Wednesday, 17 October, 2018

Why Roman concrete still stands strong while modern version decays

A researcher drills at a marine structure in Portus Cosanus Tuscany A researcher drills at a marine structure in Portus Cosanus Tuscany
Johnnie Parks | 05 July, 2017, 07:08

Modern Portland cement concrete also uses rock aggregate, but with a vital difference: the gravel particles and sand are meant to be inert.

To understand the long-term chemical processes that occurred in the Roman structures, researchers used thin, polished slices of the concrete with an electron microscope in Germany to map the distribution of elements in the mineral microstructures. In 2013, she examined mineral and microscale properties of Roman concrete and found that unlike modern cement concrete, Roman concrete's filler is chemically reactive, making it stronger and more resilient. Scientists began their search with an ancient recipe for mortar, laid down by Roman engineer Marcus Vitruvius in 30 B.C.E.

Jackson is testing new materials using seawater and volcanic rock from the western US, and has said that the planned Swansea tidal lagoon should be constructed using this ancient Roman technique. The Roman scholar Pliny the Elder described underwater concrete structures that become "a single stone mass, impregnable to the waves and every day stronger".

The team concluded that when seawater permeated through the concrete in breakwaters and in piers, it dissolved parts of the volcanic ash and allowed new minerals to form from the extremely alkaline leached fluids, mainly Al-tobermorite and phillipsite.

Previous samples from the ancient sea walls and harbors showed that the concrete contained a rare mineral named aluminum tobermorite.

"Lime (also known as calcium oxide) - exposed to seawater in the Roman concrete mixture - probably thoroughly reacted with volcanic ash early in the history of the massive harbor structures".

"Contrary to the principles of modern cement-based concrete", Jackson says, "The Romans created a rock-like concrete that thrives in open chemical exchange with seawater".

She explained that the recipe was completely lost, and although she has extensively studied ancient Roman texts, she hasn't found the precise method for mixing the marine mortar, to recreate the concrete.

"This rocklike concrete is behaving, in many ways, like volcanic deposits in submarine environments", said Jackson, according to The Washington Post.

HTC Ocean Life rumor: "5.2" screen, Snapdragon 660, Edge Sense sides
Inside, the HTC U Lifestyle smartphone will feature the recently released Snapdragon 660 processor and 2,600mAh battery. Even if that's the case, it seems as though HTC is moving forward with adding the feature to its next device.


Defeat is just unthinkable for Caixinha
A clash against either Cypriot outfit AEL Limassol or Gibraltar's St Joseph's awaits the victor in the second qualifying round. The game was initially set for Thursday, July 6, but has been rearranged due to conflcting schedules at the venue.


Alexandre Lacazette completes Arsenal medical ahead of club-record move
He arrived at Arsenal's London Colney base, Herts, today where his official pictures will be taken before being unveiled. Arsenal want to get a star name in early as there are worries that Alexis Sanchez will quit the Emirates this summer .


Marie Jackson, who led the study, said: 'This alkali-silica reaction occurs throughout the world and it's one of the main causes of destruction of Portland cement concrete structures'. She first studied tuffs and then investigated volcanic ash deposits, soon becoming fascinated with their roles in producing the remarkable durability of Roman concrete.

The ancient Romans used concrete everywhere, particularly in their mega-structures like the Pantheon and Trajan's Markets in Rome.

The combination of ash, water and lime leads to pozzolanic reaction, approximately the same processes contribute to the formation of volcanic tuffs.

"Romans were fortunate in the type of rock they had to work with", says Jackson.

In their new study, the researchers took samples of Roman concrete to the Advanced Light Source, an X-ray synchrotron located at the Lawrence Berkeley National Laboratory in California, to map out where the minerals can be found in the samples. If we were able to create concrete today in the same way the Romans did, it would survive much longer if it was a structure near the sea. The process for making Portland cement, a key ingredient of modern concrete, requires temperatures of roughly 2,640 degrees F, and the fuels burned to generate this heat are responsible for 7 percent of global carbon dioxide emissions.

An analysis of 2,000 year old cement made from volcanic ash and limestone suggests seawater was the secret ingredient. Jackson is also leading a scientific drilling project to study the production of tobermorite and other related minerals at the Surtsey volcano in Iceland.

One concern regarding future applications of volcanic ash in concrete is that "we can not take apart the Bay of Naples to build sustainable concretes around the world", Jackson said.

Jackson is trying to develop a similar concrete using materials readily available in the U.S. For those reasons, it is doubtful that Roman concrete could become widespread, but could be beneficial in specific contexts.

Jackson recently weighed in on a proposed tidal lagoon to be built in Swansea, United Kingdom, to harness tidal power. "You can imagine that, with the way we build now, it would be a mass of corroding steel by that time".

Recommended

  • Spandau Ballet determined to carry on after singer's shock exit

    Spandau Ballet determined to carry on after singer's shock exit

    Over the a year ago or so, Hadley has also enjoyed a string of solo gigs (including Let's Rock Norwich, which we wrote about). The news of his departure was met with dismay by many fans.
    Sarfraz appointed as Test Captain for Pakistan

    Sarfraz appointed as Test Captain for Pakistan

    Sarfraz is the toast of Pakistan after leading his team to victory over India at the ICC Champions Trophy in June. Players and board officials were also presented with monetary rewards announced by the premier earlier.
    BBC to invest millions in homegrown children's content

    BBC to invest millions in homegrown children's content

    The British Broadcasting Corporation's first Annual Plan was released Tuesday, July 4 , outlining its "biggest investment in children's services in a generation".
  • ME  government shutdown ends with signing of $7.1B budget

    ME government shutdown ends with signing of $7.1B budget

    New Jersey , Maine and IL are all facing at least partial government shutdowns after their legislatures failed to pass budgets. LePage conceded that the state's education system needs work but argued the larger issue is the state's stagnating economy.
    Google's DeepMind and NHS misused patient data trial, watchdog says

    Google's DeepMind and NHS misused patient data trial, watchdog says

    At the time, Google DeepMind said the report had "major errors" that misrepresented the way it and the Royal Free had used data. United Kingdom data privacy laws require organizations to have legitimate reasons for collecting personal data and using it.
    AAA's 'Tipsy Tow' gives free tow, ride home on July 4

    AAA's 'Tipsy Tow' gives free tow, ride home on July 4

    AAA Texas says you don't have to be a AAA member to use the service; however, it's only a one-way, one-time ride. Tipsy Tow will be offered from 6 p.m. on Tuesday, July 4, 2017 through 6 a.m. on Wednesday, July 5.
  • We're calling it: Donald Trump's latest tweet is his most bonkers yet

    We're calling it: Donald Trump's latest tweet is his most bonkers yet

    CNN is responding to President Donald Trump's latest tweet . "It is disgusting by this president, yet one more disgusting act". The CNN spokesperson said that Trump: "is involved in juvenile behavior far below the dignity of his office".
    Nas hails Jay-Z's 4:44 album

    Nas hails Jay-Z's 4:44 album

    The couple, who are also parents of 5-year-old daughter Blue, welcomed twins , a boy named Sir and a girl named Rumi, on June 12. But what were the circumstances that led to this and how do you feel about it?" "I want to shoot a shout out to JAY-Z".
    Child-Sized Coffin With Organs Inside Found on Philadelphia Street

    Child-Sized Coffin With Organs Inside Found on Philadelphia Street

    Authorities in North Philadelphia have a tragic mystery on their hands after a small coffin was found on a sidewalk Monday night. After noticing the coffin had been tampered with, officers found a plastic bag full of what appeared to be human organs.
  • Cardin: Democrats are willing to work with GOP on health care fixes

    Cardin: Democrats are willing to work with GOP on health care fixes

    Ted Cruz , Ron Johnson, Mike Lee , and Rand Paul are among the nine GOP senators who oppose the draft presently on the table. Pat Toomey's column (June 27) defending the Senate bill to revise the Affordable Care Act is full of misrepresentations.
    Terminally ill child draws attention from Trump, pontiff

    Terminally ill child draws attention from Trump, pontiff

    British courts have ruled that Charlie should be taken off life support as further treatment would prolong his suffering. They remain at Charlie's bedside and his condition remains stable'.
    Alexis Sanchez 'will honour' his Arsenal contract

    Alexis Sanchez 'will honour' his Arsenal contract

    While the imminent arrival of Alexandre Lacazette has led to suggestions he could be a replacement for the Chilean. Manchester City , Chelsea and Bayern Munich have all been credited with an interest in Sanchez.

Women in the White House are paid less than their male coworkers Women in the White House are paid less than their male coworkers The White House gender pay gap has nearly doubled since Barack Obama left office and is also higher than the U.S. average. In the full report, it shows that approximately half the men working in the White House make $95,000 or more annually.

Sonam Kapoor makes her debut at Paris Couture Week 2017 Sonam Kapoor makes her debut at Paris Couture Week 2017 A hint of gold on the eyes with pink lips and stunning accessories, she rounded her regal look with perfectly defined eyebrows. The Neerja actress teamed the pink gown with a silver clutch - also from Ralph and Russo - and matching stilletos.

"It Could Be infinity" --Trump the Cosmologist, Revives Nat'l Space Council In true Trump fashion there was a speech which contained a number of key phrases that may or may not have caused the space-faring legend to rase an eyebrow.

Jamal Crawford could look to force his way to Warriors Jamal Crawford could look to force his way to Warriors Last season, Crawford averaged 12.3 points and 2.6 assists per game, shooting 41.3 percent from the field and 36 percent from three.

Finally, farewell: Chris Bosh, Miami Heat formally part ways Finally, farewell: Chris Bosh, Miami Heat formally part ways After announcing the Heat would waive Bosh, they also announced that no other player would ever wear No. 1 for the Heat. Under terms of the agreement, the Heat will pay the 33-year-old Bosh $52 million over the next two years.

Mbete continues to put ANC before Parliament Mbete continues to put ANC before Parliament South Africa's parliamentary speaker says lawmakers will vote on a motion of no confidence in President Jacob Zuma on August 8. The Constitutional Court found that a secret ballot was not unconstitutional, but the decision rested with the speaker.

It's time to talk about Evil Genius 2… It's time to talk about Evil Genius 2… It's now available on GoG.com for $9.99 and is playable on modern systems. Rebellion admits that they're still very early in the process.

Top seed Angelique Kerber reaches second round at Wimbledon Top seed Angelique Kerber reaches second round at Wimbledon Raonic came into Wimbledon after playing only one match on grass, a first-round loss at Queen's. The Australian posted a 3-6, 7-6 (6), 9-7 win over Pavlyuchenkova.

IAF chopper goes missing in Arunachal Pradesh IAF chopper goes missing in Arunachal Pradesh The incident took place nearly at the same time when Mr Rijiju had a close shave after his helicopter made an emergency landing in Itanagar due to bad weather.

Ed Sheeran quits Twitter after abuse from trolls Ed Sheeran quits Twitter after abuse from trolls Celebs including Stephen Fry, Adele, Rylan Clark-Neal and Zayn Malik have all at some time temporarily quit Twitter over hate. Sheeran's Twitter account will remain active, but only for announcements and auto-populated pictures from his Instagram .

Justin Verlander, Alex Avila Reportedly Receiving Trade Interest from Cubs Justin Verlander, Alex Avila Reportedly Receiving Trade Interest from Cubs Avila makes the most sense for the Cubs but as Morosi noted they have not been involved in any trade discussions....yet. The Chicago Cubs are looking for help before the trade deadline with a pair of Detroit Tigers stars now being targeted.

Italy summons Austria envoy as migrant influx tops 100000 Italy summons Austria envoy as migrant influx tops 100000 Every year, more than five million cars cross the mountain pass, many of them from Germany. The four military vehicles have been moved to Tyrol province, on the border with Italy.

Governor humiliated me, says Mamata on Bengal communal clashes reports Governor humiliated me, says Mamata on Bengal communal clashes reports Tripathi further pointed out that he "cannot remain a mute spectator" in the wake of a threat to law and order. Communal clashes have broken out in West Bengal's North 24 Parganas district over a Facebook post .

Ananya Panday in Student Of The Year 2 opposite Tiger Shroff? Ananya Panday in Student Of The Year 2 opposite Tiger Shroff? While we all know Sridevi elder daughter Jhanvi Kapoor and Saif Ali Khan daughter Sara Ali Khan are ready to debut in Bollywood. The latest buzz is that both Jhanvi Kapoor and Chunky Pandey's daughter Ananya will be playing the female leads in the film.

British royals to bring the kids along on European tour British royals to bring the kids along on European tour Like they did with their Canada tour, they'll most likely bring along nanny Maria Borrallo to help with the children. At two months of the school year, this will also be the last time they will be able to go on a trip this year.