In a largely unprecedented step toward solidifying its place as a frontrunner in supplying green construction materials, 80-year-old, Midwest ready mixed
In a largely unprecedented step toward solidifying its place as a frontrunner in supplying green construction materials, 80-year-old, Midwest ready mixed producer Ozinga recently created the position of Vice President of Green Building, hiring longtime sustainability proponent Brian Lutey.
Working from the Mokena, Ill., office but serving all four Ozinga companies, Lutey’s primary job is developing and promoting a pervious concrete program, which includes standardizing a host of best practices and certifying contractors to mix and place the branded Filtercrete pervious concrete to exact specifications. Today, Ozinga, with its recognizable red-and-white-striped trucks, is a national member of the U.S. Green Building Council, while Lutey and Paul Ozinga are members of the USGBC Chicago chapter.
Beyond his more than 15 years of experience in ready mixed sales and production, Lutey represents a significant response and commitment from a company committed to protecting natural resources, while minimizing the impact of construction on the communities and environment in which it operates.
Lutey joined the staff of the Indiana Ready Mixed Concrete Association (IRMCA) as Promotions Manager of the Southern Region in 2003 and began developing a pervious concrete program. The IRMCA Pervious Concrete Certification Program was so successful that the association was asked to assist concrete promotional groups in more than nine states in developing their own pervious concrete programs. The Pervious Concrete Program was instrumental in IRMCA being awarded the National Ready Mixed Concrete Association (NRMCA) State Association of the Year Award for 2006.
A member of the new ASTM Pervious Concrete Subcommittee, Lutey also assisted the Indiana Department of Agriculture in the creation of a new Pervious Concrete Best Management Practice (BMP), a major component in the state Department of Environmental Management’s updated Storm Water Quality Manual.
As a result of Lutey’s exhaustive experimentation and research with pervious concrete, he has instigated a policy at Ozinga to only sell Filtercrete orders to contractors the company has personally trained and certified Û modeling education and site practice on IRMCA criteria. Other types of training are less intensive, do not include hands-on components, and may cause failures, especially in freeze-thaw environments, he asserts. The IRMCA program has trained more than 400 concrete producers and concrete contractors to make and install pervious concrete, and has not had any failures to date. If a contractor goes out and doesn’t follow the Indiana training, three failures, or even near misses due to negligence, and you’re out; the IRMCA will revoke the certification, which is often a requirement in specification documents prior to even submitting bids.
The biggest threat to the success of pervious concrete are contractors who are untrained, poorly trained, or may cut corners and screw up pours. They can give the product a bad name.
Lutey adds that when he does train contractors, he covers NRMCA program methods, but I also tell them what does and doesn’t actually work in the real world with the more intensive, hands-on Ozinga Filtercrete training program. As far as training and experience go, which is more valuable: a system with 30 years of experience with a 50 percent failure rate or one with eight years experience and no failures?
STEWARDS OF TOMORROW
As Lutey sees it, green building uses long-lasting, 100 percent recyclable materials while conserving valuable resources such as water and energy. It also represents a structure that is designed to be a healthier environment for its occupants; blend naturally with its surroundings; and, require less money and energy to build, maintain and operate. Concrete is an ideal tool for designing parking lots as well as buildings that are healthy, energy efficient, beautiful to look at, last a long time, and require less maintenance, compared to alternative materials, Lutey emphasizes. The most sustainable attribute that any material can have is a long, useful lifecycle requiring low maintenance. Concrete lasts longer than most other materials and is 100 percent recyclable when its useful life is over.
By using traditional concrete in ways that make economical and ecological sense, Ozinga introduced a line of sustainable products and materials, including recycled materials, decorative concrete floors, flowable fill, and Filtercrete, the company’s pervious concrete offering. The latter product filters water, sound, and air, while absorbing greenhouse gases. Lutey has been pushing architects, city planners, and existing customers to consider the product for stormwater systems for parking lots and pavements. Since stormwater pollution is often the largest source of pollutants in many watersheds, Filtercrete was designed to absorb some pollutants and filter others. Becoming colonized with natural microbes, moreover, it consumes pollutants from cars’ petroleum deposits and pavements with petroleum-based coatings or binders.
Filtercrete also offers the benefits of reducing urban heat-island temperatures with its lighter color that absorbs less heat from the sun; and, because air and water move through the gaps in the product, trees can be placed as close as one foot away without blocking the roots. Healthier and more plentiful trees lead to more natural shade, while also helping to stifle the heat in summer months. Furthermore, the pervious nature of the concrete means no puddles for black ice to form during the colder months, a factor Lutey notes is not lost on insurance underwriters.
Many commercial building owners are opting for pervious concrete for parking lots and sidewalks to avoid liabilities tied to injuries caused by ice and puddles. And, if ice does form due to freezing rain, de-icing salt does not damage the pavement due to the low water/cement ratio of the paste.
According to Lutey, the Filtercrete mix design can be rated anywhere from 2,000 to 4,000 psi (Chicago requires 3,000 psi in 30 days for its Green Alley Program). Pervious concrete typically has a void content target of 20 percent (although the range can go anywhere from 15 to 25 percent). A pervious pavement design allows a flat parking lot; and, the pervious concrete mix results in no curling at the edges, he says, so there’s less potential damage when plowing.
The basic components of Filtercrete consist of coarse aggregate, portland cement, fly ash and/or slag, fibers, integral coloring, water, and admixtures. The water/cement ratio is around 0.30, Lutey explains. You can go anywhere from 0.26 to 0.40 and get good results. If you’re using a high slag cement content, you may be on the low side of the range and need to watch moisture loss even closer. You only need enough cement to glue the aggregate together. And, no air entrainment is necessary; we’ve found no proven advantage to it.
A lot of working with pervious concrete is counterintuitive for those who work with ready mixed. Less cement is better, using high doses of chemicals like hydration stabilizer to basically put the mix to sleep, instead of using retarders. But the fact is, you can’t treat it like regular concrete. One can use high amounts of recycled materials like slag cement to achieve very high Albedo, or light reflective pavement. I’ve replaced mixes with up to 50 percent cement with slag.
An Iowa State University study has found that rounded aggregate works better, and Lutey agrees. Whether an aggregate material will work is a function of the size, shape and gradation of the material. It needs to provide adequate voids to accommodate the cement paste coating the surfaces of the aggregates, yet leave 20 percent voids open. The aggregate used has a great impact on achieving the strength, permeability and look a customer needs. But, not all of his quality testing is overly scientific. My moisture test is me grabbing a handful of material, he says. If the paste has an oily sheen, grab a handful of material, squeeze it, and if the aggregate sticks to the hand, it’s good.
According to Lutey, hydration stabilizing admixtures are a must. We increase the dosage as haul time and/or ambient temperature increases, or even in the winter when hot water is used, he reports.
Using pervious concrete for dry detention ponds is an acceptable best management practice used by stormwater managers to meet EPA, Phase II, NPDES requirements for stormwater mitigation. Rain passes through the material, into the stone layer, and then into the soils below with no runoff. A common design for a parking lot pavement using Filtercrete, according to Lutey, is six inches of pervious over a 6- to 10-in. layer of clean, angular stone base material. The layer of stone gives structural support for the Filtercrete and acts as a temporary storage area for water passing through the pavement. A nonwoven geotextile fabric is placed below the base material, keeping the underlying soil from migrating into the void space of the stone. If the soil is impervious, an open-graded base layer, with a perforated drain is required and is installed above the filter fabric to store the required water quality volume (WQV).
A Bunyon Stryker hydraulic roller system should be used to combine placement and compaction in one tool. The Bunyon Stryker is a spinning roller pulled across the section, often placing 25-ft.-wide sections at a time. Hand-held cross rollers are then used after the plastic is put down. The joint roller should have a pizza cutter-style roller, with a half-inch-thick fin and a radius profile on both sides, Lutey says, who explains that the thickness and radius profile create a joint that has radius edges in the pervious and densifies the top edges of the joints. Roller cutting should only be done when the pervious is still shiny. Rolling joints in pervious concrete that looks dry will result in a weaker bond and cause raveling.
Lutey prefers an environmentally friendly, soybean-derived sealant, known simply as The Bean, rather that an acrylic one, but adds that bean oil should not be used if the concrete is going to be stained, as it will prevent the acid stain from penetrating the paste. Jelly Bean color packets may be added to The Bean sealer to stain pervious concrete. He also says the curing must be done quickly and securely with The Bean sealer sprayed on immediately after the surface is finished, and then covered with 6-mm plastic, which, in combination, is the key to a successful placement.
He recommends that contractors cut and pre-roll plastic onto a 6-in. PVC pipe, cutting the plastic wide enough to overlap the edges of the pavement. Filtercrete certification calls for the practice of taping or gluing the overlapping edges so that the plastic is one piece that will cover the entire slab with no opening that would allow moisture to leak out or air to flow through. The plastic needs to be secured to the forms with button-cap nails; rebar or lumber can be used to secure the plastic in place. Plastic must remain for a minimum of seven days to allow proper curing.
Lutey admits that other than Chicago, which is rapidly building a reputation as a green city, some municipalities have been slow to embrace pervious concrete. Others, however, are open to an environmentally friendly option to the status quo: petroleum-based asphalt pavements, whose dark surfaces add to the heat island and leach pollutants into stormwater.
In his first year in the Chicago area, Lutey has seen only about a dozen or so projects using Filtercrete, but more are on the way. Until the City of Chicago started doing pervious alleys about a year and half to two years ago, no concrete producer was interested in the stuff, he says. He points to a new parking lot project for the Chicago Center for Green Technology, which Ozinga and Manning Concrete (the first Ozinga-certified contractor) are donating to the city-owned project in the spring, as a major step for the company and the product. We’re also incorporating decorative stamped pervious mix design and pervious concrete stamps to provide the look of pavers without the danger of trips and falls from settling pavers, as a part of our product line.
We’re looking to get concrete in general, and pervious concrete in particular, even more recognition in green building and LEED certification, but any change on that front is going to start on the local level, and the word has to spread from there.