Concrete-filled steel tubular columns, known in the trade as CFST columns, have become a favorite of designers of high-rise and long-span structures. The concept is elegantly synergistic. The steel tube confines the concrete core, boosting its strength and delaying crushing, while the concrete core props up the steel tube from inside, preventing the thin walls from buckling inward. The result is a column with high strength, high stiffness, and remarkable ductility, all in a compact cross-section that frees up floor space. But the column is only as good as its connections, and this is where the technology has historically stumbled.

Conventional CFST column to reinforced concrete beam joints typically require steel bars and plates to pass through the column wall or through the concrete core itself. That means drilling, cutting, and welding inside a confined space, interrupting the continuous tube and sometimes reducing the column’s load-carrying capacity precisely where the forces are greatest. The detailing is complex, quality control on site is difficult, and construction crews lose time on operations that cannot easily be standardized. For a technology whose selling points are speed and efficiency, the connection detail has been an awkward contradiction.

The solution proposed by Zha and Zhang moves the problem outside the column. Their externally stiffened ring connection wraps a stiffening ring around the outside of the steel tube, giving the beam’s forces a continuous external path to travel through rather than forcing them to penetrate the tube wall. The researchers tested two configurations: a welded version, in which the connection components are welded together into a continuous load path, and a lapped version, in which elements overlap and rely on bearing and bond. Eight specimens, all built at 1:5 scale, were fabricated and subjected to low-cycle reversed loading, the laboratory equivalent of the back-and-forth swaying a structure experiences during a strong earthquake.

The test matrix was designed to isolate two key design variables. The first was the axial compression ratio, set at either 0.33 or 0.50, which represents how heavily the column is squeezed by the gravity loads above it. Higher axial compression generally changes how a joint fails and how much ductility it retains. The second variable was the length of the corbel, the short steel bracket that projects from the column to support the beam, tested at 120 millimeters and 240 millimeters. Corbel length matters because it determines how far the beam’s forces are carried before they are transferred into the joint region, influencing whether the concrete cracks early or the steel yields in a controlled, energy-absorbing way.

The headline result is reassuring for designers: every one of the eight specimens achieved a ductility coefficient greater than 5, satisfying seismic design requirements. Ductility, the ability to deform well beyond first yield without losing strength, is the property that lets a building absorb earthquake energy and warn occupants before collapse. That all configurations cleared this threshold suggests the externally stiffened ring concept is fundamentally sound. But the tests also revealed a clear hierarchy among the variants, and the differences came down to how smoothly forces could flow through the joint.

Welded connections emerged as the standout performers. Their hysteretic loops, the force-displacement curves traced over repeated loading cycles, were full and spindle-shaped, the signature of a joint that dissipates energy steadily cycle after cycle without pinching or degradation. Stiffness degradation, the gradual softening that accumulates as damage spreads, remained stable and gradual. The researchers attribute this superior behavior to continuous force transmission through the welds, which keeps the load path uninterrupted and lets the steel yield in a distributed, controlled manner. In seismic terms, the welded joints behaved like well-tuned shock absorbers.

The lapped connections told a more cautionary tale. Those built with short 120-millimeter corbels suffered premature concrete splitting and used their materials inefficiently, because the shortened bearing length concentrated forces and cracked the concrete before the steel could do its share of the work. Lengthening the corbel to 240 millimeters improved ductility, giving the forces more room to spread and delaying local failure, but the researchers judged the longer version less economically attractive, since the added steel and dimensions eroded the cost advantages that motivated the design in the first place. The lesson is that in connection design, geometry is destiny: too short invites brittle cracking, too long wastes material.

Alongside the physical tests, the team built nonlinear finite element models in ABAQUS, the widely used simulation platform, to validate the experiments and peer inside the joints where instruments cannot reach. The models employed the concrete damaged plasticity model, a constitutive framework that tracks cracking and crushing of concrete under cyclic loading, together with a layered simulation approach that captures the distinct behaviors of steel and concrete. The simulations accurately reproduced the observed failure modes and the backbone curves, the envelopes of peak response traced across loading cycles, with errors within 10 percent. That level of agreement means engineers can now use these validated models to explore design variations without fabricating and breaking a new specimen each time, dramatically accelerating future development.

The practical upshot is a clear recommendation: welded externally stiffened ring connections are the configuration the researchers propose for real CFST frames, offering a balance of seismic performance, constructability, and design simplicity. Because the stiffening ring sits outside the column, the tube remains continuous, the concrete core is undisturbed, and the awkward through-tube detailing that has plagued conventional joints disappears. For cities in seismic zones racing to build taller and span farther with structures that must also survive the big one, a connection detail that is simultaneously stronger, simpler, and faster to build is not a small refinement. It is the kind of unglamorous innovation that quietly determines whether buildings stand or fall when the ground starts shaking.

Subject of Research: Seismic performance of externally stiffened ring connections between concrete-filled steel tubular columns and reinforced concrete beams

Article Title: Seismic performance of externally stiffened ring connections between concrete-filled steel tubular columns and reinforced concrete beams

Article References: Zha, B., & Zhang, S. (2026). Seismic performance of externally stiffened ring connections between concrete-filled steel tubular columns and reinforced concrete beams. Scientific Reports. https://doi.org/10.1038/s41598-026-75173-0

Image Credits: AI Generated

DOI: 10.1038/s41598-026-75173-0

Keywords: concrete-filled steel tube, beam-column connection, externally stiffened ring, seismic performance, quasi-static test, finite element analysis, ductility, hysteretic behavior, energy dissipation, earthquake engineering, structural engineering, reinforced concrete

The research matters because titanium alloys are leading candidates for components in proton exchange membrane fuel cells, the devices that convert hydrogen and oxygen into electricity with only water as exhaust. In that environment, any metal part must endure acidic, chloride-laden conditions that would rapidly corrode ordinary stainless steels. Titanium’s famous defense is its passive film, a nanometer-thin layer of oxide that forms spontaneously on the surface and seals the metal beneath. But a fuel cell component also has to be manufactured into thin foils, which means it must survive rolling, bending and forming without cracking. The Chinese team, led by Wenxiang Zhu and corresponding author Bingxing Wang, set out to determine whether the crystallographic texture—the preferred orientation of grains imposed by heavy deformation—could be manipulated to optimize both demands.

The researchers prepared Ti–Ni–Nb–Ta alloy foils under different thermomechanical processing routes, varying the number of intermediate annealing treatments inserted between rolling passes. They then interrogated each foil with a full arsenal of characterization techniques: microstructural imaging to reveal grain structure and dislocation density, mechanical testing to measure strength and elongation, electrochemical measurements to quantify corrosion behavior, and surface analysis to examine the chemistry of the passive films that formed. The comparison between foils with and without intermediate annealing produced a strikingly clean result about the role of crystal orientation.

The foil that received two intermediate annealing treatments delivered the best combination of strength and ductility in the study. It exhibited a yield strength of 324.28 megapascals together with an elongation of 21.47 percent—a pairing that would normally be difficult to achieve in a heavily rolled hexagonal metal. The team traced this improved ductility primarily to the weakening of the basal texture, the alignment of crystals in which the hexagonal basal planes lie parallel to the sheet surface. When that alignment is strong, most grains are poorly oriented for the slip systems that allow plastic flow, and the metal behaves in a brittle, anisotropic way. Weakening the texture opened the door to a rarer deformation mechanism: pyramidal slip involving dislocations with a c-component, denoted slip, which can accommodate strain in directions that basal slip alone cannot reach.

The second contributor to ductility was an increased fraction of high-angle grain boundaries, the interfaces between crystals whose lattices are misoriented by large angles. These boundaries act as efficient relay stations for deformation: as strain accumulates, they allow dislocations to transfer between neighboring grains and distribute plasticity more uniformly, improving what materials scientists call intergranular deformation compatibility. In a thin foil, where a single weak grain can nucleate a crack that races through the thickness, this kind of cooperative deformation is especially valuable. The annealed foil essentially taught its crystals to take turns bearing the load instead of forcing a few favorably oriented grains to fail first.

Here, however, comes the twist that gives the study its practical punch. The foil without any intermediate annealing—the one with the strongest basal texture and a relatively high dislocation density—turned out to be the corrosion champion. It recorded a corrosion current density of just 0.19 microamperes per square centimeter and a steady-state current density of 0.14 microamperes per square centimeter, the lowest values in the investigation. In electrochemical terms, low corrosion current density means the metal surrenders fewer ions to the electrolyte per unit time, which translates directly into a longer service life in aggressive environments such as the simulated operating conditions of a fuel cell.

The explanation for this unexpected advantage lies in the interplay between crystal orientation, defects and passive film formation. The authors propose that the preferential basal orientation reduces the surface’s reaction activity, because grains oriented with their basal planes exposed present a crystallographic face that is intrinsically less eager to react with the surrounding electrolyte. At the same time, the relatively high dislocation density inherited from the heavy cold rolling appears to be an asset rather than a liability. Dense dislocations provide abundant nucleation sites for the passive film, accelerating its growth and helping it spread into a compact, stable layer. The team suggests that this defect-rich surface promotes the formation of stable oxides, notably titanium dioxide, and contributes to an increased passive film thickness—a thicker, more protective barrier standing between the metal and the corrosive medium.

This picture aligns with a growing body of evidence across metallurgy that dislocation density can influence passivation kinetics in subtle ways. Recent work on stainless steels has shown that plastic deformation can accelerate passive film nucleation and growth, while studies on magnesium and aluminum alloys have demonstrated that crystallographic orientation alone can shift electrochemical activity from one grain to the next. What makes the new study distinctive is that it treats texture and dislocation density as coupled variables in a single alloy system, showing that the same processing route that softens the texture and boosts ductility simultaneously reduces the dislocation density and, with it, the corrosion protection. The result is a genuine trade-off rather than a design flaw: the two annealed foils and the as-rolled foil sit at different points on a continuum between mechanical compliance and electrochemical inertness.

For engineers designing metallic bipolar plates and other thin components for hydrogen fuel cells, the implications are immediate. If a component’s geometry is simple and its dominant failure mode is corrosion, the as-rolled, strongly textured foil with high dislocation density is the better choice, offering the lowest corrosion current densities measured in the study. If instead the component must be stamped, deep-drawn or otherwise formed into a complex shape, the twice-annealed foil with its weakened basal texture, activated pyramidal slip and abundant high-angle boundaries offers the formability to survive manufacturing, at the cost of some corrosion resistance that might be recovered through coatings or post-forming surface treatments. The study effectively hands designers a processing-structure-property map for a single alloy composition, allowing them to select the route that matches the duty cycle of the part.

Beyond fuel cells, the findings resonate with the broader push to make hydrogen infrastructure durable and affordable. Corrosion in acidic chloride environments is a persistent tax on the lifetime of metallic components throughout the hydrogen economy, and every microampere per square centimeter saved extends service intervals and lowers operating costs. The Northeastern University team’s work demonstrates that some of that saving can be extracted not from exotic alloying additions or expensive coatings, but from disciplined control of rolling schedules and annealing steps—processes that are already standard in foil production lines. As hydrogen technologies scale up, such microstructural engineering may prove to be one of the cheapest levers available. The study also adds titanium alloys to the growing list of hexagonal metals, alongside magnesium, for which texture weakening has been shown to unlock ductility through non-basal slip, suggesting that the underlying physics is general and transferable. For now, the Ti–Ni–Nb–Ta system offers a clear lesson: in the world of thin metallic foils, the crystals remember every pass of the rolling mill, and with the right thermal interruptions, they can be persuaded to serve either strength or serenity against corrosion.

Subject of Research: Microstructure-dependent mechanical and corrosion properties of Ti–Ni–Nb–Ta alloy foils for fuel cell applications

Article Title: Effect of microstructure on the mechanical properties and corrosion behavior of Ti–Ni–Nb–Ta alloy foils

Article References: Zhu, W., Liu, G., Zhu, S., Wang, B., Wang, B., & Tian, Y. (2026). Effect of microstructure on the mechanical properties and corrosion behavior of Ti–Ni–Nb–Ta alloy foils. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13856-9

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13856-9

Keywords: titanium alloys, Ti–Ni–Nb–Ta, texture, basal texture, intermediate annealing, dislocation density, passive film, corrosion resistance, yield strength, ductility, fuel cells, foil processing

The researchers fabricated the Mg–2Gd–2Zn alloy by hot extrusion at three temperatures: 280, 320 and 360 degrees Celsius. Extrusion, in which a heated billet is forced through a die, does far more than shape the metal. It plastically deforms the crystal lattice, fragments and reorganizes grains, dissolves and reprecipitates secondary phases, and generates dense tangles of dislocations, the line defects that store deformation energy inside crystals. Each of these microstructural features feeds directly into the properties an engineer cares about: how much stress the material can carry before yielding, how far it stretches before breaking, how quickly it dissolves in corrosive media, and how efficiently it conducts heat away from a hot spot. By holding composition constant and varying only temperature, the team isolated the processing variable with unusual clarity.

The microstructures that emerged fell into two distinct regimes. Alloys extruded at the lower temperatures of 280 and 320 degrees Celsius developed what metallurgists call a bimodal structure, a patchwork of coarse-grained regions interwoven with fine-grained ones. Bimodal microstructures are prized because they mimic a composite: fine grains impede dislocation motion and raise yield strength, while coarse grains accommodate plastic strain and preserve ductility. When the extrusion temperature climbed to 360 degrees Celsius, the picture changed. Grain growth and dynamic recrystallization, the process by which new strain-free grains nucleate and grow during hot deformation, were both promoted, while the dislocation density and the intensity of the deformation texture declined. The material essentially relaxed, trading stored deformation energy for a more equilibrated, coarser grain structure.

The consequences for strength were dramatic, and in the opposite direction to what a casual reader might hope. Tensile yield strength fell from 338.2 megapascals in the cooler-extruded condition to 214.7 megapascals at the highest extrusion temperature, a loss of more than 120 megapascals. The authors attribute the high yield strength of the low-temperature material to a synergistic combination of strengthening mechanisms: fine grains that block dislocation slip through the Hall–Petch relationship, nanoscale precipitates that pin moving dislocations, and a high density of dislocations that tangle and stress one another. Remove any one of these and the yield strength suffers. At 360 degrees Celsius, coarser grains, reduced dislocation density and weakened texture combined to soften the alloy considerably.

Yet the same change that sapped strength delivered a remarkable gift in ductility. Total elongation before failure rose from 8.5 percent to 24.7 percent as extrusion temperature increased, nearly tripling the material’s formability. This is the classic strength–ductility see-saw in magnesium, but the magnitude of the swing, achieved with nothing more than a temperature change on an inexpensive, low-alloyed material, is what makes the result noteworthy. A component designer could, in principle, select an extrusion temperature to position the alloy anywhere along this spectrum: a stiff, strong condition for load-bearing brackets or a soft, ductile condition for parts requiring extensive subsequent forming.

Corrosion, the Achilles heel of magnesium, also responded favorably to higher extrusion temperatures. The corrosion rate dropped from 3.32 to 2.35 milligrams per square centimeter per day as the extrusion temperature rose from 320 to 360 degrees Celsius. The team traced this improvement to the microstructural evolution itself. The lower dislocation density and reduced texture intensity at high temperature promoted the formation of a more compact and uniform corrosion product film on the surface. Such a film acts as a barrier between reactive magnesium and the environment, suppressing the localized attack, such as pitting and galvanic corrosion at microstructural inhomogeneities, that typically consumes magnesium components. In other words, the more relaxed, recrystallized microstructure corrodes not just more slowly but more evenly.

Thermal conductivity, a property increasingly demanded in heat-dissipating electronics housings and powertrain components, also improved modestly with temperature. Conductivity rose from 124.6 to 129.7 watts per meter-kelvin across the extrusion temperature range. The physics behind this trend is well understood: heat in metals is carried predominantly by conduction electrons and lattice vibrations, both of which are scattered by crystal defects. Dislocations, solute atoms in solution and fine grain boundaries all shorten the mean free path of these carriers. As higher extrusion temperatures reduced dislocation density and allowed solute to precipitate out of the magnesium matrix, scattering diminished and heat flowed more freely. The fact that this gain in conductivity accompanied a gain in corrosion resistance, rather than coming at its expense, is a genuinely useful coincidence for practical alloy design.

The broader significance of the work lies in its economics as much as its metallurgy. High-performance magnesium alloys in the aerospace and automotive literature frequently carry rare-earth contents of six, eight or even ten weight percent, often combining gadolinium, yttrium, neodymium and other costly elements. Rare-earth supply chains are geographically concentrated and price-volatile, so diluting the recipe while preserving performance is a strategic goal for the industry. The Mg–2Gd–2Zn composition studied here demonstrates that a lean, roughly four percent total alloying addition can still deliver yield strengths approaching 340 megapascals, elongation approaching 25 percent, respectable thermal conductivity above 120 watts per meter-kelvin and steadily improving corrosion resistance, all from a conventional hot extrusion route requiring no exotic equipment.

The study also adds to a growing body of evidence that bimodal and heterogeneous microstructures offer a route around the strength–ductility dilemma that has constrained magnesium for decades. Recent work cited by the authors, including studies of heterogeneous structures in magnesium alloys and low-temperature extrusion of dilute Mg–Zn–Ce and Mg–Sm systems, points to the same underlying principle: controlling not just how big the grains are, but how differently sized grains coexist within one material, lets engineers combine properties that single-scale microstructures force them to trade away. The present study extends that principle to the coupled optimization of corrosion and thermal conductivity, showing that a bimodal structure optimized for strength can coexist with acceptable, and tunable, environmental and thermal performance.

For now, the practical recipe reads like a set of dial settings rather than a finished product. Extrude near 280 to 320 degrees Celsius when strength matters most; push toward 360 degrees Celsius when ductility, corrosion resistance and heat dissipation dominate the design brief. What the Ningbo and Beijing team has shown is that these settings act coherently on every property simultaneously, through one consistent set of microstructural levers: grain size, dislocation density, recrystallization state and texture. As magnesium competes with aluminum and increasingly with engineered polymers for lightweight applications from electric vehicle battery enclosures to laptop chassis, that kind of predictable, process-based control, achieved without expensive rare-earth loading, may prove to be the decisive advantage that finally moves wrought magnesium alloys from laboratory curiosities into mass-produced components.

Subject of Research: Effect of extrusion temperature on the microstructure, mechanical properties, corrosion behavior and thermal conductivity of a low rare-earth Mg–Gd–Zn magnesium alloy

Article Title: Investigation on the microstructure evolution, mechanical properties and corrosion behavior, thermal conductivity of low rare-earth containing Mg–Gd–Zn alloy: effect of extrusion temperatures

Article References: Xu, Y., Luo, X., Wang, G., & Hu, L. (2026). Investigation on the microstructure evolution, mechanical properties and corrosion behavior, thermal conductivity of low rare-earth containing Mg–Gd–Zn alloy: effect of extrusion temperatures. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13905-3

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13905-3

Keywords: magnesium alloys, Mg–Gd–Zn, hot extrusion, dynamic recrystallization, bimodal microstructure, yield strength, ductility, corrosion resistance, thermal conductivity, rare-earth elements, grain refinement, materials science

The material at the center of the study, rubberized alkali-activated concrete, or RuAAC, combines two waste streams in a single matrix. The binder forms through a chemical reaction between an alkaline activator solution and aluminosilicate precursors, avoiding the high-temperature clinker process entirely. In this work, the binder comprised ground granulated blast furnace slag and Class F fly ash in a one-to-three ratio, activated by a blend of sodium silicate and 12 molar sodium hydroxide. The team tested three rubber gradations, a fine-graded fraction spanning 0 to 0.8 millimeters, a medium-graded fraction of 1 to 3 millimeters, and a wide-range blend covering 0 to 3 millimeters, each incorporated at 5, 10, and 20 percent replacement of fine aggregate by volume. Crucially, the rubber was used exactly as received from the tire recycling plant, with no chemical pre-treatment, a deliberate choice to preserve the environmental and economic case for the material, since soaking and rinsing procedures consume reagents, water, and generate effluent of their own.

The results on strength tell a story of trade-offs. The control mix, with no rubber, reached an impressive 72.3 megapascals at 28 days, reflecting the rapid reaction kinetics of the slag-rich binder. Adding rubber reduced compressive strength across the board, with losses ranging from 21 to 35 percent at 5 percent replacement, 30 to 46 percent at 10 percent, and 36 to 56 percent at 20 percent. But the gradation made an enormous difference. The fine-graded mixes retained the highest strengths at every dosage, reaching 57.1 megapascals at just 5 percent rubber, while the wide-range mixes performed worst, falling to 31.7 megapascals at 20 percent. The reason lies at the microscopic interface between the hydrophobic rubber particles and the hydrophilic alkali-activated gel. Residual zinc stearate from the tire vulcanization process repels the polar activator, entraining air voids at the interface and creating weak interfacial transition zones that act as flaws under load. Larger particles create larger, more critical defects, while sub-millimeter particles distribute the damage into smaller, less consequential discontinuities.

One of the most intriguing findings concerned early-age behavior. At just one day, the rubberized mixes were 40 to 72 percent weaker than the control, but this deficit narrowed substantially by 28 days. The rubber particles, it turns out, delay rather than suppress the alkali-activation reaction. The fine- and medium-graded mixes more than doubled their strength between one and seven days, recovering much of the early loss as the matrix densified around the inclusions. Statistical analysis using two-way analysis of variance confirmed this interpretation: the interaction between rubber content and gradation was significant at one day but not at later ages, meaning the gradation-specific early damage faded as the reaction progressed. By contrast, the medium-graded mix at 20 percent replacement gained almost no strength after seven days, suggesting that failure in that mix was governed by the weak interfaces around its uniform 1 to 3 millimeter particles rather than by the still-reacting matrix.

Where rubber genuinely shines is in deformation capacity. The control concrete failed in classic brittle fashion, with a sharp post-peak drop in the stress-strain curve. The rubberized mixes, by contrast, softened gradually and kept carrying load at strains approaching 0.8 percent or more. The ductility index, a measure of how much a material can deform before failure, rose by 44 percent in the fine-graded mix at 20 percent replacement compared with the control. The elastic rubber particles store strain energy and delay the coalescence of microcracks into macrocracks, transforming a sudden fracture into a controlled, gradual failure. This exchange of strength for toughness is precisely the property profile needed for applications such as crash barriers, pavement slabs, and industrial floors, where energy absorption and crack resistance matter as much as raw load capacity.

The study also broke new ground by measuring direct shear strength, load-slip response, and shear toughness of RuAAC for the first time at the material level, a gap with real safety implications. Shear failures in structural elements such as flat slabs, corbels, and deep beams occur with little warning, and design codes estimate shear capacity as a function of the square root of compressive strength using coefficients calibrated to Portland cement concrete. The team found that shear strength declined by up to 45 percent with rubber incorporation, less severely than flexural strength, which fell by as much as 67 percent, because confining stresses developed during shear testing provided mechanical interlock that partially compensated for the weak rubber-matrix bonding. Notably, at 5 percent fine-graded rubber, the shear toughness index was 25 percent higher than the control, suggesting that modest rubber dosages can genuinely improve energy dissipation along crack planes.

The durability results delivered some of the study’s most surprising wins. Water absorption in the fine-graded mix at 20 percent replacement was 9 percent lower than the control, and its capillary absorption depth at six hours was 39 percent lower, because the densely dispersed hydrophobic particles interrupt continuous capillary pathways and force water to take longer, more tortuous routes through the matrix. Bulk electrical resistivity, a proxy for resistance to chloride ingress and rebar corrosion, was 12 percent higher than the control in the same mix. Abrasion resistance told a dramatic gradation-dependent story: the fine-graded mix at 20 percent lost 29 percent less mass than the control after 500 tumbling cycles, while every medium-graded mix disintegrated completely, with the 20 percent medium-graded specimen failing by just 200 cycles. The uniform 1 to 3 millimeter particles, poorly bonded to the matrix, acted as discrete weak points that accelerated crack propagation under surface wear.

The authors distilled their findings into two practical application regimes, both built on fine-graded rubber. A mix with 5 percent fine crumb rubber retained 57.1 megapascals of compressive strength, a 25 percent higher shear toughness index, and better abrasion resistance than the control, making it suitable for pavement slabs, industrial floors, curbs, and precast panels. A mix with 20 percent fine rubber offers lower strength, 46.1 megapascals, but a 44 percent higher ductility index, reduced density, and improved workability, pointing toward crash barriers and non-structural cladding. The researchers caution that the reduced elastic modulus, between 14.2 and 19.2 gigapascals compared with 24.3 for the control, means deflection rather than strength will likely govern member sizing, and that shear-governed elements require member-scale testing before RuAAC can be deployed in them.

What makes this work resonate beyond the laboratory is its reframing of a familiar sustainability equation. Simply dumping waste into concrete is not enough; the form of the waste determines whether the resulting material is an engineering asset or a liability. By demonstrating that sub-millimeter tire rubber can simultaneously cut cement demand, divert landfill waste, improve ductility, and even enhance durability, the study offers a credible pathway for rubberized cement-free concrete to move from non-structural novelty toward genuine structural relevance. The authors call for microstructural examination of the rubber-matrix interface, extended durability testing covering chloride penetration, carbonation, freeze-thaw and creep, full-scale element testing, and a life cycle assessment quantifying embodied carbon per unit of strength. Until then, the message is clear: if you want tires to strengthen the future of concrete, grind them fine.

Subject of Research: Effect of recycled crumb rubber particle size and replacement level on the mechanical and durability properties of cement-free alkali-activated concrete

Article Title: Effect of recycled rubber particle size and replacement level on the properties of rubberized alkali-activated concrete

Article References: Elbaz, Y., Mwafy, A., El-Maaddawy, T., & El-Hassan, H. (2026). Effect of recycled rubber particle size and replacement level on the properties of rubberized alkali-activated concrete. Results in Engineering, 32, Article 113326. https://doi.org/10.1016/j.rineng.2026.113326

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113326

Keywords: alkali-activated concrete, crumb rubber, waste tires, geopolymer, compressive strength, shear strength, ductility, durability, water absorption, abrasion resistance, sustainable construction, fly ash slag binder

A new study published in the Journal of Materials Science by Xintong Zhang, Wei Sun, and colleagues at the University of Science and Technology Beijing, working with Ling Cheng of the China Electric Power Research Institute, has now traced exactly how the way a Fe50Co50 alloy is quenched before hot rolling determines whether the finished sheet emerges strong and ductile or weak and fracture-prone. The work combines microstructural characterization, first-principles calculations, uniaxial tensile testing, and actual rolling deformation into a single multiscale picture, connecting what happens at the level of individual atomic planes to the macroscopic behavior of a rolled plate.

The team prepared specimens using two different quenching routes, labeled HOQ and HWQ, and then examined the room temperature lattice and microstructural states of each before any hot rolling took place. The differences were subtle but consequential. Compared with the HOQ condition, the HWQ specimens showed an apparent relative lattice contraction of approximately 0.46 percent, a tiny squeeze of the crystal lattice that turned out to ripple through every subsequent stage of processing. Beyond the lattice itself, the two conditions also differed in grain structure, crystallographic orientation, the density of geometrically necessary dislocations, and the character of their grain boundaries.

To understand why such a small lattice change could matter, the researchers turned to density functional theory calculations, a quantum mechanical method that models the behavior of electrons in a crystal from first principles. They focused on the generalized stacking fault energy, or GSFE, a quantity that describes the energetic cost of sliding one block of atoms past another along a specific crystallographic plane. Stacking fault energies govern how easily dislocations, the line defects that carry plastic deformation, can move through a metal, and they therefore sit at the heart of any theory of ductility.

The calculations revealed a clear trend. In the undistorted model of the B2 FeCo lattice, the maximum GSFE along the selected slip pathway was 0.898 joules per square meter. When the experimentally measured 0.46 percent lattice contraction was applied to the computational cell, the maximum GSFE rose to 0.926 joules per square meter. Pushing the contraction to an exaggerated 10 percent drove the value up to 1.067 joules per square meter. In other words, squeezing the lattice makes it energetically harder for slip to proceed, which is precisely the kind of change that would be expected to embrittle the material. The authors are careful to note, however, that these DFT results illuminate slip energetics at the atomic scale and are not intended to directly represent dislocation behavior during the high temperature, high strain environment of hot rolling.

With the starting microstructures characterized and the atomic scale energetics mapped, the team subjected both quenched conditions to hot rolling and compared what came out the other side. The differences were striking. The HOQ-HR condition, meaning the HOQ-quenched alloy after hot rolling, exhibited a weaker deformation texture, meaning its grains were less strongly aligned into preferred orientations by the rolling process. It also retained a higher fraction of high angle grain boundaries, showed less pronounced local dislocation entanglement, and, critically, demonstrated better resistance to the cracking that rolling deformation tends to induce. The HWQ-HR condition told the opposite story, with a stronger deformation texture and far more extensive dislocation entanglement woven through its microstructure.

Deformation texture and dislocation entanglement are not merely cosmetic features. A strong texture means that most grains share a common crystallographic alignment, which can concentrate deformation along specific planes and directions and create paths for crack propagation. Dense dislocation entanglement, meanwhile, locks up the mobile dislocations that a metal needs in order to flow plastically, raising the local stress required for further deformation and encouraging cracks to nucleate instead. The microstructural evidence therefore painted a consistent picture: the HOQ route left the alloy in a state that could accommodate rolling deformation gracefully, while the HWQ route left it primed to accumulate damage.

Room temperature tensile tests confirmed the story quantitatively. The HWQ-HR specimens achieved an average ultimate tensile strength of 500.1 megapascals, with a standard deviation of 24.41 megapascals, but managed an elongation after fracture of only 4.6 percent, plus or minus 1.1 percent. The HOQ-HR specimens were in a different league altogether, reaching an average ultimate tensile strength of 725.4 megapascals with a remarkably tight standard deviation of 5.62 megapascals, while still stretching 19.3 percent, plus or minus 1.21 percent, before breaking. That combination of roughly 45 percent higher strength and more than four times the ductility represents a decisively more favorable strength-ductility balance for the HOQ-HR condition.

For a material class whose brittleness has historically limited its adoption, these numbers carry real industrial weight. Equiatomic FeCo and related Fe-Co-V alloys are prized for soft magnetic applications ranging from high performance electric motors to aerospace power systems, and prior research has explored routes as varied as heat treatment optimization and additive manufacturing to coax ductility out of them. The new work adds a deceptively simple lever to that toolkit: the quenching route chosen before hot deformation, which sets the lattice parameter, the dislocation density, and the grain boundary character that the alloy carries into the rolling mill.

What makes the study conceptually interesting beyond metallurgy is its multiscale architecture. Rather than treating the alloy as a black box, the researchers linked an experimentally measured lattice distortion to a computationally predicted change in slip energetics, and then connected both to observable microstructural evolution during rolling and finally to macroscopic tensile performance. Each link in that chain is independently verifiable, and together they demonstrate that a sub-percent lattice contraction, invisible to the naked eye, can cascade into a fourfold difference in ductility. As electrification drives demand for better soft magnetic alloys, understanding how processing history echoes from the atomic scale to the finished component may prove to be the difference between a material that cracks on the production line and one that rolls cleanly into the next generation of electric machines.

Subject of Research: Microstructural and atomic-scale effects of quenching conditions on the hot deformation behavior of equiatomic FeCo alloy

Article Title: Multiscale microstructural characteristics of quenched Fe50Co50 alloy and their effects on hot deformation behavior

Article References: Zhang, X., Sun, W., Xiao, X., Zhang, H., Zu, C., Li, X., Zhang, Z., Cheng, L., & Wang, Z. (2026). Multiscale microstructural characteristics of quenched Fe50Co50 alloy and their effects on hot deformation behavior. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13832-3

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13832-3

Keywords: FeCo alloy, quenching, hot rolling, lattice contraction, stacking fault energy, density functional theory, dislocation density, deformation texture, ductility, soft magnetic materials, grain boundaries, tensile strength

Precast concrete construction has become a cornerstone of building industrialization because it offers rapid assembly, easier quality control, and a smaller environmental footprint than conventional cast-in-place methods. Yet the beam-column joints that tie these structures together remain a persistent engineering challenge. These regions experience some of the most complex stress states in an entire frame, transferring and distributing internal forces while holding the structure together during violent ground shaking. In traditional precast joints, columns are typically spliced with grouted sleeves or grouted lap splices, techniques that demand exceptional workmanship on site. Incomplete grouting is a common defect, and the story-by-story assembly process requires extensive temporary shoring that consumes space, prolongs construction, and accumulates installation errors.

To overcome these shortcomings, the research team led by Xiao-Ran Wang and He-Tao Hou of Shandong University developed what they call a latticed steel-concrete composite, or LSCC, beam-column joint. The design builds on multi-story precast column technology, in which columns spanning two or three stories are cast as a single unit in the factory and hoisted into place, leaving the joint regions open for wet connections. The new joint fills these open regions with a latticed steel column connector fabricated from chords, batten plates, through-diaphragms, and welded cross stiffeners. Structurally, the chords behave like the longitudinal reinforcement of a conventional column, while the batten plates act as stirrups. Before the joint concrete is poured, the chords provide a continuous load-transfer path across the open joint zone, and the cross stiffeners restrain local distortion of the central latticed segment, giving the column temporary stiffness, integrity, and stability during transport and erection.

The connection to the beams is equally deliberate. Each precast beam end carries an embedded H-section steel connector, with the beam’s longitudinal reinforcing bars welded to the outer flange surfaces. During assembly, the H-section web is bolted to a connecting plate on the latticed column while the flanges are welded to the through-diaphragms. By substituting a latticed configuration for the solid-web steel components used in many earlier composite joints, the design cuts steel consumption substantially. The researchers calculated that an equivalent joint built with a solid-web steel tube would require roughly 103.7 kilograms of steel, whereas their latticed specimens needed only 84.6 and 79.8 kilograms, savings of 18.4 and 23.0 percent respectively.

To test the concept, the team fabricated three full-scale exterior joint specimens: a monolithic cast-in-place reference specimen and two precast LSCC specimens differing only in the width of the batten plates. The columns measured 450 by 350 millimeters in cross-section and stood 3,040 millimeters tall, while the beams were 350 by 250 millimeters and 1,780 millimeters long. All specimens used C30 concrete, Q355B steel plates, and HRB400 reinforcing bars, with weld lengths deliberately exceeding code minimums to improve reliability under cyclic loading. Each specimen was subjected to a constant axial load of about 1,050 kilonewtons on the column, representing a realistic design axial load ratio drawn from an actual multi-story precast frame project, while two hydraulic actuators pushed and pulled the beam tips in a low-cycle reversed cyclic protocol following Chinese seismic testing standards.

The differences in behavior were striking. The cast-in-place specimen developed dense diagonal cracks in the joint core, concrete spalling at the beam-column interface, and a pinched, inverse S-shaped hysteretic response caused by joint shear failure and bond-slip of the reinforcement. The two LSCC specimens, by contrast, showed minimal cracking in the joint core and plump, spindle-shaped hysteresis loops with negligible strength degradation. Their damage concentrated in the beam span, roughly 300 to 800 millimeters from the column face, rather than at the joint itself. In quantitative terms, the composite joints achieved peak loads 45.1 and 43.1 percent higher than the monolithic reference, ultimate displacements 56.6 and 50.8 percent greater, and cumulative energy dissipation at their ultimate states 135.8 and 115.6 percent higher. At a beam-tip displacement of 70 millimeters, their equivalent viscous damping coefficients exceeded the cast-in-place specimen’s by more than 80 percent.

Strain measurements and curvature analysis revealed the mechanism behind this superior performance. The embedded H-section steel stiffens the beam end so effectively that it relocates the plastic hinge, the zone of controlled flexural yielding where a structure is designed to absorb earthquake energy, away from the vulnerable joint region toward the beam span. In the cast-in-place specimen, the near-joint segment dominated flexural deformation, contributing up to 89 percent of the total displacement at large amplitudes. In the composite joints, once displacement exceeded 30 millimeters, the outer beam segments took over, with one segment alone contributing 54 percent of the deformation in a representative case. This more uniform curvature distribution allows a larger volume of material to participate in energy dissipation, which is precisely what seismic designers strive to achieve.

The team also built high-fidelity finite element models in ABAQUS, using the concrete damaged plasticity model and a reinforcement hysteretic constitutive law that accounts for bond-slip effects. The simulations reproduced the observed failure modes and damage evolution with peak-load errors below 7.1 percent, validating the modeling approach. A parametric study then explored design trade-offs. Thinning the latticed connector from 10 to 8 millimeters, a 7.4 percent steel saving, barely affected capacity, but reducing it to 4 millimeters cut peak load by 13.8 percent. Lengthening the embedded H-section steel increased capacity steadily, adding 6.9 to 13.5 kilonewtons of peak load for every 75 millimeters of additional length. Upgrading reinforcement from HRB400 to HRB500 or HRB600 raised peak capacity by 12.7 and 24.9 percent respectively, though the higher-strength bars showed slightly faster post-peak strength degradation due to their narrower plastic deformation margin.

The authors caution that their experimental conclusions rest on a single specimen per configuration, without repeated tests, so the reported improvements apply primarily to the dimensions, materials, and loading conditions investigated. Still, the implications are considerable. The study demonstrates that rational detailing, such as narrowing the batten plates in the joint core, can trim steel consumption by more than 5 percent with almost no loss of structural performance, and that a latticed connector can simultaneously solve the temporary-stability problems of multi-story precast columns and deliver seismic behavior that surpasses monolithic construction. If subsequent testing confirms these trends across a wider range of parameters, latticed steel-concrete composite joints could become an attractive option for resilient, rapidly assembled buildings in seismic zones worldwide.

Subject of Research: Seismic performance of novel prefabricated latticed steel-concrete composite beam-column joints

Article Title: Seismic performance of novel prefabricated latticed steel-concrete composite beam-column joints

Article References: Wang, X.-R., Hou, H.-T., Xia, H.-J., Zhang, B., Wang, D.-Y., & Liu, S.-Q. (2026). Seismic performance of novel prefabricated latticed steel-concrete composite beam-column joints. Results in Engineering, 32, Article 113355. https://doi.org/10.1016/j.rineng.2026.113355

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113355

Keywords: prefabricated concrete, beam-column joints, seismic performance, latticed steel connector, cyclic loading test, plastic hinge relocation, energy dissipation, finite element analysis, precast construction, steel-concrete composite, ductility, earthquake engineering

Ceramsite aerated concrete blocks, known in the literature as CACB, have been spreading rapidly through construction markets because they solve two problems at once. The blocks are remarkably light, thanks to a porous internal structure produced by gas-forming reactions during manufacture, and their trapped air voids give them excellent thermal insulation. That combination lowers dead loads on foundations and cuts heating and cooling energy, making the blocks attractive for sustainable construction. But lightness and insulation say nothing about how a wall made from these blocks behaves when the ground beneath a building shakes. A team led by Li Ruige of Taizhou University, working with collaborators from construction and materials companies in Zhejiang Province, set out to answer that question with full-scale laboratory testing rather than assumptions.

The researchers built three reinforced concrete frame specimens. One was left bare, with no infill walls at all, serving as the reference structure. The other two were fitted with CACB infill walls, one configuration solid and one incorporating a window opening, reflecting the reality that most real walls contain doors or windows. Each specimen was then subjected to quasi-static cyclic loading, a laboratory technique in which horizontal forces are pushed back and forth across the structure in progressively larger excursions. This method mimics the repeated reversals a building experiences during an earthquake and allows engineers to measure bearing capacity, stiffness, ductility, and energy dissipation with precision that real seismic events can never provide.

The findings confirm that infill walls are anything but passive. Compared with the bare frame, the frames containing CACB walls carried substantially higher horizontal loads before failing. The walls acted as diagonal bracing elements within the frame, engaging the surrounding beams and columns in compression and fundamentally altering the load path through the structure. Crucially, the walls also changed how the structure failed. Instead of concentrating damage at discrete plastic hinge zones in the beams and columns, the classic ductile mechanism that seismic design codes try to cultivate, the infilled frames developed a more uniform distribution of cracks across their members. Whether that redistribution is beneficial or hazardous depends on the design intent, but it demonstrates that ignoring infill walls in analysis means misjudging the entire failure sequence.

Stiffness and ductility told a trade-off story. The CACB infill walls increased the initial lateral stiffness of the frames, meaning the structures deflected less under a given load. That sounds desirable, and for serviceability it is, but the added stiffness came at the price of reduced ductility, the capacity to deform far beyond yield without losing strength. Ductility is the property that lets a building absorb earthquake energy through controlled damage rather than sudden collapse. The frames with solid infill walls, without window openings, lost even more ductility than the frames with pierced walls, because the unbroken panel presents a stiffer, more rigid constraint to the frame. Meanwhile, as loading cycles intensified, the infilled frames degraded in stiffness significantly faster than the bare frame, as cracking spread through the lightweight block masonry and the wall gradually shed its share of the load back to the concrete members.

Energy dissipation, the ultimate measure of how much seismic shaking a structure can absorb, produced one of the study’s most nuanced results. The solid CACB infilled frames dissipated more energy than the bare frame, with friction between cracking block surfaces and the frame interfaces contributing to damping. The frames with window openings, however, dissipated slightly less energy than the bare frame. The opening interrupts the diagonal compression strut that a solid wall forms, concentrating damage around the window reveals and reducing the effective contact area available for frictional energy loss. For architects and engineers, this means that the seismic contribution of an infill wall cannot be assessed without accounting for its openings, a detail that simplified design models routinely overlook.

To extend the reach of the experiments, the team built finite element models of all three specimens in ABAQUS, a commercial simulation platform widely used in structural engineering. The models reproduced the hysteresis loops, the force-displacement fingerprints of cyclic loading, as well as the skeleton curves that trace peak capacity across loading stages. Simulated failure characteristics and the entire force process agreed well with the laboratory observations. This validation matters because validated models allow researchers to explore configurations that would be prohibitively expensive to test physically, and it gives practicing engineers a computational tool they can trust when assessing existing buildings or designing new ones with CACB infill.

The most forward-looking part of the study concerns a humble material more familiar from car door seals than from structural engineering: ethylene propylene diene monomer, or EPDM, a synthetic rubber prized for its durability and elasticity. The researchers analyzed what happens when EPDM is placed as a flexible buffer between the infill wall and the surrounding frame. The simulation results showed that this soft interface significantly increased structural deformation capacity, energy dissipation, and ductility. In effect, the rubber layer decouples the stiff wall from the deforming frame, allowing the frame to flex during shaking without the wall acting as an unintended brace that attracts forces and then shatters. The authors conclude that EPDM functions as an effective flexible connection capable of reducing earthquake damage.

This finding places the study within a growing international research movement toward seismic isolation of infill walls. Conventional wisdom held that the stiffer the connection between wall and frame, the better the composite action. Earthquake after earthquake has exposed the flaw in that logic: rigidly connected infills create soft-story mechanisms when they fail on one floor but not another, and they shear off column ends by imposing concentrated contact forces. Flexible connections, whether rubber buffers, slotted details, or specially engineered joints, aim to let the wall ride along with the frame rather than fight it. The Taizhou results provide quantitative evidence that a simple, inexpensive elastomer strip can capture many of these benefits for lightweight aerated concrete construction.

The broader significance of the work lies at the intersection of two urgent agendas. Cities in seismic zones need buildings that protect their occupants during rare but devastating events, and the entire construction sector needs materials that cut embodied carbon and operational energy. Lightweight aerated blocks serve the second agenda beautifully, and this study shows that with informed structural design, and possibly a strip of rubber at the wall-frame interface, they can serve the first as well. The research, funded by the Zhejiang Provincial Natural Science Foundation under grant LGG20E080006 and supported by regional building materials companies, offers a template for how emerging sustainable materials should be vetted: not only for their thermal and weight advantages, but for the full, sometimes surprising, structural behavior they introduce when the ground begins to move.

Subject of Research: Seismic performance of reinforced concrete frames with ceramsite aerated concrete block infill walls

Article Title: Experimental study on seismic performance of reinforced concrete frame with ceramsite aerated concrete block infill wall

Article References: Ruige, L., Huadong, C., Yuhua, L., Jinfa, L., Yanru, W., Chongxin, L., & Lingchao, D. (2026). Experimental study on seismic performance of reinforced concrete frame with ceramsite aerated concrete block infill wall. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02642-2

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02642-2

Keywords: ceramsite aerated concrete block, infill wall, seismic performance, reinforced concrete frame, quasi-static cyclic loading, ductility, stiffness degradation, energy dissipation, EPDM flexible connection, ABAQUS finite element simulation, earthquake engineering, lightweight building materials

The research, led by L. L. Meisner together with F. A. D’yachenko, M. G. Ostapenko, S. N. Meisner, A. B. Markov, E. V. Yakovlev, P. P. Kiziridi and A. V. Solovyov, compared two fundamentally different irradiation geometries of a low-energy, high-current electron beam. In the classical axially symmetric configuration, the beam strikes the target perpendicularly, like a flashlight pointed straight at a wall. In the radially converging configuration, electrons arrive from a ring of emission sources and converge on the sample from all sides at grazing angles, wrapping the surface in a cylindrical shower of charged particles. The team deliberately held the key irradiation parameters constant: an energy density of approximately 3.7 joules per square centimetre, a pulse duration of roughly two to three microseconds, and ten pulses per treatment. Only the geometry changed.

That controlled design is what makes the result so striking. Because energy density, pulse length and pulse count were matched, any difference in the resulting surface layers could be attributed to the direction and distribution of the incoming electrons rather than to the total energy deposited. The researchers found that both treatments produced modified surface layers, but those layers differed dramatically in phase composition, crystallographic texture, residual elastic stress state, hardness and ductility. In effect, the same alloy, the same beam and the same energy budget produced two entirely different materials at the surface, depending solely on how the electrons converged.

With the axially symmetric beam, the surface layer hardened. The treatment generated high compressive residual stresses acting perpendicular to the treated surface, a state that materials engineers prize because compressive stress at the surface suppresses crack opening and thereby improves fatigue life. The perpendicular bombardment drives rapid heating and even more rapid self-quenching of a thin melt layer, and the associated phase and structural transformations leave the near-surface region in a strengthened condition. For components that must resist cyclic loading, such as turbine discs, landing gear elements or orthopaedic stems, this is exactly the kind of surface state one wants.

The radially converging geometry told the opposite story. When the beam converged on the sample from the sides, the modified layer became softer and more ductile than the original material, with hardness actually dropping below its initial value. At first glance, softening a titanium alloy surface sounds like a defect, but the authors frame it as an opportunity. A ductile surface layer can accommodate strain, delay crack initiation under contact and impact conditions, and improve the performance of parts that must deform rather than fracture. The team proposes physical explanations for this behaviour rooted in the different thermal and stress fields generated when energy arrives obliquely from all directions rather than head-on, including altered phase transformation pathways and a distinct evolution of crystallographic texture in the treated zone.

Texture, the preferred orientation of crystals, is a subtle but powerful variable in titanium alloys. Ti–6Al–4V is a two-phase alloy combining the hexagonal alpha phase with the body-centred cubic beta phase, and the mechanical response of the surface depends strongly on which crystallographic planes lie parallel to it. The investigators characterised the treated layers using X-ray diffraction and electron microscopy, quantifying phase fractions, pole figures and residual elastic stresses, and measuring hardness and ductility by instrumented indentation following the Oliver–Pharr methodology. Their analysis revealed that the two irradiation geometries select different variant populations during the rapid alpha-to-beta and back-to-alpha transformations that occur under the microsecond melt-and-quench cycle, imprinting different textures and therefore different anisotropic mechanical behaviour onto the surface.

The low-energy, high-current electron beam itself is a well-established tool with a rich history. Pioneered in Tomsk, the technique relies on a plasma-anode electron gun that delivers intense pulses of relatively low-energy electrons, typically tens of kilovolts, which deposit their energy within a micrometre-scale depth of the surface. Each pulse melts that thin layer in microseconds, and the cold bulk underneath quenches it at extraordinary cooling rates, producing refined microstructures, dissolved precipitates and dense defect populations that conventional furnace treatments cannot achieve. What the new study adds is the recognition that beam geometry is a free design parameter, one that had been largely overlooked because most installations worldwide use the conventional perpendicular configuration.

The radially converging source used in the experiments is itself a recent development. Described in earlier work by Kiziridi and Ozur, the source generates a hollow, ring-shaped beam whose energy density distribution across the cross-section was characterised in a follow-up publication in Instruments and Experimental Techniques. This apparatus allowed the team to treat samples in a configuration impossible with standard guns, opening a genuinely new processing window. The current paper builds on the group’s 2025 study in the same journal, which examined residual stress and texture evolution in Ti–6Al–4V under radially converging beams alone; the new work completes the picture by placing those results side by side with the axially symmetric case under matched conditions.

The practical implications extend across industries. Aerospace manufacturers are under constant pressure to extend the fatigue life of titanium components, and surface treatments that introduce compressive residual stress, such as shot peening and laser shock peening, are already standard practice. An electron beam process that achieves hardening with precisely controlled compressive stresses, while leaving no embedded media on the surface and treating complex shapes with a scanning beam, could compete in that space. Conversely, the ductility-enhancing radially converging treatment may suit applications where surface cracking under contact stress is the limiting failure mode, or where a compliant surface layer could improve the mechanical compatibility of implants with bone, which is stiffer than titanium and stresses the implant surface in complex ways.

What elevates the study beyond incremental process optimisation is its demonstration that surface engineering is a geometric problem, not merely an energetic one. Two beams carrying identical energy per pulse, delivered for identical durations and repeated an identical number of times, sculpted the same alloy into two different surface materials with opposite mechanical characters. As pulsed-beam sources with configurable geometries mature, designers may one day specify not just the hardness of a titanium part’s surface but the full stress-and-texture recipe, dialling in hardening or softening on demand. The Tomsk team’s comparative analysis provides the first rigorous, like-for-like evidence that the dial exists, and it points toward a future where the direction of an electron beam matters as much as its power.

Subject of Research: Surface modification of the Ti–6Al–4V titanium alloy by low-energy high-current pulsed electron beams in different irradiation geometries

Article Title: Comparative analysis of Ti–6Al–4V surface modification under axially symmetric and radially converging electron–beam irradiation configurations

Article References: Meisner, L. L., D’yachenko, F. A., Ostapenko, M. G., Meisner, S. N., Markov, A. B., Yakovlev, E. V., Kiziridi, P. P., & Solovyov, A. V. (2026). Comparative analysis of Ti–6Al–4V surface modification under axially symmetric and radially converging electron–beam irradiation configurations. Journal of Materials Science, 61(44), 35116-35144. https://doi.org/10.1007/s10853-026-13825-2

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13825-2

Keywords: Ti-6Al-4V, electron beam treatment, surface modification, low-energy high-current electron beam, radially converging beam, residual stress, crystallographic texture, hardness, ductility, titanium alloys, phase transformation, materials science

The two materials at the heart of the study could hardly be more different in character. Burnt clay bricks, or BCB, are the conventional workhorse of masonry construction in South Asia and much of the developing world, fired in kilns at high temperature and prized for their compressive strength. Unburnt sandcrete blocks, or USB, made from a sand-cement mix and cured without firing, represent a greener alternative because they avoid the energy intensity and emissions of brick kilns. In many rapidly urbanizing countries, both materials sit side by side in the same neighborhoods, often in the same buildings, yet their influence on how a frame behaves in an earthquake has rarely been compared head to head under controlled laboratory conditions. That gap is precisely what the Bangladeshi team set out to close.

The experimental program involved three small-scale multi-story, multi-bay reinforced concrete frames, each partially infilled with a different masonry unit, subjected to quasi-static cyclic loading that mimics the back-and-forth demands of a strong earthquake. The researchers evaluated seismic performance through hysteretic behavior, the looped force-displacement curves that encode a structure’s strength, stiffness, ductility and capacity to dissipate energy. These four quantities are the currency of earthquake engineering: strength determines the load a frame can carry, stiffness governs how much it sways, ductility measures how far it can deform before collapse, and energy dissipation reflects how effectively the structure absorbs the earthquake’s input rather than passing it on to its occupants.

The headline finding is that the type of infill masonry matters far more than many design codes assume. The frames with burnt clay brick infills delivered the highest lateral load capacity of the three specimens, confirming the material’s reputation for stiffness and strength. But that strength came at a cost. The BCB-infilled frames showed sudden degradation of their initial stiffness and a brittle post-peak response, meaning that once the infill panels began to fail, the loss of strength and stiffness was abrupt rather than gradual. In seismic terms, brittleness is dangerous because it gives occupants and structures little warning and little reserve capacity after the peak demand has passed.

The unburnt sandcrete block infills told a different and arguably more nuanced story. Although the USB-infilled frames reached a slightly lower maximum lateral capacity, they exhibited improved ductility and the highest post-peak cumulative energy dissipation of the studied frames. In other words, the greener material did not simply lose to the conventional one; it traded a modest amount of peak strength for a more forgiving failure mode, deforming further and absorbing more cumulative energy after its peak load had been exceeded. For engineers weighing sustainability against safety, the study suggests that the trade-off is not one-sided, and that softer, weaker infills may actually enhance the survivability of a frame in a severe event, provided the reduced strength is accounted for in design.

Beyond the material comparison, the study examined failure mechanisms in detail and found extensive damage concentrated in the frame members and infill panels near the exterior beam-column joints. This observation matters because exterior joints are precisely the locations where infill frames are most vulnerable in real earthquakes: the panels interact with the surrounding columns and beams, transferring forces that the bare frame was never designed to resist. The concentration of damage near these joints echoes a long-standing concern in the literature, dating back decades to pioneering work on infilled frames, that infills can create unintended load paths, short columns and local failure concentrations that compromise an entire building even when the code-designed frame itself is adequate.

The second half of the study turned from the laboratory to the computer. The team evaluated two available macro-models of masonry infilled reinforced concrete frames, assessing how reliably they could predict the measured seismic performance. Macro-models, typically built from equivalent diagonal struts that stand in for the infill panel, are the workhorses of seismic assessment because modeling every brick individually is computationally prohibitive for whole buildings. The verdict, however, was sobering. Implementing the two macro-models proved difficult, and neither reproduced the experimental behavior with acceptable accuracy. One model depended on substantial empirical calibration, effectively requiring test data to be tuned before it could predict test data, while the other tended to overestimate both stiffness and energy dissipation, painting an optimistic picture that real structures may not match.

These modeling shortcomings have practical consequences. Nonlinear static and dynamic analyses of infilled buildings underpin seismic retrofit decisions, loss estimates and code provisions worldwide, from FEMA guidelines to Eurocode 8 and national codes such as the Bangladesh National Building Code. If a macro-model overestimates energy dissipation, it will underpredict displacements and could lead engineers to conclude a building is safer than it is. If it requires extensive calibration, its predictive value for buildings that have never been tested, which is to say nearly all of them, is limited. The study’s experimental dataset, generated with support from the Housing and Building Research Institute and Chittagong University of Engineering and Technology, therefore serves a dual purpose: it documents how two common infill materials behave, and it provides a benchmark against which future models can be honestly judged.

The broader significance of the work lies in the collision between sustainability goals and seismic safety. As countries seek to phase out energy-hungry brick kilns, unburnt alternatives such as sandcrete blocks are being promoted on environmental grounds, sometimes with little attention to their structural implications. This study suggests that such a transition need not be seismically harmful and could even improve post-peak performance, but it also warns that the two materials produce measurably different frame responses in stiffness degradation, strength, ductility and energy dissipation. Codes and assessment procedures that treat all masonry infills as equivalent, or that ignore infills altogether, are missing behavior that the experiments show to be significant and, in the case of brittle burnt brick panels, potentially hazardous.

For a region that sits near the active boundaries of the Indian and Eurasian plates and carries the memory of devastating earthquakes, research of this kind is not academic. The study’s combination of physical testing and critical numerical evaluation offers engineers a clearer picture of what actually happens inside an infilled frame when the ground shakes, and a candid reminder that the computational tools used to certify safety still lag behind the messy reality of masonry-concrete interaction. As Mukhlis and his colleagues demonstrate, the humble brick in the wall may be the most important structural element nobody designed.

Subject of Research: Seismic performance of reinforced concrete frames infilled with burnt clay brick and unburnt sandcrete masonry

Article Title: Seismic performance of RC frames with burnt and unburnt brickwork masonry infills: experimental and macro-model evaluation

Article References: Mukhlis, M. R., Das, A., Islam, S. M. M., & Bhuiyan, M. A. R. (2026). Seismic performance of RC frames with burnt and unburnt brickwork masonry infills: experimental and macro-model evaluation. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02670-y

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02670-y

Keywords: reinforced concrete frames, masonry infill, burnt clay bricks, sandcrete blocks, seismic performance, hysteretic behavior, stiffness degradation, ductility, energy dissipation, macro-modeling, earthquake engineering, Bangladesh

The study, published in the Bulletin of Earthquake Engineering by Ju-Seong Jung of Chungwoon University and colleagues at Hanyang University’s Innovative Durable Building and Infrastructure Research Center, proposes a hybrid system the authors call BFC-FRP: a combination of prefabricated basalt fiber sheets and fiber-reinforced polymer panels applied to the surface of reinforced concrete columns. Basalt fiber, drawn by melting volcanic rock at high temperature, has attracted growing attention in structural engineering because it offers a favorable balance of mechanical performance, chemical stability, and cost compared with the glass and carbon fibers that have traditionally dominated the retrofit market.

To test the concept, the team fabricated seven large-scale columns, each with a square cross section of 350 by 350 millimeters and a clear height of 1.5 meters, dimensions representative of real building columns rather than miniature laboratory proxies. Three of the specimens were detailed to fail in shear, the most dangerous failure mode because it is sudden and brittle, while four were designed to be flexure-controlled, meaning their response is governed by bending and tends to be more ductile. Every column was then pushed sideways under reversed cyclic lateral loading, the laboratory equivalent of the back-and-forth motion an earthquake imposes, while a constant axial load corresponding to a ratio of 0.10 pressed down from above.

The strengthening scheme varied along two experimental axes. The first was coverage: some columns received strengthening only in the end regions, where damage typically concentrates, while others were wrapped over their full surface. The second was the arrangement of the prefabricated basalt fiber sheets and the FRP panels, allowing the researchers to compare how different configurations of the composite layers influenced confinement of the concrete and restraint of the longitudinal reinforcement. This systematic variation is what gives the study its practical value, because retrofit budgets rarely allow blanket coverage, and engineers need to know whether partial wrapping is enough.

The results for the shear-critical columns were striking. Full-surface BFC-FRP strengthening increased the ultimate strength by approximately 1.5 times compared with the unstrengthened control specimen, but the more important gain was in deformation: the displacement reached at ultimate strength grew by a factor of 2.0 to 2.6. In seismic terms, that transformation matters more than raw strength. A column that can keep carrying load while being pushed far sideways gives occupants time to evacuate and prevents the soft-story collapse mechanism that has killed thousands of people in recent earthquakes worldwide, from Turkey and Syria to Morocco and Japan.

For the flexure-controlled columns, which started from a more forgiving baseline, the retrofit delivered different but equally consequential improvements. The ultimate displacement increased by roughly 1.4 times, and the ductility ratio, a normalized measure of how much inelastic deformation a member can sustain before losing capacity, nearly doubled. Most notably, the energy dissipation capacity, which quantifies how much seismic energy the column can absorb and dissipate through hysteretic behavior in each loading cycle, rose by approximately 2.4 to 2.5 times. Since earthquake-resistant design fundamentally relies on structures dissipating energy rather than simply resisting force, this multiplication of dissipative capacity is arguably the study’s headline finding.

Alongside the physical tests, the researchers built nonlinear quasi-static cyclic finite element models of the columns using the disturbed stress field model, a mechanics-based formulation for reinforced concrete developed at the University of Toronto and implemented in analysis software widely used for shear-dominated members. The modeling work serves a purpose beyond reproducing the experiments: if a numerical framework can reliably predict how a wrapped column will deform and dissipate energy, engineers can extend the findings to configurations that were never tested, and design codes can eventually incorporate the strengthening system with confidence.

The models performed well. They reproduced both the load-displacement envelopes and the energy-dissipation responses of the tested columns with average deviations of approximately 10 percent, a level of accuracy that is respectable for nonlinear analysis of reinforced concrete, a material whose cracking, crushing, and bond-slip behavior is notoriously difficult to capture. The authors note that these results demonstrate the proposed BFC-FRP system can improve the deformation and energy-dissipation capacities of both shear- and flexure-controlled columns within the tested conditions, a carefully scoped conclusion that reflects the bounded nature of laboratory evidence.

The work sits within a broader and urgent engineering challenge: seismic strengthening of existing buildings. International guidelines, including documents from the American Concrete Institute and the Japan Building Disaster Prevention Association, already recognize externally bonded FRP systems as a legitimate retrofit strategy, but the field continues to search for materials that lower cost and improve sustainability. Basalt fiber fits that agenda well because its raw material is abundant volcanic rock, requiring no energy-intensive precursor chemistry of the kind needed for carbon fiber. Recent studies have explored basalt composites for repairing earthquake-damaged and corroded beam-column joints, for strengthening precast bridge piers, and even for confining columns built with recycled brick aggregates, suggesting a rapidly maturing research ecosystem.

For practitioners, the Korean team’s findings offer a concrete, quantified case for considering basalt-based wrapping when assessing older building stock, particularly in regions where shear-critical columns from pre-modern-code construction remain common. The demonstration that full-surface wrapping can more than double the deformability of brittle shear-critical columns, while partial schemes remain available where budgets constrain coverage, gives retrofit designers a tested menu of options. As with any laboratory campaign, the caveats are real: the tests covered a single axial load ratio, one column size, and specific composite arrangements, and fire performance of FRP-strengthened members remains a recognized consideration in practice. But the combination of large-scale testing, systematic parameter variation, and validated numerical modeling makes a persuasive case that volcanic rock, spun into fiber and bonded onto concrete, can help the world’s aging buildings stand up to the next big shake.

Subject of Research: Seismic retrofit of reinforced concrete columns using basalt fiber-reinforced polymer composites

Article Title: Experimental and numerical investigation on the seismic performance of reinforced concrete columns retrofitted with basalt FRP composites

Article References: Jung, J.-S., Lee, B.-G., Kim, K., & Lee, K.-S. (2026). Experimental and numerical investigation on the seismic performance of reinforced concrete columns retrofitted with basalt FRP composites. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02653-z

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02653-z

Keywords: basalt fiber, FRP, seismic retrofit, reinforced concrete columns, cyclic loading, ductility, energy dissipation, finite element analysis, disturbed stress field model, shear-controlled columns, flexure-controlled columns, earthquake engineering