Dissertations / Theses on the topic 'In concreto review'

Expression des plus polysémiques, le contrôle de proportionnalité a trouvé un sens de plus pour désigner la nouvelle modalité du contrôle de conventionnalité dont se sont saisis les juges français depuis une dizaine d’années, dans un mouvement enclenché par un arrêt de la 1re Chambre civile de la Cour de cassation du 4 décembre 2013. Le temps passé et la réflexion rendent possible, au moyen d’une meilleure compréhension de l’outil, de tirer un bilan et d’entrevoir des perspectives sur ce contrôle concret du respect de la hiérarchie des normes. Il apparaît à même de remplir de nombreuses fonctions. Promouvant l’effectivité des droits fondamentaux, il aide à la conciliation entre la régulation des comportements par la loi et les droits des individus, réalisant une individualisation sans individualisme. Permettant au juge national de se saisir de la marge nationale d’appréciation, il participe à la réalisation de l’harmonie entre le droit national et l’influence de la Cour européenne des droits de l’Homme. Soumettant la loi à un contrôle poussé et factuel, il en renforce la vigueur en lui redonnant sa majesté, puisqu’elle n’est plus tenue de prévoir explicitement des cas exceptionnels. Ces fonctions peuvent se développer sur un large terrain, car le contrôle concret du respect de la hiérarchie des normes ne peut pas, de manière convaincante, être limité à certains droits fondamentaux ou à certaines sources. En revanche, la nature même de l’outil fait qu’il n’a d’utilité que lorsque le texte appliqué dans la situation contrôlée présente un fort degré d’impérativité, n’étant à même de modifier l’issue du procès que lorsque le juge est présent pour appliquer un texte qui le guide précisément. Quoique le domaine du contrôle soit large, la menace qu’il ferait peser sur la stabilité du droit est limitée. En effet, son caractère concret, faisant qu’il ne permet d’analyser que des situations uniques, vient limiter drastiquement l’aptitude de ce contrôle, prioritairement réalisé par le juge du fond, à faire jurisprudence. De plus, là où il est craint que le contrôle entraîne une insupportable imprédictibilité du processus judiciaire en donnant au juge le pouvoir de statuer en équité, il apparaît que le contrôle dévoile plus qu’il ne cause ces maux. En les dévoilant, il permet au contraire d’en prendre la mesure et de les limiter. La compréhension de la nature et des implications du contrôle concret du respect de la hiérarchie des normes permet de voir qu’il n’est pas hors de contrôle, mais rend possible de parvenir à des décisions équitables sans que le juge ne statue en équité, par l’application des normes de valeur supérieure au cas d’espèce lorsque la loi faillit. Ces éléments conduisent, dans une perspective de promotion de l’effectivité des droits fondamentaux, à défendre le contrôle de proportionnalité sans crainte quant aux autres objectifs de la Justice
Proportionality test, a highly polysemous expression, has taken on a new meaning to designate the new form of conventionality review that French judges have been using for the past ten years, in a movement set in motion by a decision of the 1st Civil Chamber of the Court of Cassation on 4th December 2013. The time that has elapsed and the thought that has gone into it make it possible, by means of a better understanding of the tool, to take stock and glimpse the prospects for this concrete control of compliance with the hierarchy of norms.It seems capable of fulfilling many functions. By promoting the effectiveness of fundamental rights, it helps to reconcile the regulation of behaviour by law with individual rights. By allowing national courts to make use of the national margin of appreciation, it promotes harmony between national law and the influence of the European Court of Human Rights. By subjecting the law to detailed and factual scrutiny, it strengthens its force by restoring its majesty, since it is no longer required to make explicit provision for exceptional cases.These functions can be developed over a wide area since the concrete control of compliance with the hierarchy of norms cannot convincingly be limited to certain fundamental rights or certain sources. On the other hand, the very nature of the tool means that it is useful only when the text applied in the situation under review has a high degree of imperative force, being capable of modifying the outcome of the case only when the judge is present to apply a text that guides him precisely.Although the scope of the control is broad, the threat it poses to the stability of the law is limited. Indeed, its concrete nature, which means that it can only analyse unique situations, drastically limits the ability of this review, which is primarily carried out by the trial judge, to set precedents. Moreover, where it is feared that control will lead to an unbearable unpredictability of the judicial process by giving the judge the power to rule in equity, it appears that it reveals rather than causes these ills. On the contrary, by revealing them, it makes it possible to measure and limit them. An understanding of the nature and implications of the concrete control of compliance with the hierarchy of norms shows that it is not beyond control, but makes it possible to reach equitable decisions without the judge ruling in equity, by applying norms of higher value to the case in question when the law fails.From the point of view of promoting the effectiveness of fundamental rights, these factors make it possible to defend proportionality review without fear as regards the other objectives of Justice

This dissertation focuses on an in-depth review of literature on concrete crack repairs. Deterioration of concrete affects both the aesthetics and the integrity of structures. As a result, there is need to repair such defects in order to restore the aesthetics and the integrity of concrete structures. This research discusses concrete crack repairs taking into consideration the mechanisms resulting in concrete cracking, techniques to determine concrete cracking, practices for prevention of concrete cracking and concrete crack repair techniques. Causes of cracking include alkali silica reactions (ASR), steel reinforcement corrosion, shrinkage, thermal variations, foundation movements, soil settlement, vegetation effects and cracking related to earthquale effects. Non-destructive and destructive techniques to determine conrete cracking shall be discussed. Destructive techniques usually involve core drilling of samples whilst non-destructive techniques include visual inspections, ultrasonic pulse velocity test, acoustic emission, spectral analysis of surface waves, modal analysis, petrographic analysis and infrared thermography. Several concrete crack repair techniques are to be discussed such as epoxy injection, routing and sealing, near surface reinforcement, additional reinforcement, gravity filling, grouting, dry packing, crack arrest, polymer impregnation, overlay and surface treatments, crack filling, crack sealing, blanketing, stitching and external stressing. These techniques are applied differently depending on the nature and cause of the concrete cracks. Further discussions will be on various case studies around the world on concrete crack repair which demonstrate the application of various concrete crack repair techniques to different types of concrete cracking scenarios. The case studies also highlight recent developments in technology, repair materials, application fields for various techniques and limitations to concrete crack repair. Some of the case studies discussed include concrete crack repair due to ASR damage on transport infrastructure in USA, ASR effects and crack repairs on a two storey building in California (USA), ASR effects and crack repairs to concrete structures in Hokuriku District in Japan, ASR effects and crack repairs to a gravity dam in India, crack repairs at Buttermarket Shopping Center due to shrinkage cracking and concrete crack repairs in Cheshire due to thermal effects.

Yes
Cracks in concrete composites, whether autogenous or loading-initiated, are almost inevitable and often difficult to detect and repair, posing a threat to safety and durability of concrete infrastructures, especially for those with strict sealing requirements. The sustainable development of infrastructures calls for the birth of self-healing concrete composites, which has the built-in ability to autonomously repair narrow cracks. This paper reviews the fabrication, characterization, mechanisms and performances of autogenous and autonomous healing concretes. Autogenous healing materials such as mineral admixtures, fibers, nanofillers and curing agents, as well as autonomous healing methods such as electrodeposition, shape memory alloys, capsules, vascular and microbial technologies, have been proven to be effective to partially or even fully repair small cracks. As a result, the mechanical properties and durability of concrete infrastructure can be restored to some extent. However, autonomous healing techniques have shown a better performance in healing cracks than most of autogenous healing methods that are limited to healing of cracks having a narrower width than 150 µm. Self-healing concrete with biomimetic features, such as self-healing concrete based on shape memory alloys, capsules, vascular networks or bacteria, is a frontier subject in the field of material science. Self-healing technology provides concrete infrastructures with the ability to adapt and respond to the environment, exhibiting a great potential to facilitate the creation of a wide variety of smart materials and intelligent structures.
The full-text of this article will be released for public view at the end of the publisher embargo on 16 May 2021.

Concrete has an excellent intrinsic behaviour when exposed to fire, especially when compared to other building materials. However, its fire resistance should not be taken for granted and a proper structural fire design is certainly necessary. This design is based on the understanding of both the material and the structural behaviour of concrete exposed to fire. A number of complex physicochemical reactions occur when concrete is heated, causing mechanical properties as strength and stiffness to deteriorate. Furthermore, the phenomenon of spalling causes pieces of concrete to break off from the surface, reducing the cross-section of an element and possibly exposing the reinforcing to the high temperatures. Spalling can be highly dangerous and is most common in high strength concrete. However, its mechanism is still not fully understood. The Eurocode provides a number of procedures in order to design concrete structures for the fire situation, both prescriptive as performance based. However, of the latter, only the basic principles are given and several gaps still need to be filled through research. Thus in practical design, either tabulated data or a simplified calculation method is used. In many cases, these design methods fail to predict the true behaviour of concrete structures in real fires. Firstly, the standard heating curve is not able to represent the wide variety of realistic fires. Furthermore, design should investigate the behaviour of the complete structure, including alternative failure modes, whereas member analysis ignores effects as incompatible thermal expansions which can cause high thermal stresses. Although a lot of research has been performed already, more in-depth study is needed. Several elements of the behaviour of heated concrete still need to be researched. A systematic study of the effects of realistic thermal exposures is needed and a lot more work is required in order to unravel the mystery of spalling. The study of the response of complete concrete structures presents another challenge, requiring large-scale fire tests. The goal is to develop a concrete model that reflects the true behaviour of concrete structures exposed to fire. This model should incorporate the fully coupled hygro-thermal-mechanical behaviour combined with a sophisticated structural analysis, including the effect of transient strain.

Includes bibliographical references.
The Durability Index (DI) approach is a performance-based approach used in South Africa for specifying the durability of reinforced concrete structures with regard to service life and concrete quality. The approach comprises three DI tests which are used to measure the durability-related transport processes of permeation, absorption and ionic diffusion. These tests are the oxygen permeability index (OPI), water sorptivity index (WSI), and chloride conductivity index (CCI) tests, respectively. Much work has been done over the past two decades in developing the DI tests to the present stage, where they are being, and have been, used in large projects such as the Gauteng Freeway Improvement Project, which made use of the OPI and WSI tests as a basis for checking the quality of the concrete used in the major road upgrade project. Non-compliance with target values can result in rejection of the material or penalties imposed on the concrete supplier or contractor. This highlights the need for the DI tests to be accurate and reliable so that engineers have confidence in their results. This dissertation presents a critical review of the DI tests. The overall objectives were to critically examine the present DI testing regimes and identify and address areas of concern with the tests in order to make them more reliable. One of the major areas of concern related to specimen preconditioning: the 7-day oven drying regime and specimen saturation techniques have been called into question. Consequently, this work investigated the influence of the drying method and saturation processes on the DI results.

The repair and maintenance of ageing reinforced concrete (RC) structures has become increasingly costly, especially in the Cape Peninsula. Protection and maintenance of these reinforced concrete structures against concrete deterioration and rebar corrosion have become far more important for road authorities and asset managers. City Engineers are responsible for the repair and rehabilitation of RC structures in different exposure conditions, by identifying the type of deterioration and then employing the correct concrete repair solutions or corrosion resistance measures. This dissertation investigates the environmental exposure conditions in the Cape Peninsula that result in chloride-induced and carbonation-induced corrosion of reinforced concrete structures in the region. It includes a literature review on concrete deterioration mechanisms and the role of aggressive elements in rebar corrosion. The literature review also considered alternative corrosion-resistant rebar. There are a number of available alternatives, which include Fiber Reinforced Polymer (FRP), Hot Dip Galvanized (HDG) steel, and Stainless Steel rebar. Each alternative has advantages and disadvantages depending on design applications and durability requirements. The use of corrosion-resistant rebar would increase the structure's longevity, thus providing long-term cost saving for road authorities. In the City of Cape Town, city engineers have standardised the use of HDG rebar for repair solutions and new concrete structures. HDG improves corrosion resistance, thus making it desirable to road authorities. The HDG process has been developed in the construction industry with low production time and cost, proving favourable factors for engineers. In addition, engineers have to improve concrete quality and construction methods to protect the underlying rebar from corrosion. On a technical level, HDG rebar use in RC structures has benefits which outweigh their cost implications. The exclusive use of HDG rebar without sound engineering judgment based on factors such as the location of the structure, distance from the coast, the structural loading conditions, and construction methods and quality standards, might not ensure better concrete durability and structural longevity. Generally, correct structural rebar design and concrete quality can eliminate the need for the use of corrosion protection methods and materials. The use of HDG is a very attractive solution for structures within 5km from the coast; otherwise, normal steel is suited for most applications. Reinforced concrete members such as concrete bollards, bridge handrails and balustrades can be treated as consumables and can be replaced once steel corrosion or concrete deterioration has occurred and becomes unsightly, which would be about 20 years. This approach would be economically advantageous and politically favourable to the road authority as it creates skills and jobs by reducing initial internal and contractual costs. To illustrate the common forms of rebar deterioration in the Cape Peninsula region, this dissertation has included five repair and rehabilitation projects completed by the City of Cape Town's Road Authority. These rehabilitation projects have been identified for concrete repair and rehabilitation works, and some of these structures have recently undergone extensive concrete rehabilitation. City engineers are faced with many challenges that hinder service delivery, engineering processes and effectiveness. Among these are lack of staff with experience in concrete repair and asset management, and the lack of proactive maintenance tools. The lack of an adequate Bridge Management System (BMS) contributes to the inefficient allocation of resources for rehabilitation and repair projects. The Supply Chain Management System also delays the appointment of appropriate contractors due to unwieldy management systems and bureaucracy. These systemic problems are discussed to provide a better understanding of the current selection of concrete repair systems.

An experimental investigation on model slabs and on a 1/3 scale composite bridge deck showed that the ultimate punching shear load depends on the shape of the loaded area, the compressive strength of concrete, the flexural reinforcement ratio and on the arrangement of steel bars. Punching failure follows the formation of an inclined failure surface from the edge of the loaded area to the opposite slab face running through the effective depth at a mean angle of 22 to 30 degrees. A study of the application of the yield line theory proves that flexure theory alone is not recommended to treat local failure because of the violent and nonductile nature of punching shear failure. An explanation of the application of the strut and tie model to symmetric punching shear is given to provide a base for future experimental programs and the development of this approach. The mechanism of symmetric punching of slabs without shear reinforcement is described based on observations from tests. An empirical equation to determine the ultimate punching load of flat slabs is proposed. It is concluded that the proposed equation can predict the ultimate punching shear loads of flat slabs with confidence similar to Kinnunen and Nylander's model. Present North American codes should be updated to express the state of present day knowledge, particularly with the inclusion of the influence of the flexural reinforcement. (Abstract shortened by UMI.)

A two-stage procedure has been proposed for the elastic analysis phase of seismic design and safety evaluation of concrete gravity dams: (1) response spectrum analysis (RSA) in which the peak value of response is estimated directly from the earthquake design spectrum; and (2) response history analysis (RHA) of a finite element idealization of the dam monolith. Both analysis procedures include the effects of dam-water foundation interaction, known to be important in the earthquake response of dams.Presented in this thesis are two important developments that have now been added to the computer program EAGD-84, implementing the RHA procedure: (1) a set of Matlab modules ? including an easy-to-use graphical user interface (GUI) ? has been developed, providing users with the capability of pre-processing input and post-processing analysis output from EAGD-84 in the Matlab scripting language; (2) a more complete set of compliance data that govern the interaction between the dam and the foundation region has been incorporated in the program. These developments greatly improve the accessibility and functionality of the EAGD-84 program, and provide users with sufficient control over the overall damping in the dam-water-foundation system to ensure consistency with recent research. The above mentioned RSA procedure has likewise been modernized. A number of enhancements have been made to the procedure, the most significant being: (1) a more complete set of data for the parameters that characterize dam-foundation interaction has been computed and implemented; and (2) to enhance the accuracy of the procedure, a correction factor for computing beam stresses on the downstream face of the dam has been developed. In addition, a comprehensive evaluation of the accuracy of the RSA procedure has been conducted, demonstrating that it estimates stresses close enough to the "exact" results (determined by RHA) to be satisfactory for the preliminary phase in the design of new dams and in the safety evaluation of existing dams. The accuracy achieved by the procedure is noteworthy, especially considering the complicated effects of dam-water-foundation interaction and reservoir bottom absorption on the dynamics of the system, and the number of approximations necessary to develop the procedure. The updated version of the computer program EAGD-84, the new Matlab modules and the GUI, as well as a new report presenting the updated RSA procedure, have all been made publicly available through the Pacific Earthquake Engineering Research (PEER) Center.

This report describes the thermal properties, strength, and elastic modulus of lightweight, normal, and high strength concrete at elevated temperatures. Section 6 (Design for Fire Resistance) of the New Zealand standard for concrete structure (NZS3101, 1995) provides recommended values and minimum requirements for concrete at elevated temperatures. These values will be reviewed with respect to overseas standards and experimental data to find their applicability to lightweight and high strength concretes. A series of tests were performed on 1m x 1m lightweight and high strength concrete specimens to determine their insulation fire resistance. The specimens were produced in three thicknesses; 60, 130, and 175mm. This follows the method of earlier tests by Wade et al. (1991) and Wade (1992) on New Zealand aggregate concretes. It was determined that the strength reduction curve given by NZS3101 over-predicts the strength of high strength concrete at elevated temperatures, though the values for elastic modulus and insulation fire resistance can be applied to high strength concrete. The insulation fire resistance, strength, and elastic modulus values given by NZS3101 were found to also apply to lightweight concrete. The report recommends a change to the elastic modulus curve given in NZS3101. The purpose of this is to give consistency between the strength and elastic modulus curves, which do not currently reach zero at the same temperature.

The shear failure mechanisms of flexural reinforced concrete (RC) members is highly complex; its precise details cannot be explained with simple analytical relationships, and are the topic of considerable scientific debate. The studies described and examined the three most used shear theories in the world – the fixed angle truss model (45°TM), the variable angle truss model (VAT), and modified compression field theory (MCFT). These three theories rest on the assumption that a beam loaded in shear behaves as a truss. However, this assumption is applied in different ways in various codes. In this thesis, three major standards, each of which uses a different implementation of these theories (CEN, 2005; ACI-318, 2008; CSA-A23.3, 2009), were used to predict the shear force capacity of a RC railway bridge that was strengthened in flexure with near surface mounted (NSM) carbon fibre reinforced polymers (CFRP) and then tested to failure. The data obtained in this test indicated that the codes underestimated the real shear behaviour of the bridge. There are some accepted reasons for such inaccuracies, namely the use of empirically derived equations in the ACI (2008) and CSA (2009) standards and the omission of the concrete contribution in CEN (2005). Moreover, the NSM reinforcement material used exhibits elastic behaviour until the point of failure; it was found that the use of such materials introduces further decreases the accuracy of the models’ predictions. The strains that developed in the area of the bridge where shear failure was expected were monitored throughout the test using a specially-developed photographic method. The results obtained with this method were promising, especially for research purposes, since it generated reliable data using relatively affordable tools.The use of FRP for shear strengthening introduces further complications to the problem of shear in reinforced concrete members because introduces two new failure modes: debonding at the concrete interface and fibre rupture of the FRP. Extensive research has been carried out on FRP shear strengthening around the world. Much of the data gathered in these studies has been compiled in a database. By analysing this large database, it was found that the effectiveness of FRP shear strengthening is influenced by many factors, including the properties of the FRPs, the FRP strengthening configuration used, the nature of the beam’s cross-section, the shear span to depth ratio, the presence of stirrups, and the nature of the tensile reinforcement. Analysis of this database also demonstrated that most of the studies reported in the literature had focused on investigating the influence of the properties of the FRPs and the different configuration systems, and that the other factors mentioned above have been sparsely investigated if not totally ignored. The strengthening configuration and the amount of fibres influence the failure mode of the FRP and the shear force that it can carry. It appears that the side-bonded and the U-wrapped configurations are most prone to failure by debonding. This is consistent with the findings of various small experimental programs, and was confirmed by analysis of the larger dataset. These findings are relevant because failure of the FRP by debonding is more complex mechanism than is the rupture of the fibres mechanism. As is shown in this thesis, the extent to which the FRP variables (properties and strengthening configuration) can affect the point at which failure occurs and the mode by which it happens is dependent on the quantity of stirrups and tensile reinforcement in the beam, to the position of the load in relation to the size of the cross section (shear span to depth ratio), the type of strengthening configuration, the concrete and FRP properties. For design purposes, it is important to predict the shear failure of FRP shear strengthened beams with as much accuracy as possible. Therefore, a design model for debonding of the shear strengthening of concrete beams with FRP was developed and the limitations of the truss model analogy were highlighted. The fracture mechanics approach was used to analyse the behaviour of the bond between the FRP composites and the concrete. In this model, of the parameters examined, the fracture energy of concrete and the axial rigidity of the FRP are considered to be the most important. The effective strain in the FRP when debonding occurs was determined and the limitations of the anchorage length over the cross section were analysed; ultimately, a simple iterative method for shear debonding was proposed. Since the model’s predictions were considered satisfactory but not really precise, an extensive review of the literature was conducted. All of the significant theoretical models for predicting the shear capacity of FRP strengthened RC beams that have been reported over the years were analysed and commented on, and their predictions were compared to the results recorded in a preliminary experimental database. The predictions of the models that are most widely used in design were compared to the experimental results reported in the database; the model developed by the author was evaluated alongside these more established models. All of the models, including that presented in this thesis, were found to generate inaccurate predictions, but two models have been calibrated so as to provide safe estimates of the FRP shear capacity. Finally a new model for FRP shear strengthening was proposed for use in engineering. The new model was developed on the basis of an analysis of the contents of the database of experimental findings. The model incorporates several design equations adopted from various models and is set up for engineering use. The predictions of the shear force carried by the FRP strengthening material are found to be conservative.
Godkänd; 2011; 20110328 (gabsas); DISPUTATION Ämnesområde: Konstruktionsteknik/Structural Engineering Opponent: Professor Giorgio Monti, University of Rome, Italy Ordförande: Professor Björn Täljsten, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 29 april 2011, kl 13.00 Plats: F1031, Luleå tekniska universitet

INTRODUCTION The main objective of this dissertation is to compile a comprehensive literature review of surface protection systems, including their historical development, specification and use, and to conduct an industry review from the South African market. With a vast amount of deteriorating reinforced concrete structures and fast developing technology of surface treatments, it is important that engineers have a good working understanding of concrete deterioration, repair and the use of surface protection systems. Additionally, engineers need to have a good understanding of the pore structure of concrete and its transport properties as this is important to understanding the applicability and use of surface treatments (Breysse and Gérard, 1997; Leeming et al., 1997; Ballim, Alexander and Beushausen, 2009). TRANSPORT PROPERTIES The movement of ions or fluids in concrete occurs due to four basic mechanism; diffusion, permeation, absorption and migration, as briefly outlined below. The kinetics of movement is broadly governed by the size and nature of the concrete pore structure and its exposure environment (Ballim, Alexander and Beushausen, 2009; Basheer and Barbhuiya, 2010). Process Description Diffusion: Movement of ions, gas or liquid under a concentration gradient Permeation: Movement of a fluid through a concrete matrix under an externally applied pressure gradient when saturated with that fluid Absorption: Where a fluid is drawn into the pores of concrete through capillary suction Migration: Movement of ions due to an electrical potential gradient Combined transport mechanisms and long-term changes in transport behaviour may need to be considered, Additionally, the size, nature and degree of cracking is an especially important consideration (Ballim, Alexander and Beushausen, 2009). DETERIORATION OF CONCRETE Rebar corrosion is the biggest threat to the durability of reinforced concrete structures, and is influenced mainly by the quality of the concrete, its cover depth to the reinforcement and the environmental exposure conditions. The primary causes of rebar corrosion are carbonation and chloride ingress. Chemical and acid attack may be of concern in certain environments. When using reactive aggregates, alkali-aggregate reaction may also be of concern to unreinforced and reinforced concrete. Surface protection systems can assist in reducing the effects due to the influence of the above penetration processes. Additionally,in harsh environmental conditions, such as in marine areas, additional protection measures are oftenrequired to ensure that concrete (existing or new) will not prematurely deteriorate during its service life (Beckett et al., 1987; Technical Committee 60-CSC RILEM, 1988; ACI Committee 201, 2008; Larsen, 2008; Ballim, Alexander and Beushausen, 2009; Gjørv, 2011). Typically, the following repair techniques may be considered in the repair and service life extension of concrete structures (Mackechnie and Alexander, 2001): • Crack Repairs • Patch Repairs • Surface Coatings • Migrating Corrosion Inhibitors (MCI’s) • Electrochemical Techniques • Cathodic Protection • Demolition and Reconstruction REPAIR STANDARDS To ensure that a concrete repair project is successful, a systematic approach to the inspection and repair strategy development needs to be followed (Building Research Establishment, 2000b). The European standard EN 1504 and the Concrete Repair Manual from the American Concrete Institute provides such an approach. South Africa does not have such a standard, but is in the process of adopting the European standards for concrete (South African Bureau of Standards, 2017), EN 206 and EN 1992 - it would thus be highly beneficial for South Africa to move towards the adoption of the EN 1504 code as well. EN 1504-9 is a very important part of the code, as it provides a structured approach to the investigation of the cause of deterioration and outlines the “Principles of protection and repair.” EN 1504-2 covers the use of surface treatment systems, and its provisions are intended to be used as “Methods” in order to cover the “Principles” outlined in EN 1504-9 (Atkins et al., 2009; Raupach and Büttner, 2014). SURFACE PROTECTION SYSTEMS Modern technological advances have given rise to numerous surface treatment systems available on the market with various sub-categories that can assist in achieving the durability requirements of a concrete structure, from silanes, siloxanes, many types of polyurethanes and modified cementitious coatings as well as hybrid systems. Each product and system has its use, advantages and disadvantages and the selection of a system and decision on whether to apply a surface treatment or not can be a complicated matter. This decision is often left to the discretion of the engineer, and therefore engineers need to have a good working understanding of surface treatment systems (Leeming et al., 1997; Beushausen and Alexander, 2011; ACI Committee 546, 2014a). Surface protection systems can be classified according to the way in which the protective action is provided. This is the classification system used by EN 1504 and is divided as follows: HYDROPHOBIC IMPREGNATION These are low viscosity fluids which penetrate several millimetres into the concrete and considerably increase the water penetration resistance of concrete, whilst still allowing the passage of water vapour and gases. Typical examples are silanes and siloxanes. They are also referred to as pore lining penetrants (Beckett et al., 1987; Leeming et al., 1997; Bijen, 2003; ACI Committee 546, 2014b). IMPREGNATION These are low viscosity solutions that penetrate 1 - 3 mm into the concrete and effectively block pores. They differ from Hydrophobic Impregnations in that they are more restrictive to the passage of water vapour and gases. Typical examples are silicates and silicoflourides as well as certain types of polyurethanes (Beckett et al., 1987; Leeming et al., 1997). COATINGS These are treatments that form a continuous protective layer on the surface of the concrete. They are typically 0.1 mm - 5 mm thick, but may be thicker than 5 mm for certain applications. Typical examples are polymer-modified cementitious systems and polyurethanes (Beckett et al., 1987; BS EN 1504-2, 2004). Surface treatment systems need to meet specified performance criteria. In terms of the concrete durability, these are typically (Beckett et al., 1987): • Ingress protection • Moisture control • Physical resistance / Surface improvement • Resistance to chemicals • Increasing resistivity • Cathodic control Treatment systems may also be required to bridge cracks, be applied to moist concrete or operate in harsh exposure and weather conditions. Therefore, the selection of a system needs to consider these factors and testing may be required for certain critical properties on-site to determine its suitability. Engineers, owners and suppliers need to collaborate in order to achieve a good solution. EN 1504-2 (2004) provides a detailed list of performance criteria for each of the various types of treatments along with the relevant code of practice for testing. In general, suppliers recommended application guidelines should be followed in the application of the system. INDUSTRY REVIEW A review of products and recent applications from Sika and A.B.E. Construction Chemicals is provided in this work. It was found that polymer-modified systems are still the most commonly used system. Siloxanes are often used for hydrophobic impregnation treatments, as the pure silanes are intended for high-performance usage and are only used in special circumstances. Each of the suppliers provides detailed application guidelines for each of their products as well as generalised expected performance criteria. Many of the products available have been formulated such that they are applicable to a wide range of applications, and it appears that some known problems with certain products have been improved on. DISCUSSION & CONCLUSIONS Findings of this report are listed below. • The selection of a treatment system is a complex issue and therefore requires engineers to have a good appreciation of various surface treatments systems. A proper framework and set of guidelines is needed. Notwithstanding the above, collaboration between the owner, engineer and supplier will go a long way to a successful application. • South Africa is lacking in the availability of detailed information for engineers to assess, design, specify and monitor treatment systems. South Africa is also in the process of adopting the Eurocodes for concrete design. The EN 1504 repair code contains specific provisions for surface treatments systems and should now be considered for implementation in South Africa. In the interim, EN 1504 can be used to assist in ensuring a standardised approach has been followed in a repair project. • The current EN 1504 surface treatment classification divides systems into Hydrophobic Impregnation, Impregnation and Coatings. Whilst these are generally acceptable it may be worthwhile to reconsider Coatings as two types i.e. 'coatings’ for thinner coatings and 'overlays’ for thicker coatings, as these treatments may function in a very different manner - overlays function by their thickness providing protection and may not be especially complex treatments. They may also simply be applied for levelling and have a treatment or coating applied over them. • Hydrophobic Impregnation is commonly achieved by the use of silanes or siloxanes or silanesiloxane blends. In particular, silane-siloxane blends are most commonly used. This is due to cost, difficulties in application of silanes, and environmental concerns with the volatile organic compound content of silanes. • There are conflicting reports on the effectiveness in the use of silicate systems for improving concrete durability. This appears to be in-part due to the lack of agreement on the exact nature of the protection mechanism. Further research is required to reconcile differences in reporting. • Polyurethanes are very versatile and are available in various forms. Many differences were found in literature on the effectiveness of polyurethanes for improving durability, and sometimes within the same generic type. One of the problems appears to be that researchers often don’t describe precisely enough the exact nature of the polyurethane that was used in their works. A standardised reporting approach is needed. However, polyurethanes have been shown to positively effect many durability issues in concrete such as water absorption, chloride diffusion and carbonation - depending on the specific polyurethane used. • Polymer-modified cementitious coatings are the most commonly available and used surface treatments, and can be used for a wide range of applications. Their exact properties depend on their formulation, type of polymer and polymer-cement ratio. However, they are generally very versatile and most commercially available products can be used to achieve a wide range of properties, including improving the durability of existing concrete surfaces. They are sensitive to weather conditions during curing and special precautions may be required.

Approximately 5 to 14% of school age children are affected by mathematics learning disabilities. With the implementation of inclusion, many of these children are now being educated in the regular education class- room setting and may require additional support to be successful in algebra. Therefore, teachers need to know what interventions are available to them to facilitate the algebraic learning of students with mathemat- ics learning disabilities. This systematic literature review aims to identify, and critically analyze, interventions that could be used when teaching algebra to these students. The five included articles focused on interven- tions that can be used in algebra, specifically when solving equations. In the analysis of the five studies two types of interventions emerged: the concrete-representational-abstract model and graphic organizers. The concrete-representational-abstract model seems to show it can be used successfully in a variety of scenarios involving solving equations. The use of graphic organizers also seems to be helpful when teaching higher- level algebra content that may be difficult to represent concretely. This review discovered many practical implications for teachers. Namely, that the concrete-representational-abstract model of intervention is easy to implement, effective over short periods of time and appears to positively influence the achievement of all students in an inclusive classroom setting. The graphic organizer showed similar results in that it is easy to implement and appears to improve all students’ learning. This review provided a good starting point for teachers to identify interventions that could be useful in algebra; however, more research still needs to be done. Future research is suggested in inclusive classroom settings where the general education teacher is the instructor and also on higher-level algebra concepts.

Detta arbete visar en möjlig väg för skapandet av en utökad norm/lagprövning genom att öka lagrådets befogenheter samt självständighet, där den lagstiftande församlingen samt den dömande och uttolkande myndigheten får en tydligare gräns än tidigare, där lagprövning står i fokus. Detta görs utifrån svensk rättstradition, där tidigare lagar omarbetats samt omplacerats utifrån traditionell rättsutredning. Lagrådet har givits en egen personalbudget vilket tidigare låg under Högsta domstolen samt ett eget kapitel i Kungörelse (1974:152) om beslutad ny regeringsform - RF. Lagrådets befogenheter och sammansättning har utökats samt deras tillsättning har överförts från politisk tillsättning till domarnämnden vilket omfattas av flera grupper från samhället, inte bara av politiker. Dessa sammanlagda åtgärder ger ett ökat tryck på parter att göra rätt från början i ett lagarbete, men det ger också möjlighet till att i efterhand granska och omarbeta fel som visat sig på vägen i ett konkret arbete. Detta systematiska sätt att arbeta ger en ökad öppenhet samt rättssäkerhet kring lagskapande och granskande arbete på ett ekonomiskt fördelaktigt sätt.
This work shows a possible path for the inception of an expanded norm / law review by increasing the powers for Council of law and its independence, where the legislative government and the judging law reviewing parts will have a clearer boundary than before, where legal reviewing is in focus. This is done on the basis of Swedish legal tradition, where previous laws have been revised and repositioned based on traditional legal reviewing method. The law council has been given its own staff budget, which was previously under the Supreme Court, and it has been given a separate chapter in The (1974:152) Instrument of government- RF. The council's powers and composition have been expanding and their appointment has been transferred from political appointment to the judicial committee, which is covered by several groups from society, not just by politicians. These aggregated measures give a total increase in pressure on parties to do right from the start, but also give the opportunity to retrospectively review and rework errors that have proven themselves in court’s rulings. This systematic way of working provides increased transparency and legal certainty of reviewing and creating of new law in a positive economic way.

The aim of this thesis is a complex evaluation of reinforcement in reinforced concrete construction and its comparation with contract documents. In the next step we will calculate static reviews for each part of the construction. In case that some of the parts will fail this review, we will have to project such a solution that the construction wont get damaged from excessive load. In the end we will make an all in all evaluation of the examination and the construction.

The Diploma’s thesis is focused on the design of selected parts of reinforced concrete exhibition hall (prestressed concrete purlin, prestressed concrete girder, reinforced concrete column, reinforced concrete footing, post-tensioned concrete girders). The load calculation (the self weight, the permanent load, the wind load, the snow load and imposed load), the design and the review of selected reinforced concrete items and the drawing documentation are included in this thesis.

En 1908, les juges de la Cour Suprême des États-Unis citent pour la première fois des études en médecine, en sociologie et en psychologie afin de valider la constitutionnalité d’une loi. Depuis, le recours aux preuves scientifiques s’est largement développé et il a pris une place dans le travail du juge aux États-Unis et au Canada. La preuve scientifique se présente comme un outil d’information essentiel pour le juge dans le contentieux constitutionnel des droits et libertés. Elle permet ainsi de décrire les réalités sociales et les aspects techniques qui intéressent directement la résolution des questions constitutionnelles. Au delà de son rôle d'information, son recours s’inscrit dans une logique de concrétisation de l’analyse constitutionnelle. Plus précisément, les critères du contrôle de constitutionnalité impliquent des questions de faits que la preuve scientifique pourra démontrer. En prenant ainsi un tout autre rôle, le recours aux preuves scientifiques questionne sur la nature du contrôle de constitutionnalité et sur les méthodes du juge. Malgré l’intérêt des juges américain et canadien pour ce mode de preuve, leur statut et leur régime juridique dans le contentieux constitutionnel demeurent indéterminés. Ces incertitudes touchent tant des questions de procédure que des questions de fond sur leur rôle dans l’analyse constitutionnelle et dans le raisonnement du juge. Dès lors, la recherche d'un cadre méthodologique a semblé nécessaire. Ce modèle permet de revaloriser l’apport des preuves scientifiques dans le contentieux constitutionnel et il contribue à la protection des droits et libertés. Il présente, alors, un intérêt pour l'ensemble juges constitutionnels
In 1908, the U.S. Supreme Court Justices made several citations of medical, sociology andpsychology studies for the first time. Since then, the use of scientific evidence has expanded and it became an important part of the work of the Supreme Court of the U.S. as well as the Supreme Court of Canada. Scientific evidence is an essential tool to inform judges in constitutional rights cases. It gives information on social realities and technical questions which are directly relevant to resolve questions of law. However, the use of scientific evidence is more than a medium of information. Indeed, it implies an interest for facts that go beyond the parties. Constitutional doctrine itself implies empirical questions that could find answers in scientific evidence. By determining those facts, scientific evidence becomes a part of the constitutional doctrineitself. Consequently, the use of scientific evidence interrogates on the nature of judicial review and on the judge’s methods. Thought judges in the U.S. and in Canada frequently cite scientific evidence, their use is mostly unregulated and indeterminate. The uncertainties surrounding the use of scientific evidence concern procedural questions as well as questions regarding their role in decisionmaking. Those questions must be answered. Once resolved, we research a methodological framework in which scientific evidence could be used consistently by American and Canadian judges. This approach is essential to reassert the value of scientific evidence in constitutionalrights cases and to improve constitutional rights protection. Finally, this framework might be relevant for judges beyond the United States and Canada

Yes
Concrete structures in sewer systems, marine engineering, underground engineering and other humid environments are easily subjected to microbial attachment, colonization and, eventually, deterioration. With careful selection and treatment, some additives including inorganic and organic antimicrobial agents were found to be able to endow concrete with excellent antimicrobial performance. This paper reviews various types of antimicrobial concrete fabricated with different types of antimicrobial agents. The classification and methods of applying antimicrobial agents into concrete are briefly introduced. The antimicrobial and mechanical properties as well as mass/weight loss of concrete incorporating antimicrobial agents are summarised. Applications reported in this field are presented and future research opportunities and challenges of antimicrobial concrete are also discussed in this review.
National Science Foundation of China (51908103 and 51978127), China Postdoctoral Science Foundation (2019M651116)
Full text of this article will be released for public view at the end of the publisher embargo on 30 Aug 2021.

Dissertação de mestrado integrado em Engenharia Civil
Esta dissertação tem como principal objetivo estudar o comportamento à flexão de um sistema misto de aço e betão, destinado aos mercados da construção nova e da reabilitação de edifícios. Este sistema misto é composto por uma viga mista formada por perfis enformados a frio de secção em “C” e “U”, sendo preenchida por betão. A viga mista dá suporte a uma laje maciça ou mista, esta última composta por uma chapa colaborante. Este sistema não utiliza conectores metálicos discretos, sendo a transferência de esforços de corte garantida, sempre que possível, nas superfícies de contacto entre aço e betão. Desenvolveu-se uma Ferramenta de Cálculo no software Microsoft Excel com o objetivo de estudar a capacidade resistente e o comportamento do sistema misto sujeito á flexão, de acordo com os pressupostos definidos pelos Eurocódigos. Esta ferramenta permitiu a realização de uma análise paramétrica às características geométricas do perfil metálico, a altura de betão, tipo de utilização e classe de resistência dos materiais, de modo a observar a sua influência na capacidade resistente da viga mista. Posteriormente, tendo por finalidade a utilização das secções tipo otimizadas/dimensionadas pela Ferramenta de Cálculo num contexto BIM, de forma a aplicar estas secções em modelos tridimensionais destinados aos mercados da construção, elaborou-se uma ferramenta para estabelecer a troca de informação entre dois softwares, o Microsoft Excel e o Autodesk Revit. Esta interligação realizou-se recorrendo a um conjunto de scripts desenvolvidos através do programa Dynamo de modo a transferir os dados relativos às características geométricas dos sistemas mistos para um modelo 3D obtendo uma estrutura tridimensional de forma automática. Por fim, recorreu-se ao software Atena 3D, baseado no Método dos Elementos Finitos, onde foram desenvolvidos e analisados um conjunto de modelos numéricos representativos do sistema misto proposto, com variações em alguns parâmetros, relacionados com o tipo de material e características da interface aço-betão. Esses modelos foram desenvolvidos com o intuito de realizar uma análise de sensibilidade que permitisse verificar a influência de cada parâmetro na capacidade resistente da viga mista.
This dissertation aims to study the flexural behaviour of a steel and concrete composite beam solution to be used in new construction and building rehabilitation markets. This composite solution gathers a lightweight beam formed by cold-formed sections with “C” and “U” shapes, that are afterwards filled by concrete. The composite beam supports a solid or a composite slab. the composite slab consists of a cold formed profiled steel deck filled with concrete. This system has no discreet connection elements, and the stress transfer is guaranteed, when possible, by the contact surfaces between steel and concrete. A Calculation Tool was developed in the Microsoft Excel software, in order to study the load capacity and the behaviour of the system when subjected to bending, following the rules defined by the Eurocodes. This tool was used to develop a parametric analysis on the geometric characteristics of the steel profile, concrete slab height, type of use and resistance class of materials, to observe the influence of each parameter on the resistant capacity of the composite beam. Subsequently, in order to use the optimized/ dimensioned type sections by the Calculation Tool in a BIM context, to apply these sections in three-dimensional models supplied to the construction markets, a tool was developed through the interconnection between two software’s, Microsoft Excel and Autodesk Revit. This interconnection was carried out using a set of advanced scripts from the Dynamo software, in order to transfer the data relating to the geometric characteristics of the composite system, to a parametrized 3D model. Finally, the Atena 3D software, which is based on the Finite Element Method, was used. A set of numerical models representative of the proposed composite system were developed and analysed. Variations in some parameters, related to the material properties and the characteristics of steel-concrete interfaces were considered and a sensitivity analysis was developed help understanding the influence of each parameter on the bending moment capacity and the longitudinal shear capacity of the composite beam.