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Concrete Casting News from the Hill and Griffith Company

Precast Concrete Form Maintenance

Posted by Roger Roatch on Dec 1, 2017 2:29:16 PM

Properly maintaining your precast concrete forms will make them last.

Question: How can I make sure I’m getting the most longevity and use from my concrete forms?

Answer: We asked Roger Roatch with APA - the Engineered Wood Association, to respond:

When it comes to concrete structures, formwork may represent close to half the cost. Fortunately, concrete forms are durable workhorses that can be used over and over with proper maintenance and upkeep. Here are seven ways to extend the life and usefulness of your plywood concrete forms:

1. Strip forms carefully. Metal bars or pry bars should not be used on plywood because they will damage the panel surface and edge. Instead, use wood wedges, tapping gradually when necessary.

Precast Concrete From Oil Application 1.jpg

2. Clean and apply release agents. Soon after removal, plywood forms should be inspected for wear, cleaned, and repaired, spot-primed, refinished, and lightly treated with a form-release agent before reusing. Use a hardwood wedge and a stiff fiber brush for cleaning. Avoid using a metal brush because it may cause wood fibers to “wool.”

3. Apply sealants and release agents as directed. Protective sealant coatings and release agents for plywood increase form life and aid in stripping. Some panels may require only a light coating between uses. Applying a form release agent a few days before the plywood is used, then wiped so a thin film remains, will prolong the plywood’s life, increase release characteristics, and minimize staining. 

A chemically reactive release agent will give overlaid panels the longest life and should be applied before the first pour. Check with the manufacturer of the forming plywood for more details.

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4. Know the difference between release agents and coatings. Release agents and coatings can affect forms and concrete differently, so select a release agent keeping mind its influence on the finished concrete surface. For example, some release agents including waxes or silicones should not be used where the concrete is to be painted.

Plywood form coatings, such as lacquers, resin, or plastic base compounds sometimes are used to form a hard, dry, water-resistant film on plywood forms. Usually, the field-applied coatings reduce the need for application of release agents between pours and result in greater reuse.

5. Patch and repair forms. On prefabricated forms, plywood panel faces (when the grade is suitable) may be reversed if damaged. Tie holes may be patched with metal plates, plugs, or plastic materials. Nails should be removed and holes filled with patching plaster, plastic wood, or other materials.

Proper Application of Precast Concrete Form Release Agents.jpg

6. Handle and store forms properly. Be carful to prevent panel chipping, denting, and corner damage during handling. Panels should never be dropped. Forms should be carefully piled flat, face to face and back to back. Forms should be cleaned immediately after stripping and can be solid-stacked or stacked in small packages with faces together.

Hairline cracks or splits may occur in the face ply. These “checks” may be more pronounced after repeated use of the form. Checks do not mean the plywood is delaminating. Form maintenance, including careful storage to assure slow drying, will minimize face checking.

7. Consider the effects of admixtures and chemicals. Many admixtures and pozzolans increase the abrasiveness or alkalinity of the concrete. While wood and phenolic overlays resist alkaline solutions and abrasion, some admixtures may significantly decrease the lifespan of a concrete-forming panel.

There’s much to consider when it comes to proper upkeep and maintenance of concrete forms. But following these tips will ensure the best life and use of forms project after project.

Roger Roatch is an Engineered Wood Specialist for APA. For more on concrete form maintenance and selecting the best form panel for the project, download the APA Concrete Forming Design/Construction Guide here.


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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.

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 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Release Agents, Concrete Casting Supplies, Grifcote, Precast Concrete Form Release, Concrete Casting Technical Support, Concrete Form Release Application Videos, Precast Concrete Plant Videos, Application of Form Oil

Precast Concrete Plant - Application of Form Oil Video

Posted by Hill and Griffith Company on Nov 26, 2017 1:45:29 PM

NPCA Precast Concrete Plant Video Virtual Tour of US Concrete, a state of the art precast manufacturing facility acquired by Oldcastle Precast in August 2012

Application-of-Form-Oil-1.jpg

There's no job too big, too unique, or too challenging for US Concrete Precast Groups, San Diego facility. The plant is one of seven in US Concrete's Precast division, which serves the West, Southwest, and Midatlantic regions. Located in sunny southern California, it is the newest and largest facility in the family. Constructed in 2007, after years of planning, it is state of the art and designed with employee input, future growth, and the environment in mind. With 49 production workers and another 17 office employees, the plant manufactures a wide variety of products for a diverse range of customers. Standard products include site furnishings and a number of underground utility and waste water solutions. With a dedicated staff and a modern facility, custom projects are a regular part of the mix as well. 

Hello, my name is Todd Everett. I'm the general manager for US Concrete Precast Group Southern California, sunny San Diego. Our San Diego plant has been a member of the MPCA since 1981, so 31 years. To get to where we are today, we were in another location in Santee, California for over 30 years, and we got to the point through growth that we were beginning to be landlocked, could not grow anymore in the area we were in, and in 2005, we approached the board of US Concrete about expansion. We were given approval to do that so the search was on. Located the property we're on now in, I think it was late 2006. Got all the permitting done and started, broke ground in 2007, early February, and opened the plant in November of 2007.

Application-of-Form-Oil-2.jpg

Even more important than the facility are the people. The employees are part of a team, a point that is taken very seriously.

It's my belief that the keys to a successful precast operation, first they start with your people. We've been very blessed at this location, this plant, with the group of people we have assembled here. We consider ourself a team, therefor, we have team members.

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As with most precast plants, a typical day begins bright and early at 6 am for production employees.

The production crew usually starts about 6 am in the morning. They get in and there's a lot of untarping, stripping, unbolting. There's usually a flow that's been predetermined already by weeks of planning ahead already before all the molds are out there. It's a system.

Application-of-Form-Oil-4.jpg

In the center of the plant, smaller products, such as drain boxes, catch basins, and meter boxes are stripped and laid on dunnage awaiting transport to either a delivery vehicle or the yard.

On the eastern end of the plant, utility vaults as large as 40 tons are stripped and flipped.

Once all products are stripped, workers immediately begin prepping the forms, including cleaning, caulking, and the application of form oil.

Application-of-Form-Oil-5.jpg

Meanwhile, on the western end of the plant, the weld shop is busy preparing cages for the empty forms. Large vault cages are assembled upside down on a raised platform by a welder, using pre-bent rebar. A cage for a large vault can take several hours.

Over by the state of the art batch plant, the morning begins with daily preparations in anticipation of the first batch, which usually occurs around 9 am. Once details are entered into the computer, the automated batch plant comes to life.

Outside, bins release the specified amount of fine and coarse aggregate, taking into account moisture content. The aggregate falls to a conveyor belt, which transfers it into one of two hoppers. One serves a one-yard mixer, the other a two-yard mixer.

Application-of-Form-Oil-6.jpg

One in the intended hopper, the aggregate is lifted up an elevator and released into the mixer.

Meanwhile, specified amounts of cement and fly ash are pumped into the mixer. After allowing the dry ingredients to mix, the batch plant releases water, add mixtures, and if needed, color and fiber.

Inside the plant, workers place a bucket under one of two chutes. Once full, the bucket is moved by forklift to one of the many overhead cranes and taken to the needed part of the plant.

Application-of-Form-Oil-7.jpg

In this instance, a yellow tinted batch is taken to the southwest corner of the plant where it's placed into forms for sidewalk pavers.
Once the batch arrives, the forms are filled, and a quality control inspection takes place.

In addition to standard products, the plant has found a niche in the custom market.

Application-of-Form-Oil-8.jpg

The team that we have assembled over the years at US Concrete, at this facility, San Diego Precast, is a team of individuals who have a great deal of knowledge. This is definitely one of those companies where there are some senior people here that have a lot of knowledge in concrete. The way we work through a custom project that's unique to us, is we get the team together. We get those that are going to be involved. We get our draftsmen, our salesmen, project managers, plant managers, quality control. We get a group of people together and then what we do is we go over the project. The goal is to make sure that it's successful, so we need to make sure that we're all on the same page. It's not a choice of will we fail. It's a choice of here's what's been put in front of us, now how do we make that succeed. That's what makes this company so special.

One recent example of the plant's custom work, is a stress ribbon bridge the company produced in 2009.

Application-of-Form-Oil-9.jpg

The stress ribbon bridge at Lake Hodges, it's actually the world's longest stress-ribbon bridge. It consists of three spans totaling 990 foot. It was also an endangered species area where they had a lot of nesting grounds for birds and things like that. The project had to be non-intrusive to the local surroundings. At the same time, the construction had to be mindful of that, schedule-wise. The finished product was quite a surprise, I think, overall to the designer that it came out so well.

Another extremely important facet of production is the quality control process. The plant has been MPCA certified since 1988, the first year certification was offered, and was among the first group of plants to reach the 20-year Continuous Certification mark in 2008.

Quality is important because we have control of every aspect from start to finish. We can control every environment on site and they can't do that. We have the ability to produce extremely precise products. The plant was designed at our old facility and we were able to incorporate everything that we wanted into the lab. A lot of the stuff we built in is stuff that we know that we're going to use 20 years from now.

Application-of-Form-Oil-10.jpg

The plant was also designed with many environmentally friendly details.

We're very mindful of the environment. The solar panels, over 60% of our energy comes from the sun. Skylights, so we're using natural light, we're using motion sensors throughout the plant, as well as the offices. Our environmentally friendly technology in our concrete, with our fly ash and other supplemental materials. We're contemporary, cutting edge if you will, precast plant.

US Concrete Precast Groups, San Diego facility, continues to find a steady flow of orders for waste water and underground utility products, as well as its custom projects. Looking to the future, it hopes to continue the growth it's had since it was founded and adapt to the ever-changing needs of its customers.

I think through our industry, through the National Precast Concrete Association, we continue to keep pushing the envelope and challenging ourself and challenge each other to continue to advance.


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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.

Hill and Griffith Samples

Product Samples

We are pleased to provide samples in quantities large enough to allow you to "try before you buy."
Contact Us »

 

Hill and Griffith Customer Service

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 »

 

 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Release Agents, Concrete Casting Supplies, Grifcote, Precast Concrete Form Release, Concrete Casting Technical Support, Concrete Form Release Application Videos, Precast Concrete Plant Videos, Application of Form Oil

Form Oil and Rebar - More on the controversy

Posted by Hill and Griffith Company on Jul 27, 2017 3:08:52 PM

This July 10, 2017, article in PRECAST, INC. "Bond, Reinforcement Bond" concludes with more on the chemistry and physics of form oil and rebar (reinforcing bar) preparation.

"FORM OIL

Like rust, the question of how much detrimental effect form oil has on reinforcing bars is now the subject of research. The current code provisions within ACI 301, "Specifications for Structural Concrete;' section 2.3.1.15, state, "Do not allow formwork release agent to contact reinforcement;' The NPCA Quality Control Manual for Precast Concrete Plants, section 4.3.2, also states, "Reinforcement and other items to be embedded in concrete shall be free of form release agent."

However, recent research (5) casts doubt on this intuitive school of thought and current code language. Until additional data verifies results, form oil should be removed from reinforcing elements, particularly on epoxy-coated and smooth FRP bars.

(5) Belarbi, A, Richardson, NO., Swenty, MK and Taber, L.H, (2010), Effect of Combination on Reinforcing Bar-Concrete Bond, Journal of Performance of Constructed Facilities, ASCE, Vol. 24, No. 3, May -June "

Form-oil-and-rebar.jpg

 

This June 01, 1998 article in CONCRETE CONSTRUCTION references another report that found no significant difference in nine different rebar surface conditions tested in three different ways.

"HOW CLEAN MUST REBAR BE?

Most specifications require reinforcement to be free of deleterious materials. But do common construction contaminants have a harmful effect on bond?

Form-release agents, bond breakers and cement splatter sometimes contaminate reinforcing steel before concrete is placed. However ACI 301-96, "Standard Specifications for Structural Concrete," says: "When concrete is placed, all reinforcement shall be free of materials deleterious to bond." Inspectors often cite this sentence when requiring contractors to remove form-release or bond-breaker overspray and cement splatter from contaminated rebar. But is this work really necessary?

The Aberdeen Group ran a series of bond pull-out tests to assess the effect of contaminants on bond strength. Pull-out tests measure the bond force acting parallel to the bar on the interface between the bar and concrete. Clean, black Grade-60 steel bars and bars with form-release agents, curing compound/bond breakers, cement splatter, motor oil and rust on their surfaces were tested. The form release and curing compound/bond breaker were sprayed on 100% of the rebar surface to duplicate the worst case of contaminant coverage possible during construction. The used motor oil was applied to the entire bar length with a rag, and a cement paste was mixed and applied to various areas of the rebar. To produce rusted rebar, bars were dipped in hydrochloric acid then stored in a moist curing room. The results, based on 27 tests of bars with nine different surface conditions, show that the contaminants didn't adversely affect bond."

What's your opinion? Please add a comment. Thanks.


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.

Hill and Griffith Samples

Product Samples

We are pleased to provide samples in quantities large enough to allow you to "try before you buy."
Contact Us »

 

Hill and Griffith Customer Service

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 »

 

 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Casting Products, Concrete Release Agents, Concrete Casting Supplies, Form Oil, Application of Precast Concrete Form Oil, Grifcote, Precast Concrete Form Release, Concrete Form Release Application, Form Release Application, Concrete Form Oil, Application of Form Oil

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