Apple’s record stock performance leads into a discussion of Vision Pro and John Ternus’ explanation of its long-term potential. The MacVoices Live! panel considers spatial computing’s growing role in medicine, productivity, and professional workflows, along with whether the technology is ready for broader adoption. They also examine iPhone battery shipping limits, SoftRAID 9's support of RAID 6, and local versus cloud storage.
Italie : Au coeur d’une ville vivante, entre rires de passants et cliquetis de verres, elle se dresse — immobile, immense, indifférente au tumulte. L’Arène de Vérone, cicatrice sublime d’un empire révolu, attend. Sous ses arches érodées, les siècles se taisent. Un silence dense, presque sacré,...
Aujourd'hui, la réutilisation des eaux usées pour refroidir les data centers est en train de devenir un levier de préservation des ressources hydriques et de protection de l'environnement alors que ces infrastructures sont en pleine expansion partout dans le monde.
Balayer apaiserait l'esprit, frotter régulerait le système nerveux : l'idée circule des monastères zen aux cabinets de psychologues. La littérature scientifique dit autre chose. Chez les femmes actives, la charge domestique est associée à une dégradation de la santé mentale, et aucun essai n'a...
Our solution hinges on splitting the Apple Reference Image process into two phases: creating a secure digital negative, and developing that negative into a reference image. Each phase receives our strongest protections.
[…]
Apple Reference Image provides both a lower bound and an upper bound on capture time from Apple’s cryptographic timestamp service, and we guarantee the photo was taken between the two bounds. On a regular heartbeat, the device requests a cryptographic timestamp token, and retains the most recent one it has received. Globally this happens on average every 15 minutes, though the interval depends on local network conditions. This provides a proven lower bound timestamp for the photographic capture. After capture, the device requests a second timestamp to use as an upper bound, and both timestamps are embedded and signed with the sensor data.
[…]
When the user chooses to create a reference image, the device uploads the digital negative to PCC, which runs the processing steps needed to render the image — including demosaicing, tone mapping, and compression — in a highly secure, private, and verifiable environment. Experts can verify that PCC doesn’t alter a digital negative during development: they can examine the software that does the work.
[…]
Finally, as no security system is perfect, we created a revocation system that can revoke individual photos, as well as all photos from a specific sensor.
[…]
We built Apple Reference Image to avoid using an explicit, public credential for photographers, and to avoid even implicit public association between different photos taken by the same sensor. The final reference image is instead signed by Apple’s signing service, after validation by PCC.
Half a year after Iranian drone strikes knocked out multiple Amazon data centers, the US tech company has acknowledged the permanent loss of some customer data that was hosted in Bahrain and the United Arab Emirates.
Amazon Web Services was “unable to restore access to the resources and data” hosted in some of the war-damaged data centers, according to an AWS dashboard update posted on September 15. The development was first reported by Reuters and suggests that the Iranian strikes inflicted catastrophic damage on the data centers.
Customer data was irretrievably lost in one of three AWS availability zones in the United Arab Emirates region, specifically the mec1-az2 availability zone. Each availability zone is serviced by one or more Amazon data centers.
Half a year after Iranian drone strikes knocked out multiple Amazon data centers, the US tech company has acknowledged the permanent loss of some customer data that was hosted in Bahrain and the United Arab Emirates.
Amazon Web Services was “unable to restore access to the resources and data” hosted in some of the war-damaged data centers, according to an AWS dashboard update posted on September 15. The development was first reported by Reuters and suggests that the Iranian strikes inflicted catastrophic damage on the data centers.
Customer data was irretrievably lost in one of three AWS availability zones in the United Arab Emirates region, specifically the mec1-az2 availability zone. Each availability zone is serviced by one or more Amazon data centers.
Les banques de semences sont censées préserver une partie de notre patrimoine agricole pendant des décennies, voire bien davantage. Mais combien de temps ces graines peuvent-elles réellement rester capables de germer ? Une vaste analyse menée en Australie apporte une réponse moins rassurante...
A team of archaeologists digging at the site of Ursoaia, in Romania’s Iași County, has uncovered a nearly 6,000-year-old pottery kiln unlike anything previously found in the region. Described in a paper published this month in the journal Antiquity by Diana Măriuca Vornicu, Felix-Adrian Tencariu and colleagues from the Romanian Academy and Alexandru Ioan Cuza […]
Xcode 27 includes Swift 6.4 and SDKs for iOS 27, iPadOS 27, tvOS 27, watchOS 27, macOS 27, and visionOS 27. Xcode 27 supports on-device debugging in iOS 17 and later, tvOS 17 and later, watchOS 10 and later, and visionOS. Xcode 27 requires a Mac running macOS Tahoe 26.6 or later.
Building with Xcode 27 doesn’t work because of some intransparent XCStrings error… and I even can’t check with Xcode 26 anymore because Apple decided to not let me run it on macOS 27…
iPhone 18 Pro arrives with Apple concentrating its biggest changes in three areas: camera control, sustained performance, and battery life. The new Pro models retain familiar 6.3-inch and 6.9-inch display sizes, but introduce a variable-aperture main camera, the 2-nanometer A20 Pro chip, redesigned thermal hardware, and a smaller Dynamic Island.
The lineup consists of iPhone 18 Pro and iPhone 18 Pro Max, starting at $1,199 and $1,299 in the U.S., respectively. Both begin with 256GB of storage and are available in black, silver, glacier, and a new burgundy finish. Preorders opened September 12, with retail availability beginning September 18 in more than 65 countries and regions.
Rather than treating the Pro models as a cosmetic update, Apple has focused on changes that become more noticeable during demanding use, particularly photography, video work, gaming, AI processing, and long sessions away from a charger.
iPhone 18 Pro brings variable aperture to the main camera
The centerpiece is a new 48MP Fusion Main camera with a physical variable aperture, a first for the iPhone.
Six laser-cut aperture blades can adjust the amount of light reaching the sensor while also changing depth of field. The camera supports four aperture settings: ƒ/1.48, ƒ/1.8, ƒ/2.8, and ƒ/4.0.
At the wider end, the camera can gather more light in darker scenes. A narrower aperture can keep more people or background detail in focus, giving photographers another tool beyond computational depth effects and Portrait mode.
Apple also gives users direct access to those settings through new Pro controls in the Camera app. Aperture, shutter speed, and white balance can be adjusted manually, while a histogram provides a more conventional way to monitor exposure.
The feature is paired with a new main-camera sensor and updated computational imaging pipeline. Apple says the combination improves low-light performance and detail, while Photographic Styles gain texture and grain controls for additional control over an image’s appearance.
Video receives several additions as well. Cinematic effects can now be applied after recording to footage captured at up to 60 frames per second, while Time-lapse can record in 4K with Dolby Vision HDR. Audio Mix has also been updated with improved voice processing and the ability to isolate music.
For photographers who want more evidence of how an image originated, Apple is introducing Apple Reference Image. In Reference mode, the main camera signs sensor data, which Private Cloud Compute uses to create an unalterable reference version that can be compared with an edited image in Photos. Apple is also preparing support for the SynthID standard as another way of identifying AI-generated or altered content.
Image Credit: Apple Inc.
iPhone 18 Pro uses A20 Pro and a redesigned vapor chamber
A20 Pro is built using a 2-nanometer manufacturing process and contains a six-core CPU, seven-core GPU, and dual 16-core Neural Engine.
Apple says memory bandwidth is 50% higher than on A19 Pro, while GPU performance can be up to 40% faster. The Neural Engine provides 32 cores in total, doubling the AI processing capability of the previous Pro chip.
The silicon change is closely tied to a redesigned cooling system. Apple has rearranged the chip package so that the silicon die sits beside the memory rather than beneath it in the thermal path, allowing A20 Pro to connect more directly to a next-generation vapor chamber.
That vapor chamber has three times the surface area of the previous generation and uses new materials to move heat away from the processor more effectively. Apple claims the design can deliver up to a 40% gain in sustained performance compared with iPhone 17 Pro.
That distinction is more relevant than peak benchmark numbers for workloads such as extended gaming sessions, video editing, computational photography, and local AI models, where heat can force a phone to reduce performance over time.
Connectivity has also moved further toward Apple-designed silicon. The N1 wireless chip supports Wi-Fi 7, Bluetooth 6, and Thread, while the new C2 modem succeeds C1X. Apple says C2 uses 15% less energy while offering faster uploads and adds mmWave support in the U.S.
Image Credit: Apple Inc.
iPhone 18 Pro Max reaches 45 hours of video playback
Battery improvements are another major part of the new hardware.
Apple rates eSIM-only versions of iPhone 18 Pro for up to 36 hours of video playback, while iPhone 18 Pro Max reaches as much as 45 hours. Apple says Pro Max receives the largest battery-life increase ever delivered in an iPhone.
Some of that gain comes from using the space previously occupied by a physical SIM tray. In markets receiving eSIM-only models, including the U.S., Canada, Japan, Mexico, Saudi Arabia, and the UAE, the larger internal battery provides an additional two hours of rated video playback.
Charging has accelerated as well. iPhone 18 Pro can reach 50% charge in approximately 15 minutes using a supported wired setup, while wireless charging reaches 50% in around 30 minutes. Apple says five minutes of wired charging on iPhone 18 Pro Max can provide roughly seven hours of video playback.
Both devices use aluminum unibody construction with Ceramic Shield 2 on the front and Ceramic Shield on the back. Storage options run from 256GB through 2TB.
The iPhone 18 Pro weighs 211 grams, while iPhone 18 Pro Max weighs 249 grams. Display sizes remain 6.3 inches and 6.9 inches, respectively.
Image Credit: Apple Inc.
iOS 27 brings Siri AI and new Apple Intelligence tools
The hardware launches alongside iOS 27, which places Apple Intelligence and the new Siri AI more prominently across the system.
Siri AI can use personal context from information stored across apps, respond to onscreen content, perform actions in supported apps, and handle more open-ended questions. A new Siri mode in Camera lets users ask questions and take action based on objects or information visible through the viewfinder.
Photo tools include Spatial Reframing, Extend, and an upgraded Clean Up feature, while Safari can monitor selected webpages for changes such as a product restock or price adjustment.
The Dynamic Island has also been physically reduced and redesigned. It can display up to three Live Activities simultaneously while continuing to support Face ID.
Apple released iOS 27 on September 14, while Siri AI is rolling out initially as a beta in English, with additional language support planned. iPhone 18 Pro and iPhone 18 Pro Max reach stores September 18, giving Apple a Pro lineup whose most substantial additions are less about a new exterior shape and more about physical camera control, heat management, and how long the hardware can sustain demanding workloads.
Des chercheurs chinois ont publié une étonnante étude sur une solution radicale pour protéger la Terre d'un astéroïde géant : l'enfouissement d'une bombe nucléaire dans le rocher spatial. Ce n'est pas de la fiction, rien que de la physique, des simulations et des calculs. La menace est réelle,...
The page is designed in an annoying way that requires sideways scrolling, and there doesn’t seem to be a PDF list of the new features like in previous years.
[Even] though a bootable backup is properly configured to boot, they aren’t showing up as choices in either the startup disk preference pane or the startup picker. (FB24210103, reported quite a while ago, Apple friends.)
In the German state of Brandenburg, barely a hundred meters (about 330 feet) from the border with Saxony-Anhalt, the Havel River curls around a low rise of land that locals call the Pilatsch. For generations, a local legend held that a knight named Pilatus lived there, ambushing boats on the river and locking captured boatmen […]
A team led by the National Museum of Denmark has worked out, for the first time, what people actually cooked in the pots of Hama, an ancient city in western Syria, roughly 4,500 years ago. By analyzing animal bones, plant remains, and fat residues absorbed into the vessel walls, the researchers found a surprisingly varied […]
With its built-in USB / HDMI hub and a small fan to keep temperatures in check, Sharge's Disk Pro SSD is one of the more interesting (and generally useful) external storage drives in recent memory, easily earning a spot on our Best External SSD list. And the company is following that success up with a more DIY-focused Disk Pro 2, which lets you install your own M.2 drive (supporting 2230, 2242, and 2280 sizes and capacities up to 8TB), while adding greater fan flexibility, media card slots, and an HDMI port that's capable of more bandwidth – depending on the model you choose.
Sharge is offering the Disk Pro 2 in two varieties. There's the Lite model, with HDMI 2.0 (4K@60 Hz) and a 5W minimum operating power, and the Disk Pro Ultra (which we have in for testing) with HDMI 2.1 (4K@144 Hz or 8K@30 Hz), a lower 1.5W minimum power draw, and a faster card reader. Below is the full list of differences, according to the product page. The company even lists the internal chips, some of which you can see through its transparent top.
Disk Pro Ultra
Disk Pro Lite
HDMI
HDMI 2.1, 4K@144 Hz, 8K@30 Hz
HDMI 2.0, 4K@60 Hz
Minimum Operating power
1.5W
5W
Chips
VL822, VL605, RTL9210, SM2705
GVS2201S, VL822, GL3231, RTL9201
SD speed
Read 180 MB/s, Write 120 MB/s
Read 100 MB/s, Write 90 MB/s
(Image credit: Tom's Hardware)
The Ultra model is likely to appeal more to professionals and gamers, offering faster card transfers and higher monitor refresh rates. But the main limitation here is the overall bandwidth, as both models are capped at a 10 Gbps interface, just like the original Disk Pro. That makes either model better as kind of a travel-friendly Swiss Army hub than something you'd want to use as your primary hub / dock all the time. Because any modern M.2 drive can saturate all available throughput by itself, before you connect any video or USB devices. But there's no denying the utility of carrying around a pocket-friendly SSD that also lets you connect to a monitor or TV, plug in a couple extra peripherals, and empty your SD cards without an extra hub, adapters, or cables.
(Image credit: Tom's Hardware)
At 3.65 x 2.33 x 0.531 inches (92.6 × 59.2 × 13.5 mm) without the cable, the Disk Pro 2 is slightly thicker and longer than the original Disk Pro, but still smaller than some standalone drives. Again, with its size and transparent top, it reminds me of an old-school cassette tape.
(Image credit: Tom's Hardware)
One thing that has definitely improved over the original Disk Pro is that Sharge has made the USB-C cable removable. This is good in part because you don't have to worry about the cable breaking over years of use. But also, particularly if you're going to use the drive's hub capabilities, you might want something longer than the included cable's sub-nine-inch length. And when necessary, you might want to plug the drive into a USB-A port. So having the option of using different cables is a big plus.
The cable is also designed to function as a lanyard, which can be handy. But it's held in place solely by the USB-C connection, so I wouldn't trust it for much more than hanging the hub up somewhere at home, so you know where it is when you need it.
(Image credit: Tom's Hardware)
In terms of ports, starting from the bottom edge, you get the main USB-C port, capable of passing through up to 80W of power, a full-size HDMI port (2.1 on the Ultra model we're testing or 2.0 on the lite model), a USB 3.0 Type-A port, and a 10 Gbps USB-C port that can handle up to 100W of power input (and pass through up to 80W for charging a laptop or other device). The previous Disk Pro included a second USB-A 2.0 port here as well, but it's been ditched in favor of the removable USB-C cable, which I think is well worth the sacrifice.
(Image credit: Tom's Hardware)
On the opposite (top) edge, Sharge has added an SD card slot and a microSD card slot. These are capabilities the original Disk Pro didn't have, which make the newer model a lot more versatile for content creators. Just remember the Ultra model offers up faster read and write speeds for the card slots.
(Image credit: Tom's Hardware)
Around back, there's not a lot to see save for the fan intake, but the back is also magnetic, letting you snap the drive onto smartphones that support MagSafe devices or Qi2 magnetic peripherals — it's just a physical mount, though, not receiving power. I've also found this feature handy for sticking the drive to a refrigerator or other iron surface so I always know where it is when I need it.
(Image credit: Tom's Hardware)
It's also worth pointing out that the fan in the Disk Pro 2 is smaller than on the Disk Pro. But there are larger cutouts for air intake on the sides for when the hub is lying on a table or desk, and the Pro offers a three-mode switch (off, on, and turbo), whereas the original's switch had two settings (auto and on). I appreciate the active cooling, and it will certainly be helpful if you're using most of the hub's ports and the SSD at the same time. But if you're mostly using the Disk Pro 2 solely for basic, bursty storage tasks, the 10 Gbps interface and an efficient SSD aren't likely to get warm enough to require active cooling. Of course, that will heavily depend on which drive you install in the enclosure, as well.
Testing with Lexar's 710 SSD
Sharge sent along its Disk Pro 2 Ultra with a Lexar 710 M.2 SSD (a PCIe 4.0 drive that's capable of about 5x the bandwidth of the hub itself), and installing it is about as straightforward as you'd expect. Use the small included screwdriver to remove a tiny screw on the side, and the SSD cover lifts off. Loosen the drive anchor post, install the SSD, tighten the post, put the cover back on, and reinstall the cover anchor screw on the side.
You can, of course, install your SSD of choice, and below the 10 Gbps interface cap, your performance will vary by drive. Still, since the company sent along the Lexar drive, we ran a couple of our external storage benchmarks, and the Disk Pro 2 Ultra performed well for an SSD in this class, just like the original Disk Pro.
Trace Testing - PCMark 10 Storage Benchmark
PCMark 10 is a trace-based benchmark that uses a wide-ranging set of real-world traces from popular applications and everyday tasks to measure the performance of storage devices.
(Image credit: Tom's Hardware)
The Sharge Disk Pro 2 Ultra does exceptionally well here, beating everything save for Corsair's USB4-based EX400U. Impressively, the 10 Gbps drive even beat the 10 Gbps X10 Pro on this test, proving available bandwidth isn't everything when it comes to drive responsiveness.
(Image credit: Tom's Hardware)
In this real-world bulk transfer test, Sharge's Disk Pro 2 Ultra lands in a comfortable fourth place, behind 40 Gbps and 20 Gbps drives, and one spot behind the 10 Gbps Crucial X9 Pro drive on reads. But on writes, Sharge's enclosure, running the Lexar SSD, again beats everything in this chart save for Corsair's USB4 drive.
Synthetic Testing CrystalDiskMark
CrystalDiskMark (CDM) is a free and easy-to-run storage benchmarking tool that SSD companies commonly use to assign product performance specifications. It gives us insight into how each device handles different file sizes. We run this test at its default settings
(Image credit: Tom's Hardware)
Lastly, in this best-case-scenario synthetic test, the Disk Pro 2 lands in fifth place when it comes to reads, but fourth place on writes.
Again, the Disk Pro 2's performance on benchmarks will depend largely on what drive you put inside it. But it's clear that the SSD enclosure is capable of performing well, despite its 10 Gbps bandwidth limitations.
Pricing and Bottom Line
(Image credit: Tom's Hardware)
If all you really care about is dropping in a drive and moving some files around, there are plenty of cheap 10 Gbps enclosures, often on sale for $20 or less. But if you travel a lot with tech and like the idea of a drive enclosure that includes a data and video hub with PD power passthrough, the Disk Pro 2 offers a lot to like, with the Ultra version we tested capable of handling video output bandwidth as high as 8K at 30 Hz (or 4K at 144 Hz). And the inclusion of card reader slots makes the enclosure even more useful for creators on the go.
It's far from cheap, at $109 for the Ultra version we tested or $79 for the Lite version, which is still capable of 4K video at 60 Hz, but won't play as well with phones, due to a higher minimum power draw. But Sharge's devices often go on sale, and when this was written, the Late model was selling for $66.51 and $80.91, directly from the company. This is technically a pre-order price, as the enclosures are expected to start shipping on October 15th.
There are also enclosure / hub combos on Amazon and Newegg that promise similar functionality for less. But the ones I saw have generally poor reviews, are larger than the Disk Pro 2, and none of them look as pleasing or are as feature-packed as Sharge's design, with its transparent cover, active cooling, and MagSafe-compatible back. For those looking for portable connectivity and up to 8TB of storage in one device on the go, the Sharge Disk Pro 2 is in a class of its own, and easily earns a spot on our best SSD and hard drive enclosure list.
When a tunnel catches fire, temperatures inside the concrete lining can soar to 800 or 900 degrees Celsius, and the emergency response almost always involves dousing the structure with water. A new study suggests that this familiar firefighting image—flames followed by a torrent of cooling water—may be doing far more damage to the concrete than engineers have typically accounted for. Researchers investigating basalt fiber-reinforced concrete have found that how a fire-damaged structure is cooled can be as important as how hot it got in the first place, with water quenching consistently inflicting greater strength loss than slow, natural cooling across every temperature they tested.
The research, published in Case Studies in Construction Materials, systematically examined how heating temperature, cooling regime, fiber content, and impact loading combine to determine whether concrete survives a fire with its load-bearing capacity intact. The team, led by Yang Liu and colleagues including Delin Li, Jinyue Dong, Yingda Zhang, Xianliang Zhou, and Qiong Zhou, chose basalt fiber-reinforced concrete, or BFRC, as their test material because of the fiber’s unusual combination of properties. Basalt fibers, drawn from volcanic rock, offer high tensile strength, thermal stability up to melting points between 1350 and 1450 degrees Celsius, and a cost profile far more attractive than premium alternatives such as carbon fiber. This makes them an appealing candidate for tunnel linings, where fire resistance and economy must be balanced.
The experimental design was exhaustive. The researchers prepared a C35-grade concrete mix—the grade commonly recommended for tunnel design—using ordinary Portland cement, medium sand, and continuously graded gravel between 5 and 10 millimeters. Into this base mix they incorporated chopped basalt fibers, 12 millimeters long with a monofilament diameter of 17 micrometers, at volume fractions of 0, 0.1, and 0.2 percent. The fibers were added in small batches during dry mixing to prevent agglomeration, and the fresh concrete was cast into cylindrical specimens measuring 50 millimeters in diameter and 25 millimeters in height, then cured under standard conditions at 20 degrees Celsius and 95 percent relative humidity.
The thermal assault began in a high-temperature electric oven capable of reaching 1200 degrees Celsius. Specimens were heated at a controlled rate of 5 degrees Celsius per minute to target temperatures of 200, 400, 600, and 800 degrees Celsius, then held at temperature for a full hour to ensure the heat penetrated the interior. Half the specimens were then removed and allowed to cool naturally in ambient air, mimicking a structure left to cool on its own after a fire. The other half were plunged immediately into a tank of tap water, replicating the thermal shock of firefighting operations. After cooling, the water-immersed specimens were conditioned in air for seven days to return them to a natural moisture state before testing.
The dynamic mechanical properties were then probed using a split Hopkinson pressure bar, the workhorse instrument for measuring how materials behave under the extreme strain rates produced by impacts and blasts. The apparatus used bars 75 millimeters in diameter, made of high-strength steel with an elastic modulus of 210 gigapascals, with a striker bar propelled by compressed gas striking an incident bar that transmitted stress waves through the specimen. Three impact velocities—3.5, 4.4, and 5.2 meters per second—were tested, achieved by varying the operating gas pressure, with three specimens per condition. A thin pulse shaper was pasted at the impact end of the incident bar to smooth out high-frequency oscillations, and stress equilibrium between the two faces of each specimen was verified from strain-gauge signals, confirming the reliability of the data. Fragments from each impact were sieved through meshes ranging from 4.75 millimeters down to 75 micrometers so that a fractal dimension could be calculated, providing a quantitative measure of how thoroughly each specimen shattered.
The visual evidence of thermal damage followed a familiar but telling progression. At 200 degrees Celsius, the concrete surfaces turned bluish-gray, with no cracking. By 400 degrees, the color shifted to yellowish-gray, still structurally sound. At 600 degrees, fine cracks appeared along with slight surface peeling, and by 800 degrees the specimens showed severe cracking, spalling, and edge breakage. Water-cooled specimens generally exhibited more pronounced surface damage than their naturally cooled counterparts, and at 800 degrees the concave shape at the start of the stress-strain curve—evidence of pre-existing microcracks being closed under compression—was especially marked in the water-quenched samples.
The strength data told a stark quantitative story. For naturally cooled specimens containing 0.2 percent basalt fiber, the dynamic peak stress at an impact velocity of 3.5 meters per second fell from 51.1 megapascals at room temperature to 18.6 megapascals at 800 degrees—a reduction of 63.6 percent. Water cooling made matters worse across the board: at the same impact velocity, the reductions reached 23.9 percent at just 200 degrees and climbed to 64.9 percent at 800 degrees. Averaged across the temperature range, each 100-degree increment cost naturally cooled specimens roughly 6.7 to 8.0 percent of their strength, while water-cooled specimens lost about 7.5 to 8.1 percent per 100 degrees. The gap between the two cooling regimes widened at higher impact velocities: at 5.2 meters per second and 800 degrees, the water-cooled specimens suffered 6.4 percent greater strength loss than the naturally cooled ones, whereas at the lowest velocity the difference was a mere 1.3 percent. The explanation lies in competing timescales—at slow loading rates, cracks have time to propagate and dissipate energy, blunting the effect of water-induced damage, but at high rates the loading outpaces the material’s energy dissipation, and the microcracks created by thermal shock propagate catastrophically.
Against this backdrop of degradation, the basalt fibers demonstrated genuine protective power. At every temperature from 200 to 800 degrees, specimens with 0.2 percent fiber content outperformed both plain concrete and the 0.1 percent mix. At 400 degrees and an impact velocity of 3.5 meters per second, the naturally cooled fiber-reinforced specimens reached peak stresses of 40.1 megapascals, some 16.9 percent above plain concrete, while at 200 degrees under water cooling the 0.2 percent mix achieved 38.8 megapascals—a remarkable 32.4 percent improvement over unreinforced concrete. The mechanism, the authors explain, is architectural: randomly distributed fibers form a three-dimensional network that binds tightly with the cementitious matrix, reduces internal pores and cracks, and bridges microcracks before they can coalesce into fracture surfaces. But this protection has a ceiling. Above roughly 600 degrees, the fibers begin to degrade and lose their reinforcing capability, and the fiber-matrix interface—already weakened by thermal mismatch between fiber and paste—becomes a liability during water quenching.
Fractal analysis of the impact debris added another layer of insight. The fractal dimension of the fragments rose steadily with temperature, from around 1.82 at 200 degrees to above 2.3 at 800 degrees under the highest loading rate, indicating progressively finer and more complex fragmentation. Water-cooled specimens consistently shattered into finer pieces than naturally cooled ones, particularly at 600 and 800 degrees, confirming that the steep thermal gradients during quenching seed dense populations of microcracks that later explode into fracture networks under impact.
Microstructural investigation grounded these observations in chemistry and physics. X-ray diffraction of specimens heated to 800 degrees showed the disappearance of calcium hydroxide peaks and weakened calcium carbonate signals, evidence that these phases had thermally decomposed—reactions that release vapor, increase porosity, and weaken the matrix. Scanning electron microscopy revealed the deterioration in vivid detail: an unheated specimen showed a dense microstructure with abundant calcium-silicate-hydrate gel and a compact interfacial transition zone around each aggregate, while specimens heated to 800 degrees contained no detectable C-S-H gel at all, their structure riddled with pores and cracks and hosting instead a dicalcium silicate-like phase. Comparing cooling regimes at 400 degrees, the naturally cooled sample remained relatively dense and rich in hydration products, whereas its water-quenched twin displayed obvious cracks at the interfacial transition zone and a loosened surrounding matrix—the fingerprint of thermal shock stress racing through the cooling material.
The practical implications reach well beyond the laboratory. Tunnel linings that survive a fire are routinely assessed and, if necessary, repaired, but this study shows that the assessment itself must account for the cooling history. A lining quenched by firefighting water may be significantly weaker than its peak temperature alone would suggest, particularly if it subsequently faces dynamic loads from traffic vibration, rockfall impacts, or secondary events. Conversely, the results give engineers a positive tool: specifying basalt fiber reinforcement at around 0.2 percent by volume can meaningfully bolster the impact resistance of fire-exposed concrete below 600 degrees, at a modest material cost. The authors frame their work as a theoretical foundation for post-fire safety assessment of tunnel linings and for the wider engineering adoption of basalt fiber-reinforced concrete—a reminder that in structural fire engineering, what happens in the minutes after the flames matter almost as much as the fire itself.
Subject of Research: Dynamic mechanical properties and deterioration mechanisms of basalt fiber-reinforced concrete after exposure to high temperatures under natural cooling and water cooling, investigated using split Hopkinson pressure bar testing, XRD, and SEM analysis.
Article Title: Dynamic mechanical properties of basalt fiber-reinforced concrete after exposure to high temperature and different cooling methods
Article References: Liu, Y., Li, D., Dong, J., Zhang, Y., Zhou, X., & Zhou, Q. (2026). Dynamic mechanical properties of basalt fiber-reinforced concrete after exposure to high temperature and different cooling methods. Case Studies in Construction Materials, 25, Article e06505. https://doi.org/10.1016/j.cscm.2026.e06505
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