1 | ashmann

14 de December de 2008 to ● 7:13 pm

Barack Obama’s stimulus plan might include three categories of spending: healthcare, infrastructure and energy and could range from $400 billion to $700 billion. Under the energy category, the President-elect reportedly wants more energy-efficient roofs (“Upgrading America,” Los Angeles Times, December 6, 2008). MonierLifetile, the Nation’s leading manufacturer of concrete tile, has been making a green and energy efficient product for decades and has some solutions to share with the President-elect.

“Concrete roof tile has been used for centuries throughout Europe because of its sustainability and energy-efficient benefits,” said Christian Doelle, vice president of marketing and strategy for MonierLifetile. “It’s heartening to see that the U.S. is beginning to adopt similar building practices and as an industry leader, MonierLifetile is pleased to provide solutions to help move the trend forward and stimulate the economy in the process.”

Concrete roof tile manufacturer MonierLifetile has spent many years doing research into the concept of an Energy-Efficient roof with the goal to reduce energy costs for homeowners, while delivering a structurally superior and sustainable roof. The Energy Efficient Roof coupled with the inherently sustainable properties of concrete roof tile create a whole system that will help protect the structure for decades while offering the added benefit of energy savings.

Several proprietary roof components from MonierLifetile have been developed to create their Energy Efficient Roof System. Firstly, the Elevated Batten System that raises the tile off deck to create air space. The EBS provides an effective thermal barrier and air flow prevents heat build-up. Secondly, Vented Eave Risers allow additional air space ventilation at the eaves allowing cool air to enter the sub-tile area. Thirdly, the use of Zephyr Roll at the ridge allows hot air to exhaust and provides ventilation and weather-blocking. These components, in concert with a light-colored, high-profile tile, help reduce heat absorption and increase air space between the deck and the tile. The light-color high-profile tile generates the largest reductions in energy costs but the system works with medium and low-profile tiles as well.

Studies at the Oak Ridge National Laboratory have shown that using the MonierLifetile Energy Efficient Roof System reduces the amount of heat penetrating the conditioned space versus direct-to-deck installations by 50%, resulting in an approximate 20% reduction in energy consumption.

Beyond its ability to provide energy-efficiency, MonierLifetile’s concrete tile products are made from naturally occurring raw materials in the manufacturing process. Concrete tiles are non-petroleum based — unlike asphalt shingles — and are made by mixing sand, cement and pigments to form a solid, long-lasting, inert product that lasts for the life of a structure. And, if tiles are ever replaced, they can be crushed and used as road base, clean fill or even re-introduced back into new tiles — reducing the impact on our over-taxed landfills. Additionally, MonierLifetile sources most materials locally within a 500-mile project radius, and manufactures the tiles with indigenous materials and some post-industrial recycled content, including Fly Ash and Slag.

Builders using MonierLifetile’s inherently green products can meet the requirements of regional and national green building programs such as Leadership in Energy and Environmental Design (LEED), the Energy Star(R) program, Cool Roof Rating Council (CRRC), National Association of Homebuilders (NAHB) Green program and California’s Title 24.

About MonierLifetile:
Based in Irvine, Calif., MonierLifetile is the leading U.S. manufacturer of premium, high quality concrete roof tile. MonierLifetile has 14 manufacturing plants and service offices throughout the U.S., and a plant in Guadalajara, Mexico.

Builders and homeowners have turned to MonierLifetile for over four decades as the answer to sustainable roofing solutions. As the green building movement gains momentum, MonierLifetile continues to demonstrate its leadership, garnering recognition from the top building industry associations and publishers for its innovative products, energy-efficient systems, and preference by builders across the country.

Source: http://www.marketwatch.com

2 | ashmann

15 de December de 2008 to ● 12:34 am

Caribbean Cement Company general manager Anthony Haynes said that his company has reduced its carbon footprint – the measure of the impact that human activities have on the environment in terms of the amount of greenhouse gases produced – by more than 30 per cent since 2004.
Haynes disclosed to Sunday Finance yesterday that Caribbean Cement has since 1999 abided by certain guiding principles from a Cement Sustainability Initiative (CSI), which was formed to help the global cement industry address the challenges of sustainable development. Among the purposes of the initiative were the responsible use of fuel and materials, emission monitoring and reporting, and local impacts on land and communities.

Haynes said in following the guidelines, Caribbean Cement had in 2004 introduced its blended Portland-Pozzolan or all-purpose Type 1P cement which has reduced calcinations and carbon dioxide emissions significantly. The use of the Pozzolan material is universally recognized as being environmentally friendly.

“I am very pleased to say that we have followed those principles,” said Haynes. “With the new technology, we have significantly reduced coal usage and electricity.”

“Our carbon print has dropped by more than 30 per cent,” he added.

Greenhouse gas emissions have been scientifically proven to be the major factor behind global warming and climate change. Among a confluence of adverse effects, global warming is said to be responsible for extreme weather patterns, rising sea levels, and a proliferation of tropical diseases, which makes countries such as Jamaica very vulnerable.

To highlight the urgency of the issue of climate change, Haynes noted that it was a hot topic at a recent cement conference in the US. He said that he is proud of his firm’s modernization program, which he says is following all environmentally-friendly protocols.

“I have just been back from a cement conference in the US and there was a whole lot of discussion about the environment and the carbon cost,” he said. “This is what we designed, we wanted to be a world-class firm and our performance right now is world class.”

The Caribbean Cement boss also used the opportunity to take a shot at local importers, who he said was contributing significantly to global warming when they bring the product from China.

“There is a lot of discussion about leakage in the environmental industry,” he said. “When we go to China and import cement – put it on a ship, bring it on a ship and spend money for oil – what we are doing is increasing the carbon footprint all the time.”

By Julian Richardson

Source: http://www.jamaicaobserver.com

3 | ashmann

15 de December de 2008 to ● 12:44 am

Research and Markets has announced the addition of John Wiley and Sons Ltd’s new report “Materials for Sustainable Sites: A Complete Guide to the Evaluation, Selection, and Use of Sustainable Construction Materials” to their offering.

This complete guide to the evaluation, selection, and use of sustainable materials in the landscape features strategies to minimize environmental and human health impacts of conventional site construction materials as well as green materials. Providing detailed current information on construction materials for sustainable sites, the book introduces tools, techniques, ideologies and resources for evaluating, sourcing, and specifying sustainable site materials. Chapters cover types of materials, both conventional and emerging green materials, environmental and human health impacts of the material, and detailed strategies to minimize these impacts. Case studies share cost and performance information and lessons learned.

Key Topics Covered:
Materials for Sustainable Sites Defined. Background: Inputs, Outputs, and Impacts of Construction Materials. Evaluating the Environmental and Human Health Impacts of Materials. Resource Reuse: Designing with and Specifying Reclaimed, Reprocessed, and Recycled-content Materials. Concrete. Earthen Materials. Brick Masonry. Asphalt Pavement. Aggregates and Stone. Wood and Wood Products. Metals. Plastics and Rubber. Biobased Materials, BY RUTH STAFFORD. Appendix A: Embodied Energy and Embodied Carbon of Construction Materials by Weight. Appendix B: Health and Environmental Impacts of Hazardous Air Pollutants and Metals Related to Construction Materials. Index.
For more information visit http://www.researchandmarkets.com/research/d62049/materials_for_sust

Source: Research and Markets

4 | ashmann

18 de December de 2008 to ● 12:59 am

n now build public infrastructure with 100-year durability, at lower cost and with up to a 40 percent reduction in a project’s carbon footprint.

· Developed in North America, iCrete Global 100 mixes are immediately available in the Gulf region where work is already underway on the world’s tallest “superscraper” buildings and green megacities in Abu Dhabi, Saudi Arabia, and Qatar.

· iCrete creates the first truly global concrete, an infrastructure solution that dramatically reduces costs and can meet all building code standards anywhere in the world, featuring the highest strengths achievable.

(Los Angeles California) — iCrete, the world’s premier concrete technology company, announced today the availability in North America and the Middle East of customized and patented high-performance concrete mixes designed for infrastructure use worldwide. iCrete Global 100 concrete mixes will dramatically increase to a century or more the lifespan and durability of major public and private infrastructure projects – from road systems to bridges, ports, dams, and other vital high-use high-traffic public facilities and venues.

iCrete’s newest and highly durable concrete mixes will feature a minimum 100-year design life that can also substantially reduce the price, greenhouse gases and the carbon footprint of concrete by as much as 40 percent. iCrete Global 100 is the first mix design that can meet all industry and governmental standards worldwide, while saving nations around the world billions in construction spending.

iCrete licenses its technology to local ready mix producers worldwide. Its new iCrete Global 100 mixes, developed in North America, are immediately available there and in the Middle East. They will be available in Latin America, Central Asia, and Europe in the second quarter of 2009.

Said Chief Executive Officer Juan Carlos Terroba: “We are particularly pleased to offer this immediately in the Gulf region where work is already underway on the world’s tallest superscraper buildings and green megacities in Abu Dhabi, Saudi Arabia, Qatar and elsewhere across the Middle East. We are already in discussions with similar projects in Panama, Hong Kong and other world capitals where cost, durability, and environmental footprint are important factors.”

Added Terroba: “Public infrastructure is at the economic foundation of the world. It is unacceptable that most public installations and structures last only an inexcusably short 30 to 40 years and those that last longer are left standing only by an Act of God. iCrete developed our Global 100 mixes so that infrastructure worldwide – from Abu Dhabi to Beijing, Washington D.C. to Delhi, London to Panama City – will last 100 years and more, while respecting the environment.”

5 | ashmann

23 de December de 2008 to ● 9:48 am

A good cement plant shouldn’t be a polluter; it should play a role as a purifier.

Since 1985 China’s cement production has been the highest in the world for 21 consecutive years and accounts for 48 percent of the global annual output.

However, the cement industry also consumes 15 percent of all the coal burned in China, while the cbountry is the a major carbon dioxide producer in the world.

According to the 11th Five-Year Plan for the Chinese cement industry from 2006 to 2010, the energy consumption of each ton of cement is predicted to be reduced by 25 percent compared with the previous five years.

Different from traditional cement plants that are associated with high-energy consumption and high emissions, the Beijing Cement Plant, located in Machikou of Beijing’s Changping district, is one of the pioneers in the energy saving and emissions reduction campaign of China’s cement industry.

Established in 1992, the State-owned Beijing Cement Plant has been striving to clean up its production process and help the capital to safely digest its industrial wastes, household garbage and hazardous wastes.

“Through technology innovation and industrial structure reform, we have tried our best to reduce our impact on the local environment and contribute to the national goal of energy efficiency and emissions reduction,” says Fu Qiutao, general manager of Beijing Cement Plant.

Beijing is facing serious environmental challenges. In 2004, the city generated about 140,000 tons of industrial wastes and 60,000 tons of hazardous wastes including medical waste and lead-acid batteries.

In 2005, the Beijing Cement Plant launched a demonstration project using the cement kiln for processing industrial wastes.

In the central area of the plant, a cement kiln works not only for cement production but also as a facility for treating industrial wastes.

Through a huge pump, industrial liquid waste, soot and waste slag are transporting into the kiln.

The French-made kiln uses low nitrogen combustion technology to make soot, industrial liquid waste, ashes and secondary fuel combust at the same time.

At high temperatures of 1,450 to 1,700, 99.999 percent of the noxious elements can be burnt, Fu says.

Turning wastes to new materials

Heavy metal wastes are also processed into a raw material to produce cement without discharging waste residues. And organic wastes with thermal value can be burnt as secondary fuel for the kiln, Fu adds.

In 2007, Beijing Cement Plant helped the Beijing public security bureau combust about 135.3 kg drugs, worth 200 million yuan.

In the same year, Beijing Cement Plant again helped Beijing Drug Administration burn about 17 tons of illegal drugs.

So far, the Beijing Cement Plant has an annual capacity of treating 100,000 tons of industrial wastes in 28 categories.

The plant is hoping to process about 150,000 tons of industrial wastes by 2010 and produce more “green cement” for the country.

At Beijing Cement Plant, a waste heat recovery (WHR) technology has also been adopted.

Through the technology, waste heat has been collected for power generation, which can produce roughly 50 million kWh of electricity each year. It can satisfy about 20 percent of the total energy demand at the plant.

Yu Fei, an official with the Ministry of Environmental Protection, says the central government is requiring that by 2010, over 70 percent of the country’s cement should be produced by the new suspension preheater (NSP) cement production lines.

The National Development and Reform Commission hopes that 40 percent of the NSP cement production lines in China will use WHR equipment by 2010. At that time, the annual electricity produced by WHR projects will reach 8.93 billion kWh.

Yu says that by 2010, current 5,000 cement plants will be reduced to 2,000, including 10 plants with an annual capacity of 30 million tons and 40 plants with an annual capacity of 5 million tons.

She says government will intensify supervision of the cement industry and improve the overall management level, also keep cooperating with international environmental protection organizations and advanced cement enterprises.

Impact on cement Industry

Due to the deepening global financial crisis and slowdown of the Chinese economy, China’s cement production saw a slower growth at 2.8 percent year-on-year to about 1.27 billion tons in the first 11 months of this year, according to latest figures released by the Ministry of Industry and Information Technology.

It is arousing concerns over whether the Chinese cement enterprises will continue their efforts for cleaner production and environmental protection.

Fu, of Beijing Cement Plant, says: “We will further eliminate our obsolete production capacity and shoulder more social responsibility of treating industrial wastes and promoting alternative energy.”

China has unveiled a massive 4 trillion yuan stimulus package to avert an economic slump, with the fund to be spent over the next two years to finance low-price housing, rural infrastructure, water, electricity, transportation, the environment, technological innovation and rebuilding from several disasters.

About 80 percent of the package is relevant to the construction material industries. Industry insiders say that they are optimistic about the future of the cement industry in China.

Zhai Qi, deputy director of the China Business Council for Sustainable Development, says if cement enterprises can carry out reforms of production and technology, the economic crisis could become an incentive for developing a more balanced industrial structure.

SOURCE: http://www.cctv.com

6 | ashmann

25 de December de 2008 to ● 5:33 am

President-elect Obama pledged the biggest road and bridge construction program since the 1950s. But has anyone in Washington asked Wilson County, Tennessee road superintendent Steve Armistead about the price of asphalt these days? For that matter, has anyone thought about how much more cement is likely to cost when that industry has to pass through costs associated with its carbon dioxide emissions?

asphalte-road330.jpg

Bottom line: the two most essential materials of an infrastructure rebuilding program – asphalt and cement – could be so expensive that Obama won’t be able to fix nearly as many roads, bridges and buildings as he wants to, and thus fewer jobs will be created.

Armistead told The Tennessean newspaper earlier this month that, notwithstanding crude oil’s precipitous price decline, in November the price of asphalt, which is made from crude, was more than double what it was last January. Rodney Carmichael, head of the Tennessee County Highways Officials Association, told the newspaper asphalt prices will remain high because, when crude prices shot up, oil refiners tweaked their equipment to refine more gasoline, leaving less feedstock available to make asphalt. “The newer technology has backfired,” Carmichael said.

Speaking of backfires, the Obama administration’s plan to force CO2-emitting manufacturers to have to pay for their emissions appears likely to cause cement prices to surge.

The cement industry is one of the world’s worst CO2 emitters. To exempt cement manufacturers from CO2 emissions reductions would make the entire program Obama wants to impose a joke. And yet, if Canada is any example, forcing cement manufacturers to have to pay extra to offset the CO2 emissions they generate could cause cement prices to skyrocket.

Facing a carbon tax, British Columbia cement manufacturers recently told government officials in Ottawa that such a tax would eliminate their profit margins for years to come. The officials made it sound as if, even if they raise prices, they may still have to cut back manufacturing.

by: Bill Paul

SOURCE: http://seekingalpha.com

7 | ashmann

25 de December de 2008 to ● 5:36 am

To create what is being billed as one of the world’s most environmentally conscientious skyscrapers, the building’s developer, the Durst Organization, encouraged its architects to tap waste from some of the world’s dirtiest industries.

The concrete used at One Bryant Park, the angled 54-story tower that opened this year at 42nd Street and the Avenue of the Americas in Manhattan, used 45 percent less cement than would normally be used, replaced by slag from steel mills.

Concrete has existed since the public works of ancient Rome, when it was used to support aqueducts, and engineers love the material for its resilience in earthquakes and its utility in creating buildings of all shapes and sizes.

But as demand for concrete has soared, in part because of the rapid growth of cities in Asia, the environmental costs of the material are getting hard to ignore. “Concrete is a terrific material, which is why it’s been used for 2,000 years,” said Tim Christ, an architect. “But it’s a very dirty material. The air-quality issues in China we observed during the Olympics derive from concrete construction.”

That’s because every ton of new portland cement, the most common adhesive ingredient in concrete, releases roughly one ton of greenhouse gases from the kilns that bake it.

The most potent way to reduce that toll is to replace some portland cement with recycled material. Coal ash from power plants and blast-furnace slag are the easiest substitutes to find — and they tend to make concrete more valuable than portland cement alone.

As often occurs with building techniques, the U.S. government gave this practice an early proving ground. It commissioned Christ’s firm, Morphosis, based in Santa Monica, California, and headed by Thom Mayne, the Pritzker Architecture Prize winner, to design the San Francisco Federal Building in 2001.

“We proposed a 50 percent slag replacement, where 15 percent was common,” said Christ of the building, which was completed in 2007, surprising critics and passers-by with an array of bends and overhangs. Previously, use of such a high percentage of slag in the United States had mainly been limited to relatively small projects without sophisticated specifications.

The process was also gaining credibility on the East Coast around the same time. The green-minded Durst Organization opened Four Times Square, the Condé Nast Building, in 1999 as a showcase for environmentally responsible techniques, recalled the company’s co-president, Jody Durst.

To that end, the developer specified using coal ash in the building’s columns. The company wanted to use as much recycled material as it could, Durst recalled, but the skeptical contractors limited its use to columns rather than floors.

The material held up so well there, however, that Durst also used slag for the Helena, a 600-unit apartment tower on West 57th Street in Manhattan, which opened in 2005.

By the end of that project, Durst said, contractors had come around. “I think we paid a premium, but by the end of the job the contractor said he liked the way it handled,” Durst recalled. “The strength properties were superior.” The developer’s standard procedure now includes ordering slag or coal ash for concrete.

The two byproducts differ in availability and characteristics. Slag, which is left over in blast furnaces when steel is made, can make up more of the concrete mix than ash without requiring extra chemicals, but it is harder to obtain locally. (Developers like to buy supplies locally to reduce travel times and to gain points in the LEED rating system, which certifies a building’s environmental friendliness.) Slag also tends to have a lighter color than ash. Ash’s quality can vary more, but testing techniques now generally make it as reliable as slag.

Either material makes concrete stronger, explained Christian Meyer, a civil engineering professor at Columbia, by reducing the effect of heat on the integrity of the concrete. Portland cement requires more water, and the resulting concrete may become hotter in warm weather and be more susceptible to cracking. It is also more likely to harden in a mixing truck while a driver sits in traffic on a hot day, making it impossible to pour at the construction site, said Bob Mannino of Pinnacle Construction, Durst’s concrete contractor at One Bryant Park.

Compared with portland cement, slag is denser and is up to 15 percent stronger, said Dave Weber, executive director of the Slag Cement Association. “In mass concrete, for the base of a building, it can comprise up to 80 percent of the mix.”

The stronger concrete helps developers meet big-city building codes, which now require higher strength to withstand potential terrorist attacks or disasters. The Freedom Tower at ground zero and a nearby Forest City Ratner condominium, Beekman Tower, are among prominent developments using recycled material.

The greater solidity also lets developers make thinner walls, allowing for more rentable square feet, according to the architect John Cetra. Cetra’s firm, Cetra/Ruddy, decided to use slag in a condominium building called One Madison Park, which is nearing completion on 23rd Street. Like Durst, he expects to use slag or ash in all urban projects from now on.

“It doesn’t add anything to the cost,” Cetra said. “And it’s used more and more in high-performance concrete, which we like using because it means the structure can be slimmed down a bit so we can conserve space.”

As more developers are recognizing the materials’ versatility, supply networks reaching from smelters and coal-fired power plants to concrete makers have been growing. “Most electric utilities have an agreement with a marketer for storage in domes or silos, and on a daily basis trucks will come get it because the power plant needs to clear out the ash,” said Dave Goss, executive director of the American Coal Ash Association.

Utilities own ash and sell it to concrete mixing companies. Big concrete companies like France’s Lafarge and independent specialists also own and manage stocks of ash and slag, said Goss. There are several ways that such companies agree to sell, store and share profits from the material.

Growing demand for the recycled material has caused it to become costlier. With America’s relatively few steel mills oversubscribed, said Professor Meyer, some contractors are importing slag from Italy for their projects.

Weber of the Slag Cement Association said trade groups and academics are working on developing “ternary blends” that mix slag, ash and other materials for lower transport and processing costs.

More research into concrete’s environmental cost will probably change the industry further in the next 10 years. Even if ash or slag cement become universal, concrete will exact a big toll on the environment, said Professor Meyer, because up to three-quarters of it is aggregated sand or stone, which consumes lots of energy in production. Finding recycled material for aggregate will be the industry’s next challenge.

The most promising contender, Professor Meyer said, is construction debris. At Denver International Airport, which opened in 1995, roadbeds contain concrete from the former Stapleton Airport, he said. So, depending on research into the strength of debris and its chemical reaction with other ingredients, concrete — a 2,000-year-old material — may soon involve recycling buildings that have been around for only a few decades.

By Alec Appelbaum

SOURCE: http://www.iht.com
China

8 | ashmann

28 de December de 2008 to ● 3:07 am

At our company Christmas party this year we played Carbon Trading, The Game. Bascially, I devised a simple cap and trade game in a power sector, and then we played out four rounds to see what happened. The results were an interesting summary of how small rules can have big impacts in the outcome. And perhaps a good Christmas lesson to everyone involved in carbon market design. The good news, the market in our game came in well under its caps even in the early round.

Basic rules were as follows:

Players start with a certain amount of cash, and then each round bid for different types of power plants, fuel, and carbon credits each round (there were shortages of each), then run their plants (assuming they were able to acquire power plants, adequate fuel, and adequate carbon credits to operate). In our simple cap and trade model, the cap was based initially off of a coal plant’s emission factor, and declined on a per plant basis each year. Power was priced at a flat $100/MWH (makes the math simple). The winner was the one with the most cash after converting carbon to cash at the market clearing price in the last round.

The idea was that the declining cap and fuel shortage would lead to players bidding high for low emissions hydro and wind farms to get under their cap, and lead to reductions.

A few interesting outcomes. Wind and hydro plants did command premium prices, but not all the way to pricing carbon in (probably since no one was sure what then final carbon price would be – proving uncertainty wins again). And since we did not let power prices float, nor require a must run component, fuel prices went on a wild swing but eventually fell as at least two players opted for a strategy to essentially mothball plants and instead just bank the carbon credits, and buy a few more. As a result, carbon prices also stayed low in the early rounds, since fewer operating plants were hitting their caps – however, the players who has stockpiled carbon then bid up the price of the final credit of the final round to $70 instead of the $10-$20 in previous rounds (it only stopped there because they ran out of money).

The final result, that high price of carbon in round 4 meant the winning strategy ended up being buy cheap coal plants throughout the game, run them only when fuel and carbon were very cheap, and make your money off the carbon.

I am planning on revising the rules for better play, then releasing an actual carbon trading game in the near future.

Besides operating CleantechBlog.com, Neal Dikeman is a partner at cleantech merchant bank Jane Capital Partners LLC, CEO of Carbonflow, Inc., and Chariman of Cleantech.org.
Content provided by and all rights reserved to CleantechBlog.com. Also check out http://www.cleantech.org

9 | ashmann

1 de January de 2009 to ● 3:20 am

The United States will need to invest approximately USD 4.4 trillion if it needs clean energy, according to a plan drawn by Google Inc that calls for a big push in wind, solar and geothermal power to replace fossil fuels.

Contending to make the United States environmentally friendly, the World Wide Web giant is expanding a proposal to cut short the usage of oil and coal by 2030.

As per the plan, hybrid and electric cars along with renewables would get a major boost. A hybrid vehicle is a vehicle that uses two or more distinct power sources to propel the vehicle. Power sources include:
On-board or out-board rechargeable energy storage system (RESS)
Gasoline
Hydrogen
Compressed Air
Human powered e.g. pedaling or rowing
Wind
Compressed or Liquid Natural Gas
Solar
Coal, wood or other combustibles
Hybrid vehicle emissions today are getting close to or even lower than the recommended level set by the EPA (Environmental Protection Agency). The recommended levels they suggest for a typical passenger vehicle should be equated to 5.5 metric tons of carbon dioxide.

The three most popular hybrid vehicles, Honda Civic, Honda Insight and Toyota Prius, set the standards even higher by producing 4.1, 3.5, and 3.5 tons showing a major improvement in carbon monoxide emissions.
By substituting conventional vehicles with hybrid and electric vehicles, the United States would devour thirty-eight percent less oil.
Google hopes to bring down the energy industry’s reliance on coal (presently the source of 50 per cent of electricity), natural gas (20 per cent) and atomic energy (20 per cent).

According to Google projections, if the plan, which includes increasing reliability on wind generation, geothermic and solar energy, gets enforced, electricity consumption will be reduced considerably while fossil fuel use would be cut by 88 per cent and carbon emissions would be reduced by 95 per cent by 2030.
The plan would cost USD 4.4 trillion, but according to Google it will save USD 1 trillion over the 22-year life of the plan as renewables become cheaper and gasoline gets less affordable.

10 | ashmann

12 de January de 2009 to ● 4:42 am

Sectoral industry agreements have received considerable attention for their potential to reduce greenhouse gas emissions. But developing countries remain wary

As talks between the 160 nations party to the United Nations Framework Convention on Climate Change grind towards a finale in Copenhagen in December 2009, many heavy industries are keeping a close watch on what emission reduction schemes will emerge from the discussions.

Steel and aluminium producers, as well as the cement sector, are among the most fidgety, given the energy- and emissions-intensive nature of their businesses. In Europe, for example, these industries have banded together to call for exemptions to the European Union’s ever-tightening emissions trading scheme, due to be relaunched in 2013. Paying too much for emissions permits, they say, will drive factories, jobs and emissions out of Europe, especially to countries with less-stringent carbon regimes.

One way to prevent this so-called “carbon leakage”, say industries in European and other developed countries, would be to allow companies to obtain emission reduction credits within sector-specific agreements.

Such agreements would be international in scope, and include incentive mechanisms such as clean technology transfers to get producers from developing countries on board. The level of credits allocated for specific emission reductions would be based on clean technology benchmarks.

An initiative that has claimed moderate success in reducing emissions is the Cement Sustainability Initiative, coordinated by the Geneva-based World Business Council on Sustainable Development. The 18 major cement producers that signed up to the initiative reduced carbon dioxide emissions during cement production on average by 100kg of CO2 per tonne of production over the past eight years, says the WBCSD, though it remains unclear to what extent these emission reductions were a direct result of the CSI.

Claire Mathieu, from CSI member company Lafarge in Paris, says the initiative gave companies a framework for action and created an environment of peer pressure, where leading companies on emission reductions inspired others to follow suit.

While Mathieu admits that other factors beyond the CSI also influenced the decisions of firms to cut emissions, she remains convinced sectoral deals have value and potential. Nonetheless, to be truly effective in the long term, such initiatives “only make sense” if they are integrated into an international regulatory framework, she says.

Two camps

Giving existing voluntary sectoral agreements the status of internationally and potentially legally binding mechanisms will be difficult, however, at least in the context of the UNFCCC talks that were launched in Bali in December 2007. “That is certainly not going to happen,” said one UN official at the most recent round of discussions during an August UNFCCC meeting in Ghana.

The summary of the Ghana meeting says: “It was generally agreed that these approaches and actions should not replace emission reduction targets of developed countries nor form the basis of proposals for sectoral mitigation commitments or international technology benchmarks.”

Most members of the G77, a grouping of developing states that includes China, India and Brazil, are wary of international sectoral deals. They fear that industries from developed states will be at a natural advantage in setting clean technology benchmarks, particularly since those benchmarks are likely to be established against the backdrop of tightening carbon markets in rich countries or rich country groupings such as the EU.

Rich countries would also have an easier time achieving their emission reductions potentials, thus putting developing states at a competitive disadvantage, the argument goes. “We feel extremely uncomfortable with the kind of sectoral approaches that are being discussed,” Indian delegate Ajay Mathur told Reuters after the Ghana meeting.

Developed countries that are in favour of sectoral deals, notably Japan, the US and Canada, are trying to give poorer states assurances that any agreements would be fair. Clean technology transfer mechanisms and respect of the hallowed UNFCCC principle of “common but differentiated responsibilities” in tackling climate change would be upheld, they say.

But these assurances do not appear to be hitting home. Japan caused fury among G77 delegates and “almost wrecked the talks” when it tabled a proposal for a far-reaching international sectoral agreement during a UNFCCC meeting in Bangkok in April, according to the UN official quoted in Ghana.

Japan is pushing for specific emission reductions targets to be established from the bottom up, or according to what industries are able to achieve in their given circumstances and economies, rather than being established top down from governments at national level or in an international deal.

Europe divided, as usual

EU leaders, on the other hand, agree that emission reductions targets should be set from the top down by governments and not by industry. “Sectoral contributions towards emissions reductions can be useful towards meeting [national or international] targets, but cannot replace them,” a spokesman for the European commission in Brussels says.

But views diverge sharply within the union on the extent to which sectoral deals can help slash emissions.

Any international climate change deal that includes the EU “must have some sort of sectoral approach”, says Volker Franz, who deals with the issue for BusinessEurope, a major industry lobby in Brussels. To be fair to European industries that face tougher carbon restrictions, such an approach should include absolute reduction targets for advanced developing countries like China, Franz says.

This argument infuriates some of Europe’s green activists. “The real agenda of companies like ArcelorMittal and Lafarge is to get completely off the hook from EU climate change efforts,” says Claude Turmes, a Green and outspoken member of European parliament.

“This real agenda will be hidden behind some additional rhetoric – so-called benchmarking systems or global sector agreements,” Turmes says.

How these discussions play out and how industries will be treated under the EU’s internal emissions reduction regime is likely to be closely watched by other states and industries. Brussels is hoping to finalise proposals for a revised emissions trading scheme before European parliament elections in March 2009, so that the EU can flaunt its climate credentials at the Copenhagen meeting at the end of next year.

An open game?

In the meantime, most observers agree that the question of whether and how sectoral agreements will be included in any international climate change deal is still very much open. Powerful developed states and their industries are unlikely to drop the idea altogether, despite the wariness and opposition of developing states.

One possibility for preventing an impasse on the issue, says the UN official, would be to transform or expand the Kyoto protocol’s Clean Development Mechanism and Joint Implementation schemes, which allow rich country industries to obtain emissions offset credits in exchange for clean development projects in poorer countries.

The issue is being debated only occasionally by a UNFCCC working group on long-term climate solutions. Talks remain at an early stage. But the idea is potentially promising because developing states such as China have already obtained considerable clean technology transfers through the CDM and JI mechanisms, and because developing country industries are limited in how many emissions they are allowed to offset using the schemes.

With the Copenhagen summit still well over a year away, discussions remain at an early stage. A new US president in Washington next year will add greater urgency to global climate change talks, compared with the lack of interest shown by the Bush administration.

For now, one thing seems clear: given the interest in sectoral deals on the part of developed country governments and industries, and the resistance from developing states, enthusiasts of international talks on climate change can be assured of some good showdowns in the months to come.

Sector deal candidates

Energy-intensive industries that could be first in line for sector-based emissions reduction schemes are:

Steel:

* 5.22% world greenhouse gas emissions (2005).
* 10 biggest producers account for 26% of global output.

Cement:

* 4.6% world greenhouse gas emissions (2005).
* 10 biggest producers account for 25% of global output.

Aluminium:

* 0.9% world greenhouse gas emissions (2004).
* 10 biggest producers account for 54% of global output.

Source: Global sectoral industry approaches to climate change: the way forward, Centre for European Policy Studies, April 2008

11 | ashmann

13 de January de 2009 to ● 6:31 pm

British engineers have created a new kind of cement which not only requires much less heating, it also absorbs large amounts of CO2 as it hardens, making it carbon negative.

The new cement designed by London-based Novacem can absorb, over its lifecycle, around 0.6 tonnes of CO2 per tonne of cement compared standard cement which emits about 0.4 tonnes of C02.

Making the 2bn tonnes of cement used globally every year pumps out 5% of the world’s CO2 emissions – more than the entire aviation industry. And the long-term trends are upwards: a recent report by the French bank Credit Agricole estimated that, by 2020, demand for cement will increase by 50% compared to today.

Making traditional cement results in greenhouse gas emissions from two sources: it requires intense heat, and so a lot of energy to heat up the ovens that cook the raw material, such as limestone. That then releases further CO2 as it burns.

How Carbon Negative?
Novacem’s cement uses magnesium silicates which emit no CO2 when heated. Its production process also runs at much lower temperatures – around 650C. This leads to total CO2 emissions of up to 0.5 tonnes of CO2 per tonne of cement produced. But the Novacem cement formula absorb far more CO2 as it hardens – about 1.1 tonnes. So the overall carbon footprint is negative – ie the cement removes 0.6 tonnes of CO2 per tonne used.

SOURCE: http://www.yellowsandblues.com

12 | ashmann

20 de January de 2009 to ● 8:05 pm

Lafarge has announced SA’s first CEM II 52.5N premium strength cement with the launch of Rapidcem.

Thanks to its innovative properties, this new generation cement addresses the needs of a growing construction market, while reducing the impact on the environment, the company claims.

South Africa’s construction sector was the biggest mover for 2007 with construction growth increasing 18.1%, up from 14.7% in 2006. “In light of this growth we anticipate a great demand for Rapidcem, which has been developed as a superior performance cement with an innovative formulation that meets the high early strength requirements of the precast industry and large construction environments,” says Lafarge national marketing manager, Ilse Boshoff.

Boshoff says that Rapidcem combines a major innovation in that it is formulated to have a high rate of early strength development as its primary characteristic. “This is a major benefit to the productivity of precast concrete product manufacturers by allowing rapid turnaround time of moulds or formwork,” she says.

“It is ideal in applications requiring high strength concrete mixes or where high early strength is critical, such as large construction projects and concrete road repairs. The product also has a good response to heat and/or steam curing.”

She points out that Rapidcem also combats the impact of low winter temperatures on work rate. “For example, it will ensure that brick and block makers have sufficient strength gain in cold conditions to handle their products efficiently.”

Rapidcem produces concretes for those who’s needs include: high levels of early strength development – typically within 24 hours; dense durable concrete that resists destructive attack from many adverse environments; improved workability for easier handling, placing and finishing; enhanced flow ability for easier casting in complex or congested spaces; less surface cracking and better off-shutter finishes from the use of a quality fly ash in the formulation.

Sold in bulk, as it is primarily for high volume users, Rapidcem, a Class II cement classified as CEM II/A-V 52,5N Portland – fly ash cement (in accordance with SANS 50197-1 EN 197) is formulated from Portland cement clinker and 12 – 15% siliceous fly ash from Ash Resources, which is blended and / or inter-ground with the clinker, together with a strength enhancer.

For those requiring customised on-site concrete mixes Rapidcem can be further blended with fly ash, silica fume and ground granulated blast furnace slag.

“Rapidcem’s innovative formulation and the incorporation of fly ash enhances the quality and reliable performance of the product and provides enhanced benefits for precast customers and for other specialised formwork applications,” Boshoff explains.

She says that benefits include improved concrete mix workability, making it easier for concrete to be placed in precast moulds; better cohesion for more uniform casting appearance and properties; lower heat of hydration reduces risks of cracking; and denser hardened concrete with enhanced impermeability.

SOURCE: http://www.cbn.co.za

13 | ashmann

23 de January de 2009 to ● 12:45 am

European factories are cashing in on an unexpected benefit from wilting output, selling surplus carbon emissions permits worth about 1 billion euros ($1.29 billion) to raise funds on the carbon market.
A recession in Europe will dent industrial output this year and this will sap energy demand and carbon emissions, leading to a surplus of permits among big polluters including steel and cement makers.
Companies from some of the European Union’s most polluting industries are now raising funds on the carbon market to help them weather the credit crisis.
That has raised some uncomfortable questions about a scheme meant to fight climate change rather than subsidise companies during a downturn.
“This was not designed as a scheme to give corporates cheap short-term funding options in the face of a credit crunch meltdown where banks are not lending,” said Mark Lewis, Deutsche Bank carbon analyst. “But that appears to be what’s happening.”
The EU trading scheme is meant to limit greenhouse gases by giving industry a fixed quota of carbon permits that can be traded.
The sell-off has sparked a collapse in carbon prices, which have fallen by up to a third this month and could drop as low as 5 euros from a peak of 31 euros last summer, analysts say.
The carbon price adds to the cost of burning high-carbon fossil fuels and a lower price undermines incentives for companies to cut emissions.
The price falls do not yet match a rout in 2006, when it emerged that EU states had given industry too many carbon permits, creating a glut that made them worthless.
The present surplus has arisen from recession and companies have been able to raise cash because they get their quota for free rather than have to buy these through state-run auctions.
EU leaders last month agreed emissions quotas through 2020 based on assumptions of economic growth, and backed concessions to industry that could allow companies to continue to get free allowances for a decade or more.
SELL
The present sell-off started in December and the main winners are cement makers, steel, paper mills and glass factories, carbon traders say.
“It’s between 75-80 million to 150 million euros a day,” said Jean-Francois Cauvet, a trader at Sagacarbon, subsidiary of French bank Caisse des Depots, referring to buying and selling in return for immediate cash on spot markets.
“I don’t know why industrials would miss this opportunity,” he added. “They’re using it to compensate for the tightening of credit and the slowdown, to pay for redundancies.”
A global carbon market has been growing fast, nearly doubling in value last year to about $120 billion.
Now the economic slump is doing the market’s job, by limiting economic growth and emissions. Analysts say that the EU emissions cap will bite when economies grow again from 2010 or 2011, and stress that a lower carbon price has not changed the effectiveness of the carbon cap.
For some, however, the price collapse demonstrates that the EU scheme was too soft all along.
“It demonstrates that the targets after 2012 (to 2020) are too lax, especially in combination with a large use of carbon offsets,” said Cambridge University’s Karsten Neuhoff, referring to an option for companies to offset their emissions by investing in green projects in the developing world.
The potential for raising cash now is large.
The steel and cement sectors have a quota of EU allowances (EUAs) approximately matching their forecast output and emissions.
But West European iron and steel output will fall by about 14 percent this year compared to 2008 and EU cement production by 20-25 percent, analysts estimate.
That implies an EUA surplus this year of 66 million tonnes for those two sectors alone, worth about 750 million euros at Wednesday’s carbon prices.
The EU executive Commission rejected the idea that selling surpluses hurt the integrity of the scheme.
“We are sure at the end of the day the price will … provoke emissions reductions,” said Barbara Helfferich, EU Commission environment spokeswoman. “If those companies were smart they would take those profits … and invest them into greener technology.”
While industrial companies are cashing in, some banks and carbon specialists are hurting.
EUAs are one of the worst investments so far in 2009, falling more than almost any other energy commodity or index of global stocks, compressing margins for companies which generate carbon offsets in the South for sale to companies and countries facing emissions limits in the North.

14 | ashmann

3 de February de 2009 to ● 11:15 pm

Concrete is made of cement, aggregate, water and addtives.,

The quality of concrete depends on several factors such as the quality of constituent materials, the water/cement ratio, the mix proportion and the method of mixing, delivery, placement, compaction and curing.

15 | Lion of the Desert

4 de February de 2009 to ● 2:39 am

Cement is a fine, soft, powdery-type substance. It is made from a mixture of elements that are found in natural materials such as limestone, clay, sand and/or shale. When cement is mixed with water, it can bind sand and gravel into a hard, solid mass called concrete.

Cement can be purchased from most building supply stores in bags
Cement is usually gray. White cement can also be found but it is usually more expensive than gray cement.

Cement mixed with water, sand and gravel, forms concrete.

Cement mixed with water and sand, forms cement plaster.

Cement mixed with water, lime and sand, forms mortar.

Cement powder is very, very fine. One kilo (2.2 lbs) contains over 300 billion grains, although we haven’t actually counted them to see if that is completely accurate! The powder is so fine it will pass through a sieve capable of holding water.

16 | NASHWAN HAMID YAHYA AL-EMAD

4 de February de 2009 to ● 9:57 am

The essential ingredients of concrete are cement, aggregate, and water. A mixture of only cement and water is called cement paste. In large quantities, however, cement paste is prohibitively expensive for most construction purposes.

17 | NASHWAN HAMID YAHYA AL-EMAD

4 de February de 2009 to ● 10:06 am

What is Good Concrete?

A good concrete is one which has workability in the fresh state and develops adequate strength. Maximum strength of concrete can only be obtained, if the concrete has adequate degree of workability in relation to the method of compaction to be used. Concrete which is to be compacted by mechanical vibrator, will need 15% less water and 15% less cement as compared to the one which has to be compacted by hand.

GENERAL REQUIREMENTS FOR GOOD CONCRETE The first requirement for good concrete is to use a cement type suitable for the work at hand and have a satisfactory supply of sand, coarse aggregate, and water. Everything else being equal, the mix with the best graded, strongest, best shaped, and cleanest aggregate makes the strongest and most durable concrete. Second, the amount of cement, sand, coarse aggregate, and water required for each batch must be carefully weighed or measured according to project specifications. Third, even the best designed, best graded, and highest quality mix does not make good concrete if it is not workable enough to fill the form spaces thoroughly.

18 | NASHWAN HAMID YAHYA EMAD

5 de February de 2009 to ● 7:37 am

Concrete is the only major building material that can be delivered to the job site in a plastic state. This unique quality makes concrete desirable as a building material because it is able to be molded to virtually any form or shape. Concrete is also designed to permit reliable and high quality fast-track construction. Structures built with concrete are more durable and can be engineered to withstand earthquakes, hurricanes, typhoons and tornadoes.

19 | Yaser Mohammed Rageh Gamil(UTHM)

5 de February de 2009 to ● 8:09 am

The current practice of ensuring the required gamma
shielding and strength of metal-concrete casks is based on
concrete density. For this purpose high-density rocks
(magnetite, iron glance, barium sulfate, etc.) as well as
scrap, scale, broken metal chips and others are introduced
into concrete as coarse aggregates. The fine aggregate sand
fractions in such concretes are usually crushed limonite,
quartzite tailings, iron shot etc. Use of these coarse and fine
aggregates as well as special technology procedures made it
possible to increase concrete density up to ∼ 4 gm/сm3 at
strength of ∼ 79 MPa.
It is possible to increase efficiency, specific
characteristics and safety of casks due to inclusion of very
dense depleted uranium dioxide (UO2) into concrete
composition
Use of depleted uranium dioxide (UO2) in metal-concrete
casks, along with ensuring of required degree of gamma
shielding, can also provide slowdown of fast neutrons due to
high oxygen in depleted uranium dioxide (1.3 gm/cm3). This
allows capturing neutrons by thermal neutron absorption.
This property is unique for such high-density shielding
materials [1].

20 | shagea Ali Ali

7 de February de 2009 to ● 6:25 am

It is my pleasure to contribute a humble information about the concrete and how it affects and changes the humanity life .Definitely concrete is the main factor which is using in a bulidings, bridges and towers construction.Basically it consists of cement, aggregate and water ,in addition to steel to strengthen the concrete against the tension.Eventually, i would rather to express my deep thank to the one who design this website , especially prof.lee who is my favourite lecturer.

21 | NASHWAN HAMID YAHYA AL-EMAD

20 de February de 2009 to ● 3:34 am

WHY WE USE FLY ASH IN CONCRETE?

, there are many practical reasons to add some (if not a lot of) fly ash to concrete–not just in addition to portland cement, but in replacement of it. we know that the performance-enhancing effects of fly ash on workability, pumpability, strength, shrinkage, and permeability. The effects are so many, and so positive, that senior figures in the world of concrete have recently stated that concrete without fly ash belongs in a museum.

22 | Ahmed abdulrahman ali Hamid

4 de March de 2009 to ● 8:39 am

A common mistake people make is to use the words cement and concrete interchangably. It is important to remember that cement is only a component of concrete and concrete is the structural material. The cement used in concrete is not used as a building material because it would be too expensive and not as strong as concrete. So when you see a parking garage, a driveway, a sidewalk or a road remember it is made of concrete, not cement. And, by the way, that funny looking truck is a concrete mixer, not a cement mixer! But, if cement is not concrete, then what is it?

Cement is a general name for a material that binds other materials together. Yes, it is another name for glue. There are many materials which we would classify as cements and they are usually identified with certain uses, and can produce different types of “concrete”. The type of cement used to make the riding surface of some of our roads (blacktop!) is called asphalt cement. It is a petroleum bi-product, and it binds rock into the road material we call asphaltic concrete

23 | AHMED ABDULRAHMAN HAMID

4 de March de 2009 to ● 12:47 pm

Concrete provides the best fire resistance of any building material. It does not burn, it cannot be ‘set on fire’ like other materials in a building and it does not emit any toxic fumes, smoke or drip molten particles when exposed to fire. Concrete and its mineral constituents enjoy the highest fire resistance classification (class A1) under EN 13501-1.

This excellent fire performance is due in the main to concrete’s constituent materials (i.e. cement and aggregates) which, when chemically combined, form a material that is essentially inert and has poor thermal conductivity. It is this slow rate of heat transfer that enables concrete to act as an effective fire shield not only between adjacent spaces but also to protect itself from fire damage.

The only potential risk to life safety from concrete in fire occurs in the form of spalling, which principally affects High Performance and Ultra High Performance Concrete. Even here, effective measures can be taken to reduce the probability of spalling

24 | ashmann

5 de March de 2009 to ● 4:31 am

Dr. Sami Rizkalla explains that by testing the new concrete beam design to see how much weight it can bear, researchers have determined that it can handle two to three times the maximum weight it would be expected to bear.

(North Carolina) — People are always looking for ways to make something less expensive and more environmentally friendly – and a team of researchers from North Carolina State University has figured out how to do both of those things at once when raising the large-scale buildings, such as parking garages, of the future.

More specifically, the researchers have figured out a way to use 30 percent less reinforcing steel in the manufacture of the concrete beams, or spandrels, used in the construction of parking garages – without sacrificing safety. Dr. Sami Rizkalla, one of the leaders of the research team, says they developed design guidelines that use less steel while maintaining safety and reliability. The new spandrel design “simplifies construction for precast concrete producers,” Rizkalla says. In addition to using less steel, the new design cuts labor and manufacturing time in half – significantly decreasing costs.

Greg Lucier, a doctoral student at NC State who was also crucial to the research effort, says the new design guidelines include a significant margin for safety. For example, Lucier says the spandrels could handle two to three times the maximum weight they would be expected to bear. Lucier is also the lab manager of the Constructed Facilities Laboratory at NC State, which oversaw the testing of the new spandrel design.

The new design guidelines stem from a two-year project that was launched in January 2007, with support from the Precast/Prestressed Concrete Institute (PCI). PCI provided NC State with more than $400,000 in funding, materials and technical support over the life of the project.

The success of the project is already drawing interest from the concrete industry, with individual companies coming to NC State to get input on how to improve their products and manufacturing processes. For example, Rizkalla says, many companies want to collaborate with researchers at the Constructed Facilities Laboratory on research and development projects related to new materials, such as advanced composites, to be used in concrete products.

While researchers have published some elements of the research project, they will present an overview of the entire project – including new testing data – for the first time at the spring convention of the American Concrete Institute in San Antonio this month.

25 | MAGED MOHAMMED AL-ZEKRI

5 de March de 2009 to ● 6:33 am

The water/cement ratio (w/c) of the mixture has the most control over the final properties of the concrete. The water/cement ratio is the relative weight of the water to the cement in the mixture. The water/cement ratio is a design criterion for the engineer. Selection of a w/c ratio gives the engineer control over two opposing, yet desirable properties: strength and workability. A mixture with a high w/c will be more workable than a mixture with a low w/c: it will flow easier. But the less workable the mixture, the stronger the concrete will be. The engineer must decide what ratio will give the best result for the given situation. This is not an entirely free choice because the water/cement ratio needs to be about 0.25 to complete the hydration reaction. Typical values of w/c are between 0.35 and 0.40 because they give a good amount of workability without sacrificing a lot of strength

26 | YASER

25 de March de 2009 to ● 1:55 am

The importance of concrete in modern society cannot be overestimated. Look around you and you will find concrete structures everywhere such as buildings, roads, bridges, and dams. There is no escaping the impact concrete makes on your everyday life. So what is it?

Concrete is a composite material which is made up of a filler and a binder. The binder (cement paste) “glues” the filler together to form a synthetic conglomerate. The constituents used for the binder are cement and water, while the filler can be fine or coarse aggregate. The role of these constituents will be discussed in this section.

Cement, as it is commonly known, is a mixture of compounds made by burning limestone and clay together at very high temperatures ranging from 1400 to 1600 [[ring]]C.

Although there are other cements for special purposes, this module will focus solely on portland cement and its properties. The production of portland cement begins with the quarrying of limestone, CaCO3. Huge crushers break the blasted limestone into small pieces. The crushed limestone is then mixed with clay (or shale), sand, and iron ore and ground together to form a homogeneous powder. However, this powder is microscopically heterogeneous. (See flowchart.)

Figure 1: A flow diagram of Portland Cement production.

27 | YASER

25 de March de 2009 to ● 1:57 am

Strength of Concrete

The strength of concrete is very much dependent upon the hydration reaction just discussed. Water plays a critical role, particularly the amount used. The strength of concrete increases when less water is used to make concrete. The hydration reaction itself consumes a specific amount of water. Concrete is actually mixed with more water than is needed for the hydration reactions. This extra water is added to give concrete sufficient workability. Flowing concrete is desired to achieve proper filling and composition of the forms. The water not consumed in the hydration reaction will remain in the microstructure pore space. These pores make the concrete weaker due to the lack of strength-forming calcium silicate hydrate bonds. Some pores will remain no matter how well the concrete has been compacted.

28 | YASER

25 de March de 2009 to ● 1:59 am

The Alkali-Silica Reaction (ASR) is a reaction which occurs over time in concrete between the highly alkaline cement paste and reactive non-crystalline (amorphous) silica, which is found in many common aggregates.

The ASR reaction is the same as the Pozzolanic reaction which is a simple acid-base reaction between calcium hydroxide, also known as Portlandite, or (Ca(OH)2), and silicic acid (H4SiO4, or Si(OH)4). For the sake of simplicity, this reaction can be schematically represented as following:

Ca(OH)2 + H4SiO4 —> Ca2+ + H2SiO42- + 2 H2O —> CaH2SiO4 · 2 H2O

This reaction causes the expansion of the altered aggregate by the formation of a swelling gel of Calcium Silicate Hydrate (CSH). This gel increases in volume with water and exerts an expansive pressure inside the material, causing spalling and loss of strength of the concrete, finally leading to its failure.

So, ASR can cause serious expansion and cracking in concrete, resulting in critical structural problems that can even force the demolition of a particular structure.[1]

The mechanism of ASR causing the deterioration of concrete can be described in four steps as follows:

1. The alkaline solution attacks the surface of the siliceous aggregate to convert it to viscous alkali silicate gel. The aggregate is covered with the gel.
2. Consumption of alkali by the reaction induces the dissolution of Ca2+ ions into the cement porewater. Calcium ions then react with the gel to convert it to hard calcium silicate hydrate (reaction rim).
3. The reaction rim allows the penetration not of the alkali silicate but the alkaline solution. The penetrated alkaline solution converts the remaining siliceous minerals into bulky alkali silicate gel. The resultant expansive pressure is stored in the aggregate.
4. The accumulated pressure cracks the aggregate and the surrounding cement paste when the pressure exceeds the tolerance of the aggregate [2].

However, ASR can be mitigated in concrete by three complementary approaches:

1. Limit the alkali metal content of the cement. Many standards impose limits on the “Equivalent Na2O” content of cement.
2. Limit the reactive silica content of the aggregate. Certain volcanic rocks are particularly susceptible to ASR because they contains volcanic glass (obsidian) and should not be used as aggregate. The use of calcium carbonate aggregates is sometimes envisaged as a ultimate solution to avoid any problem. However, while it may be considered as a necessary condition, it is not a sufficient one. In principle, limestone (CaCO3) is not expected to contain high level of silica, but it actually depends on its purity. Indeed, some siliceous limestones (a.o., Kieselkalk found in Switzerland)[3] may be cemented by amorphous or crystalline silica and can be very sensitive to the ASR reaction as observed with some siliceous limestones exploited in quarries in the area of Tournai in Belgium.[4] So, the use of limestone as aggregate is not a guarantee against ASR in itself. The silica content of the limestone and its reactivity must remain below a threshold value that has to be carefully experimentally assessed by the aggregate producer.
3. Add very fine siliceous materials to neutralize the excessive alkalinity of cement with silicic acid by voluntary provoking a controlled pozzolanic reaction at the early stage of the cement setting. Convenient pozzolanic materials to add to the mix may be, e.g.,pozzolan, silica fume, fly ashs, or metakaolin.[5] These react preferentially with the cement alkalis without formation of an expansive pressure, because siliceous minerals in fine particles convert to alkali silicate and then to calcium silicate without formation of semipermeable reaction rims.

29 | YASER

25 de March de 2009 to ● 2:00 am

Concrete is a construction material composed of cement (commonly Portland cement) as well as other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate such as gravel, limestone, or granite, plus a fine aggregate such as sand), water, and chemical admixtures. The word concrete comes from the Latin word “concretus”, which means “hardened” or “hard”.

Concrete solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material. Concrete is used to make pavements, architectural structures, foundations, motorways/roads, bridges/overpasses, parking structures, brick/block walls and footings for gates, fences and poles.

Concrete is used more than any other man-made material in the world.[1] As of 2006, about 7 cubic kilometres of concrete are made each year—more than one cubic metre for every person on Earth.[2] Concrete powers a US $35-billion industry which employs more than two million workers in the United States alone.[citation needed] More than 55,000 miles (89,000 km) of highways in America are paved with this material. The People’s Republic of China currently consumes 40% of the world’s cement/concrete production.[citation needed]

Reinforced concrete and Prestressed concrete are the most widely used modern kinds of concrete functional extensions.

30 | YASER

25 de March de 2009 to ● 2:01 am

Portland cement is the most common type of cement in general use around the world, because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate which controls the set time, and up to 5% minor constituents (as allowed by various standards).

As defined by the European Standard EN197.1, “Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates (3CaO.SiO2 and 2CaO.SiO2), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium content (MgO) shall not exceed 5.0% by mass.” (The last two requirements were already set out in the German Standard, issued in 1909).
Blue Circle Southern Cement works near Berrima, New South Wales, Australia.

Portland cement clinker is made by heating, in a kiln, a homogeneous mixture of raw materials to a sintering temperature, which is about 1450 °C for modern cements. The aluminium oxide and iron oxide are present as a flux and contribute little to the strength. For special cements, such as Low Heat (LH) and Sulfate Resistant (SR) types, it is necessary to limit the amount of tricalcium aluminate (3CaO.Al2O3) formed. The major raw material for the clinker-making is usually limestone (CaCO3) mixed with a second material containing clay as source of alumino-silicate. Normally, an impure limestone which contains clay or SiO2 is used. The CaCO3 content of these limestones can be as low as 80%. Second raw materials (materials in the rawmix other than limestone) depend on the purity of the limestone. Some of the second raw materials used are: clay, shale, sand, iron ore, bauxite, fly ash and slag. When a cement kiln is fired by coal, the ash of the coal acts as a secondary raw material.

31 | ashmann

21 de May de 2009 to ● 3:30 am

Blended Cement for Waterproofing Applications
Radin Sumadi, Salihuddin and Chan, Poh Chin and Jasmin, Lenny Sheryme (2006) Blended Cement for Waterproofing Applications. Project Report. Faculty of Civil Engineering, Skudai, Johor. (Unpublished)

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Abstract
The application of mineral admixtures as partial cement replacement in concrete leads to a reduction in construction cost. Usually single mixture has limitation and some have contrasting influences on properties of concrete. The combination of more kinds of mineral admixtures is postulated to improve concrete properties. Since RHA is highly reactive pozzolan, it has led to the idea of focusing the study on the performance of Multiblended pozzolan as partial cement replacement in mortar. Over 8 different mixes were produced in which four mixes contained varying percentages of admixtures (Multi Blended Cement, MBC) and the remainders were single mix (Binary Blended Cement, BBC) containing optimum percentages (based on literature study) of 20% PFA, 20% RHA, 50% SLAG, and 10% POFA. Three samples for each mix, curing period and parameter tests were prepared. This work initially deals with compressive strength characteristics, water absorption, and total porosity on mortar cured (standard curing) for 7, 28, 60 and 90 days. The performance of optimum MBC mortar was studied in terms of ultimate compressive strength, water absorption and total porosity. The strength properties of the optimum mixes of MBC mortars was also examined at different curing regimes. This research also focuses on studying some durability aspects of the optimum mix of MBC mortars namely acid attack, and carbonation. Besides, the effects of saline seawater were investigated for short term exposure. Finally attempt in brief study on suitability of the optimum mixes of MBC mortars as face sheets to produce lightweight non-load bearing sandwich block was conducted. From the results obtained, it was found that the strength of control and BBC mortars at early age on average were 20% higher than MBC mortars, and at final age both were comparable with MBC mortars. The strength of all mortars at 90 days on average was 59MPa. However, the MBC system produced low permeability mortar compared to control, and BBC mortars at all ages. The total porosity and water absorption of control and BBC were 28% and 21%, and 9% and 14%, respectively. The strength of MBC mortar after 45 cycles of wet and dry curing in seawater exhibited 24% higher than control mortar. The initial water curing for 7 and 14 days and continuous air curing also exhibited 13% and 19%, and 21% and 26%, higher early strength than continuous water and air curing, respectively. The strength and durability properties of MBC mortar are more pronounced than control when it is iv provided with adequate curing. After exposure to chemical attack, the MBC mortar exhibits better resistance than control mortar. With adequate curing the MBC mortar was higher in durability than control mortar when subjected to chemical attack.

Item Type: Monograph (Project Report)
Uncontrolled Keywords: cement replacement, mineral admixtures, multi-blended pozzolan
Subjects: T Technology > TS Manufactures
ID Code: 5824
Deposited By: Noor Aklima Harun
Deposited On: 02 Jul 2008 17:01
Last Modified: 26 Sep 2008 09:24

32 | ashmann

9 de July de 2009 to ● 12:04 am

In road-building circles, the “concrete vs. asphalt” debate is every bit as intense as that drunken discussion (eventually devolving into a weepy shouting match) every year at Thanksgiving dinner between your right-wing uncle and your pinko vegan cousin.

On the rhetorical battleground, one of the strongest anti-concrete arguments has always been: “So pricey!” But perhaps that is changing. In Minneapolis, when bids came in on a project that includes new bus lanes and wider sidewalks (on Marquette and Second Aves near the convention center, for those familiar with the local terrain) the concrete and asphalt options cost more or less the same, according to a local business paper.

The underlying trend here is that asphalt’s price is closely tied to the price of oil. And when a barrel of crude when into three-digit land last year, asphalt was suddenly as expensive as concrete.

Even though the price of asphalt has come down a bit recently (according to many reports), this could still be a key moment in the debate.

We’ll take the opportunity to pick sides a bit and say we prefer using concrete whenever possible. Yes, it’s bumpy and loud to drive on and the initial construction costs have historically been a lot higher. But it’s also light of shade — that is, it absorbs a lot less heat. New concrete has an albedo as high as 0.80(meaning it reflects about 80 percent of the sun’s heat). New asphalt has an albedo as low as 0.05 (it absorbs 95 percent). That’s a *huge* difference — greater, in fact, than the difference between snow and seawater.

As we wrote about hereand here, a trio of well-regarded scientists have argued very persuasively that all the dark rooftops and roadways in our cities are heating up the planet, and we could buy a lot of time–think 20 years–in dealing with climate change if we lightened up on the double. Steven Chu, our Nobel laureate Secretary of Energy, has even weighed in in support of the idea. (We think he should put some stimulus money where his mouth is.)

We have a hunch that oil prices might headed back over $100/barrel in the next year or two. If that scenario plays out, it might offer a perfect opportunity to start migrating over to lighter pavements as a matter of national (and international) policy. Let the Great Whitening begin.

33 | ashmann

15 de September de 2009 to ● 5:09 pm

In the 2,000 or so years since the Roman Empire employed a naturally occurring form of cement to build a vast system of concrete aqueducts and other large edifices, researchers have analyzed the molecular structure of natural materials and created entirely new building materials such as steel, which has a well-documented crystalline structure at the atomic scale.

Oddly enough, the three-dimensional crystalline structure of cement hydrate – the paste that forms and quickly hardens when cement powder is mixed with water – has eluded scientific attempts at decoding, despite the fact that concrete is the most prevalent man-made material on earth and the focus of a multibillion-dollar industry that is under pressure to clean up its act. The manufacture of cement is responsible for about 5 percent of all carbon dioxide emissions worldwide, and new emission standards proposed by the U.S. Environmental Protection Agency could push the cement industry to the developing world.

“Cement is so widely used as a building material that nobody is going to replace it anytime soon. But it has a carbon dioxide problem, so a basic understanding of this material could be very timely,” said MIT Professor Sidney Yip, co-author of a paper published online in the Proceedings of the National Academy of Sciences (PNAS) during the week of Sept. 7 that announces the decoding of the three-dimensional structure of the basic unit of cement hydrate by a group of MIT researchers who have adopted the team name of Liquid Stone.

“We believe this work is a first step toward a consistent model of the molecular structure of cement hydrate, and we hope the scientific community will work with it,” said Yip, who is in MIT’s Department of Nuclear Science and Engineering (NSE). “In every field there are breakthroughs that help the research frontier moving forward. One example is Watson and Crick’s discovery of the basic structure of DNA. That structural model put biology on very sound footing.”

Scientists have long believed that at the atomic level, cement hydrate (or calcium-silica-hydrate) closely resembles the rare mineral tobermorite, which has an ordered geometry consisting of layers of infinitely long chains of three-armed silica molecules (called silica tetrahedra) interspersed with neat layers of calcium oxide.

But the MIT team found that the calcium-silica-hydrate in cement isn’t really a crystal. It’s a hybrid that shares some characteristics with crystalline structures and some with the amorphous structure of frozen liquids, such as glass or ice.

At the atomic scale, tobermorite and other minerals resemble the regular, layered geometric patterns of kilim rugs, with horizontal layers of triangles interspersed with layers of colored stripes. But a two-dimensional look at a unit of cement hydrate would show layers of triangles (the silica tetrahedra) with every third, sixth or ninth triangle turned up or down along the horizontal axis, reaching into the layer of calcium oxide above or below.

And it is in these messy areas – where breaks in the silica tetrahedra create small voids in the corresponding layers of calcium oxide – that water molecules attach, giving cement its robust quality. Those erstwhile “flaws” in the otherwise regular geometric structure provide some give to the building material at the atomic scale that transfers up to the macro scale. When under stress, the cement hydrate has the flexibility to stretch or compress just a little, rather than snapping.

“We’ve known for several years that at the nano scale, cement hydrates pack together tightly like oranges in a grocer’s pyramid. Now, we’ve finally been able to look inside the orange to find its fundamental signature. I call it the DNA of concrete,” said Franz-Josef Ulm, the Macomber Professor in the Department of Civil and Environmental Engineering (CEE), a co-author of the paper. “Whereas water weakens a material like tobermorite or jennite, it strengthens the cement hydrate. The ‘disorder’ or complexity of its chemistry creates a heterogenic, robust structure.

“Now that we have a validated molecular model, we can manipulate the chemical structure to design concrete for strength and environmental qualities, such as the ability to withstand higher pressure or temperature,” said Ulm.

CEE Visiting Professor Roland Pellenq, director of research at the Interdisciplinary Center of Nanosciences at Marseille, which is part of the French National Center of Scientific Research and Marseille University, pinned down the exact chemical shape and structure of C-S-H using atomistic modeling on 260 co-processors and a statistical method called the grand canonical Monte Carlo simulation.

Like its name, the simulation requires a bit of gambling to find the answer. Pellenq first removed all water molecules from the basic unit of tobermorite, watched the geometry collapse, then returned the water molecules singly, then doubly and so on, removing them each time to allow the geometry to reshape as it would naturally. After he added the 104th water molecule, the correct atomic weight of C-S-H was reached, and Pellenq knew he had an accurate model for the geometric structure of the basic unit of cement hydrate.

The team then used that atomistic model to perform six tests that validated its accuracy. “This gives us a starting point for experiments to improve the mechanical properties and durability of concrete. For instance, we can now start replacing silica in our model with other materials,” said Pellenq.

Other team members are graduate student Rouzbeh Shahsavari of CEE and Markus Buehler, MIT’s Esther and Harold E. Edgerton Career Development Associate Professor of Civil and Environmental Engineering; Krystyn Van Vliet, MIT’s Thomas Lord Associate Professor of Materials Science and Engineering; and NSE postdoctoral associate Akihiro Kushima.

This research was funded by the Portuguese cement manufacturer, Cimpor Corp., enabled through the MIT-Portugal Program.