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Interaction of ultrasonic waves with partially-closed surface-breaking cracks in concrete structures has been studied. Measurements have been conducted on a reinforced concrete beam containing various mechanical-load-induced cracks and compared with the baseline measurements at those locations. Influence of crack width, incident angle of waves with cracks, and distance from the cracks on travel time and amplitude of the waves have been investigated when the beam was unloaded. It has been observed that a measurable part of the waves propagate through the cracks due to the acoustic coupling between the crack faces, although attenuation can be relatively high. The travel time has shown a nearly independent behavior from remaining crack opening in the measured range of 0.05 mm to 3 mm. Measurements in directions orthogonal and parallel to the crack suggest that there is substantial anisotropy in the cracking zone. Furthermore, an effective width of the micro-cracking area around the cracks has been estimated from the measurements.

In design against fatigue, a lower bound stress range vs. endurance curve (S-N curve) is employed to characterize fatigue resistance of plain material and structural details. With respect to the inherent variability of the fatigue life, the S-N curve is related to a certain probability of exceedance, a percentile of the fatigue life. This paper is concerned with modelling and estimating uncertainties in fatigue resistance of welded joints under constant amplitude loading. A new S-N curve format is proposed and fitted to fatigue test data by using the Maximum Likelihood Method. The results have been compared with the Random Fatigue Limit Model and the Bilinear Random Fatigue Limit Model. The proposed S-N curve appears to be more accurate in describing the S-N relation in high-cycle fatigue: it presents a smooth transition from finite to infinite-life regions and, differently from previous non-linear S-N relations with fatigue limit, this transition is controlled by an independent model parameter. Thereby it provides more flexibility for statistical fitting. In addition, a Bayesian framework is defined to fit the proposed relation including informative and non-informative prior distributions. © 2017 Elsevier Ltd

tNovel nanomaterials, such as nanosilica or nano-titanium oxide, have been developed in the last decadefor the conservation of the built heritage. Among nanomaterials, nanolimes have acquired a considerablerelevance due to their potentialities as consolidant product. The so-called nanolimes, colloidal disper-sions of calcium hydroxide nanoparticles in alcohols, have been successfully applied as pre-consolidantson frescos and paper, and their use has later been extended to plasters, renders and stone. Nanolimeshave better potentialities compared to conventional inorganic consolidants based on limewater (e.g.faster carbonation rate and higher calcium hydroxide concentration). Moreover, nanolimes are consid-ered more compatible with CaCO3-based substrates than alkoxysilanes (e.g. TEOS), the most widely usedconsolidant products. Nanolimes can guarantee the recovery of the superficial cohesion of degradedmaterials. However, when a mass consolidation is required, like in the case of decayed stone, nanolimesshow some limitations. One of the problems is caused by nanolime accumulation at or just beneath thesurface of the treated material. In order to solve this problem, the transport mechanism of nanolimewithin porous materials, as stone or renders, should first be better understood. Commercial nanolimeswere applied on Maastricht limestone, a high-porosity yellowish limestone, used in the Netherlands andBelgium as traditional building material. The absorption and drying behaviour of nanolime in this lime-stone was measured and nanolime deposition in the stone was studied by optical and scanning electronmicroscopy. The results show that nanolime transport is strictly related to the properties of the solvent.The alcoholic solvent guarantees a stable dispersion that penetrates in depth in the material, but is par-tially back-transported to surface. The high volatility of the solvent and the high stability of the dispersionfavour the partial back-migration of lime nanoparticles to the surface during drying

This paper considers local buckling of perforated square aluminium plates. Plates of various slenderness with simply supported edges and subjected to uniaxial compression are studied using the finite element method. Different perforation patterns are investigated, from a single circular hole to 25 circular holes distributed over the plate. A number of aluminium alloys are considered and compared to steel grade A36. Results show that the resistance of the plates containing a single central cut-out is higher than that of plates with more holes and of equal total cut-out size. A further refinement beyond 5 holes does not influence the resistance.

The aim of this paper was to investigate the effect of natural carbonation on the pore structure, and elastic modulus (Em) of alkali-activated fly ash (FA) and ground granulated blast furnace slag (GBFS) pastes after one year of exposure in the natural laboratory conditions. The chemical changes due to carbonation were examined by X-ray diffraction (XRD), scanning electron microscope/energy-dispersive X-ray (SEM−EDX) and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR). Subsequently, the pore structure and Em of the degraded material were tested by mercury intrusion porosimetry (MIP), nitrogen (N2) adsorption, and nanoindentation. The chemical degradation of alkali-activated pastes due to natural carbonation is showed to be dependent on the GBFS content and their pore structure development. It was found that the pure alkali-activated GBFS paste was not carbonated at all within the tested period due to fine gel pore structure. On the other hand, carbonation of the gel in the pastes consisting FA and GBFS generated significant mineralogical and microstructural changes. The extensive decalcification of the gel was reflected in the increase of nanoporosity. Consequently, the Em of the carbonated pastes decreased. This study suggests that the degradation of alkali-activated FA and GBFS pastes due to carbonation may be accurately evaluated through micromechanical properties measurements rather than only by testing alkalinity of the pore solution and corrosion of reinforcement such as commonly studied carbonation effect in the ordinary Portland cement (OPC)-based materials.

Asphalt concrete has the advantageous ability to heal. During restperiods, damage present In the material is restored to a certain extent.Healing of the material can be observed in iis regaining of strengthand stiffness after rest periods. In this paper, a new test method is presented.It was developed to increase the understanding of the healingphenomenon. The test method focused on asphalt as it v/ss assumed tobe the driver of the healing performance. The test method assessedthe heaUng performance of asphalt In stiffness and strength by testingthe bond strength In tensile mode of two pieces of asphalt that wereassembled under controlled temperature and stress conditions. Withthe test method, healing tests ^yere performed on one type of binder;the load level during healing and the healing tune were varied. The tesiresults showed that after a short healing time of only 6 min, a significantamount of healing could be detected. That finding indicates the importanceof adhesion between two crack surfaces v/hen the healing capacityis assessed. It v/as also found that the maximum tensile stress reached aplateau value after 24 h of healing; the finding indicates thatfull healingcan be realized in short time periods for pure, unaged, soft binders. Itv/as also shov/n that the load level perpendicular to the damage duringheaUng had a significant effect on the observed healing.

This article presents both an experimental as well as a theoretical study on the effect of MethylHy droxyEthylCellulose (MHEC) on drying in porous materials using Nuclear Magnetic Resonance Imaging (NMR). MHEC, a water soluble polymer, is normally added to glue mortars as a water retention agent in order to improve the drying by increasing Accepted the open time. However, the exact processes that determine the drying rate of a glue mortar are unknown. In this study, we therefore focus on investigating the drying of a Fired day Brick (FCB) saturated with an aqueous MHEC solution. By using a FCB as a model system, the influence of hydration and changing of pore sizes due to hydration can be removed. The performed NMR experiments show a transition from homogeneous drying for a water saturated FCB toward an inhomogeneous (front receding) drying behavior for FCB saturated with increasing MHEC concentration. The capillary number (Ca) indicates a homogeneous drying for water saturated brick (Ca«i) and an inhomogeneous drying (Ca»1) in case of saturated brick with more than 1.5 wt% MHEC. Analysis of capillary number shows that the main parameter determining the capillary numbers are viscosity, surface tension, contact angle and evaporation rate. Among this viscosity change match with change in capillary number and therefore viscosity has a major influence on the drying behavior and rate. Based on the measured profiles, the moisture diffusivity is calculated. Using an empirical equation, the moisture diffusivity and NMR profiles were fitted to obtain the key parameters. From these analyses we conclude that 1) the moismre diffusivity scales with viscosity, which is the main parameter in shift in drying behavior. 2) Surprisingly, the presence of MHEC reduced the evaporation, which is unexpected since evaporation of MHEC solutions, for instance present in capillaries do not exhibit this behavior. 3) A minimum moisture diffusivity is found which shows to correlate to the evaporation process, which indicates that this might be the result of a vapor dominated diffusion flux.

Interaction of ultrasonic waves with partially-closed surface-breaking cracks in concrete structures has been studied. Measurements have been conducted on a reinforced concrete beam containing various mechanical-load-induced cracks and compared with the baseline measurements at those locations. Influence of crack width, incident angle of waves with cracks, and distance from the cracks on travel time and amplitude of the waves have been investigated when the beam was unloaded. It has been observed that a measurable part of the waves propagate through the cracks due to the acoustic coupling between the crack faces, although attenuation can be relatively high. The travel time has shown a nearly independent behavior from remaining crack opening in the measured range of 0.05 mm to 3 mm. Measurements in directions orthogonal and parallel to the crack suggest that there is substantial anisotropy in the cracking zone. Furthermore, an effective width of the micro-cracking area around the cracks has been estimated from the measurements.

Cement paste is the glue that holds concrete together and any improvements in material performance will come from its microstructure. For better understanding and predicting its elastic properties and fracture performance, more and more studies are carried out based on micromechanics simulations. However, the predicted results can be hardly verified experimentally due to the technical limitations. This paper presents a procedure for validating micromechanics simulation by making, testing and modelling deformation and fracture of micro cement paste cube (100 um x 100 um x 100 um). The micro scale specimens were produced by a micro dicing saw which is commonly employed in the semiconductor industry and fractured by a commercial cylindrical wedge tip mounted on a nano-indenter equipment. A combination of X-ray computed tomography technique and a discrete lattice fracture model was applied to simulate the deformation and fracture performance of the micro scale specimen under indentation. Mechanical properties of local phases are the input for this fracture simulation, which are taken from the previous study by the authors, wherein a micro scale experiment is developed to calibrate these values. Load-displacement curve and crack pattern from the simulation show a good agreement with those obtained experimentally. The proposed technique forms the basis for experimental validation of simulation tools that are used in a multi-scale framework at every scale.

The aim of this paper was to investigate the effect of natural carbonation on the pore structure, and elastic modulus (E-m) of alkali-activated fly ash (FA) and ground granulated blast furnace slag (GBFS) pastes after one year of exposure in the natural laboratory conditions. The chemical changes due to carbonation were examined by X-ray diffraction (XRD), scanning electron microscope/energy-dispersive X-ray (SEM-EDX) and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR). Subsequently, the pore structure and E-m of the degraded material were tested by mercury intrusion porosimetry (MIP), nitrogen (N-2) adsorption, and nanoindentation. The chemical degradation of alkali-activated pastes due to natural carbonation is showed to be dependent on the GBFS content and their pore structure development. It was found that the pure alkaliactivated GBFS paste was not carbonated at all within the tested period due to fine gel pore structure. On the other hand, carbonation of the gel in the pastes consisting FA and GBFS generated significant mineralogical and microstructural changes. The extensive decalcification of the gel was reflected in the increase of nanoporosity. Consequently, the Em of the carbonated pastes decreased. This study suggests that the degradation of alkali-activated FA and GBFS pastes due to carbonation may be accurately evaluated through micromechanical properties measurements rather than only by testing alkalinity of the pore solution and corrosion of reinforcement such as commonly studied carbonation effect in the ordinary Portland cement (OPC)-based materials.

De Afsluitdijk is op dit moment ruim tachtig jaar oud en heeft ons al die jaren goed tegen de krachten en invloeden van het zeewater beschermd (foto 1 en 2). Rijkswaterstaat gaat de Afsluitdijk nu een grote opknapbeurt geven, zodat hij tot ten minste 2050 mee kan. De dijk wordt zodanig versterkt dat hij bestand is tegen het stijgende zeewater. Bovendien worden de sluizen versterkt en verhoogd en wordt de waterafvoer verbeterd. Om dat te kunnen realiseren, was het noodzakelijk de betonnen kunstwerken, onder meer de spuisluizen, te laten inspecteren

The current theory of ASR gel formation in concrete between silicic acid anions with cations and is unable to explain the differences in concentration required for gel formation between e.g. potassium and sodium or the effect of calcium on the gel formation. In this paper, a new gelation mechanism is explained by means of a condensation between silicic acid anions. The role of salts on the ASR gel formation and gel time is described by their charge screening capacity of the silicic acid, resulting in the decreasing concentration range for gelation: Ca < Mg < Cs < Rb < K < Na < Li. A Cation Gelling Strength (CGS) is defined to assess the cation strength when different cations are present. Silica gel formation will moreover in many cases form a calcium silica precipitate rather than a gel that will be difficult to distinguish from CSH formed during hydration.

The current theory of ASR gel formation in concrete between silicic acid anions with cations and is unable to explain the differences in concentration required for gel formation between e.g. potassium and sodium or the effect of calcium on the gel formation. In this paper, a new gelation mechanism is explained by means of a condensation between silicic acid anions. The role of salts on the ASR gel formation and gel time is described by their charge screening capacity of the silicic acid, resulting in the decreasing concentration range for gelation: Ca < Mg < Cs < Rb < K < Na < Li. A Cation Gelling Strength (CGS) is defined to assess the cation strength when different cations are present. Silica gel formation will moreover in many cases form a calcium silica precipitate rather than a gel that will be difficult to distinguish from CSH formed during hydration.

Design methods for marine structures have evolved into load and resistance factor design, however existing partial safety factors related to berthing velocity and loads have not been verified and validated by measurement campaigns. In this study, field observations of modern seagoing vessels berthing in Bremerhaven, Rotterdam and Wilhelmshaven were used to evaluate partial safety factors for berthing energy and berthing impact loads. Various types of vessels and navigation conditions were statistically examined. The results show that characteristic values of berthing velocity with a return period of 50 years are in line with design recommendations in literature. Design values of berthing velocity are sensitive to the number of berthing operations during the lifetime of a marine structure. Typical partial safety factors for sheltered and exposed navigation conditions were derived by extrapolating distribution fits and applying extreme value theory. Differences in structural response due to soil stiffness and the type of berthing system installed influence partial safety factors for berthing impact loads. The probability of an uncontrolled berthing event was higher for exposed navigation conditions (strong tidal currents). In these circumstances, higher partial safety factors for berthing velocity should be considered in the design of marine structures. When berthing aid systems are used, the probability of extreme berthing velocities is lower, resulting in lower partial safety factors. The key findings of this study could be beneficial for the structural design of new and lifetime extension of existing marine structures. © 2017 Elsevier Ltd

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made., Materials and Structures, 50 (2), ISSN:1359-5997, ISSN:1871-6873

Carbonation of concrete at ambient CO2 concentration is a slow process. This makes the testing of the resistance of concrete against carbonation often too slow to be applicable for service life assessments of new structures. Raising the CO2-concentration will accelerate the test but the validity of an increase CO2-level is debated. If not valid, the service life can be seriously underestimated. In this paper, the effects of accelerating on the carbonation process are discussed. It is shown that a change in CO2 concentration will not change the carbonation process. Since carbonation occurs instantly, a zero CO2 concentration at the carbonation front is maintained. Moreover, it has been concluded that all hydrated and unhydrated cement ultimately carbonates. This implies that the amount of material that can carbonate can be determined on the basis of the amount of calcium in the unreacted cement. © 2013 Elsevier Ltd. All rights reserved.

The Proterozoic Bamble Sector, South Norway, is one of the world's classic amphibolite- to granulite-facies transition zones. It is characterized by a well-developed isograd sequence, with isolated ‘granulite-facies islands’ in the amphibolite-facies portion of the transition zone. The area is notable for the discovery of CO2-dominated fluid inclusions in the granulite-facies rocks by Jacques Touret in the late 1960's, which triggered discussion of the role of carbonic fluids during granulite genesis. The aim of this review is to provide an overview of the current state of knowledge of the Bamble Sector, with an emphasis on the Arendal-Froland-Nelaug-Tvedestrand area and off shore islands (most prominantly Tromøy and Hisøy) where the transition zone is best developed. After a brief overview of the history of geological research and mining in the area, aspects of sedimentary, metamorphic and magmatic petrology of the Bamble Sector are discussed, including the role of fluids. Issues relevant to current geotectonic models for SW Scandinavia, directly related to the Bamble Sector, are discussed at the end of the review.

The paper describes the methodology followed for the development of new cool products in order to widen the range of existing solutions both including coloured (even dark) materials and extending the application also to building vertical components. Cool coloured ceramic tiles and acrylic paints for façades and roof membranes have been developed and tested at lab scale. Spectral reflectance measurements have been performed demonstrating a significant improvement of reflectance in the Near InfraRed (NIR) range (up to. +0.40) while keeping dark colour and high absorbance in the visible. The development of new products has been also oriented to the improvement of durability properties, being this aspect of relevance for high reflecting materials that have to keep their cooling properties over the time. While ceramic tiles naturally offer superior resistance to outdoor ageing, a significant increase of biological growth resistance has been achieved also for roof membranes by including ZnO nanoparticles. The approach followed by the authors aimed at delivering products, that besides having higher NIR reflectance, were capable of satisfying industrial and market requirements being compatible with standard manufacturing processes and offering additional functionalities. A complementary paper will be dedicated to the extensive experimental and numerical evaluation of new materials' thermal performances. © 2014 Elsevier Ltd.

Stand-off photovoltaic systems are a popular measure for retrofitting of existing pitched roofs. Panels are generally mounted parallel to the existing roof coverings, usually roofing tiles. Full scale and wind tunnel experiments have been performed to determine the net uplift loads on these systems, which can be applied to calculate the loadbearing system. In the wind tunnel, the effect of distance between panel and roof has been investigated. Results show that loads can be expected that are substantially lower than the external loads on the roof surface, as given in wind loading standards. The effect of distance between PV system and roof surface is relatively small. The loads on the underlying roof are not significantly higher or lower compared to the case without system.

A risk-based safety approach is indispensable to support decision-making on flood protection strategies and measures. In most deltaic areas, flood risk analysis involves more than analysing the flood hazard and the potential damage, and flood defence systems also play an important role. In such systems consisting of rivers, estuaries and flood defences, interaction effects between local failures and hydraulic loadings and reliability elsewhere in the system can be significant. Hitherto, such system behaviour has been paid little attention in flood risk analysis approaches. This paper presents a computational framework for analysing flood risk while fully accounting for system behaviour. The approach is based on Monte Carlo sampling, in which the number of computationally expensive hydrodynamic model runs is reduced significantly to only those realisations, for which the flood defence system fails. A case study illustrates the approach and demonstrates that fully accounting for system behaviour can make a significant difference for both, reliability of flood defence structures and flood risk in terms of individual risk to life as well as economic damage.

Flood defence levees are crucial for flood protection, especially in riverine and deltaic areas. One of the most critical failure modes of levees is backwards internal erosion or piping. Piping reliability is largely influenced by uncertainties in ground conditions, especially by geohydrological properties such as the hydraulic conductivity of an aquifer. These properties are typically highly uncertain, which can lead to the related probabilities of failure being considerably high. Ways to reduce such uncertainties are by performing additional site investigation, incorporating information from field performance observations or monitoring. After providing some background on uplift and piping, the paper shows how Bayesian posterior analysis can be done using head monitoring observations in aquifers during extreme floods. The approach will be demonstrated by means of an illustrative example using a simplified uplift model showing also how the posterior distributions of the basic random variables change with respect to their priors. Subsequently, it will be illustrated how uncertain future measurements can be used in pre-posterior analysis to support decisions on investments in monitoring. The results suggest that the uncertainties in geohydrological conditions can be reduced significantly and that, if the monitoring cost is low compared to potential retrofitting measures, monitoring can be cost-effective. © 2013 Copyright Taylor and Francis Group, LLC.

In a BIM data flow, an essential part of the coordination between disciplines is the agreement on recesses and openings in building elements. Different disciplines will request recesses and openings in elements that are managed and maintained by others. Using the full dataset of the elements has proven to be inoperable because of the information overload, interoperability problems and contradictions in the commonly used downstream dataflow. A group of companies has been experimenting with the exchange of data that only consists of the requested openings and recesses in IFC. Coordination is being done using BCF. This approach has been fine-tuned and adjusted during several projects. This paper describes the current status of that initiative and discusses the challenges that are still open.

Tuffstone elements with a large length/width ratio, as e.g. mullions, often suffer damage in the form of cracks parallel to the surface and spalling of the outer layer. The response of tuff to moisture might be a reason for this behaviour. This research aimed at verifying if a differential dilation between parts with different moisture content (as outer and inner part of partially encased mullion) can lead to damage. The effect of moisture on the degradation of Ettringen and Weibern tuff has been investigated. A purpose-made weathering test was carried out to simulate the wetting-drying process. Despite no cracks developed during the test, existing cracks widened up and the flexural tensile strength of both materials decreased. The moisture transport properties of the stones were determined as well as their porosity and pore size. Ettringen tuff has a considerable amount of very fine porosity, resulting in slow moisture transport and significant hygroscopic adsorption. Both tuffstones have an extreme hydric dilation. Environmental X-ray diffraction analyses showed that Ettringen tuff undergoes (reversible) mineralogical changes when subjected to RH cycles, whereas this does not occur for Weibern. All results support the hypothesis that moisture gradients in tuff elements may enhance decay in this stone.

Risk Based Asset Management (RBAM), or rather Asset Management based on both a perfor-mance requirement and a supporting Risk Analysis, is a beneficial Asset Management methodology for a number of industries, including the Asset Management of infrastructure. In the implementation of RBAM at Rijkswaterstaat a number of challenges have been faced. This paper focusses on three major challenged and the solutions adopted: 1) how to RBAM into the existing asset management processes. 2) how to communi-cate effectively about the performance and its constraints with all levels within the organization, including the communication with decision makers, maintenance engineers and operators and 3) how to scale RBAM scope into manageable implementation

Modeling the stochastic evolution of a large-scale fleet or network generally proves to be challenging. This difficulty may be compounded through complex relationships between various assets in the network. Although a great number of probabilistic graph-based models (e.g., Bayesian networks) have been developed recently to describe the behavior of single assets, one can find significantly fewer approaches addressing a fully integrated network. It is proposed an extension to the standard dynamic Bayesian network (DBN) by introducing an additional dimension for multiple elements. These elements are then linked through a set of covariates that translate the probabilistic dependencies. A Markov chain is utilized to model the elements and develop a distribution-free mathematical framework to parameterize the transition probabilities without previous data. This is achieved by borrowing from Cooke's method for structured expert judgment and also applied to the quantification of the covariate relationships. Some metrics are also presented for evaluating the sensitivity of information inserted into the covariate DBN where the focus is given on two specific types of configurations. The model is applied to a real-world example of steel bridge network in the Netherlands. Numerical examples highlight the inference mechanism and show the sensitivity of information inserted in various ways. It is shown that information is most valuable very early and decreases substantially over time. Resulting observations entail the reduction of inference combinations and by extension a computational gain to select the most sensitive pieces of information. © 2017 Computer-Aided Civil and Infrastructure Engineering

The Province of Zuid-Holland encourages the development of innovations to make the provincial road network more energy efficient. This is one way the province can contribute to reducing energy consumption and CO2 emissions in accordance with the Dutch energy agreement. To this end, the Province of Zuid-Holland, Strukton Civiel and TNO have conducted joint research on road surfacing that reduces rolling resistance and hence reduces fuel consumption and CO2 emissions. This document sets out the objective of the research, as well as the methods used and the research results (both in the laboratory and the field). It also looks ahead at the impact the results could have and how the construction of such energy-saving road surfacing could best be put out to tender by road authorities

metallic tie-rods are installed under all naves to support a portion of the lateral thrust exerted by vaults and arches. After the recent failure of one tie-rod, an extensive research program was carried out to characterize the metallic material and to evaluate the axial forces and the tensile stresses of the tie-rods through dynamic testing and system identification. After a description of the methodology of the dynamic assessment of tie-rods in the Milan Cathedral, the paper presents the main results of the investigation in terms of fundamental frequencies and axial forces in the tie-rods

Risk Based Asset Management (RBAM), or rather Asset Management based on both a perfor-mance requirement and a supporting Risk Analysis, is a beneficial Asset Management methodology for a number of industries, including the Asset Management of infrastructure. In the implementation of RBAM at Rijkswaterstaat a number of challenges have been faced. This paper focusses on three major challenged and the solutions adopted: 1) how to RBAM into the existing asset management processes. 2) how to communi-cate effectively about the performance and its constraints with all levels within the organization, including the communication with decision makers, maintenance engineers and operators and 3) how to scale RBAM scope into manageable implementation

Owing to the unique molecular structure and high ion exchange capacity, hydrotalcites are believed to have a potential to be modified and tailor-made as an active corrosion protective component of reinforced concrete. In this paper, two types of modified hydrotalcites (MHT-pAB and MHT-NO2) were tested both in alkaline solution and mortar for their possibilities as chloride scavengers and inhibitor release agents for application in concrete. The test in alkaline solution showed that ion exchange occurred between free chloride ions in solution and the intercalated inhibitive anions in the MHTs. The results in mortar validated that MHTs could be promising alternatives for preventing chloride-induced corrosion when an appropriate dosage is adopted and applied in a proper way, in particular, either incorporation of a certain amount (MHT-pAB to replace 5% weight of cement) in the bulk mortar or as a coating of the reinforcing steel (MHT-pAB or MHT-NO2 at 20% weight of cement).

Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the addition of borax to sodium sulfate solutions has no influence on the wetting properties (contact angle on glass, surface tension, or evaporation rate) and therefore will not influence solution transport. Additionally, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions. This was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates. Under the here studied precipitation conditions, the addition of borax has no influence on the supersaturation ratio at the onset of crystallization, but it significantly affects the crystallization pattern of anhydrous sodium sulfate crystals (thenardite). Using RAMAN spectroscopy, two different hydrates of borax were identified after precipitation, depending on the initial concentration of the solution. Each hydrate has a different effect on the subsequent crystallization of sodium sulfate. The decahydrate polymorph of borax leads to the precipitation of hydrated sodium sulfate crystals (mirabilite) and the pentahydrate form favors the precipitation of the anhydrous sodium sulfate crystals (thenardite) with an altered crystal habit. Using X-ray diffraction, overdevelopment of the (111), (131), (222) and (153) faces of thenardite was identified. Additionally, the ratios between several peaks are reversed. These results confirm the deviation of the grown crystals of the equilibrium crystal shape of thenardite as observed with optical microscopy.

In-situ load testing of reinforced concrete (RC) structures is often performed to confirm the presence of the required resistance for the intended use (Conformity Load Testing) or to support the assessments of the residual capacity by models (Supplementary Load Testing for Condition Assessment). When performing an in-situ load test, one of the main concerns is the avoidance of irreversible damage to the structure, since that may impair the structural performance after testing and eventually reduce its residual service life. Therefore performance indicator are needed to recognize the development and/or to prevent failure during an in-situ load test of real structures. For many of the existing RC structures without transverse reinforcement, shear failure is one of the governing mechanisms. Due to its brittle character, this failure mode is difficult to sense at an early stage of its development. Up to now no good performance indicator is available for shear. In the presented study, a smart key performance indicator for in-situ load tests has been developed, with particular focus on shear failure. Results of several laboratory tests on full-scale shear beams have been examined, confirming that a change in structural behaviour at an early stage during testing can be traced by the proposed indicator. With the proposed performance indicator, performing measurements only on the top or bottom of the tested specimen is necessary, which is of importance for the applications to existing structures, with limited access for measurements. An algorithm for data analysis has been developed, which can be used to control the proposed performance indicator in real time during testing. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra

Different analytical models exist to predict the shear strength of reinforced concrete members. Generally, each of these shear strength models consists of a formulation based on certain underlying theory and fitted model coefficients. The model fitting parameters are usually established from the comparison with test data. Hence, the predictive value of a shear strength model depends, to some extent, on the quality and representativeness of the used test data. This work investigates the predictive capability of several shear strength models for reinforced concrete beams without shear reinforcement. Particular attention is given to the application domain of relatively low reinforced and high depth concrete beams where limited shear test data is available. The predictive capability of the models for this area of interest is analyzed with Bayesian Inference. This probabilistic technique calculates the posterior distributions of uncertain parameters, given a set of measured test data and some prior knowledge. The predictive capability of each shear strength model is quantified by means of a calculated model uncertainty. Furthermore, the influence of the uncertainty in model parameter values on the calculated model uncertainties is evaluated. Bayesian Inference is also used to estimate the model evidences conditionally on the used data.

In the Netherlands civil engineering structures, such as overpasses, bridges and tunnels are generally built using blast furnace slag cement (BFSC, CEM III/B) concrete, because of its high resistance against chloride penetration. Although the Dutch experience regarding durability performance of BFSC concrete has been remarkably good, its resistance to carbonation is known to be sensitive, especially when the used slag percentage is high. In a field investigation on a highway overpass damage was found in sheltered elements such as abutments and intermediate supports, which was attributed to chloride induced corrosion enhanced by carbonation that occurred prior to the chloride exposure. Many structures built using BFSC could be prone to this mechanism, i.e. carbonation enhanced chloride induced corrosion, negatively affecting their durability. Focus of the research was given on the influence of carbonation on the chloride penetration resistance of BFSC mortars with varying slag content. In light of the characteristics from the overpass case, it was assumed that first there is a period of carbonation during sheltered exposure, and subsequently joint leakage causes exposure to chlorides. In order to identify the influence of slag content on carbonation, chloride penetration resistance and their coupled effect, mortars with twelve cement blends in a range of 0-70% slag were evaluated based on chloride migration coefficient, accelerated carbonation and electrical resistivity. This study shows that carbonation of BFSC mortars increases the porosity, consequently decreasing the chloride penetration resistance. Binders with 50% or more slag were found to have a significantly lower resistance after carbonation. Consequently, the chloride penetration resistance of a given concrete cover strongly depends on the duration of carbonation and the resulting carbonation depth, hence influencing its lifespan. The service life was estimated using a simplified model for the chloride penetration time of a combined carbonated and uncarbonated layer. It was found that mortar with a slag content between 35 and 50% that was carbonated before chloride exposure show the lowest influence of carbonation on the chloride penetration resistance. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made.

In the Netherlands civil engineering structures, such as overpasses, bridges and tunnels are generally built using blast furnace slag cement (BFSC, CEM III/B) concrete, because of its high resistance against chloride penetration. Although the Dutch experience regarding durability performance of BFSC concrete has been remarkably good, its resistance to carbonation is known to be sensitive, especially when the used slag percentage is high. In a field investigation on a highway overpass damage was found in sheltered elements such as abutments and intermediate supports, which was attributed to chloride induced corrosion enhanced by carbonation that occurred prior to the chloride exposure. Many structures built using BFSC could be prone to this mechanism, i.e. carbonation enhanced chloride induced corrosion, negatively affecting their durability. Focus of the research was given on the influence of carbonation on the chloride penetration resistance of BFSC mortars with varying slag content. In light of the characteristics from the overpass case, it was assumed that first there is a period of carbonation during sheltered exposure, and subsequently joint leakage causes exposure to chlorides. In order to identify the influence of slag content on carbonation, chloride penetration resistance and their coupled effect, mortars with twelve cement blends in a range of 0-70% slag were evaluated based on chloride migration coefficient, accelerated carbonation and electrical resistivity. This study shows that carbonation of BFSC mortars increases the porosity, consequently decreasing the chloride penetration resistance. Binders with 50% or more slag were found to have a significantly lower resistance after carbonation. Consequently, the chloride penetration resistance of a given concrete cover strongly depends on the duration of carbonation and the resulting carbonation depth, hence influencing its lifespan. The service life was estimated using a simplified model for the chloride penetration time of a combined carbonated and uncarbonated layer. It was found that mortar with a slag content between 35 and 50% that was carbonated before chloride exposure show the lowest influence of carbonation on the chloride penetration resistance. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra

Clause 6.2 of EN 1993-1-1 covers the cross-sectional resistance of steel sections. The bending-shear interaction design rules for I-shaped cross-sections make use of a reduced yield stress for the web area. On this basis, a reduced design plastic resistance moment allowing for the shear force is presented. The effect of shear on the bending resistance may be neglected if the shear force is less than half of the plastic shear resistance of the cross-section. Plasticity in the Eurocode is described by the well-known Von-Mises yield criterion, however, the formula used for the reduced yield stress deviates from this criterion, resulting in sometimes greater and sometimes smaller values. The background of the Eurocode formula for reduced yield stress can be found in a publication by Drucker. The purpose of the present research is to investigate the influence of shear on the bending resistance of I-shaped steel cross-sections with as result a possible reconsideration of the Eurocode design rules. At Eindhoven University of Technology an experimental investigation on bending-shear interaction in rolled steel I-shaped sections was performed. A numerical model was developed in Abaqus Finite Element software to simulate the experiments. With the validated numerical model a larger database of numerical ‘test’ results was generated, which was subsequently used in a statistical analysis following Annex D of EN 1990 as further developed in the RFCS project Safebrictile. The statistical distributions of the steel properties recommended by Safebrictile were adopted. This paper presents the results of the statistical analysis and safety assessment of the strong axis bending-shear interaction design rule currently present in Eurocode 3. The parametric test group consists of HEA, HEM and IPE sections in the steel grades S235, S355 and S460: in total 180 numerical simulations with increasing amount of shear. A stress-strain model including strain hardening was used in the numerical simulations, since the influence of strain hardening is also largely present in the experimental test program. Based on strain hardening material behavior it is show in this paper that the current partial factor is un-conservative for shear dominated beams and should be increased. Alternatively, the design rule should be modified.

De Noordersluis bij IJmuiden is één van de grote infrastructurele werken in vooroorlogs Nederland, uitgevoerd in beton (Fig. 1). De bouw van de nieuwe sluis was onderdeel van een reeks verbeteringen aan het Noordzeekanaal: In 1909 was een staatscommissie ingesteld '(om)dat opnieuw de vraag rees of de belangen van Nederland in het algemeen en van Amsterdam in het bijzonder in de toekomst wel voldoende waren gewaarborgd door een maritiem kanaal, dat toegang uit- en naar zee verleende voor bootee van 220 m lengte, 24 m breedte en ongeveer 92 dm diepgang. In het bijzonder was op het stellen van deze vraag van invloed het feit, dat sedert 1906 de werken van het Panamakanaal met kracht waren ter hand genomen, die na de voltooiing - welke inmiddels in 1914 heeft plaats gehad - doorvaart zouden bieden voor schepen van 305 x 331/2 m bij 1261/2 dm diepgang. Ook een verbetering van het Suezkanaal was inmiddels ter hand genomen. In die omstandigheden werd het noodig geacht een onderzoek in te stellen naar de wenschelijkheid van het nemen van verdere maatregelen om op den duur een geregelden toegang tot Nederland door het Noordzeekanaal te verzekeren ...' (Gelinck 1924). Op 2 Januari 1917 publiceerde Het Staatsblad een wet die verschillende verbeteringen aan het Noordzeekanaal van Rijkswege mogelijk maakte, waaronder een nieuwe schutsluis. De sluis werd ontworpen door een team ingenieurs onder leiding van Johannes Ringers (1885-1965), de latere Directeur-generaal van Rijkswaterstaat, Regeringscommissaris voor de Wederopbouw (een benoeming een week na de Duitse inval in 1940), verzetsman en als partijloos minister na de oorlog 'Vader van de Wederopbouw' (Van der Ham 1998, Pollmann 2006ab). Het team bestond verder onder andere uit de ingenieurs J.P. Josephus Jitta, C. Tellegen, F.E. Mulder en B. Peiser. De bouw trok van begin af aandacht in binnen - en buitenland (Fig. 2), -zo bracht onder in juli 1924 een gezelschap Duitse hoogleraren een bezoek aan de bouw (anoniem 1924a)-, en ging gepaard met uitgebreid toegepast-wetenschappelijk onderzoek. De ontwerpers publiceerden hun resultaten en overwegingen in De Ingenieur (Ringers 1924, Tellegen et al. 1924, Ringers & Peiser 1925, Jospehus Jitta 1928) en Ringers kreeg er in 1930 een eredoctoraat aan de TU Delft voor.

The currently available treatment techniques for concrete structures affected by alkali-silica reaction (ASR) are limited and electrochemical lithium migration has been proposed as an alternative. Lithium compounds have shown to have beneficial effects on ASR expansion when used as admixtures to fresh concrete. During the electrochemical treatment, lithium ions area transported into concrete (or mortar) by the action of an electrical field. The same principle is behind well-established techniques such as electrochemical chloride extraction (ECE). Like during ECE treatments, the reinforcement may be used as cathode during electrochemical lithium migration. In this paper, an investigation of the use of an embedded cathode during electrochemical lithium migration is presented. Mortar specimens were cast with embedded titanium meshes, which worked as cathodes. Results showed that potassium and sodium ions accumulated in the region around the embedded mesh and, under the tested conditions, few lithium ions reached that area. The accumulation of sodium and potassium is an undesirable side effect that increases the pH, which may possibly induce further ASR development, if not enough lithium ions reach the area.

Building regulatory systems have been evolving in recent decades, first with a transition to a functional or performance basis, and more recently with the introduction of new societal objectives, including those related to sustainability and climate change resiliency. Various policy and technical challenges have been identified with this evolution, including the lack of a common basis for establishing performance expectations, quantified performance metrics, and robust mechanisms to incorporate new objectives in a manner that effectively integrates a diversity of stakeholder input and results in regulatory requirements that do not compete with long-standing objectives. Among the mechanisms being explored to facilitate a managed evolution is the use of risk as a basis for performance, and modifications within the building regulatory environment to enable this. It is posited that framing the building regulatory system as a socio-technical system (STS) will highlight the complex interactions that exist between regulators and the market, the roles stakeholders play in characterizing risk for use in building regulation, and what steps are required to shift to a risk-informed performance-based building regulatory system, taking into account different legal structures and regulatory approaches that exist between jurisdictions

Many of the Dutch movable hydraulic structures are exceeding lifetime expectancy based on the then-current standards and regulations. Also signs of ageing become apparent, regulations (e.g. about structural safety) get more and more strict and functional requirements have often increased over time due to climate change and socio-economic developments. Therefore Rijkswaterstaat wants to ensure that these hydraulic structures (and it’s system of operation) always complies to an adequate performance level. This by setting up an systematic approach replacing hydraulic structures based on their cost-effectiveness and future uncertainties. To provide useful information regarding this method a probabilistic performance framework has been set up. This framework links the performance of the object (IJmuiden Pumping Station) with the performance of the system (Noordzeekanaal & Amsterdam-Rijnkanaal) and defines, analyses and considers different measures for the object and so-called ‘adaptation’ pathways, providing insight in the most cost effective solutions considering future uncertainties

This paper discusses the development and first testing of a valid, reliable, functional and simple indicator, that represents the long term effect of short term decisions. Such an indicator can assist counteracting short term views in network level asset management decision making. Short-termism or myopia may occur in cases where service level agreements (SLA) are made upon for shorter time frames than the typical lifecycles of transport infrastructure. The developed indicator indicates the “discounted future maintenance demand” (DFMD) for a time period stretching beyond the initial agreement period (expressed in a monetary value). The main assumption here is that the effect of short term decisions are reflected in the future maintenance demand. The indicator was applied in a case using existing data and information sources. Use of the DFMD, together with other (related) indicators provides valuable insight in understanding long term effects of short term decisions.

Surface consolidation is a common practice in the conservation of the built heritage. However, the effectiveness of consolidation of calcareous materials is often doubtful, due to the lack of effective and compatible consolidation products. Dispersions of calcium hydroxide nanoparticles in alcohol, the so-called nanolimes, can recover the superficial consolidation of calcareous substrates. Nevertheless, they are often not able to guarantee an in-depth consolidation. Previous research by the authors has demonstrated that the effectiveness of nanolime can be improved by fine-tuning the properties and the application protocol of the dispersions, based on the moisture transport properties of the material to be treated. In this paper, we verify the consolidation effectiveness and physical compatibility of the developed nanolimes, when applied on coarse porous calcareous materials like Maastricht limestone and lime-based mortars. The results show that a suitable mass consolidation can be achieved with nanolimes, while maintaining a good compatibility with the substrate material. © 2017 Elsevier Ltd

In design against fatigue, a lower bound stress range vs. endurance curve (S-N curve) is employed to characterize fatigue resistance of plain material and structural details. With respect to the inherent variability of the fatigue life, the S-N curve is related to a certain probability of exceedance, a percentile of the fatigue life. This paper is concerned with modelling and estimating uncertainties in fatigue resistance of welded joints under constant amplitude loading. A new S-N curve format is proposed and fitted to fatigue test data by using the Maximum Likelihood Method. The results have been compared with the Random Fatigue Limit Model and the Bilinear Random Fatigue Limit Model. The proposed S-N curve appears to be more accurate in describing the S-N relation in high-cycle fatigue: it presents a smooth transition from finite to infinite-life regions and, differently from previous non-linear S-N relations with fatigue limit, this transition is controlled by an independent model parameter. Thereby it provides more flexibility for statistical fitting. In addition, a Bayesian framework is defined to fit the proposed relation including informative and non-informative prior distributions. © 2017 Elsevier Ltd

In the Dutch province of Groningen over the last year shallow earthquakes are induced due to large scale gas extraction from the gas field at 3 km depth. The induced earthquakes differ from the better known tectonic earthquakes all over the world, caused by movement of the earth at large depths. The structures affected by the earthquakes however have never been engineered to withstand earthquakes. Layout of the walls and standard structural details can lead to dangerous partial collapse like fall of walls, opening of cracks and even to total collapse. Based on a target level for the Individual Risk (IR), in this paper, a reliability based method is developed for the design of new structures and assessment of existing structures for the area affected by the Groningen gas field. © 2017 Taylor & Francis Group, London. European Safety and Reliability Association; UK Safety and Reliability Society; University of Strathclyde, Scotland

Many repairs of chloride induced corrosion in practice fail within 10 years due to chloride remaining after cleaning the steel, causing corrosion re-activation. An improvement of conventional repair was invented, Electro Active Repair, that electrochemically removes chlorides. After concrete removal, a temporary electrolyte and anode are installed and direct current is applied for 24 hours. Subsequently repair is as usual. Patents have been applied. Laboratory testing confirmed the principle. A cementitious material was placed between NaOH and FeCl2 solutions. More than 90% of the chloride was removed from the catholyte (FeCl2) in 20 hours at 8 A/m2 and the pH increased from 3 to 12. This will suppress re-activation of corrosion and improve the durability of the repair. The method fits in the conventional repair process. The additional cost is moderate. Applying the invention increases repair life and reduces life cycle cost of corrosion affected structures.

Alkali–silica reaction (ASR) affects numerous concrete structures worldwide. However, the intervention options for ASR in existing structures are limited. Lithium is proposed to suppress expansion. In this paper, an investigation on two-chamber lithium migration as treatment against ASR is presented. First, the influence of different levels of ASR development on lithium migration is studied. Results show that ASR development, if not followed by enough crack formation, hinders migration due to increase in resistivity. Second, the effects of different treatments, such as sodium and potassium removal, lithium migration (combined with the associated sodium and potassium removal) and lithium diffusion, on ASR expansion were evaluated. Lithium migration led to the lowest post-treatment expansion levels. © 2016 Elsevier Ltd

Testing for the chloride threshold (also called critical chloride content) for corrosion initiation of steel in concrete has been found difficult and, at best, time consuming. Nevertheless, the chloride threshold is an important parameter in service life design of new structures and for evaluation of the remaining service life of existing structures. This paper reports on an accelerated test on mortar specimens that produces results within one week to a few weeks. It is based on accelerating chloride penetration by a mild electrical field while the steel potential is monitored. Upon corrosion initiation, specimens are sampled to obtain the chloride content that initiates corrosion. Results are reported of testing in CEM I (OPC) mortar on multiple specimens. Results for reference mortar are compared to specimens with application of a hydrophobic surface treatment. The results show that in reference CEM I mortar values for the critical threshold were obtained that agree well with previous experiments using the same method. This is taken as a validation of the method. The method is thought to be suitable for comparative chloride threshold studies of different binders, without or with corrosion inhibiting additions. Results for mortar with surface applied hydrophobic treatment, however, are unexpectedly low, which is taken to suggest that the method is not suitable for (e.g. surface treated) material with inhomogeneous electrolytic conduction. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra