As consumers become more eco-conscious and more informed about how the materials they buy affect the environment, the desire for environmentally friendly products is on the rise. This holds for concrete producers and contractors as well. Whether it’s to meet specific federal and state requirements on biodegradability, volatile organic compound (VOC) exposure limits, or because customers are requesting “green” materials, owners, contractors and architects want products on their job sites that are less harmful to the environment.
There are multiple ways to measure a product’s environmental impact. These include carbon offsets, whether or not the ingredients are compostable, non-toxic, ozone-safe, recyclable, refillable, and the percentage of recycled content in the product. When it comes to chemicals used in concrete production and construction, biodegradability is a primary measurement of eco-friendliness.
WHAT QUALIFIES AS BIODEGRADABLE?
A product is classified as biodegradable when it is capable of returning to its natural, raw material state quickly through biological means. A truly biodegradable material will break down into carbon dioxide, water, biomass and other natural minerals that don’t adversely affect the ecosystem.
The Federal Trade Commission’s (FTC) Green Guides, last updated in 2012, states that for marketers to make an unqualified claim on degradability, they must prove that the “entire product or package will completely break down and return to nature within one year after customary disposal.” This issue of “customary disposal” is key because the characteristics of the environment in which the material is disposed can greatly affect its ability to break down. Exposure to air, water and sunlight would promote, say, an orange peel’s ability to biodegrade, but bury that orange peel in a landfill and the rate at which it will biodegrade is very different. For this reason, the California Advertising Statute, amended in 1991, defined biodegradable materials as those that have “the proven capability to decompose in the most common environment where the material is disposed of within three years through natural biological processes into nontoxic carbonaceous soil, water, carbon dioxide or methane.”
READILY VS. INHERENTLY VS. ULTIMATELY BIODEGRADABLE
The U.S. Environmental Protection Agency and the FTC recognize biodegradability by two classes, readily and inherently. (A third class, ultimately biodegradable, covers both readily and inherently biodegradable and more.) Readily and Inherently biodegradable products have the natural ability to biodegrade to their natural state when subjected to sunlight, water and microbial activity. The difference lies in how quickly they achieve complete biodegradation. To measure the speed of biodegradability, EPA recognizes a 28-day half-life. Half-life is the time required for one-half of a given component to decay.
Readily biodegradable: Product is capable of biodegrading from 60-100 percent in 28 days or less. In other words, these materials achieve complete biodegradation at a quick rate.
Inherently biodegradable: The product is capable of biodegrading from as low as 20 percent to less than 60 percent in 28 days. Such products will achieve less biodegradation than readily biodegradable products in the same time span, but eventually they all get to the same place.
Both readily and inherently biodegradable products include materials that come from nature and therefore, it is assumed, will return to nature as long as their natural forms haven’t been too greatly altered. However, as mentioned before, this will depend on where the materials end up. Even materials like leaves, banana peels or paper—each inherently biodegradable in soil in an aerobic (where oxygen is present) environment—will fail to biodegrade when dumped in a landfill or other anaerobic (lacking oxygen) environment.
Ultimately biodegradable: This third classification basically recognizes that everything (or nearly everything) will eventually achieve ultimate biodegradation, even if it takes centuries. For example, given sunlight, air and water, a paper towel can biodegrade in two to five months. Nylon fabric could take three to four decades under the same conditions. A glass bottle will biodegrade in about 1 million years, while a plastic bottle buried in a landfill is here forever. In many cases, the environment is already contaminated by the time the degrading process begins.
BIODEGRADABLE RELEASE AGENTS
As with any industry, concrete interests have set federal guidelines for classifying products as eco-friendly. Just as federal VOC regulations are put in place to protect the ozone, biodegradability standards are in place to protect land and water from contamination. Keep in mind, states can apply more stringent requirements.
|Biodegradable form release agents at work in architectural (opposite page) and structural precast concrete production. PHOTOS: Nox-Crete Inc.|
Water-based release agents are suitable for most concrete form surfaces to include steel, plastic, fiberglass and bare or overlaid plywood. They can be used on many rubber and closed cell foam forms and are safe for use in enclosed building sites. Water-based formulations are free of conventional form oil, diesel oil and kerosene. Because they are water-based, these release agents are susceptible to freezing, usually require mixing before use, and can have a shorter shelf life due to emulsion. While water-based release agents are typically inherently biodegradable, they are not always readily biodegradable. Even a water-based formulation must meet the EPA requirements of the 28-day half-life of 60 percent or more to be considered readily biodegradable.
Petroleum-based release agents are suitable on many form surfaces to include plywood, steel and aluminum forms and pallets. Petroleum-based formulations are usable in all weather conditions, including below-zero temperatures. They require no mixing and have a longer shelf life. While most petroleum-based release agents could be considered inherently biodegradable, not all are. Some, incorporating proprietary blends of petroleum and vegetable oils into the formulation, have actually been determined to be readily biodegradable.
When temperatures allow, an environmentally responsible, water-based release agent can produce smooth, uniform concrete surfaces without staining and with minimal surface voids while providing a crisp, positive release. When temperatures fall below freezing, a petroleum-based release agent is the next best choice. With proper research and due diligence, concrete producers and contractors can find an environmentally responsible option that yields quality results in a readily or inherently biodegradable formulation.