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Concrete Casting News from the Hill and Griffith Company

Review: "Guide for Surface Finish of Formed Concrete"

Posted by Hill and Griffith Company on Dec 6, 2018 1:05:46 PM

(This week's post is a review of the American Society of Concrete Construction's "Guide for Surface Finish of Formed Concrete." You can read it at Google Books here.)

Amazon Book's summary (April 1, 1999), "Exactly what is a smooth-form finish? What is a rough-form finish? To what extent are bugholes, voids and fins acceptable in each type? This easy-to-use guide explains and illustrates the answers to these questions and, even more importantly, serves as the standard for the differences between as-cast structural concrete finishes. The succinct, yet thorough, text includes a glossary and a handy table on as-cast finishes. But the guide's Presentation Photos are what make it truly unique. Three sets of 6 different, full-scale photographs depict various as-cast finishes, with bugholes and voids ranging from 1/16" or less to 2" across. Attach a Presentation Photo to a bid or specification to show what surface finish is to be expected."

Surface Finish of Formed Concrete.jpg 

 

(Jan 1, 2005 edition from Google Books)

Form Release Agents

Release agents are differentiated from form coatings or sealers that are usually applied in liquid form to contact surfaces either during manufacture or in the field. Coatings and sealers serve one or more of the following purposes:

  • Alter the texture of the contact surface 
  • Improve the durability of the contact surface
  • protect the contact surface from moisture

Release agents, on the other hand, are applied to the contact surface of the forms to prevent bond to the concrete and thus facilitate stripping. They can be applied to form materials during manufacture or applied to the form before each use. Manufacturers' recommendations should be followed in the use of coatings, sealers, and release agents (Reference 10-11), but ACI 347 recommends independent investigation of performance before using a new product.

There is no ACI standard to define these products, but the term form oil is frequently applied to petroleum compounds originally intended for other applications such as diesel fuel or heating oil, while release agent more often refers to products containing proprietary reactive ingredients specifically formulated for use on concrete forms. Release agents are commonly classified on the basis of how they act instead of what is in them. The two basic categories are barrier agents and chemically active agents, sometimes called reactive agents. Some release agents are a combination of the two types.

Barrier type releases agents create a physical barrier between the form surface and the fresh concrete, preventing the concrete from sticking to the form. Familiar examples are home heating oil, diesel oil, and used motor oil. U.S. environmental regulations prohibit the sale of these commodities as release agents, but they have been widely used because they are inexpensive and readily available. They are applied in relatively thick films, covering 200 to 600 sq ft per gallon, and such heavy applications can increase surface staining and bugholes on the concrete surface. If coated forms are left for several days before concrete is placed, barrier oils may evaporate, possibly leading to some sticking of the concrete to the form.

Chemically active or reactive agents contain an active ingredient that may be dissolver in an oil-based carrier or emulsified in a water-based carrier. The active ingredient is typically some type of fatty acid derived from plant or animal sources, and it combines chemically with calcium ions in the fresh concrete. The reaction product is a thin layer of what chemists refer to as a grease or metallic soap or salt; non-water-soluble, it permits the form to release readily from the hardened concrete.

The reactive fatty acid components are generally considered biodegradable and have found favor in the past decade because of increasingly stringent environmental regulations. For similar reasons, manufacturers have also been turning to water-based carriers, which will probably be subject to freezing.

 


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 Solutions, Concrete Casting Products, Bio Gold Concrete Form Release, Gricote, Concrete Casting Supplies, Concrete Casting, Concrete Safety, Precast Concrete, Concrete Form Release Agent

American Concrete Institute's Frequently Asked Questions - "Form Release Agents"

Posted by Hill and Griffith Company on Jun 7, 2018 3:46:19 PM

Form release agents

Review of an article published by the American Concrete Institute's "Frequently Asked Questions" section of their website.

Form Release Agent

Q. I need to select a form release agent for a new project requiring an architectural finish. Can you provide information on different types of form release agents and recommendations for using them? Does ACI have a publication on form release agents I could use as a reference?

A. Form release agents ease formwork removal, extending the useful life of a form and improving the smoothness and texture of concrete surfaces. Two main types are available: barrier and chemically active.

Barrier-type agents (examples include diesel oil, wax, and silicone) create a barrier between the form and the concrete. These are not recommended for architectural concrete, because they can cause stains, surface air voids, and problems with form removal in very cold or very hot weather; they also may prevent subsequent adhesion of coatings to the hardened concrete. While diesel oil was once commonly used, it’s now prohibited because the associated volatile organic content (VOC) emissions contribute to smog. (Note: In the United States, form release agents have to meet federal VOC limits of 450 g/L [3.8 lb/gal.] and may have to meet more restrictive limits of 250 g/L [2.2 lb/gal.] in some states.)

Chemically active form release agents (certain types of fatty acids) react with calcium ions in the cement paste to produce a soap that prevents concrete from bonding to the formwork. Based on the reactivity, they are divided into buffered (partially) reactive and fully reactive. Buffered agents produce an improved soap film that helps remove entrapped air and may promote better flow of a thin skin of cement paste at the surface of the form. Fully reactive agents can provide a good basic soap film that, depending on the brand, works well in most cases. Because chemically active form release agents produce fewer bugholes, stains, and surface irregularities than barrier type of form release agents, they are commonly used for architectural concrete.

For more information on this topic refer to ACI 347R “Guide to Formwork for Concrete”, ACI 303R “303R-12 Guide to Cast-in-Place Architectural Concrete Practice”, and ACI 533R “Guide for Precast Concrete Wall Panels”. 

References: ACI 347R-14; ACI 303R-12; ACI 533R-11

ABOUT ACI

  • The American Concrete Institute (ACI) is a leading authority and resource worldwide for the development, distribution and adoption of consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.


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 Solutions, Concrete Casting Products, Bio Gold Concrete Form Release, Gricote, Concrete Casting Supplies, Concrete Casting, Concrete Safety, Precast Concrete, Form Release Agents, Concrete Form Release Agent

Review of Precast Concrete Form Maintenance Article in PRECAST INC Magazine

Posted by Hill and Griffith Company on Jun 1, 2018 12:57:27 PM

Besides Bob Waterloo's Featured article, "How To Lose a Customer in 10+ Easy Ways," the recent issue of PRECAST INC has some great tips from industry professionals about precast concrete form maintenance. Here are some highlights from the artcle.

Form manufacturers and precasters were asked several questions related to form maintenance and form safety. Below are the questions and answers from the responders. 

precast-concrete-form-maintenance-1

What steps should precasters be taking to keep their formwork in good working condition? 

"Using a quality form release and cleaning forms with every use will keep the
face of the forms clean for many years. The other best practice to increase the life of your equipment is to avoid hammering on them as much as possible - abstinence is the best policy here!" - Jim Aylward, Western Forms

"Keep forms clean, since build up can change the center of gravity on pieces and parts. Keep forms oiled for easier stripping." - Blythe Coons, Spillman Company

precast-concrete-form-maintenance-2

Any tips or best practices you would like to share with precasters to help increase the lifespan of their formwork and to ensure safety? 

"Biggest tips on increasing the life of aluminum formwork: 
1. Invest in quality.
2. Use quality form release
(reactive release designed for aluminum forms) to keep the forms clean.
3. Train employees to treat the equipment with care.
4. Use proper tools associated with the formwork.
5. Reach out to manufacturers for questions and concerns."
- Jim Aylward, Western Forms

"Don't try to save money on form oil. Figure out what works best for you and keep it. Don't allow employees to use hammers to clean forms. Grease all grease fittings regularly. Take time to clean the inside of the forms." - Mike Vergona, Garden State Precast

To read the entire article go here. "Be Formal About Your Form Safety."


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 Solutions, Concrete Casting Products, Bio Gold Concrete Form Release, Gricote, Concrete Casting Supplies, Concrete Casting, Concrete Safety, Precast Concrete, Concrete Form Release Agent

Guide for Surface Finish of Formed Concrete

Posted by Hill and Griffith Company on May 26, 2018 11:03:53 PM

(This week's post is a review of the American Society of Concrete Construction's "Guide for Surface Finish of Formed Concrete." You can read it at Google Books here.)

Amazon Book's summary (April 1, 1999), "Exactly what is a smooth-form finish? What is a rough-form finish? To what extent are bugholes, voids and fins acceptable in each type? This easy-to-use guide explains and illustrates the answers to these questions and, even more importantly, serves as the standard for the differences between as-cast structural concrete finishes. The succinct, yet thorough, text includes a glossary and a handy table on as-cast finishes. But the guide's Presentation Photos are what make it truly unique. Three sets of 6 different, full-scale photographs depict various as-cast finishes, with bugholes and voids ranging from 1/16" or less to 2" across. Attach a Presentation Photo to a bid or specification to show what surface finish is to be expected."

Surface Finish of Formed Concrete.jpg 

 

(Jan 1, 2005 edition from Google Books)

Form Release Agents

Release agents are differentiated from form coatings or sealers that are usually applied in liquid form to contact surfaces either during manufacture or in the field. Coatings and sealers serve one or more of the following purposes:

  • Alter the texture of the contact surface 
  • Improve the durability of the contact surface
  • protect the contact surface from moisture

Release agents, on the other hand, are applied to the contact surface of the forms to prevent bond to the concrete and thus facilitate stripping. They can be applied to form materials during manufacture or applied to the form before each use. Manufacturers' recommendations should be followed in the use of coatings, sealers, and release agents (Reference 10-11), but ACI 347 recommends independent investigation of performance before using a new product.

There is no ACI standard to define these products, but the term form oil is frequently applied to petroleum compounds originally intended for other applications such as diesel fuel or heating oil, while release agent more often refers to products containing proprietary reactive ingredients specifically formulated for use on concrete forms. Release agents are commonly classified on the basis of how they act instead of what is in them. The two basic categories are barrier agents and chemically active agents, sometimes called reactive agents. Some release agents are a combination of the two types.

Barrier type releases agents create a physical barrier between the form surface and the fresh concrete, preventing the concrete from sticking to the form. Familiar examples are home heating oil, diesel oil, and used motor oil. U.S. environmental regulations prohibit the sale of these commodities as release agents, but they have been widely used because they are inexpensive and readily available. They are applied in relatively thick films, covering 200 to 600 sq ft per gallon, and such heavy applications can increase surface staining and bugholes on the concrete surface. If coated forms are left for several days before concrete is placed, barrier oils may evaporate, possibly leading to some sticking of the concrete to the form.

Chemically active or reactive agents contain an active ingredient that may be dissolver in an oil-based carrier or emulsified in a water-based carrier. The active ingredient is typically some type of fatty acid derived from plant or animal sources, and it combines chemically with calcium ions in the fresh concrete. The reaction product is a thin layer of what chemists refer to as a grease or metallic soap or salt; non-water-soluble, it permits the form to release readily from the hardened concrete.

The reactive fatty acid components are generally considered biodegradable and have found favor in the past decade because of increasingly stringent environmental regulations. For similar reasons, manufacturers have also been turning to water-based carriers, which will probably be subject to freezing.

 


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 Solutions, Concrete Casting Products, Bio Gold Concrete Form Release, Gricote, Concrete Casting Supplies, Concrete Casting, Concrete Safety, Precast Concrete, Concrete Form Release Agent

Proper Use of Concrete Form Release Can Save Your Forms

Posted by Hill and Griffith Company on May 10, 2018 2:37:49 PM

Concrete formwork is a major investment for a precast or prestress plant. Taking care of the forms extends form life and protects a valuable investment and contributes to a healthy bottom line.

Concrete-Form-Release-Agent-Application-1.jpg

Care of concrete forms needs to be considered every time they are used. Steel form damage can occur with lack of cleaning or with too much use of wire brushes and sandblasting. Vibrators can damage form surfaces.

Proper selection and application of release agents is necessary for lower cost, producing the best product possible and for minimizing form clean up.

Grifcote-Concrete-Form-Release-Agent-Sizes.jpg

There are two types of release agents but they can also be combined for some applications.

The first is the barrier type. They provide a barrier between the concrete and the form. Originally form oils were barrier types of diesel fuel, greases, used motor oil, etc. These produced a good release but lowered product quality by causing bug holes, and staining, resulting in poor product appearance. They hard to apply due to their high viscosity.

The second type of release agent is chemically active and react with lime in the concrete to produce a soap-like film on the form. This type of release agent is the most widely used. Because they are easily applied in a very stable thin film by spraying, wiping, or brushing, you can produce stain-free, void-free concrete surfaces even after the form has been exposed for a day or two. Reactive type release agents applied in a thin film allow the form to strip cleaner which saves on labor costs related to form cleaning and extends the life of the form.

Concrete-Form-Rust-Preventative.jpg

In September of 1999 release agent manufactures and concrete producers were required by the EPA to make and use limited VOC products. Some companies, including Hill and Griffith, saw this coming years in advance and were already producing VOC compliant products. Some states, such as California have stricter rules than that passed nationally.

There are four main application methods-spraying, wiping, mopping or brushing and dipping. Spraying is the most common method of application. Avoid over application to reduce your cost. An extremely thin film of release agent is all that is needed, "The thinner the better." Pump unit sprayers or centralized systems with air pressure regulators give a good consistent pressure and work well. Spray pressures of 35 to 50 psi are best. Higher pressures put more airborne particles in the air throughout the plant and can be harmful to personnel in the plant. Lower pressures cause puddling in the form, and wasted release agent. A flat fan spray nozzle of .1 or .2 gpm will spray a good thin release agent. Many of these thin, chemically active release agents are more expensive per gallon. But with coverage rates at 2000-2500 sq. ft. per gallon the cost is much less than a cheaper barrier release agent. A second type of application is wiping on the release agent. Architectural precasters like wiping the release agent on the form because over application is eliminated. Burial vault manufactures use a sponge for application because they clean the form each time as well. A third type of application is with mop or brush with which over application can be a problem. The mop or brush must be wrung out in order to achieve the desired results. Wipe up puddles. Dipping systems are fast, labor efficient, and assure total coverage of the form. And they collect the excess release agent that drains off the form.

The investment in forms needs to be protected from rust and corrosion, use grease, diesel fuel, or release agent. A better choice is a good rust preventative that offers quality protection, long life, ease of application, and easy removal.

Taking care of forms each time they are used can save thousands of dollars and make a concrete business more profitable.


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 Solutions, Concrete Casting Products, Gricote, Concrete Casting Supplies, Precast Concrete, Concrete Form Release

Construction Forming System Precast Concrete Release Agent Application

Posted by Hill and Griffith Company on May 1, 2017 5:42:12 PM

Care and Seasoning of Metal Forms and Rings

Would you ever have thought that you could make money just by walking around? That’s the first step (no pun intended) of a maintenance program for your metal forms and rings. Just by taking a look at these expensive pieces of equipment, you can tell whether or not they are getting the attention they need. If they are suffering from neglect, they can cost you later in terms of reduced longevity and deteriorated product quality. It helps to be armed with a little knowledge about form release agents, rust inhibitors and rust preventatives and how they react with metal. 

Read the full article here, by Bob Waterloo Technical Sales Manager of concrete release agents for The Hill and Griffith Co. in Greenwood, Ind.

Precast Concrete Release Agent Video 1.jpg 

 

(Video and image from Precise Forms, "Precise Forms is a family owned and operated business with sights set for aggressive contractors and their needs. Precise Forms manufactures standard and custom aluminum forming systems for foundations, basements, concrete homes, apartment complexes, precast, commercial structures, and agricultural buildings both nationally and internationally. The Dominator Forming System sgown is a taper tie system that can be used to create concrete homes, concrete commercial projects, or concrete precast boxes. The system can be hand set or ganged allowing for entire sections to be moved at one time saving both time and money. The Dominator creates straight, smooth walls with little to no deflection when properly braced.")


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, Gricote, Concrete Casting Supplies, Precast Concrete Dissolver, Concrete Release Agents

Grifcote® Premium Concrete Dissolver

Posted by Hill and Griffith Company on Apr 20, 2017 11:05:27 AM

GRIFCOTE® Premium Dissolver is a proprietary blend of materials that promote the removal of hardened concrete.

The reaction of GRIFCOTE® Premium Concrete Dissolver with the previously deposited concrete on the surface of a metallic surface will facilitate the removal of this material.

Hollow precast concrete wall production showing concrete release agent on form.jpg 
(Hollow precast concrete wall production showing concrete release agent on form. Image from Tachydomi Sa video.)


(Video and photos show the construction stages of hollow precast wall production in the Tachydomi SA factory. Learn more.)


Application

The recommended method for the application of the GRIFCOTE® Premium Dissolver is by utilizing a hard bristle brush, mechanical sprayer or any other compatible spray method which applies a fine mist or spray covering all of the areas that require treatment.

For optimum performance of GRIFCOTE® Premium Dissolver saturate the area of the hardened concrete and allow GRIFCOTE® Premium Dissolver to penetrate the surface for 10 to 20 minutes. After the GRIFCOTE® Premium Dissolver contacts the hardened concrete the surface will turn white and then darken. Re-treat the surface if a white residue appears on the area where the concrete remains. Re-apply surface until concrete has turned to a softened material (mush). On areas of the metal surface where a thick buildup is observed, repeat the application of the GRIFCOTE® Premium Dissolver and repeat the cleaning process until the concrete on the metal surface has softened and turned to “mush”.

**Application rate will vary depending on metal surface and application methods.

Technical Data:

Color  Light Orange
Weight per Gallon 8.1 lbs/gal
Flash Point N/A (P.M.C.C.)
Viscosity >1 @ 40° C
Specific Gravity   0.97
Density 8.1 lbs/gal
PH 1.8

A Material Safety Data Sheet should be reviewed for safety precautions prior to application.


Hollow precast concrete wall production 2.jpg
(Hollow precast concrete wall production showing cured side being set on wet side. Image from Tachydomi Sa video.)

Hollow precast concrete wall production 3.jpg
(Hollow precast concrete wall production showing finished wall being placed in storage. Image from Tachydomi Sa video.)


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, Gricote, Concrete Casting Supplies, Precast Concrete, concrete dissolver, Precast Concrete Dissolver

Application of Precast Concrete Form Oil

Posted by Hill and Griffith Company on Apr 14, 2017 10:03:48 AM

From the National Precast Concrete Association - Precast Learning Lab

Published on Feb 24, 2017 - Learn how to properly apply form oil at your precast concrete plant.
 

How To - Application of Precast Concrete Form Oil

Spokesperson, "So Lynn, Why is form release application such a critical step in the production process?"
 
Lynn, "It's so critical because it helps you in stripping product out of the form, you get a better overall finished product and it really preserves the life of your mold. As you can see behind me, we have a mold that was stripped earlier today. Before we talk about applying release agent, it’s important to know…"
 

Application of Precast Concrete Form Oil - 1.jpg

NPCA members can view the full video - part of the Precast Learning Lab series - on myNPCA. http://portal.precast.org

Application of Precast Concrete Form Oil - 2.jpg

Application of Precast Concrete Form Oil - 3.jpg

Application of Precast Concrete Form Oil - 4.jpg


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, Gricote, Concrete Casting Supplies, Precast Concrete, Form Seasoning Concrete Release Agent, Application of Precast Concrete Form Oil, Form Oil, Concrete Release Agents, Concrete Form Seasoning

Self-Consolidating Offers Concrete Bug Hole Solution

Posted by Hill and Griffith Company on Apr 6, 2017 10:38:00 AM

What you do affects the surface aesthetics of self-consolidating concrete

By

concrete-bug-hole-solution.jpgSelf-consolidating concrete (SCC) has been used to produce many aesthetically critical projects since its development nearly 20 years ago. Although mixes of various levels of strength and durability can be designed to generate smooth, defect-free surfaces, this does not ensure that the finished structure will be unflawed.

Two outside influences can greatly affect the appearance of concrete. The first is forming materials—the most popular are steel and plywood. The second factor is release agents. Different types and brands of release agents (form oils) give varying degrees of surface defect. The method of application of these agents also plays a part in the final product appearance.

(This week's concrete bug hole solution post comes from a December 21, 2005 article in Concrete Construction Magazine.)



What you do affects the surface aesthetics of self-consolidating concrete

SCC with an appropriate release agent yields defect-free surfaces.

In 2003 we launched a study to evaluate the effects of form conditions on the finished surface of SCC. Two SCC mixes were developed that could produce a defect-free formed surface. One design was a “high fines” SCC (Mix 1 in the table), and the other used a stabilizer, or viscosity modifying admixture (VMA).

Both were well-designed, stable mixes, verified by casting and testing samples. Both mixes also attained 5% ±1.5% entrained air content that met the industry accepted criteria for specific surface and spacing factors, exhibiting a very stable air matrix.

Note that entrained air content does not affect the presence of bug holes; entrapped air—air bubbles too large to benefit the concrete—is what clings to the formwork. Entrapped air can be generated during the casting process (most bug holes appear near where a form is filled), or large air bubbles can be generated and trapped in the concrete because of the superplasticizer. The new-generation polycarboxylate-based high-range water-reducing (HRWR) admixtures often contain significant amounts of defoamer to reduce air entrapment, but this can wreak havoc on the entrained air matrix.

Forms

Wood forms and metal forms will show significant differences in surface defects. Wood forms tend to produce fewer bug holes than metal because wood forms soak up excess release agent that has been hastily applied. Any small amount of extra oil on a steel form will react with the concrete mix and create small bug holes, perhaps better termed “pinholes.” Therefore, proper application is absolutely necessary. Steel forms require more attention to ensure a clean, smooth surface. Any defect on the form will create a blemish on the concrete surface.

A form's cleanliness and smoothness greatly affect the appearance of the concrete surface. This simple, logical truth cannot be overstated when dealing with SCC.

concrete-bug-hole-solution

Forms should be as smooth as possible to allow entrapped air to move easily upward along the form system; they must be kept free of paste buildup and laitance, which prevent air and water pockets from traveling to the concrete surface. In our study, as paste built up on each form with subsequent castings, the concrete surface appeared worse. Scratches or gouges will hold air against the surface of the concrete. Any steel forms pitted with rust will cause blemishes, which at times produce more bug holes than are noticeable with vibrated conventional concrete. We also noticed that when the form skin had a lower temperature than the SCC, air voids smaller than usual were present. That occurred at approximately a 25° F temperature difference.

Whenever you grind a “seasoned” steel form, you remove the protective barrier previously produced by the reactive form release agent. Rusted forms have negated the barrier that was in place. Once the form is ground, raw metal is exposed. The reactive portion of the form release agent, typically a fatty acid, has a natural affinity for metal. The fatty acid attacks the raw metal and forms metallic oleate, which acts as a protective coating. Subsequent applications of reactive form release agents are prevented from getting to the metal by the protective layer of metallic oleate, allowing the reactive portion of the form release to be available to react with the free lime on the surface of the concrete. This reaction forms a chemically inert metallic soap, which gives good release and allows free air to rise more easily to the surface on vertical walls. Until the form is seasoned, or the protective barrier is formed, the reactive portion combines with the metal, leaving nothing to react with the free lime. The steel forms used in this study were seasoned after cleaning and before further castings took place. That aided the finish somewhat but the pits left in the forming material by the rusting process trapped air voids, creating bug holes.


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, Gricote, Concrete Casting Supplies, Precast Concrete, Form Seasoning Concrete Release Agent, Concrete Release Agents, Concrete Form Seasoning

Form Seasoning Concrete Release Agent

Posted by Hill and Griffith Company on Mar 30, 2017 4:06:49 PM

Concrete Release Agent that also acts as a Form Seasoning 

Form Seasoning-Concrete-Release-Agent.jpgGrifcote CC-150-VOC is widely used to season forms for optimal concrete release.

Spraying form release agents on mixers and equipment reduces labor and cleanup at the end of the day eliminating concrete adhering to the equipment.

The Hill and Griffith Company also works closely with pipe and form equipment manufactures to provide optimum concrete release characteristics with their equipment.

Convenient and reliable

Gifcote concrete release products are non-staining and ready to use with no mixing needed and offer many unique features to improve concrete separation from forms, pallets and molds.

All Grifcote products are available in 55 gallon drums, 330- gallon totes or bulk tank wagons.

All Grifcote Form Seasoning Concrete Release Agent products have indefinite freeze/thaw cycles. You don’t need to worry about Grifcote degradation due to temperature changes.


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."
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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.
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 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Casting Products, Gricote, Concrete Casting Supplies, Precast Concrete, Form Seasoning Concrete Release Agent, Concrete Release Agents, Concrete Form Seasoning

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