Chemically active form release agents have been the standard in forming concrete for years. Usually, a petroleum-based substance (such as kerosene or mineral spirits) serves as a carrier for the active ingredients. However, rising oil costs and increased environmental concerns are two reasons you should consider switching to water-based varieties.
The switch has been slow in coming, largely because of preconceived notions about water-based release agents: They don't mix well and they freeze in cold weather. However, contractors will find the same benefits of petroleum-based release agents from water-based varieties as well as several new benefits, says Mike Linn, president of Nox-Crete Products Group, a manufacturer of both petroleum- and water-based release agents.
Petroleum-based release agents are highly effective at keeping concrete from sticking to formwork. With water-based products, you can expect the same performance, Linn says. The chemistry is the same, only the carrier is different. The active ingredients in most chemically active form release agents are a combination of plant or vegetable carboxylic acids combined with various glyceryl esters that chemically react with calcium hydroxide in concrete to produce a soap-like film that prevents concrete from sticking to a forming surface.
Because the water won't absorb the active ingredients into the solution, an emulsifying agent is required. They are mixed together in suspension prior to applying the material to the formwork.
Early versions of the water-based release agents wouldn't stay in suspension very long. This led to a misconception still held by many contractors that these products aren't very reliable. However, better emulsion technologies are keeping the material in suspension for much longer, in some cases up to 24 hours or longer without remixing.
The second issue is cold weather. Water-based release agents can freeze when the temperature drops. To combat this, you can use a concentrated release agent and mix it with water on the jobsite. By doing this, the mixture does-n't have time to freeze. However, if conditions are extremely cold, petroleum-based varieties might be your best bet. It isn't uncommon for contractors to use water-based release agents during the warmer months, and then petroleum-based versions during the winter.
Two good reasons
As gasoline prices have climbed, so has the price of petroleum-based release agents. Because water is essentially free, water-based release agents have become a cheaper alternative. When dealing with concentrated varieties, you also save the cost of shipping the water.
The benefits of water-based release agents, though, go beyond performance and price. Water-based products are safer for the environment and safer for workers to handle. Petroleum-based agents contain high amounts of volatile organic compounds (VOC), which pose a health threat to workers. Water-based release agents still contain some VOCs, but in much lower quantities.
This concern for worker's safety and the environment prompted California to be the first state to tighten its VOC standards. Since 2005, seven other states also have lowered their VOC thresholds for form release agents to 250 grams/liter. A typical petroleum-based release agent ranges about 450 grams/liter.
However, while petroleum prices may fall, the tougher VOC standards are not likely to go away. “Concern for the environment and worker health and safety will only make the need for water-based release agents grow,” Linn says.