<img alt="" src="https://secure.hims1nice.com/150891.png" style="display:none;">

Concrete Casting News from the Hill and Griffith Company

NPCA Precast Learning Lab Video: Form Oil Application

Posted by Hill and Griffith Company on Apr 2, 2020 11:34:13 AM

This NPCA video demonstrates the proper techniques and tips to apply concrete release agents to forms.

This instructive NPCA video gives some basic guidelines on how to apply concrete form release agents to avoid common problems of bug holes and staining.
 
Main take aways from this video include:
1. Avoid overapplication
2. Ensure the form is clean and form release agent does not make contact with reinforcement
3. Use appropriate sprayer nozzle and pressure
 
 NPCA Form Oil Application Tips

Application of Form Oil

 

Application methods

  • Make sure you start with a clean form before applying release agent
  • Thinner application is better
  • Use a mop or microfiber cloth to wipe away excess concrete form release agent
  • Adjust your spray nozzle depending on the temperature

Learn More


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 Form Release Agents, Biodegradable Concrete Form Release, Concrete Release Agents, Concrete Forms, Concrete Form Seasoning, Concrete Casting Supplies, Concrete Pipe, Concrete Form Release, NPCA, NPCA Video

Concrete Form Release Agents

Posted by Hill and Griffith Company on Mar 26, 2020 11:10:32 AM

When you’ve chosen the form, you’ve narrowed the choice of release agent

Excerpt from the article in Concrete Construction by Sidney Freedman

A form release agent must do several jobs:
• permit clean release of formwork from the hardened concrete during stripping
• protect the form work for long life and extensive reuse
• help produce a hard, non-powdery, stain-free concrete surface with a minimum number of defects
• prevent corrosion of steel forms and consequent staining of the concrete surface
 
Form release agents fall into a number of categories, each of which has a distinctive influence on the concrete surface. These are described in detail in the next article in this series. The principles by which they are chosen and the kinds used in various applications will be described later in this article, but first, their handling and application will be discussed.

Site storage

Release agents should have a reasonably long and stable storage life and should not be susceptible to damage from extreme temperature changes or from rough or repeated handling. Care should be taken to ensure that release agents are stored in accordance with the manufacturer’s recommendations, particularly with regard to temperature extremes. Before use, the release agents should be checked for sediment. To ensure uniformity, it may be necessary to stir them adequately. Care must also be taken to ensure that they do not become contaminated. Release agents containing volatile solvents must be stored in airtight containers to prevent a change in concentration. Release agents should not be diluted at the job site unless specifically permitted by the manufacturer. Some oils have a critical emulsifier content and dilution makes the emulsion unstable and causes poor performance.
 
Concrete Form Release Agents Help Form Removal

Application

The manufacturer’s recommendations on the rate of spread and the method of application should be sought and followed. The optimum rate of spread will depend on both the type of release agent and the surface condition of the formwork.
 
Form surfaces should be thoroughly cleaned, preferably before erection; forms that are continually reused are generally treated with the form release agent just after stripping and cleaning. Also, whenever possible, the application of the release agent should be so timed that it can dry or be absorbed into the formwork before the reinforcement is installed. This procedure prevents loose rust or dirt from the reinforcement from subsequently showing up as marks on the concrete surface. The release agent should be applied carefully to avoid contacting reinforcement or adjacent construction joints. A few release agents may have their chemical characteristics changed to some extent if directly exposed to strong sunlight for a few hours, and their application may have to be timed accordingly.
 

Application methods

Any of various application methods can be used, depending on the type of agent. Spray or rolling methods are most commonly used because they are inexpensive and they produce uniform films. When spraying, a low-pressure, fine fog fanning out from the nozzle is most desirable.
 
Agents can also be applied by brushing, mopping, wiping or dipping, but the first three methods do not produce a sufficiently uniform film. Great care should be taken to see that the wide brushes or soft brooms used for applying the release agent are clean. It is best not to use cleaning solvent on any tools used for applying release agents, but if a solvent is used, care must be taken to ensure that it is completely removed before the tools are reused.
 
Usually, the dip method of applying release agents is not practical for use on the job site. Therefore, when dipped coatings are required for lumber or plywood, pre-dipping at the mill is the most practical solution. Where a heavy application of an inexpensive coating is allowed, such as where the appearance of the concrete surface is not critical, the roller, mop or broom methods are all applicable. The wiping method is typically used only when very light film applications are required on hard surface form materials or when excess release agents previously applied by other methods must be removed.

Read More


More information from Concrete Construction:

ICRI Guide to How to Repair Concrete Structures

Building Post-Tensioned Podiums

Recylced Concrete Combined With Wood Creates New Material


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 Form Release Agents, Biodegradable Concrete Form Release, Concrete Release Agents, Concrete Forms, Concrete Form Seasoning, Concrete Casting Supplies, Concrete Pipe, Concrete Form Release, Concrete Construction Magazine

GMI: Concrete Surface Treatment Chemicals Market Size Worth $15 Billion by 2025

Posted by Hill and Griffith Company on Mar 20, 2020 11:48:57 AM

Excerpt from the May 2019 issue of Concrete Construction by Ted Worthington

The concrete surface treatment chemicals market size will likely surpass USD $15 billion by 2025, according to a new research report by Global Market Insights, Inc.
 
Escalating growth in the global population is likely to be a key growth driver in the concrete surface treatment chemicals market. Asia Pacific region is the major reason behind the increased rate of population growth.
 
The global population has risen from 6.1 billion in 2000 to 7.6 billion in 2018. Out of this, China holds an 18.4 percent share, followed by India accounting for 17.7 percent. Increasing population and rising urbanization are some factors driving the construction industry in the emerging nations. This, in turn, would boost the demand for various concrete surface treatment chemicals over the study period.
 
concrete-surface-treatment-chemicals-market-pressrelease
The global population has risen from 6.1 billion in 2000 to 7.6 billion in 2018. Out of this, China holds an 18.4 percent share, followed by India accounting for 17.7 percent. Increasing population and rising urbanization are some factors driving the construction industry in the emerging nations. This, in turn, would boost the demand for various concrete surface treatment chemicals over the study period.
 
Another growth enabler of concrete surface treatment chemicals market is the rising demand for construction chemicals. Construction chemicals help in improving the performance of the structures, are more economical, ease the installation procedures, augment the chemical and physical characteristics of the structures and make the structures more resistant to adverse weather conditions. These benefits will propel the market, especially in the developing regions.
 
Curing compounds in the concrete surface treatment chemicals market are likely to gain at a growth rate of over 6.5 percent in the study period. The product is used for providing optimal curing when protection from the solar heat is desired. It is majorly used for applications on horizontal surfaces such as streets, highways, curb paving, airports, runways, etc. It is mostly applied through spraying procedure. After spraying, it forms a thin layer on the surface to block water loss and results in accurate curing of the surface.
 
 The industrial sector is an important end-user segment in the concrete surface treatment chemicals market which will hold a share of more than 25 percent of the total industry by the end of the study period. The products are used both during new construction and repair activities, and the product demand from this sector would substantially increase in the future. Industrial development in emerging markets is one of the major reasons behind the growth of this sector in the study period.
 
Europe is one of the significant regions contributing to the growth of the concrete surface treatment chemicals market. Population in Europe has been increasing in recent years and has reached 742 million in 2018 from 727 million in 2000. Increasing immigrants, urbanization and improved living standards of people will increase the product demand in the construction market. Rising infrastructural projects and construction activities in this region will, in turn, boost the market. The construction industry of the region employs more than 18 million people and contributes approximately nine percent to the regional GDP. Hence, developments in this sector would positively impact the market in the forecast period.

Read More


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

A Short History of Concrete Pipe by the PCA

Posted by Hill and Griffith Company on Mar 12, 2020 9:30:40 AM

Concrete pipe has a well established history and reputation for being a long lasting, serviceable material.

Concrete-Form-Release-Agent-1.jpgThe Cloacae Maxima, built in about 180 B.C. as part of Rome's main sewer system, was constructed mainly of stone masonry and natural cement concrete. More than 2,000 years later, portions of the concrete sewer are still in use.

Modern day concrete sewer systems emerged during the mid-19th century when the public became conscious of the need for sanitation to control the spread of disease. The earliest recorded use of concrete pipe in the United States is a sewer installation built in 1842 at Mohawk, N.Y. Other New England cities followed suit and installed concrete pipelines in the second half of the nineteenth century. Many of these concrete pipelines are still in use today.

Milestones in development include the production of the first reinforced pipe in 1905, the invention of prestressed pipe in the 1930s, and the manufacture of the first steel-cylinder prestressed pipe in 1942. 

Sizes can range from four inches up to 17 feet in diameter. Although pipe can be manufactured in a variety of shapes, there are five standard shapes: circular, horizontal elliptical, vertical elliptical, arch, and rectangular. The pipe shape selected for a project depends on the topography of the site, importance of hydraulic and structural efficiency, erosion and deposition in the stream channel, and cost. Most often, the preferred pipe shape is the one that will alter the natural drainage flow the least.

Concrete-Form-Release-Agent-2.jpgFive Methods of Producing Pipe Made of Concrete

As with all concrete products, the basic materials are portland cement, aggregate, and water. There are five basic methods of producing pipe. Four methods -- centrifugal/spinning, dry cast, packerhead, and tamp-entail using a dry concrete mix. The fifth method, wet casting, uses a high-slump concrete mix. Wet-cast concrete mix usually has a slump less than four inches and is most frequently used for manufacturing large diameter pipe.

These types of pipe serve as a conduit material for irrigation, water supply lines, sanitary sewers, culverts, and storm drains. Culverts, usually made with arch-shaped concrete, are used to carry water under highways in non-urban areas. Storm drain systems for cities and towns are becoming more important as communities become larger and more densely populated. Recent major floods and the resulting damage only emphasize the need for efficient drainage systems.

Subsurface drainage carries away water below the surface of the pavement. This water reduces flow support capacity of the base and subgrade material causing potential damage to roads, airport runways, and building foundations. Many farm fields depend on proper underground drainage for their cultivation. Thousands of square miles of otherwise arid land rely on concrete irrigation pipe to supply water for farmland. Additionally, most of the large cities in the United States a pipe system made of concrete to transport their water supply.

(From the Portland Cement Association's web site.The PCA is a powerful and vocal advocate for sustainability, jobs creation, economic growth, infrastructure investment, and overall innovation and excellence in construction throughout the U.S.)

More information at the American Concrete Pipe Association web site.


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 Form Release Agents, Biodegradable Concrete Form Release, Concrete Release Agents, Concrete Forms, Concrete Form Seasoning, Concrete Casting Supplies, Concrete Pipe, Concrete Form Release, Portland Cement Assoc

Formwork Lubricants - Types and Uses of Release Agents for Formworks

Posted by Hill and Griffith Company on Feb 13, 2020 4:51:40 PM

Excerpt from The Constructor Magazine by Kavita Pai

Concrete formwork lubricants are high-quality form seasonings that are applied to the inner surface of a formwork before pouring concrete. Formwork lubricants are also known as form or mold release agents.

Uses of Formwork Lubricants

Release Agents are used for the following reasons:

  1. Application prevents sticking of formwork to the concrete surface thereby permitting easy stripping of formwork after the concrete has hardened.
  2. Protects the formwork and hence the formwork can be reused several times.
  3. Provides good finishing surface of the concrete with minimum defects.
  4. In the case of wooden formwork, prevents water absorption from concrete by the wooden formwork.
  5. Reduces leakage of water during the curing process.
  6. Prevents steel formwork corrosion.

Precast Concrete Form Seasoning 2

The performance of release agents are largely dependent on the type of formwork used. For wooden formwork, straight refined, pale, paraffin-based mineral oil and oil-phase emulsion have been successfully used. The oil that is chosen should be capable of penetrating the wood to some extent while leaving the surface slightly greasy to touch.

There should not be any free release agent on the wood surface. The form release agents that are good for wooden formwork are not always suitable for steel formwork. And hence the choose form release agents based on the type of formwork used for construction.

 

Types of Release Agents:

1. De-Shuttering Oil (DSO)

This is a water-based mold release agent, which produces clean and stain-free, high-quality concrete. It is available in a sprayable form and ready to use as a direct application on required places. It should be applied in light film either by brush or sprayer. If it is over applied, excess release agent should be drained before it dries. Pools of DSO cannot be allowed to dry as it causes surface retardation of concrete.

Advantages of De-Shuttering Oil are as follows:

  • DSO is economical to use.
  • It is non-toxic and non-hazardous.
  • It can be used for all types of concrete formworks.
  • It helps reduce the cleaning efforts before reusing of the formwork.
  • DSO provides a damp proof interface that protects the formwork and ensures even texture and color of concrete.

Read More


More News The Constructor Magazine

Concrete Sweating – Phenomenon, Causes and Prevention

Pre-Concrete Checks for Formwork and Release Agents


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 »

Tags: Concrete, Concrete Form Release Agents, Biodegradable Concrete Form Release, Concrete Casting Products, Concrete Release Agents, The Constructor Magazine

Get More from Your Mix - For Less

Posted by Hill and Griffith Company on Feb 6, 2020 8:00:00 AM

Excerpt from the July/August 2012 issue of Precast Inc. Magazine by Chris Von Handorf, P.E.

New material technologies and intelligent mix designs can significantly decrease production and labor costs.

Reducing material and labor costs makes sense for any manufacturing company, and increasing profits is even more imperative during a slumped economy. Companies in every industry have been forced to look at ways to lower production costs to remain competitive in our rapidly evolving marketplace. The precast concrete industry is no exception. Concrete constituents are only a portion of the costs incurred by a precast concrete manufacturing facility. This article shows how a smart mix design can help you cut costs. The important point to remember is that a lower-cost concrete does not always result in an inferior product. In fact, in some cases, lowering the cost of your mix design may actually yield a higher-quality concrete product.

Admixtures offer many cost-saving options
The cost of the materials that make up concrete is but one of the many expenses incurred by a precast concrete manufacturing facility. Another major expense is the labor cost to place and finish the product. This cost varies widely depending on a plethora of factors including: the type of product; the climate; the experience level of workers; and reinforcement required.

Here are just a few of the admixtures available that, in the right application, have the potential to significantly lower production costs:

1. Supplemental Cementitious Materials: The use of supplemental cementitious materials, such as silica fume and blast furnace slag, has the potential to enhance the performance of concrete while reducing any bleeding that may occur. When used properly, silica fume can improve concrete’s resistance to chemical attack. It can also increase concrete strength while reducing the permeability of the concrete.

2. Accelerators: The use of accelerators in precast applications has some obvious advantages. The faster concrete reaches the required stripping strength, the quicker the forms can be cleaned, prepped and used again. For a precaster, a quicker strength gain is huge if you are looking to go from pouring once per day in a given form to twice per day.

3. High-range water reducers: High-range water reducers (HRWRs) are excellent for nearly every precast concrete application. A good high-range water-reducing admixture will allow you to produce concrete batches with more consistent air entrainment and more consistent ultimate strengths. 

4. Release agents: While release agents are not a constituent of the mix, the use of a high-quality release agent is essential for a better-looking, lower-cost, finished product. As with HRWRs, release agent technology has improved significantly in recent history. Although many new release agents are more expensive per unit, most of them do allow for a lighter application than traditional release agents. As a result, the cost per square foot of coverage is often significantly lower using the newer form release agents.

Emerging technology and processes surrounding the concrete industry are rapidly advancing. Admixtures that cost only $1 to $2 per cubic yard may have the potential to save you hundreds of dollars or more in labor and rework. Many of these admixtures were not available a few years ago. Some material testing techniques that were not available years ago, or were very expensive, are now relatively inexpensive. Therefore, it is no longer economical or wise to continue precast production methods with a familiar, long-standing mix design simply because it has been the traditional way of doing things for the last 20 or 30 years.

Read More


More News from Precast Inc.

Protecting What Matters Most

For the Long Haul


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 »

Tags: Concrete, Concrete Form Release Agents, Biodegradable Concrete Form Release, Concrete Casting Products, Concrete Release Agents, Precast Inc Magazine

Avoiding Surface Imperfections in Concrete: bugholes, crazing, dusting, flaking, honeycombing and popouts

Posted by Hill and Griffith Company on Jan 30, 2020 12:01:12 PM

Excerpt from the July 2008 issue of Cement, Concrete and Aggregates Australia

Bugholes

What are bugholes

Bug holes are individually rounded or irregular cavities that are formed against the formwork and become visible when it is stripped. Small bugholes (less than, say, 10 mm) tend to be approximately hemispherical, while larger ones are irregular and often expose coarse aggregate particles. They tend to be more prevalent towards the top of a concrete placement than at the bottom, due to the increased compaction and static head at the bottom layer of the pour. Generally, they are regarded as an appearance problem though a concentration of large bugholes may lead to loss of durability. Under AS 3610 Formwork for Concrete, the size/extent of bugholes is, therefore, one of the criteria by which an off-form surface finish can be evaluated. This Standard incorporates full-size photographs, which enable a particular surface to be assessed for compliance with the specified class of finish. When using normal (i.e., impermeable) forms, it is impossible to achieve a bughole-free surface. However, the use of permeable forms may significantly reduce, if not eliminate, the incidence of bugholes.

toa-heftiba-WeW4RbApL6s-unsplash cropped

What Causes Bugholes?

Bugholes are caused by the entrapment of air against the inside face of the formwork. The extent to which they occur is dependent on:

  • the texture and stickiness of the formwork surface,
  • the inclination of the surface (the incidence of blowholes is increased where the formwork surface slopes inwards), 
  • the use of a poorly proportioned or sticky concrete mix, and
  • the amount of vibration.

Practices to Minimize the Occurrence of Bugholes

To minimize the incidence of bugholes:

  • Use rigid well-braced formwork.
  • Avoid the use of inwardly-sloping forms where possible.
  • Apply a thin coat of a form-release agent that spreads evenly and is not sticky.
  • Where appropriate use permeable formwork.
  • Avoid "sticky" concrete mixes, e.g., ones that may be over-sanded or have a high percentage of air-entrainment, and mixes that are too lean.
  • Place concrete at a rate such that its rise up the form is not less than 2 m/h vertically.
  • Ensure that the member is adequately compacted (see Compaction of Concrete data sheet for guidance on size of vibrator, spacing of insertion points and technique).
  • Pull vibrator up slowly through the concrete layer allowing time for the entrapped air to rise to the surface. 
  • Ensure the concrete against the surface is properly compacted.
  • Re-vibrate the top placement layer at about the same time as if a further layer was being placed on top.

Read More

Crazing

What is Crazing?

Crazing or craze cracking (sometimes referred to as map cracking) is a network of fine random surface cracks spaced from 10 to 70 mm apart, dividing the surface up into irregular hexagonal areas. They are always most prominent when the surface has been wet and then dries off, leaving the damp cracks outlined against the dry surface. They are a surface feature and though unsightly, are unlikely to lead to structural or serviceability problems. There is no repair method; thus it is best to take precautions, as outlined below, to avoid them.

What causes Crazing?

Crazing is caused by the shrinkage of the surface layer relative to the base concrete. Usually, it occurs because one or more poor concrete practices are adopted, for example: 

  • Using too wet a mix
  • Finishing of the surface too early, i.e., while bleed water is present
  • Overworking the surface, thus bringing too many fines to the surface
  • Adding driers to the surface to try and remove bleed water
  • Not commencing curing early enough (three hours after completion of finishing is too late) or using inadequate curing procedures (such as intermittent wetting and drying).
On formed surfaces, it usually occurs where shiny, impermeable formwork is used and this is coupled with inadequate curing.

 

shivanshu-gaur-tYans8xqIHw-unsplash

Flaking

What is Flaking?

Flaking is where discrete pieces of the surface become detached, leaving a rough indentation behind. The pieces are usually flat, hence the name "flakes." Scaling should not be confused with flaking. Scaling is delamination of the concrete surface when exposed to freeze-thaw cycles, and although the appearance is similar, the mechanism is different.

What Causes Flaking Floors?

Flaking is caused by inappropriate finishing techniques that seal the surface and trap the water, which would otherwise have risen to the surface as bleed water. This water accumulates below the surface, forming a plane of weakness and resulting in delamination of the surface layer. Premature sealing of the surface can be caused by:

  • Commencing finishing too early because the ambient conditions dry the bleed water from the surface and the lack of sheen suggests that bleeding has finished. Note that some finishing tools more than others tend to seal the surface, e.g., a hand strike-off with a magnesium straightedge tends to seal the surface while a strike-off with a wood or magnesium bull-float pass leaves the surface open5.
  • The use of driers on the surface to absorb bleed water

andrew-buchanan-XUbIShMDGSM-unsplash

Read More

What is Dusting

A dusting floor surface is marked by an accumulation of fine material requiring to be swept up after the floor has been used. Also, a hand rubbed over the surface of a dusting floor will be coated with a fine powder

Read More

What is Honeycombing?

Honeycombing refers to voids in concrete caused by the mortar not filling the spaces between the coarse aggregate particles. It usually becomes apparent when the formwork is stripped, revealing a rough and 'stony' concrete surface with air voids between the coarse aggregate. Sometimes, however, a surface skin of mortar masks the extent of the defect. Honeycombing may extend some depth into the member. Honeycombing is always an aesthetic problem, and depending on the depth and extent may reduce both the durability performance and the structural strength of the member.

Read More

Popouts

Popouts are roughly conical depressions in the concrete surface created by localized pressure within the concrete, usually occurring after the concrete has been in place for some time. They can be categorized as small, medium or large depending on whether the diameter of the cavity is 10 mm or less, 10 to 50 mm, or greater than 50 mm respectively.

Read More


More News from Cement, Concrete and Aggregate Australia

Concrete Overview

Concrete Puts Its Stamp on Shaw Wines' Success


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 »

Tags: Concrete, Concrete Form Release Agents, Biodegradable Concrete Form Release, Concrete Casting Products, Concrete Release Agents, Cement, Concrete and Aggregates Australia

Formwork Rust: Reasons and Prevention

Posted by Hill and Griffith Company on Jan 23, 2020 8:00:00 AM

Excerpt from the April 2007 issue of Concrete Construction by Peter Boos and Reiner Haerdtl

Rust on steel formwork leads to stains on the concrete unit

Introduction

Steel formwork is used in prefabrication operations because of its robustness and reusability, as well as its ability to produce prefabricated units with smooth surfaces. On these steel molds, brownish-reddish rust spots sometimes form while the concrete hardens. This rust could lead to brown or red spotty discolorations on the concrete surface lower the concrete element's appearance. Removing these discolorations by sanding and resurfacing is costly and time-consuming.

Rusted Concrete Form

Reasons for corrosion

There are several reasons for metal corrosion, and thus different forms: contact corrosion, crack corrosion, inter-crystalline corrosion, pitting corrosion, etc. The corrosion of iron and/or steel is an electrochemical process in the presence of water and oxygen. Metal corrosion occurs at the spot with the higher electro-negative potential. Here, the metal ions dissolve from the surface into the solution and when they collide with hydroxide ions they precipitate as iron hydroxide.

The resulting iron minerals are formed, depending on temperature and air humidity. Due to constant recrystallization, no permanent protective rust layer is formed on the surface that would prevent further corrosion. Corrosion is prevented by protective coatings, such as greasy lubricants, a coat of varnish or other metals that prevent air and moisture from contacting the iron surface. Unfortunately, under the daily production load of a prefabrication plant, no protective layer will last long.

The appearance of rust on steel formworks can look quite different. While some steel molds rust over their whole surface, others show rust spots arranged linearly like pearls on a string. In other cases, rust spots occur only along the edges of the casting tables near the clamps. Frequently, rust appears periodically in certain seasons and disappears. Most causes for rust formation can be classified as process-related causes or environmental causes and causes related to concrete technology.

Process-related causes

Steel in direct contact with concrete forms a protective passivation layer in the alkaline milieu of concrete, which suppresses rusting. This hardened non-carbonated concrete is the best corrosion protection for reinforcement. Release agents are used to ensure reliable separation of the concrete from the formwork. This means that it acts like a contact barrier between steel formwork and concrete. Due to that, the formation of the protecting passivation is either slowed down or totally suppressed. Nevertheless, release agents prevent the direct contact of water to the steel surface. But a reliably effective form release agent is no rust protection agent for steel formwork, although a release agent may well contain small amounts of rust inhibitors. By taking the thinness of the release agent layers into account, no rust protection can be provided in this way.

In concrete's alkaline state, the metallic oxidation of the steel required for this effect to materialize does not take place. Rust can therefore develop only where water films or specific chemical elements and compounds enable oxidation, for example, in case of condensation water. It is always recommended to consult the supplier of the release agent when problems with rusting arise.

Magnets can promote rusting of steel casting tables, especially in contact with water. Clamps are placed over the magnets and positioned on the steel tables. When the magnets are placed on the casting tables before the surface has been sprayed and protected with release agent or when the steel surface underneath the clamps are not fully covered by the release agent, rust is more likely to occur. Typically, linear rust spot patterns are due to magnets.

Removing rust mechanically, such as by sanding, can lead to "activated" steel surfaces, which are especially prone to rust. Some manufacturers of casting tables sand the steel surfaces as a service. After sanding, the surface is treated with waxes and chemicals that penetrate deeply into the pores of the steel, which protect it from rusting for a period of time. Without such a treatment the formwork will definitely show rusting.

But this provides no long-term solution unless the real reason of the rust problem is eliminated. In the long-term, new rust will develop and the protective layer will wear off in the course of ordinary mechanical load. When the cause of rusting is analyzed and eliminated the rust spots will generally encapsulate themselves on their own (deeply embedded black rust).

Using chemicals to remove rust or attempts to form a protective coating on the casting tables, such as by phosphorizing, are usually no solution. The black coating that is produced in the process is not resistant to the mechanical load imposed on the surface during production and chips off, so steel surfaces can rust again. This chemical treatment may even lead to additional black discolorations on the concrete surfaces.

Environmental Causes

Read more

Technological Causes

Read more

Recommendations for Prevention

Read more


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 »

Tags: Concrete, Concrete Form Release Agents, Biodegradable Concrete Form Release, Concrete Casting Products, Concrete Release Agents, Concrete Construction Magazine

Applying Concrete Form Release Agent

Posted by Hill and Griffith Company on Jan 16, 2020 8:00:00 AM

Excerpt from the August 2010 issue of Concrete Construction

Q: How often should concrete release agent be applied to plywood form panels?

A: Plywood forming panels usually are treated with a concrete form release agent at the mill, but it's still important to evaluate their condition carefully before using them for the first time. Unless the mill treatment is reasonably fresh, the panels may need another treatment of release agent before the first use. Even medium-density overlays should be treated with a chemical release agent before the first use and between each pour. 

Concrete_From_Release_1

Applying a thin film of concrete form release agent to both reused panels and new panels that are not freshly mill-treated will:

  • prolong the panel's life
  • enhance its release characteristics
  • minimize the potential for staining the concrete

Apply the release agent a few days before using the forms for best results.

You also should determine whether an edge sealer was applied at the mill, and if not, seal any cut edges with two coats of polyurethane paint or varnish before the first pour. Otherwise, the forming panels will absorb moisture and swell at the edges.

Read more


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 »

Tags: Concrete, Concrete Form Release Agents, Biodegradable Concrete Form Release, Concrete Casting Products, Concrete Release Agents, Concrete Construction Magazine

Cutting-Edge Production Management System is a Game-Changer for Canadian Precast Manufacturer

Posted by Hill and Griffith Company on Jan 9, 2020 8:00:00 AM

Excerpt from issue 6 of Concrete Plant International by Claude Goguen

Traditional wetcast production plant setups make it nearly impossible to drive productivity because there are too many variables and there is no linear process flow that can be easily tracked, measured, analyzed and optimized. The Prima wetcast system offers a solution to this by organizing the different work processes in the plant and by tracking and measuring these processes for analysis and evaluation. Precast producers like M-Con Pipe & Products Inc have found that Prima helps them organize the wetcast production of many different kinds of products and is the solution they were seeking to drive efficiency while maintaining high quality.

1906_ro_afinitas

The Problem: Inefficiency and Floor Space

Doug Galloway had a problem and an idea. The president of Ontario-based M-Con Pipe & Products Inc., Galloway was out of space on his wetcast production floor and looking for ways to work more efficiently.

That was the problem. The idea? Some type of carousel system that would move forms to workstations set up on a production line - like an auto assembly plant. Instead of moving buckets of concrete and production teams around the plant to strip, prep and fill the forms, bring the forms to the workers. 

Galloway took the idea to HawkeyePedershaab in 2013, and, little more than a year later, the Precast Industrial Management System, or Prima, was born. The HawkeyePedershaab engineering and sales team took Galloway's concept and brought it to life, creating a wetcast production system that saves space, reduces labor, increases the throughput of products and provides comprehensive analytics to management.

Based in Ayr, Ontario, just west of Toronto, Canada, M-Con Pipe is known as an innovative leader in providing precast concrete infrastructure products throughout Central and Southwestern Ontario. Even though they have a 100,000 sq. ft. (approximately 9300 m2) manufacturing facility, things were tight on the production floor.

"We were doing a lot of wetcast products, and they were taking up a lot of floor space," Galloway said. "The floor space was crammed with products and forms, and we were having to move them with lift trucks to strip the product and to pour concrete. So, we were looking for a more efficient way to manage wetcast forms. That's when we started thinking of this system. Because of the work we had done in the past with Hawkeye, we approached them about putting together this carousel-type system that they eventually called Prima."

The Solution: Prima Automated Wetcast Production

To understand how Prima works, let's follow one form down the production line. At the beginning of the day, the form is located in its assigned spot on the floor, monitored by an RFID tag. As the production line starts, the previous day's product is stripped from the form and moved out to the yard by a chain conveyor.

The form sits on a cart that rides on a moving conveyor that sends it to the next station, where the form is cleaned, oiled and set up for pouring. From there, it moves to the reinforcement station, where the steel is placed. At this stage, there may be an option to pull the form offline if it needs any special preparation, reinserting it after the additional prep.

The next stop is the form filling station, where the operator confirms that all the preparation has been completed and the concrete is poured into the form. An automated overhead manipulator then moves the green product to predetermined curing location where the product cures in the form until it is ready to return to the production loop to start the process over. There is more to the system, of course, according to Randy Beelman, Eastern North America Sale Manager for HawkeyePedershaab.

Read more


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 »

Tags: Concrete, Concrete Form Release Agents, Biodegradable Concrete Form Release, Concrete Casting Products, Concrete Release Agents, Concrete Plant International Magazine

Subscribe to Concrete News

Concrete Posts

Concrete Casting News Categories

see all