Â鶹´«Ã½

Sci-Tech

    • Mystery of why Roman buildings have survived so long has been unravelled, scientists say

    Tourists visit Rome's Colosseum in June 2019. (EyesWideOpen/Getty Images) Tourists visit Rome's Colosseum in June 2019. (EyesWideOpen/Getty Images)
    Share

    The majestic structures of ancient Rome have survived for millennia — a testament to the ingenuity of Roman engineers, who perfected the use of concrete.

    But how did their construction materials help keep colossal buildings like the Pantheon (which has the world's largest unreinforced dome) and the Colosseum standing for more than 2,000 years?

    Roman concrete, in many cases, has proven to be longer-lasting than its modern equivalent, which can deteriorate within decades. Now, scientists behind a new study say they have uncovered the mystery ingredient that allowed the Romans to make their construction material so durable and build elaborate structures in challenging places such as docks, sewers and earthquake zones.

    The study team, including researchers from the United States, Italy and Switzerland, analyzed 2,000-year-old concrete samples that were taken from a city wall at the archaeological site of Privernum, in central Italy, and are similar in composition to other concrete found throughout the Roman Empire.

    They found that white chunks in the concrete, referred to as lime clasts, gave the concrete the ability to heal cracks that formed over time. The white chunks previously had been overlooked as evidence of sloppy mixing or poor-quality raw material.

    "For me, it was really difficult to believe that ancient Roman (engineers) would not do a good job because they really made careful effort when choosing and processing materials," said study author Admir Masic, an associate professor of civil and environmental engineering at the Massachusetts Institute of Technology.

    "Scholars wrote down precise recipes and imposed them on construction sites (across the Roman Empire)," Masic added.

    The new finding could help make manufacturing today's concrete more sustainable, potentially shaking up society as the Romans once did.

    "Concrete allowed the Romans to have an architectural revolution," Masic said. "Romans were able to create and turn the cities into something that is extraordinary and beautiful to live in. And that revolution basically changed completely the way humans live."

    Lime clasts and concrete's durability

    Concrete is essentially artificial stone or rock, formed by mixing cement, a binding agent typically made from limestone, water, fine aggregate (sand or finely crushed rock ) and coarse aggregate (gravel or crushed rock).

    Roman texts had suggested the use of slaked lime (when lime is first combined with water before being mixed) in the binding agent, and that's why scholars had assumed that this was how Roman concrete was made, Masic said.

    With further study, the researchers concluded that lime clasts arose because of the use of quicklime (calcium oxide) — the most reactive, and dangerous, dry form of limestone — when mixing the concrete, rather than or in addition to slaked lime.

    Additional analysis of the concrete showed that the lime clasts formed at extreme temperatures expected from the use of quicklime, and "hot mixing" was key to the concrete's durable nature.

    "The benefits of hot mixing are twofold," Masic said in a news release. "First, when the overall concrete is heated to high temperatures, it allows chemistries that are not possible if you only used slaked lime, producing high-temperature-associated compounds that would not otherwise form. Second, this increased temperature significantly reduces curing and setting times since all the reactions are accelerated, allowing for much faster construction."

    To investigate whether the lime clasts were responsible for Roman concrete's apparent ability to repair itself, the team conducted an experiment.

    They made two samples of concrete, one following Roman formulations and the other made to modern standards, and deliberately cracked them. After two weeks, water could not flow through the concrete made with a Roman recipe, whereas it passed right through the chunk of concrete made without quicklime.

    Their findings suggest that the lime clasts can dissolve into cracks and recrystallize after exposure to water, healing cracks created by weathering before they spread. The researchers said this self-healing potential could pave the way to producing more long-lasting, and thus more sustainable, modern concrete. Such a move would reduce concrete's carbon footprint, which accounts for up to 8% of global greenhouse gas emissions, according to the study.

    For many years, researchers had thought that volcanic ash from the area of Pozzuoli, on the Bay of Naples, was what made Roman concrete so strong. This kind of ash was transported across the vast Roman empire to be used in construction, and was described as a key ingredient for concrete in accounts by architects and historians at the time.

    Masic said that both components are important, but lime was overlooked in the past.

    The research was published in the

    CTVNews.ca Top Stories

    A team of tornado experts is heading to Fergus, Ont. after a storm ripped through the area Sunday night.

    Why brain aging can vary dramatically between people

    Researchers are uncovering deeper insights into how the human brain ages and what factors may be tied to healthier cognitive aging, including exercising, avoiding tobacco, speaking a second language or even playing a musical instrument.

    Canada

    • A team of tornado experts is heading to Fergus, Ont. after a storm ripped through the area Sunday night.

    • Two nephews of the beloved Harry R. Hamilton share stories about his life and legacy.

    • The union representing some 1,200 dockworkers at the Port of Montreal has overwhelmingly rejected a deal with their employers association.

    • A man who was critically injured in a police-involved shooting in Hamilton late Sunday afternoon has died in hospital, says the province’s police watchdog.

    World

    Politics

    • Murray Sinclair’s family members say the late justice and senator has been laid to rest according to his wishes.

    • Prime Minister Justin Trudeau announced voters in Cloverdale—Langley City will pick their next member of Parliament on Dec. 16.

    Health

    Sci-Tech

    Entertainment

    Business

    Lifestyle

    Sports

    Autos

    Local Spotlight

    For the second year in a row, the ‘Gift-a-Family’ campaign is hoping to make the holidays happier for children and families in need throughout Barrie.

    Some of the most prolific photographers behind CTV Skywatch Pics of the Day use the medium for fun, therapy, and connection.

    A young family from Codroy Valley, N.L., is happy to be on land and resting with their newborn daughter, Miley, after an overwhelming, yet exciting experience at sea.

    As Connor Nijsse prepared to remove some old drywall during his garage renovation, he feared the worst.

    A group of women in Chester, N.S., has been busy on the weekends making quilts – not for themselves, but for those in need.

    A Vancouver artist whose streetside singing led to a chance encounter with one of the world's biggest musicians is encouraging aspiring performers to try their hand at busking.

    Ten-thousand hand-knit poppies were taken from the Sanctuary Arts Centre and displayed on the fence surrounding the Dartmouth Cenotaph on Monday.

    A Vancouver man is saying goodbye to his nine-to-five and embarking on a road trip from the Canadian Arctic to Antarctica.

    • LIVE

      LIVE

      Thousands of people are gathered in downtown Vancouver to observe the city’s 100th Remembrance Day ceremony.

    • A suspect was arrested for allegedly brandishing a knife outside a Vancouver elementary school on Friday – just as the young students were heading home for the day.

    • Toronto is expected to see an economic boost to the tune of nearly $300 million thanks to Taylor Swift’s upcoming Eras Tour, which will be making a stop in Canada’s largest city for a six-show run later this month.

    • A man believed to be in his 40s has been rushed to a trauma centre following a stabbing in downtown Toronto.

    • Calgarians will be observing Remembrance Day at a number of different ceremonies across the city, including at the Hangar Flight Museum.

    • July 2025 may seem like it’s in the distant future, but for the St. Luke playground committee time is ticking to fundraise the $340,000 they still need to build a new playground.

    • Getting out to the mountains is even easier with a new bus route from a growing Germany-based service.

    • Crowds gathered in Ottawa and eastern Ontario on Monday to honour the sacrifice of men and women in uniform who gave their lives in service of Canada.

    • CTVNewsOttawa.ca looks at Remembrance Day ceremonies in Ottawa.

    • After months of controversy surrounding a dog park in Ottawa's west end, a solution has been reached to divide the park in half.

    • A 36-year-old Montreal man who was out on bail after allegedly uttering death threats to a woman is now accused of murdering her on the South Shore.

    • With fewer interments and rising maintenance fees, the money for Canada's largest military cemetery will run out in three to four years.

    • Montreal Metro passengers can now flag a safety concern by texting a new phone number launched by the STM.

    • LIVE @ 10:45 A.M. MT

      LIVE @ 10:45 A.M. MT

      Monday is Remembrance Day, a time to honour armed forces members who have died in the line of duty.

    • WEATHER

      WEATHER

      This is shaping up to be one of the warmest Remembrance Days in the past decade, at least, for temperatures.

    • Many Maritimers turned out in wet and windy weather Monday to remember those who have served, and continue to serve, in Canada's armed forces for Remembrance Day.

    • A Cape Breton senior recalls her life in German-occupied France, and her mother’s death, during the Second World War.

    • Thousand of people gathered at the Menin Gate in the Ypres, Belgium for Monday’s Remembrance Day Ceremony.

    • Remembrance Day is today, and a number of ceremonies are taking place around the province to honour those who gave their lives to serve our country.

    • A pillar in Canada’s history was honoured in Winnipeg Sunday afternoon, with thousands showing up to pay tribute to the life and legacy of the late Murray Sinclair.

    • Winnipeg police have identified two men involved in a stabbing incident earlier this week.

    • There will be two ceremonies taking place in Regina for Remembrance Day, hosted by the Royal Canadian Legion.

    • Regina author Valerie Crowther is celebrating the release of her book ‘War Letters: Linking Lives in the Second World War.’

    • It was a somber day at Mosaic Stadium as members of the Saskatchewan Roughriders officially cleaned out their stalls and closed the book on the 2024 season.

    • Saskatchewan RCMP are searching for a suspect after a man was seriously injured in a farm-related incident in Montreal Lake.

    • It was a somber day at Mosaic Stadium as members of the Saskatchewan Roughriders officially cleaned out their stalls and closed the book on the 2024 season.

    • The Regina Rams claimed the Hardy Cup after a hard fought battle against the Saskatoon Huskies 19-14 on Saturday in the first all Saskatchewan U-Sports western conference final since 2002.

    • Emergency crews responded to the scene on Road 68/Highway 2 east of Thamesford around 7 p.m.

    • The events will start at 10:15 a.m. with a parade that forms up in front of the Delta London Armories, marches east on Dundas Street and turns north onto Waterloo Street to Dufferin Avenue, the west to the Cenotaph.

    • A team of tornado experts is heading to Fergus, Ont. after a storm ripped through the area Sunday night.

    • A Barrie man is at the centre of an alleged $2.2 million stolen used car scheme.

    • Environment Canada issued a weather alert for Barrie, Collingwood and surrounding areas, alerting residents about the wicked winds that are expected to pick up to 80 kilometres per hour in the afternoon hours.

    • Barrie residents gathered on Monday to honour Canada’s veterans and pay tribute to those who served and sacrificed for the country.

    • Representatives of the Windsor Veterans Memorial Services Committee, military representatives, wreath bearers, government officials, and members of the public will attend the Cenotaph at City Hall Square for the outdoor service.

    • Windsor Paralympic champion, Danielle Campo, has been crowned the number one Inspirational Speaker of the Year for 2024 at the Inspirational Speaking Finals.

    • One person has been arrested after Chatham-Kent Police Service (CKPS) received multiple complaints about an alleged drunk driver.

    • Environment Canada says heavy rain and winds could cause power outages on Vancouver Island as an "intense" storm system is set to hit the B.C. coast Sunday.

    • Six deer were struck by vehicles in six different locations in a six-hour period on B.C. highways on Saturday, according to the transportation ministry.

    • The union for locked-out port workers in British Columbia says the BC Maritime Employers Association cut off talks in less than an hour Saturday, refusing to budge on a final offer that the union has so far rejected.

    • The emergency department at South Okanagan General Hospital in Oliver, B.C., will be closed for 31 hours this weekend, the second such closure in a week and the third since the start of November.

    • Police in Kamloops, B.C., are reminding parents and guardians to check their children's Halloween candy after receiving a report of a mother finding a razor blade in one of her daughter's treats.

    • More than two years after Alannah Brown and Douglas Barker were found dead north of Penticton, police are asking for help identifying a vehicle they believe was associated with the crime.

    • The Southern Alberta Recreation Association is officially announcing the Town of Taber as next year’s host for the Southern Alberta Summer Games.

    • The Lethbridge Hurricanes broke open a close game with three goals in the first two minutes of the third period as they defeated the Warriors 7-3 in a game played Friday night in Moose Jaw.

    • There might not a lot snow just yet, but many southern Albertans are still itching to get outdoors.

    • It was just days before the COVID-19 pandemic shut the world down when the Shaft Bottom Boys of Sudbury broke a world record for 'Deepest Concert Underground.' Now, more than four years later, a Timmins band is looking to take the title.

    • Police have arrested a 15-year-old in connection with a break-in and $50,000 in damage done to the Centennial Arena in Elliot Lake in September.

    • Mayors of the five largest cities in northern Ontario met in North Bay the last two days to discuss a range of critical issues impacting their cities and the region.

    N.L.

    Shopping Trends

    The Shopping Trends team is independent of the journalists at Â鶹´«Ã½. We may earn a commission when you use our links to shop. Read about us.

    Stay Connected
    Follow Â鶹´«Ã½