cement

We here at Spectrum have been busy researching Photo Catalytic Concrete to help improve build our skateparks Eco-Smart. As concrete is used for many other things besides building skateparks, we thought we should share our research with everyone else out in BuildingGreen land. Enjoy!

Photo-Catalytic Concrete

1. “A Concrete Step toward Cleaner Air” by Bruno Giussani, article on InnoEurope website:

http://innoeurope2.cma.ee/index.php?lang=eng&main_id=16&id=121

- Italian Pavilion in Venice Biennale incorporated this product. Parts of the concrete walls and grounds have been built with cement containing an active agent that, in presence of light, breaks down air pollutants such as carbon monoxide, nitrogen oxide, benzene, and others through a natural chemical process called photo catalysis.

- The technology, called TX Active, has been under development for almost 10 years in the labs of Italcementi, and is starting to be applied commercially to buildings and streets in Italy, France, Belgium, and elsewhere.

- A street in the town of Segrate, near Milan, with an average traffic of 1,000 cars per hour, has been repaved with the compound, "and we have measured a reduction in nitric oxides of around 60%,"

- Active principle in TX Active is a blend of titanium dioxide that acts as a photo catalyser—can be incorporated in cement, mortar, paints, and plaster.

- In the presence of light, speeds up the natural oxidation processes that cause the decomposition of pollutants, transforming them into less harmful compounds such as water, nitrates, or carbon dioxide.

- In Italy, the product is also known as "cemento mangiasmog" or "smog-eating cement".

- It does costs more than typical cement, but active principle only need to be used on the surface.

- "To transform the facade of a five-story building into a photo catalytic surface would add only 100 or so euros ($120) to the cost of a traditional paint or plaster".

- Photo catalytic blocks cost about one-third more than usual paving.

- Used in Richard Meier’s Dives in Misericordia church in Rome (2003), also Air France headquarters inside Charles de Gaulle airport in Paris.

- Architects/ designers like it because it stays white, thus an aesthetic benefit.

2. Photo catalysis Background Info.

http://dev.nsta.org/evwebs/1952/photocatalysis.htm

- Photo catalysis is a reaction which uses light to activate a substance which modifies the rate of a chemical reaction without being involved itself.

- Semiconductors are what are usually used for this.

- Chemically speaking: “…semiconductors are usually selected as photo catalysts, because semiconductors have a narrow gap between the valence and conduction bands. In order for photo catalysis to proceed, the semiconductors need to absorb energy equal to or more than its energy gap. This movement of electrons forms e-/h+ or negatively charged electron/positively charged hole pairs. The hole can oxidize donor molecules…”

- Titanium Dioxide (TiO2) is used because:
-inert
-resists corrosion
-inexpensive
-can react in mild operating conditions
- However, needs UV light for photo catalysis to occur.

3. TX Active - Photo catalytic cement technology.
This is the specific product line, available in North America through Essroc Cement Corp (www.essroc.com)

http://www.essroc.com/default.aspx?pageid=216

TX Active line has 2 products:

1. TX Arca cement, concrete with self-cleaning benefit. Photo catalysis reduces maintenance by destroying most organic/inorganic pollutants that contact concrete and cause discoloration.

2. TX Aria cement, has added ability to mitigate environmental pollution. Effectively destroys airborne pollutants, which are responsible for urban organic pollution.

- How do they work? Products use hydraulic binder with photo catalytic properties.

- Developed over a decade’s R&D by Italcementi’s Technical Research Center in Bergamo, Italy.

- TX Active concrete can be used in vertical, horizontal, structural, architectural pre-cast, plaster and coatings, concrete blocks, jersey barriers, retaining walls, concrete paving and cementitious tiles.

- Photo catalysis also has antibacterial benefits.

4. Concrete That Cleans Air, blog entry on Shawn Hogan fan club blog.

http://www.shawnhogan.com/2006/11/concrete-that-cleans-air.html

- “The results so far are astonishing: A street in the town of Segrate, near Milan, with an average traffic of 1,000 cars per hour, has been repaved with the compound, "and we have measured a reduction in nitric oxides of around 60%," says Italcementi's spokesperson Alberto Ghisalberti. In a test over an 8,000 square meter (or approximately 2 acres) industrial area paved with active blocks near Bergamo, Italcementi's hometown, the reduction was measured at 45%. “
- “In large cities such as Milan, with persistent pollution problems caused by car emissions, smoke from heating systems, and industrial activities, both the company and outside experts estimate that covering 15% of all visible urban surfaces (painting the walls, repaving the roads) with products containing TX Active could abate pollution by up to 50%, depending on the specific atmospheric conditions. „

4. Air-Cleaning Concrete –

http://www.sciencenews.org/articles/20050101/bob9.asp

Grancrete is a tough reinforcement-free ceramic building material, created by Jim Paul as a replacement for concrete, and it is made from an environmentally friendly mix of locally available materials: 50 percent sand or sandy soil, 25 percent ash and 25 percent binding material. Binding material is composed of magnesium oxide and potassium phosphate, the latter of which is a biodegradable element in fertilizer. If Grancrete were to decompose (its lifespan is calculated at 100 years+) it would revitalize the soil. Early in the development stage, Mr. Paul had problems with cracking, so he turned to Arun Wagh (an amazing man!) of The Argonne National Laboratory, who in 1996 created a material called Ceramicrete, originally developed to encase nuclear waste, and has since led to many other uses.
Grancrete is 20% lighter than and twice as strong as concrete, is fire resistant and can withstand both tropical and sub-freezing temperatures. It has the ability to set quickly in a much greater range of temperatures than concrete. It has a short curing time (15 to 20 minutes), is pH tolerant, impervious to water (including salt) and even cures underwater. It bonds to all surfaces, except glass and plastics, and will not expand or contract, meaning no control joints are necessary.
Grancrete can be sprayed, poured, troweled, coloured, painted, whatever you can dream up. It shall be fascinating to see what develops in the future.....

Early photos of Gancrete being sprayed over a styrofoam structure:

Grancrete, Inc.

Inspired by mid-century modernism, the Minimalist concrete tile line by designer David-Michael for Smith-Laredo is suitable indoors or outdoors. Minimalist offers the durability and easy maintenance of a standard concrete made with Portland cement (which is not a green material), but the difference with these tiles lies in their composition: they are made from crushed limestone, sand, water and aggregate quarried near the firm's San Diego base, and pigments are derived from naturally occurring oxides. NO energy is used to fire these tiles - they cure naturally over a period of three weeks.
Minimalist is available in seven colors, and comes in four sizes: 18"x18", 18"x9", 9"x9", and 4.25"x4.25". Brilliant.

Smith-Laredo

Gigacrete is a new, eco-friendly cementitious building material that uses no Portland cement; rather, it consists of a proprietary nontoxic binder, and a filler utilizing waste ash from coal fired power generation stations, of all grades, not just the fly ash currently used as a ten percent filler in concrete. Other fillers include waste paper, cardboard and plastics, styrofoam packaging, sludge from paper mills, and agricultural waste fibers (leftover from food crops like rice, corn, wheat and other grains). Since most of these materials would just end up in a landfill (sacrilege!), they instead make a great alternative building material. All of the above materials become totally fireproof and can be made very lightweight, yet are as strong as traditional concrete, sometimes even more so. Gigacrete composites do not shrink or crack like concrete, they're fireproof and water/insect/vermin/mold/hurricane/earthquake resistant. Products include: PanelSystem, Stuccomax, StuccoMax-E (Environmental), Floor Overlay, PlasterMax, GigaCast and GigaPatch. The site is definitely worth a look-see.

From the site:
PanelSystem is the basis of a complete panelized building system with many residential, commercial, and industrial applications. Utilizing new manufacturing technology, the PanelSystem is vertically cast in a factory and delivered to job sites ready for rapid installation. The PanelSystem is engineered to be fireproof and water, insect, vermin, mold, hurricane, and earthquake resistant. While GigaCrete™ panels have minimum compressive strengths of 1,200 PSI, the panels are a fraction of the weight of most Portland-based concrete panels and require only hand labor to move and construct. The GigaCrete PanelSystem can be molded for structural walls, interior walls, floors, and roofing - providing a turnkey building system that significantly reduces the time and cost of construction.

GigacreteUSA

Voted one of the top 25 "Best of Green Design", by Popular Mechanics

Fly ash is the fine residue powder byproduct from coal-fired electric generating plants. Since the burning of coal provides up to 85% of our electricity (depending on where you live), a great deal of this powder is produced. Some 63 million tons of fly ash were produced in 2002, resulting in 63 tons of mercury byproduct.

Currently, the fly ash is released into the air, buried in a landfill or illegally dumped into our oceans. fly ash contains approximately 1 part per million of mercury (NOTE: The maximum level of mercury in drinking water permitted by the EPA is 2 parts per billion.) The mercury seeps into our groundwater and contaminates our fish. Humans eat the fish, and the mercury accumulates in our bodies.

Mercury has been linked to numerous health problems, including autism in newborns, endocrine disruption and cardiovascular disease. Since 1990, there has been a 10-fold increase in the incidence of autism. One can quickly see a need for an alternate use of this fly ash.

(NOTE: It only takes 1/70th of a teaspoon of mercury to contaminate a 20 acre body of water and make all fish within it toxic to humans. This is about the amount of mercury in a typical medical thermometer.)

Concrete is a mixture of sand, water, stone, and Portland Cement. The cement is the key ingredient in concrete, comprising about 12% of the mix weight, acting as the binding agent that holds sand and other aggregates together in a hard, stone-like mass.

Energy consumption is the biggest environmental concern with Portland Cement, requiring a great deal of energy to mine out of the Earth, grind up, heat in a kiln and process into the final product. Cement production is one of the most energy intensive of all industrial manufacturing processes. One can also see a need to find an alternative for cement.

Kevin,

I very much like your show, and last night saw the episode in which you poured a foundation using "fly ash" to substitute for cement. While this may have certain environmental advantages, some fly ash is slightly radioactive, depending on the original coal. This may result in a foundation with issues similar to the radon accumulation issue in homes with basements. Especially in an energy efficient home, where the air circulation level may be low, I would at least look into what the radon emitting characteristics of the fly ash will be.

Best regards,
Cas Milner

Yikes! I learn something new every day. Someone else alerted me to the radioactive possibility in fly ash. I actually had a Geiger counter brought in to test our concrete. There was no evidence of radioactivity. Radon is different from Radioactivity. It emanates naturally from the ground, particularly in certain regions, especially (but not only) regions with granitic soils. However, not all granitic regions are prone to high emissions of radon. Depending on how houses are built and ventilated, radon may accumulate in basements and dwellings. Many methods can reduce radon in homes. I would like any scientific information you or others have about radioactivity in fly ash.

Sincerely,

Kevin

Kevin,

Is that pot or fly ash that you used in the concrete? Years ago I heard that about a 30 percent mixture waterproofed the concrete. What are the advantages of using ash? Why is it a green choice?

Thanks,

Gary

Gary,

This document will tell you everything you need to know about fly ash concrete.

Kevin