Ticking Time Bomb

Login Form






Lost Password?
No account yet? Register

Home
Self repairing concrete
User Rating: / 0

Experimental concrete that patches up cracks by itself is to undergo outdoor testing.

The concrete contains limestone-producing bacteria, which are activated by corrosive rainwater working its way into the structure.

The new material could potentially increase the service life of the concrete - with considerable cost savings as a result.

The work is taking place at Delft Technical University, the Netherlands.

It is the brainchild of microbiologist Henk Jonkers and concrete technologist Eric Schlangen.

If all goes well, Dr Jonkers says they could start the process of commercialising the system in 2-3 years.

Concrete is the world's most widely used building material. But it is prone to cracks, which means that structures need to be substantially reinforced with steel.

"Micro-cracks" are an expected part of the hardening process and do not directly cause strength loss. Fractures with a width of about 0.2mm are allowed under norms used by the concrete industry.

But over time, water - along with aggressive chemicals in it - gets into these cracks and corrodes the concrete.

Longer life

"For durability reasons - in order to improve the service life of the construction - it is important to get these micro-cracks healed," Dr Jonkers told BBC News.

Bacterial spores and the nutrients they will need to feed on are added as granules into the concrete mix. But water is the missing ingredient required for the microbes to grow.

  Concrete is the world's most popular building material, but cracking is a problem

So the spores remain dormant until rainwater works its way into the cracks and activates them. The harmless bacteria - belonging to the Bacillus genus - then feed on the nutrients to produce limestone.

The bacterial food incorporated into the healing agent is calcium lactate - a component of milk. The microbes used in the granules are able to tolerate the highly alkaline environment of the concrete.

"In the lab we have been able to show healing of cracks with a width of 0.5mm - two to three times higher than the norms state," Dr Jonkers explained.

"Now we are upscaling. We have to produce the self-healing agent in huge quantities and we are starting to do outdoor tests, looking at different constructions, different types of concrete to see if this concept really works in practice."

The main challenge is to ensure the healing agent is robust enough to survive the mixing process. But, in order to do so, says Dr Jonkers, "we have to apply a coating to the particles, which is very expensive".

The team is currently trying to reduce the cost this adds to the process. But he expects an improved system to be ready in about six months.

The outdoor tests should begin after this; the team is already talking to several construction firms that could provide help.

The concrete will then have to be monitored for a minimum of two years to see how it behaves in this real-world setting.

"Then, if everybody's happy, we can think about trying to commercialise the product," said the TU Delft researcher.

Even if the healing agent adds 50% to the concrete cost, this makes up just 1-2% of the total construction cost. Maintenance is a much higher percentage of this total cost, so Dr Jonkers expects big savings through extending the concrete's service life.

 
Worlds smallest petrol engine
User Rating: / 0

SCIENTISTS have built the smallest petrol engine, tiny enough to power a WATCH.

 The mini-motor, which runs for two years on a single squirt of lighter fuel, is set to revolutionise world technology. It produces 700 times more energy than a conventional battery despite being less than a centimetre long (Not even half an inch!).

It could be used to operate laptops and mobile phones for months doing away with the need for recharging. Experts believe it could be phasing out batteries in such items within just six years. The engine, minute enough to be balanced on a fingertip, has been produced by engineers at the University of Birmingham .

Dr Kyle Jiang, lead investigator from the Department of Mechanical Engineering, said: “We are looking at an industrial revolution happening in peoples’ pockets. The breakthrough is an enormous step forward. Devices which need re- charging or new batteries are a problem but in six years will be a thing of the past.”

Other applications for the engine could include medical and military uses, such as running heart pacemakers or mini reconnaissance robots. At present, charging an ordinary battery to deliver one unit of energy involves putting 2,000 units into it.

The little engine, because energy is produced locally, is far more effective. One of the main problems faced by engineers who have tried to produce micro motors in the past has been the levels of heat produced. The engines got so hot they burned themselves out and could not be re-used.

The Birmingham team overcame this by using heat-resistant materials such as ceramic and silicon carbide. Professor Graham Davies, head of the university’s engineering school, said: “we've brought together all the engineering disciplines, materials, chemical engineering, civil engineering, and mechanical engineering.

What better place to have the second industrial revolution in nano-technology than where the first took place, in the heart of the West Midlands.

 
Japans sea bed ice gas
User Rating: / 0

Japan has extracted natural "ice" gas from methane hydrates beneath the sea off its coasts in a technological coup, opening up a super-resource that could meet the country's gas needs for the next century and radically change the world's energy outlook.

The state-owned oil and gas company JOGMEC said an exploration ship had successfully drilled 300 metres below the seabed into deposits of methane hydrate, an ice-like solid that stores gas molecules but requires great skill to extract safely.

"Methane hydrates available within Japan's territorial waters may well be able to supply the nation's natural gas needs for a century," said the company, adding that the waters under exploration also contain large reserves of rare earth metals.

Government officials said it was the world's first off-shore experiment of its kind, though Japan been working closely with the Canadians. The US and China have their own probes underway.

The US Geological Survey said methane hydrates offer an "immense carbon reservoir", twice all other known fossil fuels on earth. However, it warned that the ecological impact is "very poorly understood".  

The immediate discoveries in Japan's Eastern Tankai Trough are thought to hold 40 trillion cubic feet of methane, equal to eleven years gas imports. The company described the gas as "burnable ice", saying the trick is free it from a crystaline cage of water molecules by lowering the pressure. Tokyo hopes to bring the gas to market on a commercial scale within five years.

The breakthrough comes after 17 years of research and several hundred million dollars of investment. It could be the answer to Japan's prayers, ending its reliance on expensive imports of fuel to meet almost all energy needs.

The country's trade surplus has vanished since the government shut down all but two of its 54 nuclear reactors after the Fukushima disaster in 2011 and switched to other fuels, mostly liquefied natural gas (LNG).

It imported a record 87m tonnes of LNG last year at roughly five times the cost of shale gas available to US chemical companies and key industries, putting Japanese firms at a huge disadvantage.

Japan's Institute of Energy Economics said methane hydrate could be the "game-changer" that restores Japan's flagging fortunes, acting as a catalyst for revival much like the shale revolution in the US.

The state oil group plans to drill as deep as 7,000 metres below the sea floor eventually, going out in seas with depth of up to 4,000 metres.

Environmentalists are deeply alarmed by new focus on ice gas, fearing that it will set off a fresh energy race in the fragile eco-systems of the oceans and may cause landslides on the seabed.

The risk of methane leakage into the atmosphere could be a major snag. The US Geological Survey says the gas has ten times the global warming impact of carbon dioxide.

 
<< Start < Prev 1 2 3 4 5 6 7 8 9 10 Next > End >>

Results 29 - 32 of 193

Polls

What's your preferred energy generation options?
 
© 2017 The Environmentalist
Joomla! is Free Software released under the GNU/GPL License.