From Dust to Block

Greening traditional products requires sound research.

Source: CONCRETE PRODUCER MAGAZINE
Publication date: 2009-02-01

By Rick Yelton

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Not too long ago, the idea of shipping a green block was a bad thing. It meant that the unit hadn't been fully cured and may not have enough compressive strength to comply with specifications.

In today's frenzy of developing new sustainable construction techniques, the term <i>green block</i> is taking on new meaning. Like all segments of the concrete production industry, block producers are struggling to develop business approaches to capture their share of the green building construction market.

One aspect of the greening of the block process has been an effort to include non-traditional materials as ingredients. Currently, ASTM C 90, Standard Specification for Loadbearing Concrete Masonry Units, covers units made “from hydraulic cement, water, and mineral aggregates, with or without the inclusion of other materials.” Note that the percentage of the ingredients in a mix design is left entirely to the producer.

The specification does specifically list common green ingredients such as pozzolans and blast furnace slag cement. These must meet the applicable ASTM standard. And C 90 also allows other non-listed constituents as long as they are “previously established as suitable for use in concrete masonry units and shall conform to applicable ASTM standards.”

But what about potential ingredients that haven't been used before in the blockmaking process? The standard allows producers to incorporate new materials as long as the producer can document that the product “by test or experience, not to be detrimental to the durability of the concrete masonry units or any material customarily used in masonry construction.”

It's this aspect of the standard that is intriguing and baffling to innovative producers.

John Porterfield, owner of Porter Block, discusses the results of the compressive break of concrete made with mine tailings with Mike Meyer, lab technician at the World Center for Concrete Technology.

Not every potential ingredient can be a good thing. For example, take the effort of a producer who was approached by a neighboring manufacturing facility to help solve a waste stream problem. The manufacturing plant contacted the producer's QC department to consider including a plastic aggregate generated by a shot/paint process. The results of some preliminary lab testing suggested that the material could be used.

Despite the initial success, the producer dropped the project. Staffers discovered the plastic product had been reported as a production waste material to the EPA. As such, should the producer include the plastic aggregate in any product, it would have to submit a special RECLA report seeking permission to have the waste material cross state lines.

Fortunately for an industry steeped in conservatism and strong product performance, there's a ready resource to help answer the question of how to best select ingredients in block production that transforms one man's trash into another man's treasure.

The staff at the World Center for Concrete Technology (WCCT), with support from the faculty at Alpena Community College (ACC), both in Alpena, Mich., have guided both producers and manufacturers in developing our next green building stones. In the last two years, they have taken on a number of proprietary research efforts. They expect the trend to increase.

The idea of using concrete block to recycle waste is not new. Just ask Eric Krebs. The WCCT co-director has worked with producers from around the world for more than 25 years to try to create successful recipes of exotic materials for block. He has experimented with all types of aggregates, sands, and other particulate matter.

“Believe it or not, we've even had requests to experiment with biomass as potential fillers,” says Krebs. Fortunately, that idea went away fast.

Krebs says the review process is now easier than ever using WCCT's resources. The facility has a fully equipped materials testing lab and computer research capability. What makes it unique is the capability of actually mixing concrete and making block. According to Krebs, the full-scale blockmaking activity is what can separate a good idea from a profitable one.

There's another aspect of the WCCT mission that benefits the industry. Students attending ACC perform much of the work on special projects. WCCT and the faculty of the concrete program share the same building and lab facilities. ACC offers an associate in Applied Science degree with an emphasis on concrete technology.

The program started in the late 1960s as one of the original associate degree curriculums offered by the PCA. It's the only two-year program that continues.

Each student must complete a faculty-approved, self-selected research project. “Our clients often find that the real value of having the WCCT perform the research is that no only do they receive needed information, but they hire the student who did the work,” says WCCT co-director Bob Eller.

John Porterfield watches block production at the World Center for Concrete Technology.

One of the WCCT's greatest supporters is John Porterfield, owner of Porter Block in Whitefish, Mont. Spurred by a desire to cast a block that is environmentally friendly in its hardened form, he has been involved in a two-year relationship with WCCT to determine the feasibility of using mine tailing as aggregate in blockmaking.

Porterfield says that commercial development in Montana is at a near-standstill due to opposition of both quarry and mine development. So when he tried to establish a blockmaking facility in his hometown, he discovered his greatest constraint to success was rock. His passion for the environment and for masonry construction led him to think outside the cube, and to approach a local mining concern about the availability of mine tailings.

Porterfield says his project is akin to how Plains Indians used the buffalo. When the braves killed a buffalo, the community didn't waste any part of the carcass. He plans to utilize the rock recovered from the mine in the same way. The mining company can sell its refined ore; Porterfield will use what's leftover.

“There's an abundance of tailings in our area, so if we are successful in our blockmaking concept, I'm providing a win-win proposition for everyone,” Porterfield says. “The mining company won't need to keep expanding its tailing contaminate areas. We won't need to establish new aggregate sources for block. And we can provide our communities a durable, safe, and sustainable masonry product.”

Porterfield credits Krebs and Eller in helping him achieve his goal. The men, with support from the ACC faculty, have not only proven an effective way to pelletize the fine dust-like tailings in pea-sized aggregate, they have also developed a mix design that produces a block that conforms to the requirements as outlined in C 90.

Porterfield has been impressed by the dedicated approach that WCCT and ACC bring to concrete research. “Kevin Lundquist, the ACC student who has performed much of the study's work, has been very helpful,” says Porterfield. With results indicating that mine tailings can be a successful aggregate, Porterfield plans to move forward. He wants to establish a new blockmaking facility in Whitefish.

While much of the WCCT work has been on using recycled aggregate sources to develop a green block, manufacturers of other ingredients have also taken advantage of the center's experience. Hycrete, a New Jersey-based manufacturer, has worked with the staff to determine how its waterproofing admixture can benefit the masonry industry.

Hycrete's staff is heavily involved in stainability. Their product has been certified Cradle-to-Cradle by McDonough Braungart Design Chemistry. When used, a system admixture waterproofs the entire structure. It can eliminate the need for external membranes typically used to waterproof concrete. This approach also makes the concrete more easily recyclable following demolition, and can eliminate thousands of pounds of Volatile Organic Compounds (VOCs), CO2, and non-renewable content.

“As the clean technology and material science industries progress, there will be a natural evolution toward intelligent building materials,” says Shayne Veramallay, Hycrete's director of sustainability and business development. Hycrete is already an example of such innovation where its hydrophobic concrete technology platform combines the functionality of a traditional exterior waterproofing membrane directly into the concrete.

Other cleantech companies are also working on building products that offer high R-value materials, high levels of recycled content, intelligent water management, or even high solar reflectivity. All of these technologies simplify design while offering greater life cycle value and minimal environmental impact.

Traditionally, the manufacturer focused its efforts on the ready-mixed concrete market. But with the work done at WCCT, it is looking toward blockmaking as the next opportunity.

“Eco-friendly building materials that save construction costs and streamline the construction schedule are truly rare finds,” says David Rosenberg, Hycrete's CEO. Many contractors, architects, and building engineers believe green materials don't make sense during economically challenging times. But Hycrete is an exception because it's less-expensive than membranes, it can shave weeks, even months, off construction schedules and it ultimately helps buildings last longer with its anti-corrosion benefits.

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