The 2030 Agenda for Sustainable Development and its 12 Sustainable Development Goals, amongst their other priorities, urge countries to achieve sustainable management, the efficient use of natural resources, and significantly less waste generation through prevention, reduction, recycling, and reuse. In the Basque Country, Electric Arc Furnace Slag (EAFS) is the main type of steelmaking waste. The transformation of EAFS into a raw material for use in cement will also reduce the consumption of natural resources. The behavior of EAFS reinforced concrete was therefore analyzed for use in real construction works. 600 L of concrete were mixed to produce four-meter-long beams. The beams then underwent three-point and four-point bending tests, to evaluate their bending, shear, and long-term deflection behaviors. Comparison of the experimental results with the predictions based on the formulae of current codes/standards led us to conclude that reinforced EAFS concrete can be designed using the current codes/standards within acceptable safety margins.

Industrial production of iron and steel within Spain has historically been situated in the north area of Spain. Although a major economic activity for the region, the industry also generates large volumes of waste that have hitherto been dumped in unsightly landfill sites. Over 25 years ago, a group of engineers and researchers from the same area set themselves the challenge of regenerating this waste. In this study, the advances developed in the technology of green slag concrete are reviewed, focusing on the expertise that the research group has accumulated over the past 25 years. Electric arc furnace slag is a stony material that is now often used as aggregate in hydraulic and bituminous mixes. Its use in hydraulic cement-based materials and the important properties of slag aggregates for mix workability are analyzed. Likewise, the mechanical behavior and the durability of slag concrete specimens is presented, paying special attention to expansive compounds and to the performance of electric arc furnace concrete in marine environments. In addition, real scale elements manufactured with slag concrete and their behavior are analyzed, as well as the advantages of applying current standards to their design. Finally, new lines of research are discussed for the use of electric arc furnace slag in cement-based materials.

The quenching and partitioning (Q&P) steels have shown to be promising candidates to be applied in fields where wear resistance is required. In this study, a medium and a high C steel are heat treated by Q&P and the resulting microstructure, hardness, and wear resistance are characterized. The mechanical stability of the austenite phase under wear test conditions is investigated. It is found that the stability of austenite is very high in the high C steel and decreases in the medium C steel. Additionally, the hardness and wear behavior of the Q&P‐treated steels are compared with the results obtained for quenching and tempering (Q&T) treated samples, showing that, although the hardness of Q&P steels is quite lower, the obtained wear rates are similar. It means that in the studied Q&P steels, although the austenite transformation into martensite does not occur considerably, the presence of austenite might play a key role in the wear resistance.

One of the limitations of the L-PBF technology is the high surface roughness of the parts. The resulting surface roughness morphology is a combination of the layer-by-layer building strategy and a stochastic pattern of spherical particles partially adhered to the surface. This stochastic pattern is composed by partially melted powder particles due to the heat transfer between the melt-pool and the powder particles at the part boundary. In this study, an experimental setup was designed to analyze the influence of the heat transfer of the L-PBF process on the adhered particles on the surface. Thus, the test parts consist on vertical walls distributed at different distances, from 0.2 mm to 5 mm, in order to promote different thermal gradients between surfaces. The manufacturing process was monitored using an IR camera, in order to find the relationship between the heat transfer and the mechanism of adhesion of particles. Moreover, the morphology of the resulting surface roughness of the parts was also analyzed. The results show a correlation between the temperature gradients and the number of adhered particles on the surfaces.

One of the key aspects of the laser powder bed fusion (L-PBF) process is the quality of the raw powder since it affects the final properties of the manufactured parts. In this study, 13 batches of Inconel® 718 powder were analysed, all of them being specially designed for L-PBF technology and meeting similar requirements but coming from different suppliers. Therefore, these batches have certain differences in their characteristics, including the particle size distribution (PSD). This study presents the relationship between the PSD of each batch and the surface roughness obtained in the manufactured parts. For the roughness study, Sa and Sz parameters are presented; in addition, the size and frequency of the particles adhered to the surface were quantified, and an autocorrelation analysis was carried out. Furthermore, after this analysis, the parts were sandblasted in order to repeat the same analysis after removing the adhered particles from the surface. This work points to the fact that the particles adhered to the surface are the smallest particles in the powder batch, and their size affects the roughness of the final part. This means that the surface roughness is strongly related to the fraction of smaller particles within the PSD of the batch, while there is no relationship between the surface roughness and the larger particles.

In this work, two medium Mn steels (5.8 and 5.7 wt pct Mn) were subjected to a quenching and partitioning (Q&P) treatment employing a partitioning temperature which corresponded to the start of austenite reverse transformation (ART). The influence of a 1.6 wt pct Ni addition in one of the steels and cycle parameters on austenite stability and mechanical properties was also studied. High contents of retained austenite were obtained in the lower quenching temperature (QT) condition, which at the same time resulted in a finer microstructure. The addition of Ni was effective in stabilizing higher contents of austenite. The partitioning of Mn and Ni from martensite into austenite was observed by TEM–EDS. The partitioning behaviour of Mn depended on the QT condition. The lower QT condition facilitated Mn enrichment of austenite laths during partitioning and stabilization of a higher content of austenite. The medium Mn steel containing Ni showed outstanding values of the product of tensile strength (TS) and total elongation (TEL) in the lower QT condition and a higher mechanical stability of the austenite.

We live in a consumer society that generates excessive amounts of waste. Innovative techniques to reduce these volumes of waste are therefore important lines of research in engineering. The Electric Arc Furnace steelmaking industry in the Basque Country produces almost 1% of global electric-arc-steel production. Although driving the economy, it also implies the generation of a huge amounts of waste that has to be managed within a small region. Concrete is an extensively used product, which can absorb notable amounts of Electric Arc Furnace slag but, at the moment, there are only applications for use in unreinforced concrete. In this research work, real scale concrete beams containing electric arc furnace slag concrete are manufactured, in order to study their structural behavior. Our results showed that reinforced concrete elements containing electric arc furnace slag can be safely manufactured using current design standards.

Self-compacting structural mortars (SCSM) incorporating slags from electric steelmaking as aggregates are manufactured and tested in this study. Their design requires careful proportioning and grading of the aggregates to prevent the negative impacts of slag on mixture workability. In general, these mixes with 60% of the natural aggregates in volume substituted by the slag aggregates met in the fresh state the prescriptive conditions of current normative standards for self-compacting mixes. The internal structure of the hardened mixes, characterized by Mercury Intrusion Porosimetry (MIP) and Computerized Axial Tomography (CAT), revealed the typical features of quality mortars. Shrinkage tests at room temperature and accelerated potential expansion tests at higher temperatures were also performed on the mixtures, to evaluate their long-term dimensional stability. The mechanical properties of the mortars over time also showed good behavior in terms of both compressive and tensile strength and suitable stiffness values. Globally considered, the characteristics of these mortars manufactured with slag in both the fresh and the hardened state were satisfactory for use in masonry and construction.

The structure of self-compacting concretes containing electric arc-furnace slag, their mechanical behavior, and their durability are all studied in an extensive experimental campaign, to evaluate the suitability of three concrete mixes for use in real construction works. Specimens manufactured with self-compacting electric arc-furnace slag concrete are subjected to wetting-drying and freezing-thawing test procedures, for their study in aggressive environments, especially marine environments. In general, all the test results were quite encouraging. It was once again demonstrated that the use of electric arc-furnace slag in concrete represents an opportunity to reduce both the volume of siderurgical waste generated in our society, and the consumption of fresh raw materials.

Ladle furnace slag is a significant by-product of the steel-making industry.Depending on the production conditions, the steel-refining process yields two types of basic slag, which are either low or high in silica and alumina, depending on the fluxing temperature and the saturation method.The present investigation focuses on the feasibility of producing mortar mixes, by incorporating both ladle furnace slag types in partial replacement of Portland cement, in amounts of 10%, 20%, 30% and 40% by weight.The fresh and hardened properties of the mortars are analysed, and the hydraulic properties of both types of ladle slag are evaluated.These kinds of by-products are affordable applications in mortars that add useful qualities to the building materials.Their use in partial replacement of cement contributes to global sustainability through the reduction of cement consumption, thereby reducing greenhouse gas emissions.

Whilst it is known that mean stress has an effect on the fatigue endurance of steel components, this effect is not considered when designing mooring system components. The S-N and T-N fatigue design curves for mooring chain in the standards are based on tests carried out at a single mean load, which is 20% of the chain minimum breaking load (MBL), and these curves are used to compute the damage of all load cycles regardless of their mean value. Lately it has been found that the effect of the mean load can be larger than probably expected, and that mooring chains exhibit a significant increase of fatigue capacity when cyclically loaded at reduced mean load. In the majority of the floating units, the pre-tension of the moorings without environmental loads is below or well below 15% of the chain MBL, and most, if not all, of the in-service damage is produced at mean loads below 20% MBL. This in practice results in additional conservatism to the fatigue life computed using the existing design curves. Some deepwater units, subjected to high pre-tension level, can experience some or relevant damage occurring at mean loads above 20% MBL, which would be underestimated with the present design approach. The paper provides an insight on the effect of the mean load on the fatigue endurance of mooring chains and quantifies this dependency based on a large number of fatigue tests carried out on different chain diameters between 70 and 171 mm, different grades, and different mean loads ranging between 7% and 20% of the MBL of the tested chains. The Smith-Watson-Topper (SWT) mean stress correction model is used to transform the stress state of the tested chains into different stress states associated to different mean loads. Then regression analyses are performed and correction functions derived for the design curves of both S-N and T-N approaches to account for the mean load while keeping the same confidence of the existing curves.

Volumetric expansion tests are performed on both ladle furnace slag and mixtures with natural soils, with a view to their use in civil engineering projects such as embankment construction and related earth works. The study provides an analysis of the effects of magnesium oxide and proposes an analytical model to predict LFS expansion within shorter time frames than the potential expansion tests specified in the ASTM D 4792 standard. It was found that major chemical reactions between the mixture of clayey soils and the slag occurred in the first 40 h of the potential expansion test. An acceptable relationship was also established between the values of the potential expansion test and the CBR swelling test described in ASTM D 1883. (C) 2019 Elsevier Ltd. All rights reserved.

The durability of structural concrete mixes prepared with electric steelmaking aggregates is tested for use in normal and aggressive environments. Samples of “pumpable” and “self-compacting” concrete mixes are shown to have good physical characteristics, mechanical properties and dimensional stability. The mixes were subjected to severe freezing-thawing and drying-wetting tests up until deterioration, to assess their resistance to inland environments. Real immersion in the tidal zone of a harbor and laboratory tests on reinforcement bar corrosion were also performed to evaluate the quality and utility of this sort of concrete in marine environments. The behavior of the mixes in these exposure tests was satisfactory, confirming their suitability for use in structural applications exposed to different environments.

Electric arc-furnace slag (EAFS) is an industrial by-product that can be employed in hydraulic mixes used in the field of construction and civil engineering. The design and preparation of self-compacting mixes with this aggregate is a challenge, due to the loss of workability that always accompanies its use in concrete. Only through careful design of the characteristics and proportions of the components in each mixture will an acceptable workability be achieved. Thus, criteria and methods are proposed in this paper for successful preparation of these types of mixtures. Several concrete mixes are manufactured to obtain self-compaction characteristics and their main properties are analyzed with regard to their use as structural concrete. Electron microscopy observations and dispersive energy analysis are used to study the microstructural features of these mixes. Finally, a numerical simulation is proposed as a useful method that estimates the viscous properties of the mixes and their workability, based on the dosage and the characteristics of their components.

In this research, the possibility of making a porous asphalt mixture manufactured completely with recycled aggregates from carbon steel production was explored. Electric arc furnace slag (EAFS) was used as coarse aggregate and ladle furnace slag (LFS) as fine aggregate and filler. Initially, the properties of both slags and their suitability to be used in the manufacture of porous mixtures were analyzed. Then, a series of asphalt mixtures were developed incorporating these slags and they were compared with a reference mixture, made with conventional components. A series of tests were performed, including concepts such as mechanical behavior, durability, moisture susceptibility, rutting resistance, permeability or skid resistance. The results show that it is possible to make a suitable porous asphalt mixture with 100% of steel slag aggregates, complying with the standard requirements and obtaining a durable and environmentally sustainable mixture.

Tantalum nitride (TaNx) coatings deposited by High Power Pulsed Magnetron Sputtering (HPPMS) technology at different N-2-to-Ar ratios; i.e. 0, 0.25, 0.625 and 1, corresponding to different N/Ta atomic ratio in the film, were investigated as suitable candidates to improve SS316L bipolar plates performance and durability for polymer electrolyte membrane fuel cells (PEMFC). The corrosion resistance of TaNx. coatings was evaluated by potentiodynamic and potentiostatic tests carried out under different cathodic potentials (0.8 V-SHE, 1 V-SHE, and 1.4 V-SHE), electrolyte acidities (pH 3 and pH 6) and test durations (5 and 180 min) in order to mimic real fuel cell operation conditions. Corrosion currents observed for all TaNx. coatings were relatively low (1-15 mu A cm(-2)) regardless of N/Ta atomic ratio and applied variable testing parameters. However, considerable differences in Interfacial Contact Resistance (ICR) values were observed after polarization, depending on tested coating material and conditions. The ICR increased with increasing applied potential, electrolyte pH and test duration for the substrate and all TaNx. coatings. Ta coated SS316L exhibited lower ICR (42-82 m Omega cm(2)) values than the uncoated SS316L (47-278 m Omega cm(2)) at potentials higher than 1 V-SHE. A significant rise in ICR was detected for all nitride TaN films after 180 min of polarization at 1.4 V-SHE in pH 3, showing ICR values from 362 to 538 m Omega cm(2), depending on N2-to-Ar ratio. Ta coated SS316L polarized at 0.8 V-SHE showed low ICR values, around 25-37 m Omega) cm(2). Auger electron spectroscopy (AES) was performed before and after polarization to investigate barrier oxide film formation kinetics. AES study revealed the growth of different composition and thickness oxide layers for each TaNx coating, exposing the great importance of coating composition on subsequent type of oxide formation. Barrier oxide layer characteristics have been found to dominate the ICR response of TaNx films after polarization. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The electric steelmaking industry is of great importance to the economy of the Basque Country (Spain). In all, 600,000 tons of electric arc-furnace (EAF) slag are produced every year; a by-product that this research group believes can be transformed into a useful resource. One of the uses of this material is as an aggregate in hydraulic mixes. Many studies have demonstrated that hydraulic mixes manufactured with EAF slag have at least the same mechanical behaviour and durability as ordinary concrete. However, their weaknesses are their higher density and poorer workability. In this paper, the aim is to demonstrate that manufacturing slag concrete to an acknowledged standard of workability is possible; so the objective is to manufacture self-compacting concrete using EAF slag in partial substitution of aggregates. Our analysis of the successful manufacture of three different self-compacting mixes, their properties in the fresh state and their mechanical behaviour yielded very encouraging results.

Electric arc furnace slag (EAFS) has for many years simply been dumped in landfill sites; over the past few decades many researchers have investigated its reuse in cement mortar and concrete. By doing so, a waste product may be converted into a useful material with added value as a substitute for natural resources, the consumption of which is also minimized. Hydraulic mixes manufactured with EAFS normally have similar or even better hardened properties than mixes manufactured with natural aggregates. One disadvantage in the use of EAFS has been the poorer workability of the mixes, due to its higher density, porosity and water absorption levels. In this research, different EAFS mixes are manufactured and their properties in the fresh and the hardened state are closely analyzed; the results were very promising. The aim of this research is to demonstrate that EAFS concrete can achieve an acceptable workability at the correct dosages.