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Concrete Casting News from the Hill and Griffith Company

Protect Your Precast Forms with Reactive Release Agents and Rust Preventatives

Posted by Hill and Griffith Company on Aug 18, 2018 8:17:40 PM

Taking care of your precast concrete forms extends their life and protects a valuable investment.

Precast-Concrete-Careers-6

It starts with day-to-day mainentance. Steel form problems can happen with poor cleaning or excessive use of wire brushes or sandblasting. They can also be damaged by vibrators.

The selection of a good concrete release agent is another important aspect of form care. There are two main types of concrete releases.



Diesel fuel, greases, used motor oil, etc. barrier type products provide a barrier between the form and the concree allowing it to strip. These provided a good release, but cause surface voids, staining, and over all poor finished appearance. They are harder to apply due to their higher viscosity.

precast-concrete-form-maintenance-1

Reactive type are chemically active and contain compounds that react with the free lime in the concrete to produce a soap-like film between the form and the concrete. This type of release agent is the most widely used. They are only require a thin film to produce a stain-free, void-free concrete surfaces. Reactive type release allow the form to strip cleaner.

Proper application of release agents is necessary for economy and for producing the best product possible and for minimizing form clean up.

Another aspect of concrete form care is protection in storage when they are out of service between jobs. The forms need to be protected from rust and corrosion. Some use grease, diesel fuel, or release agent but a rust preventative is a beter choice. For your rust preentative know the quality of protection, length of protection, ease of application, and ease to remove.

Formwork is a big investment for producers. Proper care insures product quality and extends their life. It will make your concrete business more profitable.


Precast Concrete In The Google and NPCA News:

Precast concrete could mean better local roads in the future

Precast concrete barn has all the bells and whistles for 280 Alberta dairy cattle

Senior Living Community Selects Precast Concrete for New Construction


 

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 Forms, Concrete Form Release Agents, Concrete Release Agents, Concrete Form Seasoning, Concrete Casting Supplies, Rust Inhibitors, Concrete Form Release

Hollowcore Precast Concrete Video Showing Form Release Application

Posted by Alli Myers on Jul 6, 2017 6:17:32 PM

A hollowcore precast concrete plank is prestressed concrete used in the construction of multi-story building floors.

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The concrete hollowcore method is popular in insect prone, coastal, earthquake and severe weather areas. It offers fast building assembly and lower material weight.

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The hollowcore slab has tubular voids extending the full length of the slab. This makes it lighter than a solid concrete floor of equal thickness.

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The reduced weight lowers transportation and material costs. They are typically 4 to 5 feet wide with thicknesses between 10 and 16 inches.

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Prestressed reinforcing steel wire rope provides resistance to bending moment from loads.

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The manufacturing process involves extruding wet concrete from a moving mold over a steel bed on which the form release application has dried.

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The continuous slab is cut by circular diamond saws to the length required. Factory production provides the advantages of reduced time, labor and training.

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Hollow core voids can be used for conduit or coated for use as a ventilation duct.

(Video and stills from Alli Myers' YouTube Channel; text from Wikipedia)


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

All Grifcote products are readily biodegradable, which means they have a half-life of 28 days or fewer. And by definition, all Grifcote products are inherently biodegradable with a half-life of 60 days or fewer.

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 Casting Supplies, Concrete Release Agents, Grifcote, Precast Concrete Form Release, Concrete Form Release Application, Concrete Form Seasoning, Form Release Application

Concrete Form Seasoning and Material Selection

Posted by Hill and Griffith Company on Jun 29, 2017 10:28:35 AM

Which concrete form substrates and finishes are best for your application?

Considering what form substrate what form substrate material and what surface finish will be best for an application depends on the surface finish specified for the concrete, the number of form reuses the project requires, the strength and deflection characteristics of the substrate, price, and perhaps the thickness tolerances of a product—especially important for architectural concrete work.

Choices for form substrates and surface finishes range from inexpensive CDX plywood that serves as both the substrate and the surface finish, to more expensive aluminum, steel, or plastic resin composite materials with exotic finished surfaces for multiple reuses.The latter may be the bargain compared to plywood when considering the per placement cost versus the original purchase cost.

Which substrate and surface finish to use is driven by project requirements. If the forms will be reused 100 times, form panels should be purchased to meet the requirement. Refacing a form assembly halfway through a project causes delays and is expensive. Conversely, it isn't cost productive to invest in materials that can get 100 uses for a job that will only require 20.

Concrete-Form-Seasoning-1.jpg
(Image from Wharton Concrete Forms.)

This article was published on Nov 25, 2008 in CONCRETE CONSTRUCTION Magazine by 

Substrate materials

Plywood, steel, aluminum, and composite materials are used for both vertical and horizontal forming systems as a substrate material. Located behind these panels are an array of strong-backs, whalers, and trusses that also are made from wood, steel, or aluminum.

There are many substrate material and surface surface finish choices choices in the marketplace, each each with advantages with advantages, disadvantages, and costs. The challenge is to select the right product for the product the job.

Wood substrates.
For single-use applications, CDX plywood is probably the cheapest substrate material when the concrete finish doesn't matter. For example, the back side of a unique retaining wall section not in public view might be a good application for a single-use form. But be aware that CDX is designed for other purposes, has only 5 plys, and isn't rated for the pressures that concrete can impose. For repetitive work, better grades of plywood are necessary. They don't absorb as much moisture and help to reduce the concrete build up (laitance build) on the casting surface. These can be pre-oiled panels or substrate plywood panels with waterproof surface finishes.

Most plywood for concrete forming is 7 ply, though there is some plywood available with more laminations. Although some 5-ply sheets are available, most contractors prefer 7 ply because they are stronger and have less deflection. Sheets are manufactured by either a one-or two-step process. Manufacturing a one-step sheet involves placing the overlay material and all the veneers with waterproof and boil proof glue in a hot press. The resulting panel has thickness tolerances of ± 1/32 inch. Two-step panel processing involves gluing the veneers in a press, repairing panel faces with poly-patch compounds, sanding the surfaces smooth to a tight tolerance, and then bonding the overlay surface to the panel in a hot press. These panels have thickness tolerances of ± 0.005 to 0.006 inch with no transfer of grain lines or knot holes to the concrete, making them a good choice for high-end, architectural concrete finishes.

The first place deterioration starts on a wood panel is along the edges because water can easily enter and cause swelling. Manufacturers of overlay panels typically seal the edges with polymer products so every cut you make also should be sealed. Here are some of the wood substrate classifications available.

B-face
B-back, oiled, and edge sealed (BBOES). Plywood panel surfaces are ranked as “A,” “B,” or “C.” Surfaces marked as “B” permit 20 to 25 knot holes and exposed grain on a 4x8-foot sheet. “Oiled” refers to the panel being oiled during the manufacturing process to allow for easier release from the concrete. “Edge sealed” means the panel edges are sealed at the factory to reduce moisture absorption. BBOES is typically made from either Southern Yellow Pine (SYP) or Douglas Fir (DF). SYP panels are less expensive than DF and usually are heavier. DF panels typically are better quality than SYP because moisture doesn't cause them to swell or move as much and they are almost always the panels used for overlay surfaces. All BBOES products will exhibit grain and patch transfer to the finished concrete. You can expect four to eight uses and the application of release agents is required before each concrete placement.

Hardwood panels.
Hardwood veneers on top of DF panels offer blemish-free surfaces with less moisture absorption. The wood for these veneers includes maple, oak, Brazilian, and Indonesian hardwoods. Used as overlay panels, they are cleaner and offer better adhesion for overlay resins.

Steel substrates.
The typical substrate thickness of a steel panel is 3/16 to ¼ inch, but can be as little as 14 gauge for handset panels. With a life expectancy of several decades, or even a lifetime, deflection of these panels is minimal and create very smooth concrete surfaces. When using steel forms, designers usually are concerned more about panel joint and tie-hole locations than finish. Steel deck forms feature a steel frame, a plywood substrate, and a resin surface finish. Form manufacturers generally require thin-film, reactive-type form release compounds for good form release.

Aluminum substrates.
Like steel, the aluminum in a panel serves as both the substrate and the finished surface. Standard substrate thicknesses range from 0.094 to 0.120 inch, but they can be more for gang form wall panels where greater head pressures are anticipated. The panels are much lighter than steel, are built to have little deflection under load, and can provide very smooth concrete finishes. When they are properly cared for, you can achieve more than 2000 uses. New forms must be “seasoned” (some manufacturers preseason them) to avoid a reaction between the aluminum and the alkali of the cement that results in a disfigured surface.

Overlay finishes
Material that is factory applied to any given substrate is referred to as an overlay. Overlay panels are alkali resistant and minimize labor costs by reducing clean up time between placements. They are more resistant to moisture penetration—increasing resistance to cracking or “checking” as well—extending the life of the form. They also produce smooth concrete finishes.

There are two categories of form surfaces with a resin impregnated paper: medium-density overlays (MDO) and high-density overlays (HDO). MDOs consist of a large family of phenolic resin impregnated overlays designed for use on engineered wood substrates. Easy field use combined with the ability to produce superior matt or architectural finishes make them a favorite choice for concrete contractors.

Concrete-Form-Seasoning-2.jpg
(Image from Wharton Concrete Forms.)

MDO panels. MDO 1 step panels incorporate a layer of Kraft brown resin impregnated paper. The concrete surfaces produced by them are smooth with some grain and patch transfer. You typically can expect eight to 12 placements. MDO 2 step panels provide a smoother finish. Surface blemishes in the base panel are repaired and sanded before the resin impregnated Kraft paper is added. The result is a smooth matt finish that can handle 12 to 15 concrete placements.

HDO panels.
HDO form surfaces are especially good for high-gloss architectural finishes. Like MDOs, they encapsulate paper in resin, but the resin content in HDOs is higher—varying from 48% to 58%. There are two types of HDO.

HDO 1 Side 1 Step. Paper and resin is placed on both sides of an engineered panel to minimize moisture penetration, thereby helping panels to stay flatter or balance the sheet. The expected usage is 20 to 35 concrete placements.

HDO 2 Side 2 Step. Substrates are first glued, patched, and sanded to close even thickness tolerances. Then 48% to 58% resin impregnated paper is bonded to both sides.

Melamine overlays.
The least expensive version is a very thin melamine layer over particle board for limited-use application. The more durable version features 2-mil build ups that add both weight and expense to a form. But the number of reuses makes it worth the cost and finishes are architectural grade.

Composite resin systems.
These create perhaps the best overlay system of all—the only ones that can be applied over a metal surface. They are made with polyethylene and polypropylene, or mixtures of plastic materials. Nail holes and dents can be easily repaired. They are more expensive to purchase but with proper care and maintenance are reusable as many as 100 times.

Composite systems.
One substrate panel is built with foamed polypropylene sandwiched between thin sheets of aluminum or fiberglass with polypropylene surface finishes. Because there is no wood in the system, cleaning can be achieved in less time by using a pressure washer and 1000 reuses are possible.

Urethanes.
Urethane creates a hard, durable finish and concrete contractors sometimes apply them over inexpensive forms. But considering the cost of the material and labor to apply, this approach is perhaps not worth it.

Form releases
All surface finish products require the use of form release products and all forms manufacturers stress the need to use minimal amounts that won't affect surfaces adversely. Excessive amounts of release agents can cause a vacuum or sticking affect on some denser surfaces. Most of the recommended products react with the alkalinity of concrete to produce soapy films that break the bond between forms and concrete.

Choosing a system
Contractors sometimes make the mistake of choosing a form panel system based on initial cost. If they know they will need to reuse their panels 80 times on a project and choose a product that will only get 60 reuses, they will have to remove the panels from their form system and replace them in order to complete the job—this adds labor, job downtime, and new panel costs. There is a cost advantage to choosing a system that will complete all the placements. Calculate the total uses for a project and buy in order to complete the entire job with one purchase.

Marcus M. Chase is senior vice president of market development and sales for MAXAM Industries Inc. He brings nearly 22 years of experience, with a special focus on wood and the concrete forming industry. He has either developed or assisted in development of new concrete forming panel technologies in high reuse, no oil, and LEED-compliant materials. Joe Nasvik is a senior editor for CONCRETE CONSTRUCTION magazine.

Forest Stewardship Council (FCS)

You may see a specification for FSC panels. This refers to how the lumber was grown, farmed, or cut from native stands. In order to produce FSC panels, the manufacturer of the forms must be certified as well as the logging enterprise and all parties in the transaction. This is referred to as the “chain of custody.” Only a handful of mills are certified at this point but you will undoubtedly see more specifications for FSC products.

Tips on how to maintain forms
Every time you cut a panel be sure to apply edge seal over the new cut.
When you stack form sheets, stack them face to face.
Don't expose form surfaces to the sun for long periods of time.
Use a good form release product and apply it sparingly before each concrete placement.
Clean form surfaces shortly after removing them after a concrete placement.
Repair nail fastener holes and dents as they occur (few contractors do this).


Grifcote CC-150-VOC is widely used for concrete form seasoning 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.

All Grifcote products are readily biodegradable, which means they have a half-life of 28 days or fewer. And by definition, all Grifcote products are inherently biodegradable with a half-life of 60 days or fewer.

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 Casting Supplies, Concrete Release Agents, Grifcote, Precast Concrete Form Release, Concrete Form Release Application, Concrete Form Seasoning

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

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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."
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

Precast Wall Concrete Form Release Application Video

Posted by Hill and Griffith Company on Aug 25, 2016 10:33:02 AM

(We love "How It's Made" and this episode shows how precast concrete walls are made and includes video of the application of release agent.)

Concrete-Form-Release-Application-Video.jpgPublished on May 14, 2015 by the Science Channel.

"A mix of limestone gravel, minerals and additives are mixed into a slurry. After a test sample is hardened and tested, workers pour it into pre-made molds."

 Here's a list of the sections of the video:

  • Concrete mixing

  • Form set up

  • Foam letter placement for imprint on wall

  • Form release application

  • Steel cable placement and pre-tensioning

  • Rebar placement

  • Wire mesh placement

  • Pour first layer of concrete

  • Place second set of rebar and mesh

  • Place insulating foam

  • Pour second layer of concrete

  • Curing for three days
  • Sand blast decorative parts of the wall

  • Wall placement

 


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 Forms, Concrete Form Release Agents, Concrete Release Agents, Concrete Form Seasoning, Biodegradable Concrete Form Release, Concrete Casting Supplies, Concrete Voids, Concrete Form Release

"Precast 101," illustrating concrete form release agent application

Posted by Hill and Griffith Company on Aug 18, 2016 5:10:40 PM

(This week's post is a video share from Oldcastle Precast, view the YouTube Channel here. Published on June 19, 2015, it's the complete story of design, engineering, construction, production / pouring of concrete, form release, storage and delivery of the final product to the customer. Very nicely done! Thank you, Oldcastle Precast.)

Concrete-Form-Release-Agent-Application.jpg

Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment. This allow maximum quality control over the process and results in a consistently durable, high quality product. From here it is transported to the construction site and lifted into place.


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 Forms, Concrete Form Release Agents, Concrete Release Agents, Concrete Form Seasoning, Biodegradable Concrete Form Release, Concrete Casting Supplies, Concrete Voids, Concrete Form Release

Care of Forms and Use of Concrete Form Release Agents

Posted by Hill and Griffith Company on Aug 11, 2016 11:41:40 AM

 

(This week's post is an educational article by Bill Rostine from "Pre-Cast Concrete News." )

Concrete-Form-Release-Agent-Application-1.jpgConcrete formwork is one of the biggest investments a precast or prestress plant has. Therefore, taking care of the forms extends form life and protects a valuable investment. This makes economic sense and contributes to a healthy bottom line.

Care of concrete forms starts with the day-to-day use. Problems on steel forms can occur with inadequate cleaning or with excessive use of wire brushes or sandblasting. Form surfaces can also be damaged by internal vibrators.

Another important aspect of form care is the selection and proper application of a good release agent. Proper application of release agents is necessary for economy and for producing the best product possible and for minimizing form clean up. 

There are three main types of release agents.

The first is the barrier type. These products, as the name implies, provide a barrier between the concrete and the form allowing it to strip. The original, modern-day, form oils were barrier types-diesel fuel, greases, used motor oil, etc. These allowed for a good release, but negatively affected product quality by causing surface voids, staining, and over all poor product appearance. They are heavier in nature and are harder to apply due to their higher viscosity.

The second type of release agent is the reactive type. These are chemically active and contain compounds that react with the free lime in the concrete to produce a soap-like film between the form and the concrete. This type of release agency is the most widely used. They are easily applied in a thin film. Because they can be applied in a thin film by spraying, wiping, or brushing, you can produce stain-free, void-free concrete surfaces. 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.

The third type of form release agent is a combination of the other two types.

Grifcote-Concrete-Form-Release-Agent-Sizes.jpgCoating manufacturers and coating formulations, including those of release agents, were affected by the Clean Air Act of 1990 passed by Congress. This law allowed the Environmental Protection Agency to set into motion a process to limit nationwide the amount of Volatile Organic Compound (VOC) that a coating should contain. VOC’s are thought to react with sunlight and cause ground level ozone or smog. The original law called for testing or different VOC’s to see how much, if any, reactive capability a given VOC had with sunlight and the formation of smog. When this testing wasn’t done properly many coating manufacturers (mainly California paint companies and other concerned parties) took the EPA to court to fight the law. After several court fights, lawsuits and rulings during the1990’s, the EPA prevailed and the law limiting VOC’s was allowed to take effect. In September of 1999 release agent manufactures and concrete producers were required 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. All new products were formulated based on the new EPA law. 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 probably the most common and efficient method of application. Care should be taken to avoid over application for the reason mentioned earlier. An extremely thin film of release agent can be applied with proper equipment and technique. Working application pressures of 35 to 50 psi are best. Pump unit sprayers or centralized systems with air pressure regulators give a good consistent pressure and work well. Higher pressures put more airborne particles in the air throughout the plant and can be harmful to personnel in the plant. Lower pressures allow for over application, puddling in the form, and waste. A flat fan spray nozzle of .5 gpm maximum size will work with many release agents. Better yet is a flat fan spay nozzle of .1 or .2 gmp spraying 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 applied cost is much less than a cheaper, less effective release agent. A second type of application is wiping on the release agent. This can be done with a rag or sponge with excellent results. Architectural precasters like this method because over application is eliminated. Some burial vault manufactures use a sponge for application because they clean the form with every application of release agent. A third type of application is by mopping or brushing. When using this method over application can be a problem. As with wiping, the application device must be wrung out in order to achieve the desired results. If puddles occur, they should be wiped up. A fourth method of application is dipping. Dipping systems are fast, labor efficient, and assure total coverage of the form. Dip tanks collect the excess release agent that drains off the form. Over application is probable, but this type of application works well in some operations. Whatever method is used for applying the release agent care should be taken to keep it off reinforcing steel.

Concrete-Form-Rust-Preventative.jpgAnother important aspect of form care is protection of forms in storage. Precast concrete producers, especially those with diverse product lines, occasionally take forms out of service between jobs. The investment in forms needs to be protected from rust and corrosion. Some producers user grease, diesel fuel, or release agent and apply it to the forms. Application with these products needs to be done irregularly with limited protection of the forms. A better choice is a good rust preventative. When shopping for the best product, there are four things to consider.

First is quality of protection, second is length of protection, third is ease of application, and fourth is ease of removal. 

Formwork is a major investment for precast concrete producers. Utmost care should be taken to insure product quality and exend the life of these valuable assets. Money spent taking care of forms now can save hundreds or thousands of dollars in the future and make a concrete business more profitable.


Hill and Griffith Customer Service

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Tags: Concrete Forms, Concrete Form Release Agents, Concrete Release Agents, Concrete Form Seasoning, Biodegradable Concrete Form Release, Concrete Casting Supplies, Concrete Voids, Concrete Form Release

How Can I Eliminate Surface Concrete Casting Voids?

Posted by Hill and Griffith Company on Aug 4, 2016 2:32:41 PM

 

(From Smooth On Concrete Casting Products. This is one of the best Q&A for concrete casting defects we have seen. Enjoy!

 

Concrete-Voids-1_copy.jpgHOW CAN I ELIMINATE SURFACE CONCRETE CASTING VOIDS?

Surface voids (small holes, also known as bug holes or pitting) found on the surface of concrete castings have affected anyone who has ever cast concrete. A significant number of concrete casting voids must be post finished or discarded, resulting in wasted product, time and labor. Understanding the causes of surface voids and what can be done to minimize them is the first step to a more efficient and productive casting operation.

The following information has been compiled through our (Smooth On Concrete Casting Products) experience with professionals who cast concrete for a living. Some of the tricks found here are results of many years of research and development. Although one may not find all the answers here, many of the common problems encountered when casting concrete will be addressed.

Question: What are surface voids?
Answer:
Surface voids are the cavities or little holes that appear on the surface of concrete castings. Surface voids (commonly known as pitting) are referred to as "bug holes" or "fish eyes". These voids may produce an unacceptable appearance on the surface of the finished casting.

Question: How are surface voids caused?
Answer:
Surface voids are generally attributed to the following three factors: release agent, water or air (sometimes a combination of the three).

Concrete-Voids-2_copy.jpgQuestion: How does a release agent affect the surface of a concrete casting?
Answer:
Release agents act as a "lubricant" between the mold and the concrete itself. The proper application of a release agent will yield castings without surface voids. However, when a release agent is over applied, it may "pool" or "puddle" on the lower extremities of the mold. As the concrete is poured into the mold these pools prevent the concrete from filling in all the detail. When the casting is removed from the mold voids will be apparent in the areas where pooling occurred. Vibration magnifies this problem by forcing additional release agent into the lower extremities of the mold. Voids caused by too much release agent are recognizable as small spherical voids on the surface
of the finished casting. These voids usually measure about 1/8" (.31 cm).

Question: How does water cause surface voids?
Answer:
Similar to release agents, water is also trapped against the mold's working surface resulting in voids. As the concrete cures and the residual water evaporates, a cavity is left behind on the surface of the casting. Vibration also tends to force water from the cementious material, however most voids caused by water are a result of a high water to cement ratio. Similar to release agents, water is also trapped against the mold's working surface resulting in voids. As the concrete cures and the residual water evaporates, a cavity is left behind on the surface of the casting. Vibration also tends to force water from the cementious material, however most voids caused by water are a result of a high water to cement ratio.

Question: How does air cause surface voids on my finished concrete casting?
Answer:
In most circumstances, air voids have an irregular shape and tend to be much larger (1/2" or 1.27 cm.) than those caused by water or release agents. The air voids are caused by air trapped between the mold surface and the concrete. They generally appear in low slump concrete and can be found underneath irregular (non-spherical) shaped pieces of crushed aggregate.
This is a result of having too little mortar to fill the spaces around the aggregate. Voids caused by air may also be found in castings that have severe undercuts.


HOW TO ELIMINATE VOIDS IN A CONCRETE CASTING:

While many variables must be considered in the elimination of surface voids or bug holes in concrete castings, there are a number of precautions that can remedy this unsightly problem.

Careful preparation and methodical practices can eliminate even the worst of surface voids. The following section describes procedures and materials that will produce finished castings that even the most discerning eye will accept.

Question: Will adding more mortar to the concrete assist in reducing surface voids?
Answer:
Yes. Increasing the amount of mortar in the cementious material will help make the material more fluid. A mixture that has a higher mortar content will assist in encapsulation of the aggregate. By encapsulating the aggregate, mortar also provides a chimney or venting system that will allow air and water bubbles to escape from the mixture. During vibration these bubbles will rise through the mortar and escape through the opening of your mold. A higher mortar content in your mixture also allows larger pieces of aggregate to easily move during vibration and thereby release any air that may have been trapped.

Question: What will happen to my casting if I use a larger aggregate?
Answer:
Using a larger aggregate may cause more surface voids because air is entrapped under the irregular shapes of this material. There is also a larger volume of voids between larger aggregate pieces than smaller pieces. It is therefore recommended that a smaller aggregate be used or that a smaller aggregate be mixed with the larger particles. The smaller aggregate will act as a "roller system" to assist in turning the larger pieces of aggregate during vibration. It is recommended to use aggregate that passes through a number 50, 100 or 200 sieve.

Question: Does the type of cement I use in my mixture make a difference?
Answer:
Cement acts as a lubricant during vibration and allows larger pieces of aggregate to move around freely. Therefore it is recommended that a very fine cement be used to achieve a more fluid consistency. Fly ash, which is finer than cement particles, will increase the lubricity of the cement even further.

Question: What precautions should I take if my concrete has a low water-cement ratio?
Answer:
If the concrete you are casting has a low water-cement ratio, more mixing time will ensure that water and air bubbles are forced away from the aggregate and thereby eliminate the voids on the casting surface. Low water-cement ratio concrete also requires an increased vibration period.

Question: I've heard that adding plasticizers to my concrete mixture will help eliminate surface voids. Is this true?
Answer:
Yes. The addition of plasticizers are used effectively in creating large slump increases. The benefit of using a plasticizer is that these large increases can be attained without effecting the water-cement ratio. The result of increasing the slump will assist air, water and aggregate to move more freely throughout the mixture. Although plasticizers will permit a large increase in slump, the concrete will begin to set much quicker. This means that there is a much smaller time period for the concrete to be vibrated. In order to eliminate surface voids from appearing we recommend using a release agent in tandem with plasticizers. The release agent will allow the concrete to move freely and force voids away from the surface of the casting

Question: What type of mold or form material should I use?
Answer:
Form or mold surfaces be as smooth as possible to decrease the surface tension between the concrete and the mold. Rubber molds are being used more and more for just this reason. The proper release used on a rubber mold will give the best possible surface.

Question: I'm vibrating the concrete, but still have bug holes in the casting?
Answer:
This occurs because air and water bubbles are the lightest elements of the concrete and will naturally flow to the most fluid portion of the mix. It just happens that this area is next to vibrator. So if you are using an external vibrator, the form or mold should be hammered. Hammering allows the mortar to flow toward the area being hit, consequently pushing air and water bubbles to the opening of your mold. This technique is recommended for molds with deep undercuts, where air and water bubbles tend to be predominate.

Question: How beneficial are release agents?
Answer:
Not only do release agents assist in eliminating surface voids, they also prolong the life of your mold. However, choosing the correct release agent and proper application are extremely critical. Various release agents will provide different surface finishes of your concrete casting. We recommend a chemically active release agent.

The amount of release that is applied to the mold or form will greatly effect the surface of your casting. Excess release agent tends to consolidate into spheres that cause bug holes. Too much release agent can be evidenced by voids on the lower portions of your casting. Applying release agent in a thin coat will eliminate these voids.



HELPFUL HINTS TO VOID FREE CASTING:
As any professional caster will tell you casting concrete is not an exact science. There are many variables and therefore no way to ensure void free castings. Voids can be minimized, however, and the following hints are offered to improve your chances for success.

Hint # 1
Extend the mix time to help break up any residual air or water bubbles. This will promote a more uniform and workable consistency.

Hint # 2
Make sure to that release agents are applied in thin films. This will eliminated any pooling or puddling in the lower portions of your mold.

Hint # 3
Lower the viscosity of cement by adding sand or fly ash. This allows large aggregate to move more freely and reduces the amount of air entrapment.

Hint # 4
Use aggregate that is more uniform in shape. Irregular shaped pieces of aggregate tend to make the concrete less fluid.

Hint # 5
Techniques used during vibration can eliminate most surface voids. Vibrating both the outside and inside of your mold will draw most air and water bubbles away from the surface of the concrete. Hammering the mold can eliminate any residual voids.

Disclaimer
This FAQ article is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Safety Data Sheets (SDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.


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 Forms, Concrete Form Release Agents, Concrete Release Agents, Concrete Form Seasoning, Biodegradable Concrete Form Release, Concrete Casting Supplies, Concrete Voids, Concrete Form Release

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