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Acid mine drainage (AMD) is one of the biggest environmental issues faced by the mining industry. The concerns towards AMD rises when the waste rock and tailings are enriched in pyrite and/or pyrrhotite. The presence of trace of heavy metals bearing minerals increases the environmental hazard of such material. And the large volume of solid waste produced during operation leads to a
high pollution risk.
AMD is characterized by the release of acidic runoff water enriched in sulfate and metals. However, the impacts associated with AMD are beyond environmental, besides disturbing aquatic life and contaminating soil and water streams, the areas affected by AMD faces the visual impact associated with its characteristic “ochre” color and can have their water supply or tourism affected by the
pollution. Additionally, the expenditures to recover these sites are extremely high. A reliable AMD
assessment is crucial to design an appropriate tailings management strategy capable of preventing AMD generation and a suitable rehabilitation plan able to reduce the footprint of such operations in the surrounding areas.
The oxidation of iron-bearing sulfides (pyrite, pyrrhotite and marcasite) occurs naturally when in
contact with moister and oxygen, however, mining increases the exposure of these rocks whereas the comminution process increases the reactivity of the minerals by affecting its degree of liberation
and particle size. Hence, the oxidation process is enhanced by mining operations. Acid mine drainage generation depends mainly on the ability of neutralizing minerals to buffer the acidity produced by pyrite oxidation. Besides that, particle size and liberation degree define the reactivity of the acidproducing and acid-neutralizing phases. Hence, these parameters influence the oxidation rate and the overall geochemical evolution of the leachate released.
The traditional methods used to assess AMD does not consider particle size and liberation degree. However, to achieve a reliable AMD prediction, account to these parameters are of utmost importance. This master thesis aims to analyze the effect of liberation degree in AMD generation using tailings coming from Dundee Precious Metals Chelopech (DPM-Ch). The tailings produced by the concentration process in DPM-Ch is characterized by enrichment in pyrite. Quartz and kaolinite are the main non-sulfide gangue whereas no carbonate mineral is present in the ore. Thus, no neutralizing mineral is present in the tailing assemblage. Moreover, the presence of trace arsenic bearing minerals which are not recovered during the process increases the environmental concern toward this material. Particularly because this element is mobile under acidic conditions and can be toxic to humans, plants and animals in low concentration.
To achieve this objective an integrated approach, that combined process mineralogy techniques and geochemical testwork (static and kinetic test), was used to assess the AMD potential of the tailings from DPM-Ch processing plant. Samples from the tailings management facility (TMF) were collected and pyrite flotation was performed aiming to recover the free pyrite while the locked pyrite remained in the tailings. Thereafter, SEM-EDS analysis was done to characterize each flotation stream regarding its modal mineralogy, liberation degree and particle size. Geochemical tests (static and kinetic tests) were performed in the pre-floated samples and tailings after pyrite flotation. The results showed that the reactivity of the tailings is highly dependent on the liberation degree and that the finer fraction dictates the overall geochemical behavior of the material.
Furthermore, 40% of the tailings produced in Chelopech is used to backfill the stopes. This technique enhances the productivity of the mine, increases the safety of the underground workplace and decreases the volume of tailings being handled on the surface. In addition to that, the cemented paste has the potential of decreasing pyrite reactivity by encapsulating this mineral inside a cemented matrix. However, a proper study of the geochemical behavior of the paste should be conducted to evaluate the environmental performance of the cemented paste backfill (CPB). This was done by using monolithic leaching test (MLT) and mineralogical analysis. The results showed that the calcium phases present in the cement buffer the acidic water that percolates the stopes. Likewise, this technique may reduce pyrite oxidation.

Acid mine drainage --- Tailing management facility --- Static test --- Kinetic test --- Liberation degree --- Sulfide minerals --- mineralogy --- cemented paste backfill --- environmental behavior --- tailings --- geometallurgy --- monolithic leaching test --- Ingénierie, informatique & technologie > Géologie, ingénierie du pétrole & des mines

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The Special Issue “Non-Destructive Testing of Structures” has been proposed to present the recent developments in the field of the diagnostics of structural materials and components in civil and mechanical engineering. The papers highlighted in this editorial concern various aspects of non-invasive diagnostics, including such topics as the condition assessments of civil and mechanical structures and the connections of structural elements, the inspection of cultural heritage monuments, the testing of structural materials, structural health monitoring systems, the integration of non-destructive testing methods, advanced signal processing for the non-destructive testing of structures (NDT), damage detection and damage imaging, as well as modeling and numerical analyses for supporting structural health monitoring (SHM) systems.

History of engineering & technology --- capillary-based structural health monitoring --- fatigue crack growth --- fatigue crack initiation --- XFEM --- straight lug --- cast-in-place concrete --- temperature --- boundary conditions --- on-line monitoring --- numerical simulations --- strength --- extradosed bridge --- SHM system --- delamination --- width-to-depth ratio (WTDR) --- concrete bridge deck --- handheld IR camera (H-IRC) --- UAV IR camera (UAV-IRC) --- passive IRT --- non-destructive technique --- concrete structure --- non-destructive evaluation --- crack effect --- metal magnetic memory --- magnetic intensity gradient --- stress --- non-destructive testing --- ultrasonic tomography --- graph theory --- concrete --- damage mechanics --- elastic degradation --- damage parameter --- internal length --- experimental research --- methodology --- floors --- cement-based materials --- casting --- forming --- non-destructive and semi-destructive tests --- laser scanning --- photogrammetry --- tachymetry --- bridge deflection --- non-contact measurement --- wave propagation --- damage detection --- numerical modelling --- hardness --- Barkhausen noise --- number of events --- non-destructive testing inverse problem --- adhesive joint --- concrete beam --- guided waves --- debonding --- damage imaging --- root mean square --- cracking pattern --- cracks --- cement composites --- image analysis --- historical floor --- integrated diagnostics --- ground penetrating radar --- ultrasonic testing --- in situ surveys --- finite-difference time-domain modeling --- masonry structures --- autoclaved aerated concrete masonry units (AAC) --- compressive strength --- minor-destructive (MDT) techniques --- non-destructive techniques (NDT) --- acoustoelastic effect (AE) --- quasi-brittle cement composites --- acoustic emission --- acoustic spectrum --- micro events --- acoustic nondestructive methods --- large format tiles --- real-life application --- mechanical load --- failure --- vibration signal analysis --- nondestructive testing --- Kalman filtering --- parameter identification --- magnetic Barkhausen noise --- magnetic anisotropy --- grain oriented steel --- time-frequency representation --- signal processing --- data mining methods --- digital image correlation --- region-based convolutional neural network --- machine learning --- crack monitoring --- crack detection and localization --- elastic waves --- neural networks --- force prediction --- flange connection --- static test --- soil-steel bridge --- terrestrial laser scanning --- finite element method (FEM) --- modelling and simulations --- material parameters identification --- vibration measurements --- testing --- operational modal analysis --- lighthouse --- historic tower --- steel structures --- stressed-skin effect --- diaphragm design --- trapezoidal sheeting --- condition assessment of steel structure --- structural health monitoring --- civil engineering structures --- mechanical structures --- damage detection and visualization --- modeling and simulations --- capillary-based structural health monitoring --- fatigue crack growth --- fatigue crack initiation --- XFEM --- straight lug --- cast-in-place concrete --- temperature --- boundary conditions --- on-line monitoring --- numerical simulations --- strength --- extradosed bridge --- SHM system --- delamination --- width-to-depth ratio (WTDR) --- concrete bridge deck --- handheld IR camera (H-IRC) --- UAV IR camera (UAV-IRC) --- passive IRT --- non-destructive technique --- concrete structure --- non-destructive evaluation --- crack effect --- metal magnetic memory --- magnetic intensity gradient --- stress --- non-destructive testing --- ultrasonic tomography --- graph theory --- concrete --- damage mechanics --- elastic degradation --- damage parameter --- internal length --- experimental research --- methodology --- floors --- cement-based materials --- casting --- forming --- non-destructive and semi-destructive tests --- laser scanning --- photogrammetry --- tachymetry --- bridge deflection --- non-contact measurement --- wave propagation --- damage detection --- numerical modelling --- hardness --- Barkhausen noise --- number of events --- non-destructive testing inverse problem --- adhesive joint --- concrete beam --- guided waves --- debonding --- damage imaging --- root mean square --- cracking pattern --- cracks --- cement composites --- image analysis --- historical floor --- integrated diagnostics --- ground penetrating radar --- ultrasonic testing --- in situ surveys --- finite-difference time-domain modeling --- masonry structures --- autoclaved aerated concrete masonry units (AAC) --- compressive strength --- minor-destructive (MDT) techniques --- non-destructive techniques (NDT) --- acoustoelastic effect (AE) --- quasi-brittle cement composites --- acoustic emission --- acoustic spectrum --- micro events --- acoustic nondestructive methods --- large format tiles --- real-life application --- mechanical load --- failure --- vibration signal analysis --- nondestructive testing --- Kalman filtering --- parameter identification --- magnetic Barkhausen noise --- magnetic anisotropy --- grain oriented steel --- time-frequency representation --- signal processing --- data mining methods --- digital image correlation --- region-based convolutional neural network --- machine learning --- crack monitoring --- crack detection and localization --- elastic waves --- neural networks --- force prediction --- flange connection --- static test --- soil-steel bridge --- terrestrial laser scanning --- finite element method (FEM) --- modelling and simulations --- material parameters identification --- vibration measurements --- testing --- operational modal analysis --- lighthouse --- historic tower --- steel structures --- stressed-skin effect --- diaphragm design --- trapezoidal sheeting --- condition assessment of steel structure --- structural health monitoring --- civil engineering structures --- mechanical structures --- damage detection and visualization --- modeling and simulations

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The Special Issue “Non-Destructive Testing of Structures” has been proposed to present the recent developments in the field of the diagnostics of structural materials and components in civil and mechanical engineering. The papers highlighted in this editorial concern various aspects of non-invasive diagnostics, including such topics as the condition assessments of civil and mechanical structures and the connections of structural elements, the inspection of cultural heritage monuments, the testing of structural materials, structural health monitoring systems, the integration of non-destructive testing methods, advanced signal processing for the non-destructive testing of structures (NDT), damage detection and damage imaging, as well as modeling and numerical analyses for supporting structural health monitoring (SHM) systems.

History of engineering & technology --- capillary-based structural health monitoring --- fatigue crack growth --- fatigue crack initiation --- XFEM --- straight lug --- cast-in-place concrete --- temperature --- boundary conditions --- on-line monitoring --- numerical simulations --- strength --- extradosed bridge --- SHM system --- delamination --- width-to-depth ratio (WTDR) --- concrete bridge deck --- handheld IR camera (H-IRC) --- UAV IR camera (UAV-IRC) --- passive IRT --- non-destructive technique --- concrete structure --- non-destructive evaluation --- crack effect --- metal magnetic memory --- magnetic intensity gradient --- stress --- non-destructive testing --- ultrasonic tomography --- graph theory --- concrete --- damage mechanics --- elastic degradation --- damage parameter --- internal length --- experimental research --- methodology --- floors --- cement-based materials --- casting --- forming --- non-destructive and semi-destructive tests --- laser scanning --- photogrammetry --- tachymetry --- bridge deflection --- non-contact measurement --- wave propagation --- damage detection --- numerical modelling --- hardness --- Barkhausen noise --- number of events --- non-destructive testing inverse problem --- adhesive joint --- concrete beam --- guided waves --- debonding --- damage imaging --- root mean square --- cracking pattern --- cracks --- cement composites --- image analysis --- historical floor --- integrated diagnostics --- ground penetrating radar --- ultrasonic testing --- in situ surveys --- finite-difference time-domain modeling --- masonry structures --- autoclaved aerated concrete masonry units (AAC) --- compressive strength --- minor-destructive (MDT) techniques --- non-destructive techniques (NDT) --- acoustoelastic effect (AE) --- quasi-brittle cement composites --- acoustic emission --- acoustic spectrum --- micro events --- acoustic nondestructive methods --- large format tiles --- real-life application --- mechanical load --- failure --- vibration signal analysis --- nondestructive testing --- Kalman filtering --- parameter identification --- magnetic Barkhausen noise --- magnetic anisotropy --- grain oriented steel --- time-frequency representation --- signal processing --- data mining methods --- digital image correlation --- region-based convolutional neural network --- machine learning --- crack monitoring --- crack detection and localization --- elastic waves --- neural networks --- force prediction --- flange connection --- static test --- soil-steel bridge --- terrestrial laser scanning --- finite element method (FEM) --- modelling and simulations --- material parameters identification --- vibration measurements --- testing --- operational modal analysis --- lighthouse --- historic tower --- steel structures --- stressed-skin effect --- diaphragm design --- trapezoidal sheeting --- condition assessment of steel structure --- structural health monitoring --- civil engineering structures --- mechanical structures --- damage detection and visualization --- modeling and simulations

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Exceptional loads on buildings and structures may have different causes, including high-strain dynamic effects due to natural hazards, man-made attacks, and accidents, as well as extreme operational conditions (severe temperature variations, humidity, etc.). All of these aspects can be critical for specific structural typologies and/or materials that are particularly sensitive to external conditions. In this regard, dedicated and refined methods are required for their design, analysis, and maintenance under the expected lifetime. There are major challenges related to the structural typology and material properties with respect to the key features of the imposed design load. Further issues can be derived from the need for risk mitigation or retrofit of existing structures as well as from the optimal and safe design of innovative materials/systems. Finally, in some cases, no appropriate design recommendations are available and, thus, experimental investigations can have a key role within the overall process. In this Special Issue, original research studies, review papers, and experimental and/or numerical investigations are presented for the structural performance assessment of buildings and structures under various extreme conditions that are of interest for design.

damping device --- seismic design --- design base shear --- nonlinear response history analysis --- liquid storage tank --- earthquake --- wind --- dynamic response --- fluid–solid interaction --- composite shear wall --- seismic behavior --- quasi-static test --- design strength model --- bored-pile --- global strain extensometer --- pile friction resistance --- real-time monitoring --- snow–wind combined experiment facility --- snowdrift --- field observation --- scale experiments --- similarity criterion --- underwater explosion --- composite pressure hull --- whipping --- breathing --- failure index --- laminated glass (LG) --- free vibrations --- fundamental frequency --- mechanical restraints --- field experiments --- analytical modelling --- Finite Element (FE) numerical modelling --- super large cooling tower --- whole construction process --- wind vibration coefficient --- buckling stability --- ultimate bearing capacity --- snow load --- complex roof --- EOF analysis --- characteristics decomposition --- RABT fire curve --- fire simulation --- tunnel fire --- high temperature --- fire safety --- fire accident --- vertical earthquake motion --- seismic response --- atrium-style metro station --- shaking table test --- wind characteristics --- boundary layer --- typhoon --- hurricane --- field measurement --- train derailment --- derailment containment provisions --- collision testing --- post-derailment behavior --- slurry pipe jacking --- friction resistance --- effective friction coefficient --- pipe-soil-slurry interaction --- lubrication efficiency --- concrete --- blast load --- Monte Carlo analysis --- seismic demand --- pushover --- suction caisson --- suction penetration --- soil plug --- hydraulic gradient --- visual tests --- mountainous valley --- bridge site --- boundary transition section (BTS) --- numerical simulation --- wind tunnel test --- small radius TBM interval --- equivalent continuous model --- Winkler elastic foundation beam theory --- transfer matrix method --- horizontal axis deviation --- tall timber buildings --- timber composites --- seismic retrofitting --- Eurocode 8 --- structural assessment --- masonry buildings --- earthquakes --- seismic loads --- existing structures --- reliability --- rehabilitation --- risk --- blast loading --- welded haunch connection --- steel frame structures --- non-linear dynamic analysis --- ABAQUS --- multiple degree of freedom (MDOF) --- frame ductility ratio --- n/a --- fluid-solid interaction --- snow-wind combined experiment facility

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This book was proposed and organized as a means to present recent developments in the field of testing of materials and elements in civil engineering. For this reason, the articles highlighted in this editorial relate to different aspects of testing of different materials and elements in civil engineering, from building materials to building structures. The current trend in the development of testing of materials and elements in civil engineering is mainly concerned with the detection of flaws and defects in concrete elements and structures, and acoustic methods predominate in this field. As in medicine, the trend is towards designing test equipment that allows one to obtain a picture of the inside of the tested element and materials. Interesting results with significance for building practices were obtained.

Technology. --- rock bolt --- grouting quality --- dynamic response --- natural frequency --- finite element method --- monitoring --- historical masonry wall --- hygrothermal processes --- internal insulation --- testing of building materials --- test uncertainty --- validation of test methods --- sustainable test methods --- recycling --- foamed asphalt mixtures with cement (FAC) --- base layer --- reclaimed asphalt pavement (RAP) --- fatigue durability --- GFRP --- FRP reinforcement --- shear --- capacity --- reinforced concrete beams --- column --- stiffness --- FRCM --- PBO mesh --- PBO–FRCM --- carpentry joints --- scarf and splice joints --- stop-splayed scarf joints (‘bolt of lightning’) --- static behaviour --- experimental research --- concrete --- non-destructive testing --- ultrasounds --- ultrasonic tomography --- acoustic methods --- defects --- diagnostic --- detection --- convolutional neural networks --- transfer learning --- monitoring FBG --- power transmission tower --- civil engineering --- X-ray microtomography --- microstructure characteristics --- infiltration damage --- high-strength concrete --- steel fibres --- flexural tensile strength --- fracture energy --- numerical analysis --- concrete floors --- compressive strength --- strength distribution --- industrial floors --- ultrasound tests --- ventilated facades --- large-scale facade model --- fire safety --- fiber cement board --- large-slab ceramic tile --- plasterboards --- moisture content --- hydration processes --- mechanical properties --- ultrasound measurements --- ESD resin --- expansion joint --- quasi-plastic material --- energy absorption --- asphalt mix --- compaction index --- volumetric parameters --- stiffness modulus --- moisture resistance --- roughness --- texture --- close-range photogrammetry --- bond strength --- random field generation --- semivariograms --- hybrid truss bridge --- steel–concrete connection joint --- mechanical behavior --- failure mode --- strain --- static test --- static elastic modulus --- dynamic elastic modulus --- machine learning --- P-wave --- S-wave --- resonance frequency test --- nondestructive method --- Al–Ti laminate --- fracture --- acoustic emission diagnostic --- pattern recognition --- clustering AE signal --- storage systems --- tab connector --- flexural test --- capable design moment --- restrained ring test --- autogenous shrinkage cracking --- concrete cracking test --- concrete shrinkage cracking test --- restrined ring calibration --- cement–fiber boards --- acoustic emission method --- k-means algorithm --- wavelet analysis --- fiber composites --- ground penetrating radar (GPR) --- HMA dielectric constant --- road pavement thickness estimation --- early age concrete --- damage processes detection before loading --- strength of structures --- aggregate --- classification --- wire mesh --- roundness --- tilting angle --- opening size --- concrete centrifugation --- morphology --- image processing --- porosity --- cement --- waste paper sludge ash (WPSA) --- controlled low-strength material (CLSM) --- unconfined compressive strength --- bearing capacity --- backfill material --- P-wave velocity --- amplitude attenuation --- resistivity --- CT scan --- sandstone --- damage variable --- nuclear magnetic resonance --- spin-lattice relaxometry --- proton --- hydration kinetics --- superplasticizer --- ready-mixed concrete --- construction material --- quality assessment --- conformity criteria --- statistical-fuzzy method --- FRTP --- rivet --- connection --- polyethylene pipe --- mechanical properties of polyethylene --- resistance strain --- computer simulation --- residual shear stress --- particle crushing --- ring shear test --- particle flow code (PFC2D) --- frictional work --- fibre-reinforced concrete --- recycled steel fibres --- micro-computed tomography --- scanning electron microscopy --- tensile strength --- reinforced concrete --- diagnostic testing --- corrosion --- carbonation --- galvanostatic pulse method --- phase composition analysis --- X-ray analysis --- thermal analysis --- quasi-brittle cement composites --- low-module polypropylene fibres --- elastic range --- digital image correlation --- Arcan shear test --- wood --- orthotropic shear modulus --- elastic-plastic material --- shear wave velocity --- sand --- bender elements test --- grain-size characteristics --- complex modulus --- shrinkage analysis --- reclaimed asphalt --- mineral–cement emulsion mixtures --- cement dusty by-products (UCPPs) --- degradation of glass panels --- effective area ratio --- relative mass loss --- visible light transmittance --- windblown sand --- wood-plastic composites --- methods of testing resistance to fungi --- methods of assessment --- ground-penetrating radar (GPR) --- non-destructive techniques (NDT) --- corrosion of reinforcement --- slip resistance --- granite floor --- slip resistance value --- ramp test --- acceptance angle --- sliding friction coefficient --- comparability of test methods --- wall temperature --- fibre bragg grating sensors --- freeze-thaw cycles --- signal analysis --- short-time Fourier transform --- fast Fourier transform --- brine --- sodium chloride --- X-ray --- partition walls --- brick walls --- bending strength --- cracking --- post-tension --- cable --- girder --- destructive test --- non-destructive test --- structural health monitoring --- safety --- monitoring fibre Bragg grating --- mining areas --- strain/stress distribution --- geopolymer concrete --- fly-ash --- bottom-ash --- neural network --- sustainability --- industrial waste management --- flexural strength --- cladding --- AE acoustic emission --- micro-events --- sound spectrum --- traditional and quasi-brittle cement composites --- residual-state creep --- saturation front --- landslides --- erosional stability --- laboratory testing --- grout mixtures --- groundwater --- test apparatus --- testing --- building materials --- elements