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Concrete Casting News from the Hill and Griffith Company

5 Options for Dry-Cast Concrete Pipe Dip Tank Maintenance

Posted by Hill and Griffith Company on Oct 10, 2019 2:24:06 PM

Originally published in the May-June issue of 2015 PRECAST INC, by Bob Waterloo

Maintaining the optimum reactive level of form release agents in pipe production dip tanks ensures performance and quality. 

Dip tanks play a critical role in the dry-cast pipe production process for many manufacturers. The reactive properties of the fatty acids in the form release agent enable the pipe to release from the pallet/header smoothly. Here’s the problem. The cement/concrete residue left behind when headers are dipped starts to negate the reactive properties of the fatty acids.

Left unchecked, the form release agent eventually begins to lose its effectiveness, pipes will not pull easily from the headers and quality could suffer. The solution: implement a regular program of monitoring and maintenance that keeps the form release at the optimum reactive release level and reduces replacement and disposal costs.

Precast Pipe Dip Tank Maintenance

Benefits of a dip tank
Reactive form release agents are the accepted standard in today’s precast and pipe-forming operations. Fatty acids, which are found in an infinite number of blends, are the most commonly used reactive material. Fatty acids have the unique ability to react with the free lime on the surface of the concrete, which results in a nonviolent chemical reaction. This neutralization (or saponification) forms a metallic soap, allowing the product to release easily.

There are several benefits to using a dip tank to apply form release during pipe-forming operations, including complete coverage, proper release and reduced chance of operator error. However, a common occurrence when using this method of manufacturing is increasing difficulty with “pulls” or “tip-outs” during stripping over a period of production time. This is generally the result of decreased reactive material in the dip tank as contaminants enter the system and negate some of the reactive material.

Maintaining the dip tank
Two areas must be addressed in the preventive maintenance program for this type of equipment:

  1. Regular maintenance to remove sludge that accumulates in the bottom of the dip tank
  2. Regular maintenance of the release agent’s reactive levels for effective release

The sludge generated in the dip tank includes contaminants from previously dipped headers/joint rings. These contaminants negate the reactive portion of the form release. As the reactive portion of the release agent gradually decreases, the possibility of concrete sticking to the headers increases, causing a more difficult release. The rate of decrease is gradual and depends on many factors, including rate of production and amount of contaminants allowed to enter the dip tank.

Ring-Oiling

Removing contaminants
Rather than disposing of the entire tank of form release, transfer it to a holding tank and shovel out the sludge. Because the sludge typically contains petroleum hydrocarbons, disposal should be in compliance with local regulations. Then, transfer the recovered form release agent back into the dip tank and top it off with fresh release agent.

Remember that by adding fresh release agent to the recovered material, rather than using all new release agent, reactive levels will be reduced and release problems will occur sooner unless the reactive portion is tested and brought back to a normal level. The discoloration of the recovered material from the dip tank is not relevant to the release characteristics, or levels of reactive material.

Maintaining reactive release levels
Maintaining the correct level of reactive agent in the form release is quite simple. Test the recovered material and bring the reactive portion back to optimum levels.

Test a sample from the dip tank (less than one ounce is sufficient) for the reactive level through either titration or infrared analysis. Your release agent supplier should be able to tell you the optimum level of reactive material required and may be able to run the analysis for you. Once you determine the level of fatty acids, a number of simple calculations determine the amount of pure reactive agent to be added to the dip tank to bring it back to the optimum reactive level.

After adding the recommended amount of reactive material to the dip tank, use an air lance for mixing for a minimum of two minutes, making sure to cover the entire area of the dip tank. Then top off the dip tank with fresh release agent and air lance again for good distribution.

Depending on the amount of contaminants and reduced reactive material, the timeframe between tests will vary. One way to determine the frequency between tests is to establish a baseline. Begin with tests every 30 days, which should be recorded, until a history can be compiled to determine the needed frequency. The normal frequency of adding more reactive ingredients is typically five gallons for every six weeks of regular production.

In many cases, production workers can see the reduced effectiveness of release agents. It’s important to train them to notify management to add additional reactive material to the dip tank. As usual, science is best, but practical application and analysis are also important.

Total replacement of form release
While removing sludge and maintaining dip tanks by adding new release as needed make sense from an environmental and cost perspective, on occasion, you may feel it necessary to clean the entire dip tank to remove all residual sludge and refill the cleaned dip tank with fresh release agent.

Cost-effectiveness
Dip tank maintenance comes down to five options. Option 1 is the least cost-effective, while Option 5 is the most cost-effective.

Option 1: Drain the dip tank, dispose of the sludge and old release material, then refill only with fresh form release agent.
Option 2: Remove the form release from the dip tank, dispose of the sludge, refill the dip tank with fresh form release, then use the recovered form release to replenish the dip tank as necessary.
Option 3: Remove the form release from the dip tank, dispose of the sludge, refill the tank with recovered form release, then top off with fresh form release.
Option 4: Remove the form release from dip tank, dispose of the sludge, test the recovered form release, add reactive ingredient to bring it back to an optimum level, then top off with fresh form release.
Option 5: If there is not enough sludge to remove but the release is not as good as it should be, test for the reactive level of the release agent in the tank, then add reactive material to return it to an optimum level.

In the long run, a little care and attention to the reactive content level in the dip tank will help to reduce labor costs and maintain or improve casting appearance.


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 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Form Release Agents, Concrete Casting Products, Concrete Casting Supplies, Concrete Pipe, Concrete Safety, Precast Concrete, Grifcote FR 50 Concrete Form Release, Bio Gold Concrete Form Release, Grifcote, Precast Inc Magazine

Preventing Bug Holes in Precast Concrete

Posted by Hill and Griffith Company on Sep 26, 2019 4:40:25 PM

From the June 2, 2014 PRECAST Magazine post Causes and Fixes for SCC Bug Holes, by John Pelicone

bugholes_th.jpgLike a persistent mosquito, one question has plagued precast concrete producers for years: “How can I eliminate bug holes?” In the past, this question was much harder to answer, because concrete was placed at a stiffer consistency that required excessive vibration. And excessive vibration sometimes caused more bug holes. After the introduction of self-consolidating concrete (SCC), bug holes(ii) became a less common occurrence. Yet, as a recent online industry discussion revealed, this perturbing problem is still with us.

"Two types of release agents

  1. Chemically reactive agents: When a chemically reactive form release agent is used, a nonviolent chemical reaction takes place when fatty acids react with free lime on the surface of fresh concrete. This reaction results in the formation of a metallic soap, a slippery material that allows air bubbles to rise along the vertical surface. This “soapy” film also prevents the hardened concrete from adhering to the forms during stripping.
  2. Barrier release agents: Thicker coatings on forms are typical of the older barrier-type materials, like heavyweight used motor oil, vegetable oils, diesel fuel and kerosene. Barrier type release agents are less expensive than chemically reactive agents, but they are not generally recommended for reducing SCC bug holes."

SCC-Bug-Holes-1

Read More

In summary,

"Bug Hole voids are formed during placement. Small pockets of air or water are trapped against the form. The problem increases with the height of the lift. Vibration may not be adequate or well spaced. The mix may be sticky.

  • Primarily caused by the way concrete is placed and compacted
  • Entrapped air not removed by vibration, air bubbles move to the form
  • Improper application of Form Release agent or wrong type 

SOLUTION I PREVENTION: Avoiding Bug Holes

  • Work the voids at the form face up and out of each lift
  • Let the vibrator drop through the lift, then vibrate upward
  • Don't overvibrate at the center of the wall
  • Move the vibrator as close to the form as possible
  • Add upward external vibration if necessary
  • Reduce the height of each lift to make void removal easier
  • Aggregate - consult ready mix producer and review aggregate size and shape
  • Reduce sand content
  • Use low slump 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.

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 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Form Release Agents, Concrete Casting Products, Concrete Casting Supplies, Concrete Safety, Precast Concrete, Grifcote FR 50 Concrete Form Release, Concrete Form Release for Wood, Bio Gold Concrete Form Release, Grifcote, Precast Inc Magazine

Choosing and Using a Form Release Agent

Posted by Hill and Griffith Company on Aug 15, 2019 3:16:52 PM

Excerpt from the article by M.K. Hurd in the October 1996 issue of Concrete Construction

Concrete Form Release Agents Help Form Removal

Most form materials require the application of a release agent to prevent adhesion of concrete to the face of the form. Many form oils and other release agents adequately prevent sticking, but using the correct type of agent for the form material can also help to minimize concrete color variations, staining, bugholes, and poor surface durability. Article discusses the two basic types of release agents (barrier and chemically active), how to select a release agent for different form materials, and release-agent application methods. It also describes the newer types of water-based release agents, which are formulated to meet environmental regulations limiting volatile organic compounds (VOCs).

Photo caption: Forms will strip cleanly and easily if you use the correct form release agent and apply it properly. - Photo by Bob Sawyer

With the wide range of release agents available today, how do you choose the best one for your forms?

Types of Release Agents Historically, form release agents have been grouped in the following categories :
• Petroleum oils
• Emulsions—either water- or oil-based
• Nonreactive coatings with volatile solvents
• Chemically active agents
• Waxes

Though products in these categories are still available, new products and new formulations are being introduced to meet environmental regulations limiting volatile organic compounds (VOCs). Also, manufacturers may combine release-agent types, such as a chemically reactive product and an emulsion, to produce a product that has the advantages of both. Many newer form release agents, therefore, do not fit neatly into the above categories. Because environmental restrictions have caused changes in the commercially available agents, and because of the great variety of chemical formulations, manufacturers now simply classify release agents in terms of how they act instead of what’s in them. The two basic categories are barrier agents and chemically active agents. Read More.

Precautions in Selecting A Release Agent

A release agent may be incompatible with concrete that contains a number of admixtures. Compatibility problems have been reported when chemically active agents were used with concretes containing microsilica, high-range water reducers, and unusually high amounts of admixtures. Be sure to discuss possible compatibility problems with the admixture and release-agent suppliers. Read More.

Application Methods

Use enough release agent to prevent adhesion, but don’t apply too much. When overapplied, the material runs to low points in the form face where it can retard cement hydration or produce staining. Most manufacturers recommend a thin, uniform coating. With some products, the thinner the better; sometimes as little as 1 ⁄2 mil (0.0005 inch) is recommended on nonabsorbent form surfaces. Read More.

Precautions to Take During Release Agent Application

•Keep release agents off construction joints and reinforcing steel. To avoid spilling release agent on rebar, apply it before placing the steel.

• Never use release agents containing wax or silicone if the concrete surface is to be painted.

• Follow manufacturer recommendations for when to apply release agent. Some agents must dry or cure before concrete is deposited, while others can be applied only minutes ahead of concrete placement. Generally, the shorter the time between applying release agent and placing concrete, the better. Too long a wait can result in the agent drying out, running down the form face, or being washed away by the rain. (Note: Some agents are rainproof.)

• If there is any ponding or puddling of release agent, be sure to wipe away the excess material.

• After coating form faces, protect them from contamination and weather.

SELECTING A RELEASE AGENT FOR DIFFERENT FORM MATERIALS

Read the complete article in Concrete Construction Magazine


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Hill and Griffith Customer Service

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

Prefabricating Individual Components Within the Concrete Manufacturing Process

Posted by Hill and Griffith Company on Aug 8, 2019 6:39:04 PM

Excerpt from the article by Thomas Friedrich in the March 2019 issue of Concrete Plant International 

Screen Shot 2019-08-08 at 3.25.32 PM-1

Multifunctional construction components produced with traditional prefabrication methods need themselves to be divided up again into prefabricated modules, which are then pieced together as end products. Production work in a factory consists of assembling and connecting individual components to create an end product. The greater the number of components being installed in a concrete construction component, the greater the need to connect individual components together in advance so that they can be inserted as a unit on a ready and waiting formwork table. This defines prefabrication of components either pieced together locally in a production facility or supplied as finished components as in the automobile industry. Classic processes in a precast production facility are changing as there is an increasing demand for assembly activities. Concrete acts as a glue holding all components together. This division of labor enables product quality to be enhanced while, at the same time, accelerating production processes. Pipelines can be fastened to the reinforcement, for example. Specially created meshes can be employed in an optimum way for this purpose. Other components needing to be inserted can also be fastened to the reinforcement during installation.

Photo caption: Multifunctional concrete floors: load-bearing elements with fully integrated technical building services

The trend toward multifunctional construction components and the consequences in manufacturing

In the future, there is a growing likelihood of companies producing more than just a "concrete bed." The industry is redefining increased complexity in the shape of numerous floor components.

This requires skilled labor to achieve at a construction site.

  • For example, laying empty electrical conduits during the shell construction stage can't happen concurrently with laying pipelines.
  • Different tradesmen work on the shell during different times. 
  • This strategy requires specialized firms to organize and coordinate the work and teams

The solution for flat-shaped construction components requires manufacturing processes with large-sized framework tables. Construction happens rapidly on these tables to make the most of the large expense of building stationary units on a track or tilting table.

Prefabricated reinforcing elements

An assembly unit for reinforcement generally consists of several components, such as single bars for the span reinforcement, which is supplemented with lattice girders and stirrup cages. A steel bar mesh is employed to this end that serves as a load-bearing unit for other reinforcement elements and installed components. Read more.

Screen Shot 2019-08-08 at 3.25.41 PM-1

Photo caption: Prefabricated meshes including pipelines for room air conditioning (cooling and heating above the concrete floor).

Supplementary elements in a composite construction method (hybrid construction method)

A composite construction method is often envisaged in order to create large web plate openings. This is because secondary moments occasioned by shear load can only be absorbed with a steel structure. Read more.

Pipelines for heating and cooling with a concrete slab (modified building component activation according to the Ceiltec® principle)

Building component activation for cost-effective heating and cooling via a concrete floor is increasingly gaining in importance. Its lower temperature level is making its contribution to this trend, along with the use of renewable energy. Prefabrication is particularly useful in creating the right pipeline arrangement for the air-conditioning planned. Read more.

Entirely prefabricated load-bearing ribs as semi-finished components

Instead of prefabricated reinforcement cages for load-bearing ribs of prefabricated slabs, the rib itself can be prefabricated as a reinforced concrete construction component and then installed with starter bars on the lower slab. Read more.

Preparation on formwork tables

Some installed components are inserted directly into the underside of the floor with multifunctional floor elements. Appropriate construction components, which can be fastened directly to the formwork base are needed for this purpose. Read more.

Process in successful manufacturing

The complexity of multifunctional elements requires different processes in manufacturing. Concrete, as a material, also makes its contribution as a load-bearing element and in keeping individual construction components together. Concrete in its hardened state offers a flexible environment for installing all components. Read more.

Results with the finished product

The result with this elaborate formwork plus all its inserted components and reinforced elements is reflected in the finished product once the concrete has hardened. The appearance of the outer concrete mantle is that of a sophisticated work of art despite the high density of components, which then disappear in the concrete. Read more.

Screen Shot 2019-08-08 at 4.32.31 PM

Photo caption: Finished floor elements for large span widths on a stationary system.


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

Eliminate Surface Concrete Casting Bug Holes

Posted by Hill and Griffith Company on Aug 2, 2019 8:24:46 AM

 

(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

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We are pleased to provide samples in quantities large enough to allow you to "try before you buy."
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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 Form Release Agents, Biodegradable Concrete Form Release, Concrete Release Agents, Concrete Forms, Concrete Form Seasoning, Concrete Casting Supplies, Concrete Voids, Concrete Form Release, Bug Holes

The Hill and Griffith Company Welcomes Executive-Level Director of Sales

Posted by Hill and Griffith Company on Jun 17, 2019 2:58:41 PM

The Hill and Griffith Company is proud to announce and welcome Ryan Canfield as the company’s Director of Sales & Business Development.

Ryan Canfield 560

Ryan will be responsible for sales team leadership, driving revenue, contributing to product selection, marketing, as well as general management responsibilities.

Canfield also comes to H&G with 17+ years of experience in sales, technical support, marketing and engineering for the foundry, die cast, precast and prestress concrete industries. Ryan’s proven track record was instrumental in increasing annual company revenue, customer retention and customer satisfaction ratings in previous direct sales and management roles. He also holds an Engineering Degree from Trine University in Angola, IN.

He joins the H&G team from Carbo Ceramics located in Houston, TX.

#marketing #sales #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.

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We are pleased to provide samples in quantities large enough to allow you to "try before you buy."
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 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete Form Release Agents, Concrete Release Agents, Ryan Canfield

Precast Concrete - Care and Seasoning of Metal Forms and Rings

Posted by Hill and Griffith Company on Jun 13, 2019 3:56:20 PM

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.

concrete_bio_gold_form-1-1

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 concrete form release agents, rust inhibitors and rust preventatives and how they react with metal.

By Bob Waterloo, Technical Sales Manager of concrete release agents for The Hill and Griffith Company.
Forms and rings are part of our lives, and we need to maintain them in order for them to perform and provide us with profits and saleable castings.

With just a little effort, we can prepare these forms for optimum production, minimize labor required to keep them clean and functional, and just make our lives a lot easier.

First, here are some of the basic items needed for form and ring storage and maintenance:

  • Level area
  • Concrete platform or timber material on which to store them
  • Covers or tarps for moisture and dust protection (indoor covered storage is ideal but often unavailable)
  • Power washer
  • Putty knife or long-handled ice scrape
  • Brass wool, scrub pads or other minimally abrasive material for cleaning
  • Electric grinder with wire brush head (not recommended unless absolutely necessary)
  • Release agent (petroleum solvent-based) for long-term form protection

In an ideal world, all of this expensive equipment would be stored indoors in a protected, heated and dry area. Unfortunately this is not the case in the real world, so we need to take care to give our equipment the best possible care with what we have available.

 

Short-term and long-term storage
For short-term storage, a good quality VOC compliant petroleum solvent-based form release will normally serve our needs. Before the form is put into storage, apply a liberal coating of the form release. If the forms are stored outside, even for a short period of time, a quick walk-by is often necessary to be sure the form release has not washed off from the rain. If any evidence of rust is present, apply another coat of the form release on the forms and rings as quickly as possible.

For long-term storage, a good quality VOC compliant form release will do the job, but as outlined above, recoat with the form release on a regular basis. A biodegradable form release (meeting the EPA definition of biodegradability, but not a water-based material) is preferred, as over-application is desired and some of the material will end up on the ground.

The second alternative for long-term storage is a rust inhibitor. Rust inhibitors should have the capacity to displace the mechanically held water on the surface of the form. The form also needs to be protected with a plastic cover or inverted so that rain and snow do not wear the rust inhibitor away. With rust inhibitors, the form can generally be brought back into production with a minimum of labor required to remove the inhibitor. If you are using a water-based form release, it is best to apply a rust inhibitor or rust preventative as quickly as possible, as the residual water will cause rusting immediately.

The third alternative is a rust preventative. These are typically epoxy-based materials that can be compared to a layer of paint. While rust preventatives generally do a good job in protecting the forms, they are fairly labor intensive in application and should be removed before bringing the forms and rings back into production. Grinding is usually necessary to remove the rust preventative, which in turn destroys the “seasoning” of the form.

When storing equipment, it should be stored in such a fashion that it can be put back into production without having to spend time adjusting or repairing. Rings (pallets and headers) should be stored in flat racks in a stack and, if possible, on pallets.

Seasoning
Reactive form release agents, the most commonly used release agents in precast and pipe production, typically contain fatty acids. Fatty acids are mild acids composed of animal fats and vegetable oils. Of course there are a very great number of possible combinations of animal fats and vegetable oils, and not all combinations will serve as “good” reactive form release agents.

The reactive portion of the form release agent serves two initially important functions. First, fatty acids have a natural affinity for metal. This includes gray, ductile and malleable iron, brass, bronze, aluminum and mild steel. Fatty acids react with metal to form a protective barrier, which is a coating of metallic oleate. This process is known as seasoning. This protective layer prevents further application of fatty acids from migrating to the metal of the form and allows the fatty acid to remain on the surface of the form to react with the free lime on the surface of the casting.

Try using this analogy on your production workers to help them understand some of the concepts of seasoning:

A fisherman always has his “favorite” frying pan. There is no way that he would ever let that frying pan be put in water and scrubbed clean with a scouring pad. Why? Because it would remove the seasoning that is part of the pan. If he has to buy a new pan, what is the first thing he does? He gets some lard or vegetable oil (both are simple examples of fatty acids), puts it in the pan and places the pan in the oven at a high temperature for an extended period of time. Why? So the pan can become seasoned.

This same seasoning holds true for your forms and pallets. When concrete is poured into the form, the reactive portion of the form release (the fatty acid) reacts with the free lime on the surface of the concrete to form a metallic soap. This reaction is called neutralization. As fatty acids (typically a pH of 6.8) react with the free lime on the surface of the concrete (typically a pH of 11.5), they neutralize one another and create the metallic soap, a reaction known as saponification.

This soap, then, also serves two purposes. First, it enhances the easy separation of the form from the castings. Second, as it is a soap, it allows free air to rise more easily on the vertical surfaces of the castings, resulting in fewer surface defects.

Once this metallic oleate layer is created on the metal form, any grinding or surface abrasiveness, including welding to repair a form or grinding with wire brushes, will destroy the protective layer. The next time a reactive form release is applied, the fatty acid will react with the form, leaving nothing to react with the free lime. It is very important to minimize grinding on forms, and usually nothing finer than a putty knife or an ice scraper should be used to remove splatter or “stickers.” In the case of sticker, there is a reason that this occurs, and normally an application of a seasoning agent to this small area will help prevent future sticking and buildup.

Seasoning of forms is a very basic requirement to help minimize the amount of labor involved when forms are stripped or pipes are tipped out. If forms, pallets and headers are properly maintained, labor cost and better looking castings are the end result.

Forms in storage, new forms, pallets and headers
New forms, pallets and headers will frequently arrive with a protective coating on them to help prevent rusting in transit or until the forms are sold and delivered. This protective coating can be allowed to wear off, but at that point it is allowing raw metal to be exposed. While the first few pours might be satisfactory, now that raw metal is exposed, the reactive portion of the form release agent will now start to react with the raw metal, leaving nothing to react with the free lime and form the metallic soap. An alternative is to remove the protective coating with solvents or grinding and apply a seasoning agent, allowing it to set for a minimum of four hours. A 24-hour period is better, as it allows more seasoning to take place. Also, forms that are exposed to the sun will season more quickly as higher temperatures increase the reactivity with the metal forms and rings.

Forms that have been in storage and have rusted also need to be re-seasoned. Rust is nothing more than oxidized metal, and when rusting occurs, the metallic oleate barrier has been destroyed. Casting can be done without removing the rust, but again, once the raw metal is exposed, the fatty acid will react with the raw metal until the form is seasoned. The rust stain will also transfer to the casting. An alternative is to grind down the form/pallet/headers, apply a seasoning agent and allow time for the reaction to take place to allow the metallic oleate to form.

The old saying of “An ounce of prevention is worth a pound of cure” holds true to maintaining your forms, pallets and headers by getting them seasoned and keeping them seasoned. A little attention today will save a lot of grief tomorrow.

Proper treatment of this very costly equipment with the care it deserves will enable you to be more competitive in the marketplace and be a better steward of our environment.


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Tags: Concrete Form Release Agents, Concrete Release Agents

Prestressed Concrete Pressure Pipe & Concrete Steel Pressure Pipe, Review of AWWA Standard for Potable Water

Posted by Hill and Griffith Company on May 24, 2019 10:06:05 PM

"The forms shall be cleaned thoroughly and coated with a form-release agent before each use."

Concrete Pressure Pipr 101

There are two types of prestressed concrete steel-cylinder pipe:

(1) the lined-cylinder type, with a core composed of a steel cylinder lined with concrete and subsequently wire-wrapped directly on the steel cylinder and coated with mortar; and

(2) the embedded-cylinder type, with a core composed of a steel cylinder encased in concrete and subsequently wire-wrapped on the exterior concrete surface and coated with cement mortar.

(Image from PUBLIC WORKS Magazine.)

I. Introduction

I.A. Background

 

The lined-cylinder type, which was first used in the United States in 1942, is furnished in sizes from 16 in. (410 mm) to 60 in. (1,520 mm). The embedded-cylinder type, which was developed later and first installed in 1953, is most commonly manufactured in sizes 48 in. (1,220 mm) and larger. Both types are designed for the specific combination of internal pressure and external load required for the project in accordance with the procedures outlined in ANSI/AWWA C304, Standard for Design of Prestressed Concrete Cylinder Pipe. Prestressed concrete steel-cylinder pipe is used for transmission mains, distribution feeder mains, pressure siphons (including river crossings), penstocks, industrial pressure lines, water intake lines, and other applications. In the manufacture of lined-cylinder pipe, the first step is to fabricate and hydrostatically test the steel cylinder with joint rings attached. The cylinder is then lined with concrete to form the core. The concrete is placed either centrifugally, by vertical casting, or by a radial compaction method. The concrete lining is cured and high-tensile wire is wrapped around the core directly on the steel cylinder. For a selected wire size, the tension and spacing of the wire are controlled to produce a predetermined residual compression in the core to meet design requirements. The wrapped core is then covered with a dense premixed mortar coating applied by a mechanical impact method. In the manufacture of embedded-cylinder pipe, the cylinder and joint rings are constructed and tested in the same manner as lined-cylinder pipe. The cylinder is encased in concrete by vertical casting and mechanical vibration to constitute the core. After curing, the wire reinforcement is wound under tension in one or more layers around the outside of the concrete core containing the cylinder, instead of directly on the cylinder. The exterior coating of premixed mortar is placed by impaction. 

Concrete Pressure Pipe Basics

(Image from PUBLIC WORKS Magazine.)

4.6.5 Concrete for pipe core.

4.6.5.1 General. The concrete in the cores may be placed by the centrifugal method, by the vertical casting method, or by other approved methods.

4.6.5.10 Placing concrete by vertical casting method. The concrete lining or core shall be cast on-end on a cast-iron or steel base ring with rigid steel collapsible forms for the concrete surfaces. The forms shall be designed to ensure that they will have smooth contact surfaces, tight joints, and that they will be firmly and accurately held in proper position without distortion during the placing of the concrete. The forms shall be designed to allow the pipe core to be removed without damaging the surfaces of the concrete. The forms shall be cleaned thoroughly and coated with a form-release agent before each use.

(Remember that any concrete form release used for potable water needs to be NSF approved, like Grifcote LV-50 Plus.)

The transporting and placing of concrete shall be carried out by methods that will not cause the separation of concrete materials or the displacement of the steel cylinder or forms from their proper positions. Adequate methods of mechanical vibration shall be used to compact the concrete in the forms and to ensure satisfactory surfaces. 


Precast Concrete In The Google and NPCA News:

Precast Products - National Precast Concrete Association

Precast Concrete Pipe - National Precast Concrete Association

Precast Concrete Pipe Durability - American Concrete Pipe Association


Hill and Griffith Customer Service

We're known for our hands on approach. Let us visit your plant and recommend concrete release agents, packerhead concrete form releases, concrete form seasoning, potable water concrete form release, non-petroleum concrete form release, biodegradable concrete form release, rust inhibitors, NSF potable water concrete release agents and concrete dissolver products that suit your needs.

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Bulletins and Technical Papers for Concrete Casting Products

 

Tags: Concrete Form Release Agents, Concrete Release Agents, Concrete Forms, Concrete Casting Supplies, Concrete Form Release, NSF Potable Water Concrete Release Agents, Grifcote LV-50 Plus, Prestressed Concrete Pressure Pipe, Concrete Steel Pressure Pipe, AWWA

ACPA Education Review: "Concrete Pipe – Pre & Post Pour Inspections"

Posted by Hill and Griffith Company on Apr 18, 2019 3:21:42 PM

The American Concrete Pipe Association's PPT, "Pre & Post Pour Inspections" contains information on Documentation, Pre-Pour Inspection of Equipment & Reinforcement, and Post-Pour Inspection of Stripping, Handling, Visual & Dimensions 

This is an excellent presentation of all the steps involved in producing high-quality concrete pipe. 

Concrete Pipe Pre Pour Documentation
Go to this link to download the PowerPoint.

Download a PDF.


Concrete Pipe Pre Pour Form Release

Concrete Pipe Manufacturing Pre-Pour Inspection - Form Release: Application methods, brush, spray; How much is enough??, Too Little, Too Much, Affects concrete finish, may affect curing

 

Concrete Pipe Pre Pour Barrier Form Release

Concrete Pipe Manufacturing Pre-Pour Inspection - Form Release: Barrier (non-reactive); Examples, Petroleum-based diesel, heating oils, used crankcase oil;

Advantages, Creates a physical barrier between form and fresh concrete;

Disadvantages, Need heavy application for easy release (200-400 ft2/gal), Can cause staining and bugholes, May not meet VOC requirements, Can cause buildup on forms

Concrete Pipe Pre Pour Chemically Reactive Form Release

Concrete Pipe Manufacturing Pre-Pour Inspection - Form Release: Chemically Reactive; Examples, Fatty acids (vegetable and mineral oils) are chemically reactive agents that combine with calcium in fresh cement paste to produce a soap-like film between the concrete and the form;

Advantages, Prevents bonding of concrete to form, Ultra-thin Layer (Approximately 0.005”), Reduce bugholes, stains, dusting, Typically meets VOC requirements (verify)

Disadvantages, Typically more costly per gallon

Concrete Pipe Pre Pour Seasoning

Concrete Pipe Manufacturing Pre-Pour Inspection - Seasoning

1. Remove protective coating to prevent staining, sticking, poor finish

  • Wear off during production
  • Solvents
  • Grind
  • Blast

2. Apply high fatty acid concentrate release agent; Let it react (forms metallic soap barrier). If using a barrier agent, use it for seasoning.

3. Ideally allow 24-hr sit-time

4. Apply release agent

5. Put into use

Concrete Pipe Post Pour Bug Holes

The American Concrete Pipe Association was originally conceived in 1907 by a small group of concrete farm drain tile manufacturers as the Interstate Cement Tile Manufacturers Association in Ames, Iowa.

The group needed some means of exchanging ideas and establishing a high quality, standardized products. In 1914, the organization was renamed the American Concrete Pipe Association. Throughout the 20th century, the concrete pipe industry has experienced tremendous growth. As more and more people moved from farms to cities, it created increased demand for concrete sewer and drainage products. The introduction of the automobile and subsequent highway development extended the uses of concrete pipe storm drains and culverts. There are currently over 400 plants operated by ACPA members in the United States and Canada. Over 40 countries are represented in the membership of the American Concrete Pipe Association. ACPA’s international headquarters are located in Irving, Texas USA.


Precast Concrete Manufacturing Resources from the American Concrete Pipe Association

14 Reasons to Choose Concrete Pipe

Concrete Pipe Design Manual

Concrete Pipe Specifications


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 and non-petroleum concrete form release, biodegradable releases, 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.
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Bulletins and Technical Papers for Concrete Casting Products 

Tags: Concrete Form Release Agents, Concrete Release Agents, Concrete Forms, Concrete Casting Supplies, Concrete Form Release, American Concrete Pipe Association

Article Review: "Concrete Pipe – Health and Safety  in Severe Weather Conditions"

Posted by Hill and Griffith Company on Apr 11, 2019 4:48:45 PM

After more than 175 years, concrete pipe continues to be a product of choice for specifiers, contractors, and design engineers.

Throughout its 111-year history, the American Concrete Pipe Association and its members have met the demands of infrastructure owners while improving the quality and performance of concrete drainage and collection systems through advancements in product design, plant production, and concrete mixes. Contemporary de-signs of production plants in automated and robotic facilities ensure quality of products, health and safety, especially built to overcome severe weather conditions.

Concrete Pipe Health & Safety

 

Article by Russell Tripp, P.E., President, American Concrete Pipe Association, USA, and published in CPI - Concrete Plant international May 2018. To read the entire article go to the introductory page at American Concrete Pipe Association's web site.

The U.S. has sustained 230 weather and climate disasters since 1980 where overall damages/costs reached or exceeded $1 billion (including Consumer Price Index adjustment to 2018). The total cost of these 230 events exceeded $1.5 trillion (www.ncdc.noaa.gov/billions). As of April 6, 2018, there have been 3 weather and climate disaster events with losses exceeding $1 billion each across the United States. [1]  The California wildfires, which burned more than 9.8 million acres in 2017, destroyed over 15,000 homes and businesses, caused 44 deaths, and racked up a cost of $18 billion. [2] 

Following disaster events, news reports documented pipeline systems and culverts that were irreparably damaged. Failed thermoplastic or corrugated metal drainage systems, from the wild fires in California to the hurricane damage in Texas and Florida, were identified as the primary cause of many road failures.

Unlike concrete, thermoplastic pipes will melt and burn. Based on recent fires in California, damage to a thermoplastic drainage system has extended far beyond the damaged pipe itself to include sidewalks, roadway, gas/oil pipelines, drinking water systems and nearby structures. Thermoplastic pipe materials installed close to the surface or where there is an ex-posed pipeline inlet or outlet run the risk of being damaged or destroyed by fire regardless of the use of special end treatments. Fires in concrete pipeline systems generally don’t affect structural strength or flow capacity; the two fundamental requirements of a gravity pipeline drainage or collection system. The repair or replacement of infrastructure is incredibly expensive, and the community impacts include the interruption of service, localize flooding and damaged roadways that severely disrupt traffic based on damaged thermoplastic or metal pipelines found in, or adjacent to road rights of way. Thermoplastic pipe culvert failures have been documented recently where access by emergency service vehicles were blocked resulting in loss of property and more threats to health and safety.

Concrete Pipe Advantages
Before and after burn. Using the QR-Code you can see the ACPA Comparative Flammability Demonstration October 21, 2015 on www.youtube.com/watch?v=FoXuyWnaJm4

Concrete pipe production facilities produce one of the world’s most enduring products for storm drainage and sewage collection systems. The long-lasting performance of precast concrete pipe and box drainage systems is well documented in severe weather conditions. Compared to thermo-plastic drainage systems, concrete pipe has always been and will continue to be rigid, rugged, and resilient.

Russell Tripp, P.E., Clemson University alumnus, earned his Bachelor of Science degree in Civil Engineering in 1982. He spent the first 21 years of his professional career working in the natural gas industry. He then served three years in the PVC sheet pile industry and four years in the plastic drainage industry before joining the ACPA.


 

Precast Concrete Manufacturing Resources from the American Concrete Pipe Association

14 Reasons to Choose Concrete Pipe

Concrete Pipe Design Manual

Concrete Pipe Specifications


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 and non-petroleum concrete form release, biodegradable releases, 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 Form Release Agents, Concrete Release Agents, Concrete Forms, Concrete Casting Supplies, Concrete Form Release, American Concrete Pipe Association

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