In Focus: Carbon Reduced Concrete

carbon-reduced-concreteKansas State University civil engineers are developing the right mix to reduce concrete’s carbon footprint and make it stronger. Their innovative ingredient: biofuel byproducts.

“The idea is to use bioethanol production byproducts to produce a material to use in concrete as a partial replacement of cement,” said Feraidon Ataie, doctoral student in civil engineering, Kabul, Afghanistan. “By using these materials we can reduce the carbon footprint of concrete materials.”

Concrete is made from three major components: portland cement, water and aggregate. The world uses nearly 7 billion cubic meters of concrete a year, making concrete the most-used industrial material after water, said Kyle Riding, assistant professor of civil engineering and Ataie’s faculty mentor.

“Even though making concrete is less energy intensive than making steel or other building materials, we use so much of it that concrete production accounts for between 3 to 8 per cent of global carbon dioxide emissions,” Riding said.

To reduce carbon dioxide emissions from concrete production, the researchers are studying environmentally friendly materials that can replace part of the portland cement used in concrete. They are finding success using the byproducts of biofuels made from corn stover, wheat straw and rice straw.

“It is predicted that bioethanol production will increase in the future because of sustainability,” Ataie said. “As bioethanol production increases, the amount of the byproduct produced also increases. This byproduct can be used in concrete.”

The researchers are specifically looking at byproducts from production of cellulosic ethanol, which is biofuel produced from inedible material such as wood chips, wheat straw or other agricultural residue. Cellulosic ethanol is different from traditional bioethanol, which uses corn and grain to make biofuel. Corn ethanol’s byproduct (called distiller’s dried grains) can be used as cattle feed, but cellulosic ethanol’s byproduct (called high-lignin residue) is often perceived as less valuable.

“With the cellulosic ethanol process, you have leftover material that has lignin and some cellulose in it, but it’s not really a feed material anymore,” Riding said. “Your choices of how to use it are a lot lower. The most common choices would be to either burn it for electricity or dispose of the ash.”

When the researchers added the high-lignin ash byproduct to cement, the ash reacted chemically with the cement to make it stronger. The researchers tested the finished concrete material and found that replacing 20 per cent of the cement with cellulosic material after burning increased the strength of the concrete by 32 per cent.

“We have been working on applying viable biofuel pretreatments to materials to see if we can improve the behaviour and use of ash and concrete,” Riding said. “This has the potential to make biofuel manufacture more cost effective by better using all of the resources that are being wasted and getting value from otherwise wasteful material and leftover materials. It has the potential to improve the strength and durability of concrete. It benefits both industries.”

The research could greatly affect Kansas and other agricultural states that produce crops such as wheat and corn. After harvesting these crops, the leftover wheat straw and corn stover can be used for making cellulosic ethanol. Cellulosic ethanol byproducts then can be added to cement to strengthen concrete.

“The utilization of this byproduct is important in both concrete materials and biofuel production,” Ataie said. “If you use this in concrete to increase strength and quality, then you add value to this byproduct rather than just landfilling it. If you add value to this byproduct, then it is a positive factor for the industry. It can help to reduce the cost of bioethanol production.”

The researchers have published some of their work in the American Society of Civil Engineer’s Journal of Materials in Civil Engineering and are preparing several other publications. Ataie also was one of two Kansas State University graduate students named a winner at the 2013 Capitol Graduate Research Summit in Topeka. His poster was titled “Utilization of high lignin residue ash (HLRA) in concrete materials.”

The research at Kansas State University was funded by more than $210,000 from the National Science Foundation. The researchers collaborated with the University of Texas, North Carolina State University and the National Renewable Energy Laboratory in Golden, Colo. The research also involved Antoine Borden, senior in civil engineering, Colorado Springs, Colo.

image: Mazwebs

Original Article on Green Building Canada


In Focus: Carbon Neutral Concrete from CarbonCure


Concrete, the world’s most abundant man-made substance, ranks second to coal as the world’s dirtiest industrial material. Now, a company in Halifax, Canada, is working to make concrete plants carbon neutral, using captured CO2 to improve their product.

By injecting CO2 into concrete during production, CarbonCure sequesters stores that would otherwise pollute the atmosphere. According to Sean Monkman, the company’s Vice President of technology development, CO2 makes concrete stronger and more durable – qualities that translate into reduced waste and energy consumption, and reduced costs for manufacturers and builders.

“CO2 isn’t just a harmful greenhouse gas”, says Robert Nevins, CEO of CarbonCure. “We can use it to make better materials.”

Nevins isn’t alone in spotting this potential. California-based Celera sends its emissions through seawater to create a chalky bicarbonate by-product that, when mixed with concrete, improves its quality. Celera has built a demonstration plant in Monterey to showcase the “beneficial uses” of CO2. Carbon Sciences, also in California, offsets CO2 emissions from coal and steel production plants by sequestering the greenhouse gas in concrete, thereby strengthening the material. And Novacem of London says that its magnesium silicate cement absorbs enough emissions to make it carbon negative.

To date, however, companies have not demonstrated that clean concrete can be produced to meet industry demands, or that the energy used to build new “green” production plants won’t counter its ecological benefits. According to Noel Morrin, Senior Vice President of sustainability at Skanska, effective carbon storage in concrete is “never going to be more than an interesting lab experiment.”

But Nevins’ model may have an answer to these concerns. Rather than building new production plants, CarbonCure is partnering with North American manufacturers, including Basalite and Atlas Block, to bring their concept to facilities that already have established markets and the capacity to produce large quantities. Currently, they’re working with three plants in the U.S. and Canada. Plans to expand include the development of other product types, including pipes and pavements.

by Katherine Rowland at Green Futures

This article originally appeared in Green Futures, the magazine of independent sustainability experts Forum for the Future.

photo courtesy Iwan Gabovitch

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In Focus: The 2030 Challenge

Globally, about one-quarter of greenhouse gas emissions are building related. And that figure is even higher in developed nations. With this massive opportunity to cut GHGs, the non-profit Architecture 2030 has created the 2030 Challenge, an initiative that asks the global architecture and building communities to go carbon neutral by 2030.

The Challenge specifically targets new buildings, developments and major renovations, asking them to reduce energy consumption and fossil fuel/GHG emissions to 60 per cent below the regional or country standard for that specific type of building. That figure increases to 70 per cent in 2015, 80 per cent in 2020, 90 per cent in 2025, ending at carbon neutral in 2030.

Architecture 2030 suggests these reductions come from sustainable building and design practices as well as generating renewable power on-site. Purchasing renewable energy is also an option, but one that’s seen as a last resort with a 20 per cent cap being placed on it.

Existing developments are challenged to reduce their GHG emissions as well. Under this plan they would be expected to reduce fossil-fuel use for buildings, CO2 from transportation and water production by 10 per cent, gradually increasing to 50 per cent in 2030.

The Challenge has gained some serious backers in the few years since its inception. The American Institute of Architects, with its 80,000 members, have accepted the Challenge. As have the U.S. Conference of Mayors, the U.S. Green Building Council and a number of other architecture, building and environmental groups as well as many businesses and universities.

In practice, government has given the Challenge quite a boost. The EPA now uses the 2030 Challenge’s targets in their web-based calculator. As of December 2007, the Energy Independence and Security Act made it mandatory for all new construction and major renovation of federal buildings to adhere to the standards of the 2030 Challenge. State, city and county governments have also issued their own initiatives in line with the Challenge.

A Design Futures Council poll found that in the U.S. approximately 40 per cent of all architecture firms have adopted the Challenge. And 73 per cent of the 30 largest architecture and engineering firms in the country have also agreed to this initiative. These large firms operate multinationally and the hope is that they will spread the ideals of the 2030 Challenge to the projects they work on.

As the adoption and implementation rate of the 2030 Challenge picks up, the market for green building and related materials and renewable energy systems expands. In this way the building industry is building a way out of greenhouse gas emissions and creating a more sustainable built environment. A much needed change for a highly consumptive industry.

For more information visit Architecture 2030.
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