This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent ...literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis.
Abstract The reinforcement technique using rigid inclusions is a practical, cost-effective, and time-saving foundation solution. This technique has already proven successful in supporting structures ...that are subject to high seismic demands, such as the Rio-Antirrio bridge in Greece. In a performance-based design approach, it is important to consider the dynamic soil-structure interaction phenomenon, which is specially relevant when dealing with soft soils. Direct approaches simulating the whole soil-structure system within the same numerical model are still computationally expensive and the classic modal response spectrum analyses, based on the superposition principle, are not capable of taking into account most of nonlinear mechanisms. The macro-element approach is therefore a promising method, as it allows modelling of non-linear soil-structure interaction mechanisms at the base of the structure without increasing the numerical cost. This approach has shown particularly good performance in the dynamic analysis of shallow and piled foundations. The present paper aims to extend the application of the macro-element approach to foundations on rigid inclusions. To this end, the upper-bound kinematic exterior approach is employed to derive a yield surface corresponding to this type of foundation. Its potential application in the context of non-linear soil-structure interaction studies is also discussed.
Over the past three decades, the strengthening and repair of existing civil engineering structures using FRP laminates has attracted a great deal of attention. With the advances in polymer science, ...adhesive bonding has become a common joining technology in these applications. Despite numerous studies that address the short-term behaviour of adhesively bonded FRP/steel joints, uncertainty with respect to long-term performance still remains. This knowledge gap is regarded as a critical barrier, hindering the widespread application of FRPs to strengthen and retrofit steel structures. This paper presents the state of the art in terms of the durability of FRP/steel joints used in civil engineering applications. Important influential factors relating to the durability of adhesively bonded joints are reviewed and different damage mechanisms are discussed. Moreover, related investigations of the combined environmental durability of these joints are critically reviewed and the findings are presented. The paper concludes with a discussion to motivate future research topics, while it is emphasised that the generalisation of the available results is questionable.
Summary Geophysics and Geotechnical Engineering commonly use one-dimensional (1D) wave propagation analysis, simplifying complex scenarios by assuming flat and homogeneous soil layers, vertical ...seismic wave propagation, and negligible pore water pressure effects (total stress analysis). These assumptions are commonly used in practice, providing the basis for applications like analyzing site responses to earthquakes and characterizing soil properties through inversion processes. These processes involve various in-situ tests to estimate the subsurface soil’s material profile, providing insights into its behavior during seismic events. This study seeks to address the limitations inherent to 1D analyses by using three-dimensional (3D) physics-based simulations to replicate in-situ tests performed in the Argostoli basin, Greece. Active and passive source surveys are simulated, and their results are used to determine material properties at specific locations, employing standard geophysical methods. Our findings underscore the potential of 3D simulations to explore different scenarios, considering different survey configurations, source types, and array sets.
In the Cigéo project for deep geological of radioactive waste, the project manager has to follow the convergence of tunnel (cells) cross-section built at 490 m depth. This convergence is due to the ...mechanical pressure in the rock layer. Vibrating Wire Extensometers (VWE) are ised to measure the strain at their locations. Our objective is to optimize the location of sensors to estimate the horizontal stress due to strain observations. This issue is solved using an inverse problem, which first requires the creation of a direct model that represents the bahviour of a cross-section. From rock data measured on site, thanks to an underground demonstrator, a numerical model is developed to generate s strain database for different VWE locations with different rock stresses and rigidities. The theoritical orientation of the sensors is orthoradial, but they can have angle and intrinsic errors. Considering various types of uncertainties, an inverse model based on Bayesian approach is developped to calculate the probability distribution of stresses. The last step is to use a genetic algorithm to determine the optimal sensor distribution. The best sensor placements is found to be near the kidneys, i.e. at more or less 45° around 0° and 180°.
This book is a compilation of selected papers from the 10th PIANC Smart Rivers Conference (Smart Rivers 2022). The work focuses on novel techniques for inland waterways and navigation structures. The ...contents make valuable contributions to academic researchers, engineers in the industry, and regulators of aviation authorities. As well, readers will encounter new ideas for realizing Green Waterways and Sustainable Navigations. This is an open access book.
This paper takes place in improving the energy performance assessment of cob buildings, by evaluating thevariability of its hygrothermal properties at the material scale, related to the traditional ...construction process. Forso, we proposed and analysed data to handle the variability of the hygrothermal properties. The specimens weremanufactured using a moulding method representative of on-site cob wall manufacturing process, for three plants species (hemp shiv, flax yarn and hay stalk) and three fibre content (0, 1% and 3%). Using non-destructivetests and statistical analysis, the random variability of cob composites hygrothermal properties (density, thermalconductivity, specific heat capacity, water-vapor permeability, moisture buffering value and sorption isotherms)was found as well as the variability distribution. It has been shown that the variability of properties is sensitive tothe nature of plant fibres specie and the fibre content. Using the variability indicators, it has been found on thermal conductivity, a low coefficient of variation of 2.88% for 1%-flax fibred mixture (lower than unfibred material) and a high one for 3%-hemp composites of 10.88%. The variability of sorption isotherms was usually found to be high at lower humidity loads. It has been shown that increase fibre content stabilizes the variability of properties. Moreover, some evolution trends of the variability according to mixes was proposed; two parameters were found: the first, either FCmax highlighting the fibre content for which the maximum of variability was achieved or FCmin for the opposite; the second is FCres highlighting the residual variability, for high fibre content. The distribution of properties were found to be generally centered.
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