Development of a Wireless MEMS Multifunction Sensor System and Field Demonstration of Embedded Sensors for Monitoring Concrete Pavements, TR-637, 2016

Pavements tend to deteriorate with time under repeated traffic and/or environmental loading. By detecting pavement distresses and damage early enough, it is possible for transportation agencies to develop more effective pavement maintenance and rehabilitation programs and thereby achieve significant cost and time savings. The structural health monitoring (SHM) concept can be considered as a systematic method for assessing the structural state of pavement infrastructure systems and documenting their condition. Over the past several years, this process has traditionally been accomplished through the use of wired sensors embedded in bridge and highway pavement. However, the use of wired sensors has limitations for long-term SHM and presents other associated cost and safety concerns. Recently, micro-electromechanical sensors and systems (MEMS) and nano-electromechanical systems (NEMS) have emerged as advanced/smart-sensing technologies with potential for cost-effective and long-term SHM. This two-pronged study evaluated the performance of commercial off-the-shelf (COTS) MEMS sensors embedded in concrete pavement (Final Report Volume I) and developed a wireless MEMS multifunctional sensor system for health monitoring of concrete pavement (Final Report Volume II).

Preliminary design of a prestressed concrete viaduct

O presente Trabalho Final de Mestrado consiste na elaboração de um Estudo Prévio de um viaduto rodoviário, em betão armado pré-esforçado. O viaduto, com tabuleiro em laje vigada, é constituído por 10 tramos, prevendo-se que seja construído tramo a tramo, com juntas de betonagem a quintos de vão. A plataforma do viaduto é constituída por duas vias de tráfego com 3.5m cada, duas bermas de 1.00 m e dois passeios laterais com 1.10 m cada, perfazendo uma largura total de 11.20. O viaduto localiza-se em Polónia e foi dimensionado de acordo com os Eurocódigos e os Anexos Nacionais desse país.

BEHAVIOR OF FIBER REINFORCED POLYMER COMPOSITE PILES WITH ELLIPTICAL CROSS SECTIONS IN INTEGRAL ABUTMENT BRIDGE FOUNDATIONS

Every year in the US and other cold-climate countries considerable amount of money is spent to restore structural damages in conventional bridges resulting from (or “caused by”) salt corrosion in bridge expansion joints. Frequent usage of deicing salt in conventional bridges with expansion joints results in corrosion and other damages to the expansion joints, steel girders, stiffeners, concrete rebar, and any structural steel members in the abutments. The best way to prevent these damages is to eliminate the expansion joints at the abutment and elsewhere and make the entire bridge abutment and deck a continuous monolithic structural system. This type of bridge is called Integral Abutment Bridge which is now widely used in the US and other cold-climate countries. In order to provide lateral flexibility, the entire abutment is constructed on piles. Piles used in integral abutments should have enough capacity in the perpendicular direction to support the vertical forces. In addition, piles should be able to withstand corrosive environments near the surface of the ground and maintain their performance during the lifespan of the bridge. Fiber Reinforced Polymer (FRP) piles are a new type of pile that can not only accommodate large displacements, but can also resist corrosion significantly better than traditional steel or concrete piles. The use of FRP piles extends the life of the pile which in turn extends the life of the bridge. This dissertation studies FRP piles with elliptical shapes. The elliptical shapes can simultaneously provide flexibility and stiffness in two perpendicular axes. The elliptical shapes can be made using the filament winding method which is a less expensive method of manufacturing compared to the pultrusion or other manufacturing methods. In this dissertation a new way is introduced to construct the desired elliptical shapes with the filament winding method. Pile specifications such as dimensions, number of layers, fiber orientation angles, material, and soil stiffness are defined as parameters and the effects of each parameter on the pile stresses and pile failure have been studied. The ANSYS software has been used to model the composite materials. More than 14,000 nonlinear finite element pile models have been created, each slightly different from the others. The outputs of analyses have been used to draw curves. Optimum values of the parameters have been defined using generated curves. The best approaches to find optimum shape, angle of fibers and types of composite material have been discussed.

Spectral graph theory with applications to quantum adiabatic optimization

In this dissertation I draw a connection between quantum adiabatic optimization, spectral graph theory, heat-diffusion, and sub-stochastic processes through the operators that govern these processes and their associated spectra. In particular, we study Hamiltonians which have recently become known as ``stoquastic'' or, equivalently, the generators of sub-stochastic processes. The operators corresponding to these Hamiltonians are of interest in all of the settings mentioned above. I predominantly explore the connection between the spectral gap of an operator, or the difference between the two lowest energies of that operator, and certain equilibrium behavior. In the context of adiabatic optimization, this corresponds to the likelihood of solving the optimization problem of interest. I will provide an instance of an optimization problem that is easy to solve classically, but leaves open the possibility to being difficult adiabatically. Aside from this concrete example, the work in this dissertation is predominantly mathematical and we focus on bounding the spectral gap. Our primary tool for doing this is spectral graph theory, which provides the most natural approach to this task by simply considering Dirichlet eigenvalues of subgraphs of host graphs. I will derive tight bounds for the gap of one-dimensional, hypercube, and general convex subgraphs. The techniques used will also adapt methods recently used by Andrews and Clutterbuck to prove the long-standing ``Fundamental Gap Conjecture''.

Air-coupled ultrasonic tomographic imaging of concrete elements

Ultrasonic tomography is a powerful tool for identifying defects within an object or structure. This method can be applied on structures where x-ray tomography is impractical due to size, low contrast, or safety concerns. By taking many ultrasonic pulse velocity (UPV) readings through the object, an image of the internal velocity variations can be constructed. Air-coupled UPV can allow for more automated and rapid collection of data for tomography of concrete. This research aims to integrate recent developments in air-coupled ultrasonic measurements with advanced tomography technology and apply them to concrete structures. First, non-contact and semi-contact sensor systems are developed for making rapid and accurate UPV measurements through PVC and concrete test samples. A customized tomographic reconstruction program is developed to provide full control over the imaging process including full and reduced spectrum tomographs with percent error and ray density calculations. Finite element models are also used to determine optimal measurement configurations and analysis procedures for efficient data collection and processing. Non-contact UPV is then implemented to image various inclusions within 6 inch (152 mm) PVC and concrete cylinders. Although there is some difficulty in identifying high velocity inclusions, reconstruction error values were in the range of 1.1-1.7% for PVC and 3.6% for concrete. Based upon the success of those tests, further data are collected using non-contact, semi-contact, and full contact measurements to image 12 inch (305 mm) square concrete cross-sections with 1 inch (25 mm) reinforcing bars and 2 inch (51 mm) square embedded damage regions. Due to higher noise levels in collected signals, tomographs of these larger specimens show reconstruction error values in the range of 10-18%. Finally, issues related to the application of these techniques to full-scale concrete structures are discussed.

PARTNERSHIP, SOCIOCULTURAL INFORMATION AND STIMULATION IN SMALL BRAZILIAN MUNICIPALITIES: CONCRETE EXAMPLES

The text came from the UNESP-Project in Partnership with the Public Administration: City of Echaporã ‖, a multidisciplinary project, interdepartmental and that results from a term partnership signed between the State University / Campus Marilia, the Regional Office of Articulation Planning and the Municipality of Echaporã.Given the serious social problems diagnosed in this county Administrative Region of Marilia, somaramse forces and, since April 2002, Echaporã account with the performance of a design matrix that involves the community in six (6) subprojects, among which a which emphasizes the dissemination of information (the public library as a center of information and knowledge irradiator for urban and rural areas, seeking to enter the Society daInformação). By their nature, the project-matrix is considered open and can accommodate new subprojects, where they concern the problems identified in the initial diagnosis. For its validity, each subproject has its own methodology, some innovative and will be subject to further systematization and dissemination, however, after a few months of deployment, the results show the correctness of community involvement (being representative) in all discussions and steps of research, and activities developed, widely disseminated to the target audience. The membership of the community, the leaders and the authorities can be considered a good barometer of the actions carried out in Echaporã and evidence of change in information culture that is already noticeable in the city, setting the socio-cultural dynamics of the same, in terms a new public policy to be strengthened with the participation of specialists in this specific area, in direct work with local managers, in this case, specific examples relating to the strength of information in the process of change in small municipalities.

Accelerated and natural carbonation of concretes with internal curing and shrinkage/viscosity modifiers

Abstract In many parts of the world, corrosion of reinforcing steel in concrete induced by carbonation of the concrete continues to be a major durability concern. This paper investigates the accelerated and natural carbonation resistance of a set of seven concretes, specifically evaluating the effects of internal curing and/or shrinkage/viscosity modifiers on carbonation resistance. In addition to five different ordinary portland cement (OPC) concretes, two concretes containing 20 % of a Class F fly ash as replacement for cement on a mass basis are also evaluated. For all seven concrete mixtures, a good correlation between accelerated (lab) and natural (field) measured carbonation coefficients is observed. Conversely, there is less correlation observed between the specimens’ carbonation resistance and their respective 28 days compressive strengths, with the mixtures containing the shrinkage/viscosity modifier specifically exhibiting an anomalous behavior of higher carbonation resistance at lower strength levels. For both the accelerated and natural exposures, the lowest carbonation coefficients are obtained for two mixtures, one containing the shrinkage/viscosity modifier added in the mixing water and the other containing a solution of the same admixture used to pre-wet fine lightweight aggregate. Additionally, the fly ash mixtures exhibited a significantly higher carbonation coefficient in both exposures than their corresponding OPC concretes.

Influence of autogenous shrinkage on mass transport properties of concrete

La retracción autógena en el hormigón es el cambio volumétrico una vez iniciado su proceso de fraguado. Se desarrolla a edades muy tempranas debido a la retracción química y a la autodesecación. Éstos causan microfisuras en hormigones de alta resistencia y permiten el ingreso de agentes nocivos como dióxido de carbono, cloruros y sulfatos que deterioran al hormigón. A pesar de haber estudios de la retracción autógena, existe incertidumbre sobre su influencia en la durabilidad del hormigón. Por ello, el motivo del presente estudio es cuantificar y analizar el efecto de la retracción autógena en el hormigón usando tres pruebas de transporte: difusión de oxígeno, permeabilidad de oxígeno y absorción de agua. Dos métodos, para tres diferentes aglutinantes, fueron usados para determinar la mezcla control que produce menor retracción: utilizando SRA y realizando el curado en un cuarto de niebla. Posteriormente, los resultados de las pruebas de transporte entre la mezcla de control seleccionada y mezclas altamente afectadas por retracción autógena fueron comparados para diferentes aglutinantes. Resultados revelaron que muestras con SRA presentan menores retracciones autógenas y se sugiere que estas muestras sean consideradas de control. Se demostró que la retracción autógena afecta significativamente los coeficientes de transporte los cuales en un punto de vista de servicio pueden reducir la vida útil de cualquier estructura realizada con hormigón de alta resistencia. Esta investigación además confirmó que la mayor deformación autógena ocurre durante las dos primeras semanas; por lo tanto, se debe tomar cuidado suficiente en el curado.

The Performance and Service Life Prediction of High Performance Concrete in Sulfate and Acidic Environments

Concrete substructures are often subjected to environmental deterioration, such as sulfate and acid attack, which leads to severe damage and causes structure degradation or even failure. In order to improve the durability of concrete, the High Performance Concrete (HPC) has become widely used by partially replacing cement with pozzolanic materials. However, HPC degradation mechanisms in sulfate and acidic environments are not completely understood. It is therefore important to evaluate the performance of the HPC in such conditions and predict concrete service life by establishing degradation models. This study began with a review of available environmental data in the State of Florida. A total of seven bridges have been inspected. Concrete cores were taken from these bridge piles and were subjected for microstructural analysis using Scanning Electron Microscope (SEM). Ettringite is found to be the products of sulfate attack in sulfate and acidic condition. In order to quantitatively analyze concrete deterioration level, an image processing program is designed using Matlab to obtain quantitative data. Crack percentage (Acrack/Asurface) is used to evaluate concrete deterioration. Thereafter, correlation analysis was performed to find the correlation between five related variables and concrete deterioration. Environmental sulfate concentration and bridge age were found to be positively correlated, while environmental pH level was found to be negatively correlated. Besides environmental conditions, concrete property factor was also included in the equation. It was derived from laboratory testing data. Experimental tests were carried out implementing accelerated expansion test under controlled environment. Specimens of eight different mix designs were prepared. The effect of pozzolanic replacement rate was taken into consideration in the empirical equation. And the empirical equation was validated with existing bridges. Results show that the proposed equations compared well with field test results with a maximum deviation of ± 20%. Two examples showing how to use the proposed equations are provided to guide the practical implementation. In conclusion, the proposed approach of relating microcracks to deterioration is a better method than existing diffusion and sorption models since sulfate attack cause cracking in concrete. Imaging technique provided in this study can also be used to quantitatively analyze concrete samples.

Portfolio of compositions with commentaries 2012-2015

This writing forms part of a portfolio of works which gathers together notations and recordings made between 2012 and 2015. The writing divides into four chapters. The first chapter undertakes an examination of abstraction. From the proposition obtained therein, that it is possible to extend within abstraction beyond a correspondence between its terms and concrete manifestations, I ask in what way abstraction may be considered to function therefrom. The second chapter performs an analysis of radical music notations from the nineteenth, twentieth, and twenty-first centuries. The central analysis identifies what is essentially an evolution of what I call ''figuration'' throughout three non-chronological phases of Christian Wolff's notations. The chapter closes by questioning what form of understanding might yet be pursued in respect of this work given (a) its nature, and (b) the nature of our inquiry. The third chapter reflects on some of the philosophical problematics raised in the preceding chapters, at the same time as it prepares for those that follow in the final chapter. The final chapter is a record of the development of my thought appertaining to my compositional work. It sets out two case studies (prepared piano and postcard notations) before proceeding to a selected set of commentaries. Finally, the notion of the functioning of written and acoustical ''marks'' developed in the preceding commentaries is generalised as I develop an aesthetics of scriptural experience.

Enhancing student learning with case-based teaching and audience response systems in an interdisciplinary Food Science course

A growing body of research in higher education suggests that teachers should move away from traditional lecturing towards more active and student-focus education approaches. Several classroom techniques are available to engage students and achieve more effective teaching and better learning experiences. The purpose of this paper is to share an example of how two of them – case-based teaching, and the use of response technologies – were implemented into a graduate-level food science course. The paper focuses in particular on teaching sensory science and sensometrics, including several concrete examples used during the course, and discussing in each case some of the observed outcomes. Overall, it was observed that the particular initiatives were effective in engaging student participation and promoting a more active way of learning. Case-base teaching provided students with the opportunity to apply their knowledge and their analytical skills to complex, real-life scenarios relevant to the subject matter. The use of audience response systems further facilitated class discussion, and was extremely well received by the students, providing a more enjoyable classroom experience.

Performance of concrete incorporating amorphous silica residue and biomass fly ash

L'industrie du ciment est l'une des principales sources d'émission de dioxyde de carbone. L'industrie mondiale du ciment contribue à environ 7% des émissions de gaz à effet de serre dans l'atmosphère. Afin d'aborder les effets environnementaux associés à la fabrication de ciment exploitant en permanence les ressources naturelles, il est nécessaire de développer des liants alternatifs pour fabriquer du béton durable. Ainsi, de nombreux sous-produits industriels ont été utilisés pour remplacer partiellement le ciment dans le béton afin de générer plus d'économie et de durabilité. La performance d'un additif de ciment est dans la cinétique d'hydratation et de la synergie entre les additions et de ciment Portland. Dans ce projet, deux sous-produits industriels sont étudiés comme des matériaux cimentaires alternatifs: le résidu de silice amorphe (RSA) et les cendres des boues de désencrage. Le RSA est un sous-produit de la production de magnésium provenant de l'Alliance Magnésium des villes d'Asbestos et Thedford Mines, et les cendres des boues de désencrage est un sous-produit de la combustion des boues de désencrage, l'écorce et les résidus de bois dans le système à lit fluidisé de l'usine de Brompton située près de Sherbrooke, Québec, Canada. Récemment, les cendres des boues de désencrage ont été utilisées comme des matériaux cimentaires alternatifs. L'utilisation de ces cendres comme matériau cimentaire dans la fabrication du béton conduit à réduire la qualité des bétons. Ces problèmes sont causés par des produits d'hydratation perturbateurs des cendres volantes de la biomasse quand ces cendres sont partiellement mélangées avec du ciment dans la fabrication du béton. Le processus de pré-mouillage de la cendre de boue de désencrage avant la fabrication du béton réduit les produits d'hydratation perturbateurs et par conséquent les propriétés mécaniques du béton sont améliorées. Les approches pour étudier la cendre de boue de désencrage dans ce projet sont : 1) caractérisation de cette cendre volante régulière et pré-humidifiée, 2) l'étude de la performance du mortier et du béton incorporant cette cendre volante régulière et pré-humidifiée. Le RSA est un nouveau sous-produit industriel. La haute teneur en silice amorphe en RSA est un excellent potentiel en tant que matériau cimentaire dans le béton. Dans ce projet, l'évaluation des RSA comme matériaux cimentaires alternatifs compose trois étapes. Tout d'abord, la caractérisation par la détermination des propriétés minéralogiques, physiques et chimiques des RSA, ensuite, l'optimisation du taux de remplacement du ciment par le RSA dans le mortier, et enfin l'évaluation du RSA en remplacement partiel du ciment dans différents types de béton dans le système binaire et ternaire. Cette étude a révélé que le béton de haute performance (BHP) incorporant le RSA a montré des propriétés mécaniques et la durabilité, similaire du contrôle. Le RSA a amélioré les propriétés des mécaniques et la durabilité du béton ordinaire (BO). Le béton autoplaçant (BAP) incorporant le RSA est stable, homogène et a montré de bonnes propriétés mécaniques et la durabilité. Le RSA avait une bonne synergie en combinaison de liant ternaire avec d'autres matériaux cimentaires supplémentaires. Cette étude a montré que le RSA peut être utilisé comme nouveaux matériaux cimentaires dans le béton.

Numerical modelling of braided fibres for reinforced concrete

Fire has been always a major concern for designers of steel and concrete structures. Designing fire-resistant structural elements is not an easy task due to several limitations such as the lack of fire-resistant construction materials. Concrete reinforcement cover and external insulation are the most commonly adopted systems to protect concrete and steel from overheating, while spalling of concrete is minimised by using HPFRC instead of standard concrete. Although these methodologies work very well for low rise concrete structures, this is not the case for high-rise and inaccessible buildings where fire loading is much longer. Fire can permanently damage structures that cost a lot of money. This is unsafe and can lead to loss of life. In this research, the author proposes a new type of main reinforcement for concrete structures which can provide better fire-resistance than steel or FRP re-bars. This consists of continuous braided fibre rope, generally made from fire-resistant materials such as carbon or glass fibre. These fibres have excellent tensile strengths, sometimes in excess of ten times greater than steel. In addition to fire-resistance, these ropes can produce lighter and corrosive resistant structures. Avoiding the use of expensive resin binders, fibres are easily bound together using braiding techniques, ensuring that tensile stress is evenly distributed throughout the reinforcement. In order to consider braided ropes as a form of reinforcement it is first necessary to establish the mechanical performance at room temperature and investigate the pull-out resistance for both unribbed and ribbed ropes. Ribbing of ropes was achieved by braiding the rope over a series of glass beads. Adhesion between the rope and concrete was drastically improved due to ribbing, and further improved by pre-stressing ropes and reducing the slacked fibres. Two types of material have been considered for the ropes: carbon and aramid. An implicit finite element approach is proposed to model braided fibres using Total Lagrangian formulation, based on the theory of small strains and large rotations. Modelling tows and strands as elastic transversely isotropic materials was a good assumption when stiff and brittle fibres such as carbon and glass fibres are considered. The rope-to-concrete and strand-to-strand bond interaction/adhesion was numerically simulated using newly proposed hierarchical higher order interface elements. Elastic and linear damage cohesive models were used effectively to simulate non-penetrative 'free' sliding interaction between strands, and the adhesion between ropes and concrete respectively. Numerical simulation showed similar de-bonding features when compared with experimental pull-out results of braided ribbed rope reinforced concrete.

Quick concrete

QUICK CONCRETE es un emprendimiento el cual se planteó como una empresa prestadora de servicios en el sector de la construcción en la ciudad de Ibagué, Colombia. Con ayuda de empresas ya reconocidas a nivel regional como lo son: la distribuidora de materiales y ferretería La Española, A&C y la ladrillera Ladrillos Roma. Se espera impactar en el mercado con un método diferente y un precio competitivo de servicio. El mayor impulso de la construcción puede estar asociado a una mayor demanda de vivienda por parte de ciudadanos bogotanos que ven en Ibagué una posibilidad rentable para invertir en vivienda, así como también el crecimiento del comercio que requiere la construcción de centros comerciales y el programa de viviendas de interés social del Gobierno que benefició a Ibague. Sin embargo, este es una actividad bastante cíclica y con una alta rotación de trabajadores.

Experimental and numerical investigation on short and long term performance of macro-synthetic fibre reinforced concrete materials

Fibre Reinforced Concretes are innovative composite materials whose applications are growing considerably nowadays. Being composite materials, their performance depends on the mechanical properties of both components, fibre and matrix and, above all, on the interface. The variables to account for the mechanical characterization of the material, could be proper of the material itself, i.e. fibre and concrete type, or external factors, i.e. environmental conditions. The first part of the research presented is focused on the experimental and numerical characterization of the interface properties and short term response of fibre reinforced concretes with macro-synthetic fibers. The experimental database produced represents the starting point for numerical models calibration and validation with two principal purposes: the calibration of a local constitutive law and calibration and validation of a model predictive of the whole material response. In the perspective of the design of sustainable admixtures, the optimization of the matrix of cement-based fibre reinforced composites is realized with partial substitution of the cement amount. In the second part of the research, the effect of time dependent phenomena on MSFRCs response is studied. An extended experimental campaign of creep tests is performed analysing the effect of time and temperature variations in different loading conditions. On the results achieved, a numerical model able to account for the viscoelastic nature of both concrete and reinforcement, together with the environmental conditions, is calibrated with the LDPM theory. Different type of regression models are also elaborated correlating the mechanical properties investigated, bond strength and residual flexural behaviour, regarding the short term analysis and creep coefficient on time, for the time dependent behaviour, with the variable investigated. The experimental studies carried out emphasize the several aspects influencing the material mechanical performance allowing also the identification of those properties that the numerical approach should consider in order to be reliable.