For this week's educational news article we'll highlight an excellent article written by Olympic Panel Products, Shelton, WA. You can download the full article here.
Form Oil / Release Agent Selection Criteria
Concrete form oils or release agents, are manes typically used to identify materials that prevent concrete forms from sticking or adhering to hardened concrete.
Concrete Form Oil / Release Agents and How They Work
Concrete form oils / release agents can be broken up into three basic categories: barrier, reactive (or chemically active), or a combination of both.
- Barrier types (non-reactive) work by creating a barrier between the form and the fresh concrete in the same way butter prevents cookies from sticking to the cookie sheet.
- Reactive release agents contain proprietary ingredients that combine with the calcium of fresh cement past to prevent the set of a minute surface film of concrete.
Concrete Form Composition Dictates Form Oils / Release Agent Composition
- Porous, or coarse wood forms like plywood or dimensional lumber require a more reactive type of release agent, and typically requires a heavier material application rate of 800 to 1,000 square feet per gallon or 20 to 25 square meters per liter.
- High density overlaid plywood forms (HDO) require a less reactive type of release agent, which is typically applied a light material application rate of 3,000 square feet per gallon or 75 square meters per liter.
- Medium density overlaid plywood forms (MDO) require a reactive level and application rate in between that of dimensional lumber and HDO plywood, 1,500 to 2,000 square feet per gallons or 38 to 50 square meters per liter.
Governmental Regulations of Concrete Form Oils / Release Agents
- In general, the active fatty content of reactive release agents is usually not considered hazardous to either health or environment.
- The vehicle or carrier system in reactive release agents as well as many other of the components of most barrier type form oils, may pose health and environmental problems.
Concrete Mix Design
The concrete mix design can significantly affect the releasing material performance. Generally speaking, the use of pozzolans such as fly ash, blast furnace slag, and microscilia slow concrete curing time, and increase the time necessary for the concrete surface to achieve sufficient strength to allow form removal without adhesion. Cold weather worsens this situation.
Concrete Surface Requirements
Concrete surface objectives also influence selection of the releasing material. When the surface appearance is critical, the use of a barrier type release agent is not recommended, since they tend to stain concrete and increase the number of concrete surface defects i.e., spalls caused by adhesions or bug holes.
With the overwhelming number of releasing material types available, proper section can be difficult. The best choice would be a product that poses the least exposure to harmful or potentially carcinogenic compounds, and can be safely transported across public roads.
(Photo from the National Precast Concrete Association)
Hill and Griffith Customer Service
We're known for our hands on approach. Let us visit your plant and recommend concrete release agents, packerhead concrete form releases, concrete form seasoning, potable water concrete form release, non-petroleum concrete form release, biodegradable concrete form release, rust inhibitors and concrete dissolver products that suit your needs.
We are pleased to provide samples in quantities large enough to allow you to "try before you buy."
Contact Us »
Technical Services & Support
On-site casting defect investigations, product testing, machine start-ups and much more. Also, lab facilities are available to provide testing upon request.
Contact Us »