of the most significant causes of deterioration of reinforced concrete structures in atmospheric environment. However, current models based on the laboratory tests cannot predict carbonation depth accurately. In this paper, the BP neural network is optimized by the particle swarm optimization (PSO) algorithm to establish the model of the length of the partial carbonation zone for concrete. After simulation training, the improved model is applied to a concrete bridge for carbonation depth prediction. The results show that the improved model, which has faster a convergence rate, has a good ability in predicting the length of the …

Compression Testing And Failure Modes Of Steel-Concrete Composite (Sc) Structures For Nuclear Containment, Patrick Michael Wanamaker, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Although being able to provide much cleaner power than burning coal and other fossil fuels, nuclear power plants are still a tough sell to the general public due to their history of being spontaneously dangerous. The containment structures surrounding these nuclear plants, however, can play a huge role in reducing the risks associated with them. Relatively new designs for these containment assemblies, known as SC (steel-concrete composite) structures, aim to increase the strength and durability of the containment facilities while keeping costs down. By varying the spacing between shear studs, the ratio of concrete to steel, and the ratio of …