Using coal residue to make a greener brick
Most Silicon Valley investors and entrepreneurs are more comfortable talking about software algorithms and chips than bricks and concrete. But some of them are trying to reinvent the building industry with green tech.
Calstar Products later this year plans to open a factory to manufacture a brick that uses fly ash--the residue from burning coal at power plants--as an ingredient while drastically reducing the amount of energy used in production.
The company is now in the process of raising $15 million in series C funding from venture-capital firms to help finance the operation, which will be in Wisconsin near a coal-fired power plant run by We Energies, according to Calstar Products CEO Michael Kane. It plans to officially launch the product at the GreenBuild conference in November.
(Credit:
Calstar Products)
Calstar Products is one of many green-tech start-ups designing different materials and processes to make builders greener. Along with energy storage and smart grid, it's a busy area of investment. Another company, Serious Materials, which makes a drywall that requires less energy to produce, said on Tuesday it raised an additional $60 million.
With Calstar's bricks, the company says it can reduce the "embedded energy" by 85 percent compared to existing brick-making techniques. Building materials are very energy-intensive: to make bricks, clay is melted at more than 2,000 degrees Fahrenheit for more than a day. Brick production creates 13 billion pounds of carbon dioxide per year and the cement industry is said to be the second largest emitter of pollutants after utilities.
Calstar's process replaces the clay and concrete used in bricks with fly ash so that 40 percent of the product is recycled material, Kane explained. It uses a small percentage of its own additive, which it can adjust for the different chemical properties of the coal that generated the fly ash. The process "captures" the fly ash within the brick so there's no leaching, Kane said.
The business plan is to sell the bricks, which are identical in look to traditional bricks, as replacements for buildings, pavers, and retaining walls at the same price as traditional bricks. Initially, it will be targeting architects and builders seeking out materials for green buildings.
In the U.S. Green Building Council's LEED rating, there aren't points for embedded energy, but Kane thinks that architects can get four points for using innovative and recycled building material.
Kane, who joined the company from the buildings material industry earlier this year to commercialize the product, said that incumbent companies would never have developed this sort of brick.
"Conventional companies can't get their heads around why they should do it. That's why we needed a technology disruptor from the outside the change the rules of the game," he said.
The company plans start manufacturing at full scale early next year and, to try to compete with those incumbents, Calstar Products is establishing a distribution channel in some Midwest states.
The venture may not deliver the giant-size returns that tech-oriented venture capitalists typically expect. But once the company starts selling products, its cash flow should be able to finance additional plants, Kane forecasts.
"When this company was started, it was a highly speculative concept. If it weren't for Silicon Valley, this concept probably wouldn't have happened," he said.
Martin LaMonica is a senior writer for CNET's Green Tech blog. He started at CNET News in 2002, covering IT and Web development. Before that, he was executive editor at IT publication InfoWorld. E-mail Martin. 
Let's make the stupid libs use the bricks for their houses since they hate cheap energy like coal.
Excess CO2 is clearly bad. You can try and argue that global warming isn't caused by man, but the CO2 production clearly is. That excess CO2 has costs- like changing the pH of the oceans. Since those are the source of much of our oxygen, I would say it is a bad thing to be altering them. Coal is cheap, but not so cheap if you include the costs of environmental destruction from the current mining methods as well as the leftover ash.
Don't get me wrong, I am all for doing things better, faster, cheaper. So if they can produce brick using less energy than that is fine with me. As long as the materials in the brick are safe. They mention the material is encased and can't leach but what happens to all the broken bricks or bricks that need cut before putting in place? What happens years from now when brick buildings are left to rot and decay? Lets not create one mess while trying to clean up another (supposed) mess.
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WARNING! Those who can't recognize sarcasm reader discretion is advised.
Well, these are brilliant and intriguing questions you raise. I propose we take tens of thousands our best and brightest minds from all over the world and train them for years with the most rigorous methods and a broad well formed expert knowledge base on these subjects, lets call them say I don't know... Scientists, and before they declare any theory valid after intense investigation they reach a broad consensus on a scholars paper with their peers say at a gathering called oh I don't... A climate change conference, and it can be scrutinized in say a... Scientific journal If the research passes muster it can be called peer reviewed. Let's make sure a very very strong majority of them agree on any theory that may be called oh I don't know... 'Global warming due to man made green house gas emmisions.' and then, surely then those of us with out the time or 'where with all' don't have to come up with irrelevant, unwarranted, unacceptable half baked personal musings on the subject and try to pass them of on the internet as valid ideas to refute the immense investigative work of tens of thousands of true experts.
Still, if I were to throw out some guess's ; the previous changes in earths climate you speak of would have something to do with fluctuating atmospheric carbon dioxide and methane, changes in the earths orbit around the sun, variations in solar output, impact of relatively large meteors and volcanism including eruptions of super volcanoes and changes in the relative location and amount of continental and oceanic crust on the Earth's surface, which affect wind and ocean currents. But I'm no scientist. So...
Oh and before you ask; apparently some schmucks looked at tiny air bubbles trapped in an ice core from East Antarctica; today?s rising atmospheric carbon dioxide concentration is now 27 percent higher than its highest recorded level during the last 650,000 years and some other smucks say there has been around 12 ice ages in that time both minor and major. But with out those scientists and a strong consensus, who's to say?
I'm grew up near Scranton, Pennsylvania (anthracite coal country) in the '60s. "Cinder blocks" were used as a common building material.
The data is hidden away in Calstar Products (previously Calstar Cement) website ? http://calstarproducts.com/resources/gradient-memorandum/
As suspected, fly ash bricks leach toxic metals ? the data shows that even with EPAs very liberal leaching tests, metals including arsenic, antimony, beryllium, cadmium, lead, manganese, mercury and nickel rapidly leach from the bricks within a few hours.
Recall that, Calstar (Luke Pustejovsky, Director of Marketing) was previously claiming that no metals leached from the bricks.
Now, Calstar has changed its story and is claiming that the levels of the metals are below EPA control levels, and so their bricks are safe!
These are the very same EPA tests that have been used to declare fly ash stored in dumps as safe ? that lie has been exposed many times with the discovery of severe water contamination and and poisoning of people and the environment by toxic metals leaching from fly ash ? for example the recent TVA spill.
It is very telling that Calstar has chosen tests that have been shown many times to be seriously flawed and not properly assess hazard. The coal/fly ash industry has hidden behind these same tests for decades and used them to claim that fly ash is safe.
The danger of Calstar?s fly ash bricks is clear from the fact that even these very mild tests result in the leaching of a range of toxic metals. The leaching of these toxins and exposure to people will in reality be much worse.
More proof that Calstar is selling a toxic product that will poison people and the environment.
Gradient Corporation ? which did the report for Calstar, is a contract firm that works with the Coal and Fly Ash industries to promote fly ash as safe ? in fact, it has been funded by EPRI ? the Electric Power Research Institute ? which is directly funded by the power generators who produce all the fly ash!
This explains why Calstar approached Gradient for this ?report?. Gradient is not independent ? it is a lackey of the coal and fly ash industries and has a history of working with these industries and promoting fly ash with dubious ?evidence? for its safety.
This also explains why the report was not prepared by the lab (ACZ laboratories) which actually carried out the leaching tests ? ACZ probably refused to provide a risk assessment ? unlike Gradient. This shows Calstar?s desperation in wanting to claim fly ash bricks are safe.
Yet more proof of a desperate company trying to sell a dangerous product.
In the case of Arsenic (a listed Carcinogen) ? the results show that a staggering 800 ug of Arsenic will leach from one brick in one month ? or almost 10 mg of arsenic per brick per year. THE ARSENIC FROM JUST ONE BRICK IS ENOUGH TO POISON OVER 250 GALLONS OF WATER. This is from Calstar?s own (selective) data.
How about the toxic cocktail of other metals that leach from Calstar?s bricks ? beryllium, cadmium, copper, lead, manganese, mercury, nickel and thallium? OVER 2 GRAMS OF HIGHLY TOXIC METALS WILL LEACH FROM ONE BRICK ? POISONING OVER 1,000 GALLONS OF WATER. JUST ONE BRICK.
How about a house faced with fly ash bricks? A standard residence in WI has about 1,500-2,000 square feet of wall face, requiring about 8,000 ? 10,000 of standard facing bricks.
SO, A RESIDENCE FACED WITH CALSTAR?S FLY ASH BRICKS WILL HAVE A TOTAL TOXIC METALS CONTNT OF OVER 20 POUNDS! 20 POUNDS OF TOXIC METALS SURROUNDING THE OCCUPANTS.
THE FLY ASH BRICKS USED IN ONE HOUSE ARE ENOUGH TO POISON OVER 10 MILLION GALLONS OF WATER.
A HOUSE THAT HAS CALSTAR?S FLY ASH BRICKS IS A MINI FLY ASH LANDFILL ? LEACHING TOXIC METALS ? POLLUTING ALL OF THE SURROUNDINGS AND POISONING THE RESIDENTS ALL AROUND. JUST LIKE A TOXIC FLY ASH SPILL ? LIKE THE TVA FLY ASH SPILL IN TENNESSEE. YOUR HOUSE IS NOW A HAZARDOUS WASTE DUMP.
For comparison ? what toxic metals do clay bricks leach? NONE.
CLAY BRICKS DO NOT LEACH ANY OF THE TOXIC METALS THAT LEACH OUT FROM CALSTAR?S FLY ASH BRICKS. PERIOD.
CALSTAR PRODUCTS ? THE TOXIC FLY ASH BRICK COMPANY.
CALSTAR PRODUCTS ? THE COMPANY THAT WANTS TO MAKE MONEY BY TURNING HOUSES INTO TOXIC WASTE DUMPS.
Save the Gay Whales. - Save the tuna, eat dolphin. - Nuke the bastards.
If you have something to say - or a point to get across - why don't have back up your words with some actual data for the rest of us. I think people also have to realize that competitors often post on these to plant the seed of doubt. The "Green" industry is coming whether you guys want it to or not - and it's about time.
Someone had made reference to "why don't the people of Calstar put the bricks on their home?" - I encourage that person to actually check out Calstar's website and go through their board of directors. You will find a team that is totally dedicated to being the leaders in the "Green" building industry. Here is an excerpt about Paul Holland, one of Calstar's Board of Directors "In addition to coordinating the clean-tech practice at Foundation Capital, Paul and his wife are building what will be perhaps the highest-rated LEED Platinum residence in the U.S"
I am NOT an employee of Calstar and I'm not even in the brick market for my home. But when I see people blasting good people, someone needs to find out just what is really going on. My hats off to Calstar and other companies who are trying to make a difference. I wish you negative guys would take your energy and put it into something productive instead of destructive!!
So nice of you to have warm fuzzy feelings for a Greenwash company managed by crooks and supported by modern-day brigands who call themselves Green VCs. oh.... I almost forgot - and who pay your salary, Luke.
As always - a lot of blather and no data to present. Really Luke - I am disappointed - you still cannot come out in the open and defend your "product"? Why so scared? Worried about your bricks? Liability issues?
If you insist - I am more than happy to humor you - what is "Green" or "Sustainable" about Calstar's fly ash bricks? Pray - do tell?
Since when is a hazardous byproduct of a polluting industrial behemoth "Green".
Since when is a byproduct of a non-sustainable fossil fuel "Sustainable"?
Actually Luke - the best illustrations of what a Greenwash your product is can be found on your website and the posts:
Look at all that lovely efflorescence on the bricks.
Look at the lovely salt transfer from your bricks to mortar.
Look at all the lovely edge delamination and crazing on the bricks.
Look at all the lovely toxic metals leaching from the bricks.
Perhaps you have new definitions of "Green" and "Sustainable"? Definitions more to the liking of your line-your-pocket-with-Greenwash money friends?
Luke - I do wish you would stop creeping around under different pseudonyms - it is most tiresome and illustrates your level of desperation.
So - run along to your "good people" and see what new marketing strategy you can dream up for your Toxic Greenwashed Fly Ash bricks.
Fly ash bricks in the UK and EU are fired clay-fly ash or clay-shale-fly ash bricks. They are perfectly safe and have very similar performance profiles to fired clay bricks.
Fired fly ash bricks have nothing in common with the sub-standard, toxic and greenwashed non-fired fly ash bricks that Calstar is making
http://www.cbsnews.com/stories/2009/10/01/60minutes/main5356202.shtml
Some interesting quotes from the investigation:
"Some of the ingredients, according to the EPA, were arsenic, lead, mercury, selenium, cadmium and other toxic metals".
Sounds familiar? These are the same toxins present in Calstar Product's fly ash bricks - and their own data show that they leach out.
"while the government has never formally labeled coal ash a hazardous waste, it's being treated as such at the Kingston site"
"The new head of the EPA, Lisa Jackson, is reviewing whether the federal government should get involved by labeling coal ash a "hazardous waste,"
There you have it - fly ash - the toxic waste that the power industry wants to get rid of, that the EPA does not regulate, and that the disingenuous Greenwash company Calstar Products is trying to profit from.
Coal ash is so toxic that you need a respirator and protective clothing to handle it, and you and all equipment then need to be thoroughly hosed down after any contact. Coal ash is very hazardous. No wonder that the coal power plants are so keen to get rid of it any way they can.
Coal fly ash bricks are a time bomb just like the ash dumps. The EPA requires that coal ash is stored in ponds with protective clay or plastic liners to prevent the toxic heavy metals from leaching out and poisoning the environment and water supplies. The report on Calstars bricks website (the url is: http://calstarproducts.com/resources/gradient-memorandum/) shows that heavy metals leach into water.
Is Calstar going to use liners to prevent the toxic metals from leaching out of their bricks? The bricks are like miniature ash dumps that are loaded with toxic metals that leach out when they are in contact with water. Is Calstar going to coat or paint the bricks to prevent contact with the fly ash content? Why even make a toxic fly ash brick if you then have to then coat it with something inert to make it safe to handle?
And what EHS measures is Calstar taking to protect the workers at the factory? From articles and pictures it looks like there are no safety measures and that workers are being directly exposed to the hazard. And what about the retailers and the contractors and the consumers - how will they be protected from the toxic ash bricks? Will Calstar hand out protective clothing to everyone who comes into contact with the bricks?
Why is this company allowed to operate and make such a dangerous product?
NRDC categorizes coal fly ash as a Contaminated Coal Waste
NRDC states ?toxic material is laced throughout? the fly ash
NRDC states ?Coal ash contains many toxic metals, including arsenic, which unchecked, can leak into ground water and be extremely hazardous to breathe?
NRDC states that coal ash ?is contaminated by 10 metals classified as toxic by the Agency for Toxic Substances and Disease Registry (ATSDR): Antimony, Arsenic, Beryllium, Cadmium, Chromium, Cobalt, Lead, Manganese, Mercury, Nickel and Selenium.?
NRDCs states ?Coal-fired power plants produced more than 126 million tons of contaminated coal waste?
It also states ?the waste produced in a single year contains nearly 100,000 tons of toxic metals?
This is the waste that Calstar wants to make bricks of and sell to unsuspecting consumers.
Bricks that are laced with toxic metals.
Toxic metals that leach out from the bricks ? according to Calstar?s own data.
Calstar would like people to believe that the toxicity of fly ash is not an issue.
Calstar would like people to believe that bricks made from a Contaminated Coal Waste laced with toxic metals are not an issue.
Calstar would lke people to believe that it is ?beneficially recycling? toxic fly ash and producing a ?Green? product.
How is a product that is laced with toxic metals ?Beneficial?? Beneficial for lining Calstar?s managements pockets?
How is a product that is laced with toxic metals that leach out ?Green?? Is polluting the environment and poisoning people with a contaminated waste the new ?Green?? Perhaps the ?Green? is the money Calstar is hoping to make from selling the toxic bricks.
Does the management of Calstar have any decency?
Calstar ? a company bereft of morals, trying to sell the new Asbestos.
NRDC categorizes coal fly ash as a Contaminated Coal Waste
NRDC states ?toxic material is laced throughout? the fly ash
NRDC states ?Coal ash contains many toxic metals, including arsenic, which unchecked, can leak into ground water and be extremely hazardous to breathe?
NRDC states that coal ash ?is contaminated by 10 metals classified as toxic by the Agency for Toxic Substances and Disease Registry (ATSDR): Antimony, Arsenic, Beryllium, Cadmium, Chromium, Cobalt, Lead, Manganese, Mercury, Nickel and Selenium.?
NRDCs states ?Coal-fired power plants produced more than 126 million tons of contaminated coal waste?
It also states ?the waste produced in a single year contains nearly 100,000 tons of toxic metals?
This is the waste that Calstar wants to make bricks of and sell to unsuspecting consumers.
Bricks that are laced with toxic metals.
Toxic metals that leach out from the bricks ? according to Calstar?s own data.
Calstar would like people to believe that the toxicity of fly ash is not an issue.
Calstar would like people to believe that bricks made from a Contaminated Coal Waste laced with toxic metals are not an issue.
Calstar would lke people to believe that it is ?beneficially recycling? toxic fly ash and producing a ?Green? product.
How is a product that is laced with toxic metals ?Beneficial?? Beneficial for lining Calstar?s managements pockets?
How is a product that is laced with toxic metals that leach out ?Green?? Is polluting the environment and poisoning people with a contaminated waste the new ?Green?? Perhaps the ?Green? is the money Calstar is hoping to make from selling the toxic bricks.
Does the management of Calstar have any decency?
Calstar ? a company bereft of morals, trying to sell the new Asbestos.
They claim: ?Our commitment to green extends to product safety; we test our products extensively to ensure they are safe throughout their lifecycle, from manufacture to placement to use (and reuse) to end-of-life disposal?
This is very far from the truth ? Calstar has not done any manufacturing ? not even pilot runs, and have not produced enough bricks to do placement, reuse, disposal or any of the elements of lifecycle testing. Oh, and of course, they have not done an environmental footprint assessment of LCA ? because, they know very well that will show what a Greenwash their product is.
They claim: ?Our process for making fly ash into bricks binds the materials within a strong crystalline matrix that holds even if exposed to the intense acids found in landfills.?.
This is nonsense. Calstar?s curing process does not form any significant crystalline matrix ? the borate-alkanolamine system they use has been known for decades and is known to form an amorphous matrix which degrades over time and is not effective at binding toxic metals. In fact, alkanolamines increase metal leaching, and that is why they are not used in fly ash products. And what strong acids are they talking about? The short-duration leaching tests they cite use very dilute solutions which effect a very mild leach. And their own results show that toxic metals rapidly leach even under these very mild conditions.
They claim: ?While hundreds of millions of tons of fly ash have been safely included in concrete buildings and infrastructures around the world for decades?.
Nice spin. Fly ash has indeed been used extensively in concrete around the world ? however, in all cases, the fly ash is safely encapsulated with portland cement and/or blast furnace slag ? these are known from decades of research to react with the fly ash and effectively bind toxic metals, and the products are known to be stable and safe. This has nothing to do with Calstar?s bricks.
They claim: ?CalStar Products, Inc. has undertaken extensive testing of our products to ensure the same levels of safety apply. Test results on our products from respected third-party laboratories have been reviewed and analyzed by Gradient, a respected environmental consultancy in Cambridge, Massachusetts. They find that ?the presence of coal fly ash metals in newly manufactured CalStar bricks is not expected to result in any exposures of health concern?.
More spin. Calstar has done no significant safety testing of their product, and has used a contract firm that is associated with the fly ash industry and which promotes fly ash, to certify its products. Important point here ? Gradient did not do any of the tests ? they were paid by Calstar to ?interpret? the tests ? hence the careful wording of the safety statement. If Calstar does any meaningful testing, the toxicity of the bricks will become very apparent ? Calstar knows this all too well. The irony is that even their very mild preliminary tests show that the bricks are not safe and that metals leach out.
They claim on their web site that ?Our process for making fly ash into bricks binds the materials within a strong crystalline matrix that holds even if exposed to the intense acids found in landfills.?.
So fly ash bricks are resistant to "intense acids"?
Lets look at the facts: Calstar's test data are for the EPA's TCLP and SPLP tests - in these tests, the bricks are exposed to very dilute acids for less than 24 h. TCLP uses a dilute organic acid with pH 5 and SPLP uses a dilute mineral acid with pH 4.2.
These are much weaker than stomach acid (pH 1-3) lemon juice (pH 2-3) and vinegar (pH 3-4), and even common soda (pH 2 to 4)! In fact, the acids used in Calstar's leaching tests are about the same acid strength as rainwater (pH 4-5).
So these are "intense acids" according to Calstar ? Is Calstar's R&D so incompetent that they do not even know a strong acid from a weak acid? Or are they intentionally misstating facts and covering up the hazard of their fly ash bricks? Or is it both?
When the cement, concrete and clay brick industry talk about acid, they are typically referring to Muriatic (hydrochloric) acid - 31% Muriatic acid is routinely used for cleaning clay bricks and portland cement/concrete. This acid is 31% by concentration - while the acid used in Calstar's tests is about 0.02% concentration. So, the muriatic acid used for routing cleaning of masonry is about about 1,500 times more concentrated than the very weak acids used in Calstar's tests.
Why does'nt Calstar test their fly ash bricks against Muriatic acid? The answer is simple - because fly ash bricks will disintegrate in Muriatic acid - unlike clay bricks and portland cement/concrete, fly ash bricks are not resistant to Muriatic acid. And worse still, Calstar's own data show that fly ash bricks leach even in very, very dilute acids that are weaker than lemon juice, vinegar and soda.
So much for Calstar's claim about their bricks being resistant to "intense acids". Total fabrication and spin!
I am skeptical of their product but it is a area that does warrant further research.
The pH of 5.6 you mention is for water acidified with carbon dioxide alone- in practice, there are other components (aerosols, etc) which reduce rainwater pH considerably - in fact, the pH of rainwater in the US varies from 4.2 to 5.8, with most of the US being in the pH 4.5 to 5.3 range, as I indicated before.
The rainwater pH data for the US is: The pH of rainwater is 4.2 to 5.0 for the Eastern-US, 4.8 to 5.1 for the mid-US and 5.0 to 6.1 for Western-US (USGS, Met and NASA data).
The pH in WI (where the fly ash is sourced) is 4.4-4.6 - ie. the acidity is the same as Calstar's leaching solutions.
So, as I noted before, their bricks leach even in rainwater - hardly the "intense acids" that Calstar claims.
Calstar's CEO Michael Kane is claiming that NO toxic metals leach from the bricks - to quote - he says the bricks are "inert with no leaching of any chemicals from the coal ash that is locked into the products chemically and permanently" (see the articles on Calstar's bricks - for example on zdnet).
This is a blatant lie. Their own data shows that the CEO's statement is untrue - a whole range of toxic metals, including arsenic, antimony, beryllium, cadmium, lead, manganese, mercury and nickel leach from the bricks.
These toxics leach very rapidly - within a few hours. Not only that - the toxics leach in very mild solutions comparable to rainwater.
Does Calstar's management know no bounds for spin and deceit? Or are they so clueless about their fly ash bricks, even in the face of their own test results that show unequivocally that the bricks are toxic?
Is Calstar's financial situation so desperate that its management is willing to say anything to sell its toxic fly ash bricks?
- by bkwaas November 9, 2009 8:35 AM PST
- How does the safety of cement and concrete products containing fly ash compare with Calstar?s fly ash bricks?
- Like this Reply to this comment
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Showing 1 of 2 pages (33 Comments)Here is a quick overview:
Fly ash is used worldwide throughout the Portland cement/concrete production chain ? for production of cement clinker, in blended cements and as a cement replacement in concrete ? particularly in the EU, Canada, China and Asia and S. Africa.
The standards in these countries for blended cements and Portland cement-substituted concretes allow for usages from ~ 0% to 20% in the US, and from ~ 5% to 40% in the rest of the world. The actual usage rates are lower: ~ 0% to 15% in the US and ~ 0% to 25% in the rest of the world, with the overall averages being about ~ 3% to 5%.
When fly ash is used to manufacture cement clinker, it partially substitutes for clay, bauxite and iron ore, and the final product is indistinguishable from normal cement (the toxic metals present in the fly ash are vaporized ? and the emissions from the kiln are scrubbed).
When fly ash is used in blended cements or in concrete, it undergoes a series of reactions with calcium-containing phases in Portland cement, resulting in the etching of fly ash particles, precipitation of calcium silicates/aluminates, exchange of calcium and magnesium in silicate/aluminate minerals with toxic metals, release of calcium and further etching and formation of silicate/aluminate phases, etc. The net effect is that the Portland cement degrades, mobilizes and mineralizes fly ash and in doing so binds the toxics into stable silicate/aluminate minerals. Portland cement is unique in this respect ? its high calcium content and reactivity enable it to encapsulate and effectively immobilize fly ash and other hazardous wastes ? including heavy-metal containing industrial sludges, low-level radioactive waste, etc.
A number of studies have shown that at low fly ash levels, fly ash is quite effectively encapsulated by Portland cement, and that cements, concretes and products made with Portland cement plus fly ash appear to be stable and have a low hazard. However, there is still a significant hazard of metals leaching from the fly ash under certain conditions ? such as in salt water, acid rain, etc, and of metals exposure during recycling.
In the case of Calstar?s fly ash bricks, there are a number of problems that make their bricks unsafe:
1) Fly ash, even high-calcium class C fly ash, does not contain enough of the mobile calcium-containing phases to act as a reactive encapsulant in the same way as Portland cement (as seen from the leaching of toxics from the bricks).
2) The ?proprietary? chemistry that Calstar ? borates plus alkanolamines, is very poor in terms of hydraulic reactivity and binder capacity. Calstar?s chemistry is not proprietary ? it is taken from decades-old formulations that were abandoned because of poor product performance.
3) Calstar appears to be using efflorescence control agents to reduce salt leaching ? these are known to compromise hydraulic reactivity, set, strength and metal binding (as seen from the powdery white surface deposits and chalking).
4) Calstar is using sand in its bricks (probably for the purposes of improving texture and hardness) ? however, the formulation they are using shows no matrix-aggregate bond, and this results in decreased strength, and increased permeability and leaching of toxics (as seen from poor edge structure, and surface porosity and efflorescence on the bricks).
All of the above problems arise because of Calstar?s ?proprietary? technology ? it is a badly performing decades-old abandoned technology known to have a range of serious problems.
The irony is that there are any number of ways to greatly increase the safety of the fly ash bricks ? incorporate lime, Portland cement, use efficient fly ash binder and cure formulations, etc.
The fact that Calstar has such a poor product using such an outdated and substandard formulation shows that the company is dangerously inept and ignorant.