3D Printed Concrete Bridge

Today world’s first 3D printed reinforced, pre-stressed concrete bridge was opened. The cycle bridge is part of a new road around the village of Gemert, in the Netherlands. It was printed at Eindhoven University of Technology. With the knowledge the researchers gained in this project, they are now able to design even larger printed concrete structures.
The bridge is the first civil infrastructure project to be realized with 3D-concrete printing. The bridge is 8 meters long (clear span 6.5 meters) and 3.5 meters wide. As it is a ‘worlds first’, the developers did not take any chances and tested the bridge by putting a load of 5 tons on it, which is a lot more than the load the bridge will actually carry.

CLICK ON THE IMAGE TO ENJOY THE VIDEO

The bridge has to meet all regular requirements of course. It is designed to do its duty – to carry cyclists – for thirty years or more. With more cycles than people in the Netherlands, it is expected that hundreds of cyclists will ride over the printed bridge every day. It is part of a large road construction project, led by the company BAM Infra, and commissioned by the province of North-Brabant.
An important detail is that the researchers at Eindhoven University of Technology have succeeded in developing a process to incorporate steel reinforcement cable while laying a strip of concrete. The steel cable is the equivalent of the reinforcement mesh used in conventional concrete. It handles the tensile stress because concrete cannot deal with tensile stress adequately, but steel can.
One of the main advantages of printing concrete is that much less concrete is needed than in the conventional technique, in which a mold (formwork) is filled with concrete. By contrast, the printer deposits only the concrete where it is needed, which decreases the use of cement. This reduces CO2 emissions, as cement production has a very high carbon footprint.

Another benefit lies in the freedom of form: the printer can make any desired shape, whereas conventional concrete shapes tend to be unwieldy in shape due to use of formwork. Concrete printing also enables a much higher realization speed. No formwork structures have to be built and dismantled, and reinforcement mesh does not have to be put in place separately. Overall, the researchers think the realization will eventually be roughly three times faster than conventional concrete techniques.

Source: https://www.tue.nl/

Nanostructured High-Strength LightWeight Concrete

Scientists from the Peter the Great Saint-Petersburg Polytechnic University (SPbPU) in Russia, have created several types of building blocks based on nanostructured high-strength lightweight concrete, reinforced with skew-angular composite coarse grids. The development has unique characteristics, enabling the increase of load-carrying capability by more than 200% and decrease in specific density of the construction by 80%. In addition, among the advantages, are resistance to corrosion, aggressive environments and excessive frost resistance.

Researchers calculated that the service life of the building structures, made with the use of this reinforcement system, will increase at least 2-3 times in comparison with its modern analogs.

Such system allows to ensure the structure integrity even in conditions of seismic activity, since the load is distributed throughout the structure as a whole, and not by individual reinforcement bars. The invention can be used in the construction of bridges and pedestrian crossings, non-metallic ships, low-rise residential buildings” says Alexander Rassokhin, graduate student at SPbPU. Andrey Ponomarev, Professor of the Institute of Civil Engineering is the co-inventor of the new  construction technology.

The fundamentals of the research have been described in an article “Hybrid wood-polymer composites in civil engineering” at the Magazine of Civil Engineering.

Source: https://www.eurekalert.org/

Wooden SkyScrapers

High-rise wooden buildings, such as 14-storey apartment building “The Tree” in Norway, are altering city skylines in what the timber industry is heralding as a new era that will dent the supremacy of concrete and steel.

wooden skyscraper

CLICK ON THE IMAGE TO ENJOY THE VIDEO

Situated on the Bergen waterfront, The Tree is the tallest wooden building in the world. The 52.8 metre high structure is one of a growing number of so-called Plyscrapers altering city skylines. The timber industry say it’s an environmental solution, as countries seek to reduce emissions.

It will never totally displace concrete and steel, but it’s definitely a part in our solution towards our struggle towards a CO2 neutral society,”  says Ole Herman Kleppe, Chief Project Manager.

The architects insist that fears of fire in such timber homes are groundless.  “These columns and these CLT panels they don’t burn. They’re so thick that they don’t burn. In addition, they are painted with fire resistant paint and the house is sprinkled so we have all possible ways to prevent a fire in the house. So actually, this is the safest house in Bergen regarding fire.” explains Kleppe.

The 14-storey structure is made of sustainable wood. But concrete makers dispute the idea that timber is greener, insisting that deforestation causes more CO2 emissions. The Tree’s structure isn’t entirely wooden.

It’s concrete on this roof because it adds weight and it was necessary to add weight to this wooden building because it kind of dampens the swinging,” adds Per Reigstad, architect at Artec.

Later this year a wooden building that’s two inches taller will open in Vancouver. Even taller structures are being planned in Vienna and London.

Source: http://www.reuters.com/

Bones and Shells, Inspiration For New Materials

Researchers at MIT are seeking to redesign concrete — the most widely used human-made material in the world — by following nature’s blueprints. In a paper published online in the journal Construction and Building Materials, the team contrasts cement pasteconcrete’s binding ingredient — with the structure and properties of natural materials such as bones, shells, and deep-sea sponges. As the researchers observed, these biological materials are exceptionally strong and durable, thanks in part to their precise assembly of structures at multiple length scales, from the molecular to the macro, or visible, level.

From their observations, the team, led by Oral Buyukozturk, a professor in MIT’s Department of Civil and Environmental Engineering (CEE), proposed a new bioinspired, “bottom-upapproach for designing cement paste.

bones molecular structure

These materials are assembled in a fascinating fashion, with simple constituents arranging in complex geometric configurations that are beautiful to observe,” Buyukozturk says. “We want to see what kinds of micromechanisms exist within them that provide such superior properties, and how we can adopt a similar building-block-based approach for concrete.”

Ultimately, the team hopes to identify materials in nature that may be used as sustainable and longer-lasting alternatives to Portland cement, which requires a huge amount of energy to manufacture. “If we can replace cement, partially or totally, with some other materials that may be readily and amply available in nature, we can meet our objectives for sustainability,” Buyukozturk says.

Source: http://news.mit.edu/2016/