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Dřevo tvrdé jako ocel

  Dřevo je levný a užitečný materiál, ovšem nepříliš tvrdý, což ho pro některá využití diskvalifikuje. Vědci nyní ale vyvinuli postup, kterým lze slisovat dřevo tak, aby bylo tvrdé jako ocel, ale zároveň mnohem lehčí a levnější. Nový materiál slibuje možnosti širokého využití, zatím je ale výroba náročná.
Tým výzkumníků z Marylandské univerzity vyvinul poměrně jednoduchý postup, jak slibný materiál vytvořit. Dřevo nejprve čeká chemická lázeň: výzkumníci využili roztok hydroxidu sodného a siřičitanu sodného, ve kterém dřevo vařili 7 hodin. Tím byla ve dřevě zachována celulóza, ale odstraněny některé polymery, včetně části ligninu, který ve dřevě zpevňuje buněčné stěny.

Strengthening wood to replace concrete in construction

   Concrete is an impressive materiál; it  is much more complex than its unassuming dull gray surface might suggest. With recent advances in computational modeling and molecular analysis techniques, scientists have been active in an effort to better understand concrete’s strength. Ultimately, that knowledge can help to boost the strengthand reduce the high environmental impact of concrete-its huge carbon footprint: current concrete manufacturing accounts for 8%–9% of anthropogenic CO2 emissions and 2%–3% of global primary energy.

New Concrete Safer During Disasters

 


Dr Alan Richardson, of Northumbria University.               Credit: Northumbria University

 

  Researchers are developing a new type of concrete that could significantly lower death tolls during bomb blasts, earthquakes and other disasters.

The international team- comprised of researchers from the U.K., India and Canada -are working to create a tougher form of concrete using 3D fiber reinforcement rather than the traditional 2D variety.

Advance in Testing Micro-Scale Compressive Strength of Cement

Experimental setup for applying micropillar compression        Photo J.W. Dixon


 Researchers from North Carolina State University have, for the first time, used a “micropillar compression” technique to characterize the microscale strength of cement, allowing for the development of cement with desirable strength properties for civil engineering applications. “The information collected using this technique can be used to better understand the behavior of concrete when it fails, as well as providing key data for ‘constitutive’ models that are used for designing and determining the safety of large-scale civil engineering structures,” says Rahnuma Shahrin, a civil engineering Ph.D. student at NC State and lead author of a paper on the work.

Sea urchin-inspired cement could enable more fracture-resistant concrete

 Nature loves a good brick and mortar-style construction. And that’s for good reason—it’s one of the toughest designs you can get, combining both strength and flexibility.
 For instance, nacre (aka mother of pearl) uses stacks of aragonite nanoplatelet bricks to provide strength to this super strong biomaterial. The goal here is not necessarily to prevent cracking altogether—but rather to prevent a crack from catastrophically propagating through the entire material. Although the brick material in a brick-and-mortar design may crack, a softer in-between mortar material helps absorb crack energy, preventing in from ripping through the entire material.
 Sea urchins use a similar strategy to build their spines, layering hard, crystalline calcite blocks with softer, amorphous calcium carbonate materials. Such bioinspired engineering principles have been used before to design stronger glass or ceramicmaterials, but could they be applied to build better cement, too?

Stronger concrete by adding plastic flakes

  Discarded plastic bottles could one day be used to build stronger, more flexible concrete structures, from sidewalks and street barriers, to buildings and bridges, according to a new study. MIT undergraduate students have found that, by exposing plastic flakes to small, harmless doses of gamma radiation, then pulverizing the flakes into a fine powder, they can mix the irradiated plastic with cement paste and fly ash to produce concrete that is up to 15 percent stronger than conventional concrete.
  Concrete is, after water, the second most widely used material on the planet. The manufacturing of concrete generates about 4.5 percent of the world’s human-induced carbon dioxide emissions. Replacing even a small portion of concrete with irradiated plastic could thus help reduce the cement industry’s global carbon footprint. Reusing plastics as concrete additives could also redirect old water and soda bottles, the bulk of which would otherwise end up in a landfill. 

HeidelbergCement to sell its calcium silicate unit business

HeidelbergCement announces that it has signed an agreement with H+H International A/S and its subsidiary H+H Deutschland GmbH to sell its German and Swiss calcium silicate unit business (“HDKS”). The enterprise value of the transaction amounts to about € 110 million. HeidelbergCement expects the transaction to close in the first quarter of 2018.
 “HDKS has a strong market position in the North-East and South-West of Germany as well as in Switzerland, but the focus of its product portfolio on calcium silicate units is outside the core businesses of HeidelbergCement,” said Dr. Bernd Scheifele, CEO of HeidelbergCement. “The disposal is part of our portfolio review and optimization with the goal to generate additional cash flow in order to support our disciplined growth and increase shareholder returns.”

Infrastruktura ČR se vzdaluje úrovni EU

Stavebnictví nedokázalo využít fondy EU 
 

Petr Zahradník

   Stavebnictví, a obzvláště inženýrské stavitelství, má v českých podmínkách nevšední potenciál. Díky stávajícímu systému financování může náklady na řadu českých projektů hradit ve velké míře západoevropský daňový poplatník prostřednictvím fondů EU.
   Pokud stavebnictví dobře funguje, má mezi všemi ekonomickými činnostmi druhý nejvyšší synergický efekt. Navíc je v jinak mimořádně otevřené ekonomice málo dovozně náročné. Může za to především veřejný sektor, jenž nedokáže skloubit ohromný objem peněz s věcnými požadavky na jejich uvolnění tak, aby byl dárce spokojen.

Ceny bytů v Česku dále rostou

foto :E 15

Prodejní ceny bytů v Praze a v krajských městech ČR vzrostly ve 2. čtvrtletí letošního roku meziročně o 10,7 procenta na 49.800 korun za metr čtvereční. Nejdražší byla Praha s průměrnou cenou 65 700 korun, naopak v nejlevnějším Ústí nad Labem to bylo 11 800 korun.
Vyplývá to z údajů portálu CenovaMapa.org, které dnes zveřejnila poradenská společnost Deloitte. Portál zpracovává informace o skutečných prodejních cenách přímo z kupních smluv evidovaných v katastru nemovitostí.

New design makes concrete floor thinner and lighter

Unreinforced concrete flooring inspired by Gothic cathedrals on display at the Venice Biennale.
Credit: Block Research Group

 
   Concrete—one of the most widely used construction materials across the globe—is not very friendly to the planet we call home. Estimates suggest that production of standard Portland cement alone accounts for nearly 5% of the world’s total carbon emissions. Plus, incorporation of so much concrete in our landscapes doesn’t come without its own; our Earth is hardening...

Strengthens brick business in Germany and Poland

  Wienerberger
   As of September 1, 2017, Wienerberger AG takes over the Reetz clay block plant from Röben Klinkerwerke GmbH in Germany. The plant has about 45 employees and is located in the German State of Brandenburg approx. 100 kilometers south-east of Berlin. It produces high-quality bricks filled with mineral wool as well as precision-ground and traditional clay blocks. The plant has an annual production capacity of 190 million NF (standard format for bricks), which corresponds to about 4,600 single-family houses. The main markets supplied by the plant are regions in the eastern part of Germany and in the west of Poland.

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Kalendář

30.05.2018 - 2.06.2018
Ceramics China 2018
Guangzhou/CN
11.06.2018 - 15.06.2018
ACHEMA 2018
Frankfurt/Main
9.07.2018 - 12.07.2018
16.Electroceramics Conference
Hasselt / Belgium
9.10.2018 - 10.10.2018
SUROVINY
Praha/CZ