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Concrete Casting News from the Hill and Griffith Company

Precast Concrete Bugholes: Questions from the Field

Posted by Hill and Griffith Company on Mar 4, 2021 5:38:49 PM

Excerpt from NPCA's Precast Inc. Questions & Answers section from the March/April 2019 issue

Paul writes:

What factors could cause bugholes? How does aggregate gradation affect bugholes?

NPCA Technical Services engineers answered:

There are many different variables that could affect the surface finish of hardened concrete and cause bugholes. For conventional wet-cast concrete, the consensus is that the primary culprit is improper vibration, but that’s true even with self-consolidating concrete. The rapid placement of SCC could lead to entrapped air and, if procedures to remove the air aren’t in place, bugholes could form. 

Pouring Concrete to Reduce Bug Holes

Try to slow down the placement of fresh SCC into the form to see if this provides beneficial results. Also, you may need to reevaluate where the concrete is being placed in the form. The concrete may be getting pushed too far and trapping air on tricky corner sections or in areas with heavy reinforcement congestion. Other factors, including not properly applying form release agent, could also promote bughole development.

Your suggestion of aggregate gradations certainly can contribute to surface defects, including bugholes. The Portland Cement Association states, "Mix design can also be considered a significant contributor to bughole formation. Mix designs vary widely in their use of aggregate type, size, and grading and their use of admixtures and air-entrainment."

PCA also states, "Workable, flowing mixtures are easier to place and consolidate and therefore reduce the risk of bughole formation. Concrete with an optimally graded aggregate that avoids excessive quantities of fine aggregate, properly proportioned cement content, and any admixture that provides increased flow, workability, or ease of consolidation contributes to bughole reduction."

Another item to look into is the gradation of the fines. Very fine sands tend to hold more water, increase bleed water and add to the potential for trapped water, all of which could lead to bugholes. Also, sands that are very coarse without uniform gradation have been known to trap more air and, consequently, form bugholes. The best solution is to set up trial mixes to optimize the best results.

If you have a technical question, contact us by calling (800) 366-7731 or visit precast.org/technical-services.

Read More


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Hill and Griffith Customer Service

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

Hill and Griffith Samples

Product Samples

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

 

Hill and Griffith Customer Service

Technical Services & Support

On-site casting defect investigations, product testing, machine start-ups and much more. Also, lab facilities are available to provide testing upon request.
Contact Us »

 

 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete, Casting Solutions, Concrete Casting Products, Concrete Casting Supplies, Concrete Casting, Precast Concrete, Concrete Form Release Agent, American Concrete Pipe Association, NPCA

Top 5 Mistakes When Designing a Buried Pipe

Posted by Hill and Griffith Company on Feb 25, 2021 4:38:38 PM

Designing a buried pipe? Be sure to avoid these common—and potentially costly—mistakes.

Excerpt from the American Concrete Pipe Association (ACPA) website June 2020 article by Josh Beakley, P.E.

The design of buried pipe encompasses many of the basic civil engineering concepts we learned in college: hydraulics, soils engineering, and structural engineering. Yet, I’m willing to bet most of us didn't take a class specifically dealing with the design of buried pipe. Thus, it's easy to miss some of the finer nuances when designing buried pipe. Here are some areas where we have seen issues throughout our years in the industry. 

Top 5 Mistakes in Designing Buried Concrete Pipe 

 

 
 

1.  Relying on the installation more than the pipe

Pipe gets built in the manufacturing plant in a controlled environment, whereas the installation surrounding the pipe gets built in whatever Mother Nature provides. So, when the going gets tough, why ask the contractor to produce miracles? (Remember the saying, "it is not nice to fool with Mother Nature.") The pipe producer can typically build a product to accommodate the environment.

#ProTip – Just because you can't find a standard class of pipe, doesn't mean our manufacturers cannot make what you need. Contact a manufacturer near your location to discuss your options.

2.  Blindly using fill height tables

It sure is easy to look up what you need in a reference/fill height table, isn't it? No calculations involved! But somewhere along the way, calculations were performed to develop those fill height tables. Do you know what assumptions were made in those calculations? Do they match your site conditions?

#ProTip – Take a moment to review what assumptions were made and see if they match your site conditions. If the assumptions and your reality don't align, it's worth your time to calculate the correct value.

3.  Using direct vs. indirect design

Of course, you can calculate the stress and/or strain in the pipe based upon a particular soil-structure model for the pipe and its installed condition, and then specify the required properties of the pipe based on your direct design. Or, you could determine the load on the pipe, utilize a simplified relationship between the installed condition and a test condition in the plant, and employ an indirect design method to establish proof of performance of the pipe. Both methods have their uses.

#ProTip – Generally speaking, if you can find reinforcement requirements for the pipe in the tables of ASTM C76/AASHTO M170, Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe, then the indirect design method is your best bet. If you can't find reinforcement values in C76/M170, then you'll be performing a direct design.

4. Overlooking Pipe Joint Requirements

5. Cut-and-Pasting Specifications

Read about the next 2 tips


More News from APCA

4 Ideas for Thinking Outside the Box (Culvert)

Is Concrete Pipe Innovative? Here are 4 Areas to Explore.


Hill and Griffith Customer Service

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

Hill and Griffith Samples

Product Samples

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

 

Hill and Griffith Customer Service

Technical Services & Support

On-site casting defect investigations, product testing, machine start-ups and much more. Also, lab facilities are available to provide testing upon request.
Contact Us »

 

 Bulletins and Technical Papers for Concrete Casting Products

Tags: Concrete, Casting Solutions, Concrete Casting Products, Concrete Casting Supplies, Concrete Casting, Precast Concrete, Concrete Form Release Agent, American Concrete Pipe Association, Precast Pipe

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.
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

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

Quality Control and Testing of Concrete Pipe

Posted by Hill and Griffith Company on Apr 4, 2019 3:26:47 PM

The American Concrete Pipe Association is the spokesperson for the concrete pipe industry in all matters affecting the industry’s welfare.

We researched their content and found some great free resources. Their home page section on "Pipe & Box Resources" starts off with Design and "14 Reasons to Choose Concrete."

Precast Concrete Pipe Design Manual

"Concrete is the world’s most commonly used building material.

In its simplest form, concrete is a mixture of paste and aggregates. The material (paste) used to manufacture concrete pipe is composed principally of Portland cement and water, and is used to coat the surface of the fine and coarse aggregates. The Portland cement is a closely controlled chemical combination of calcium, silicon, aluminum, iron, and small amounts of other compounds, to which gypsum is added in the final grinding process to regulate the setting time of the concrete. Portland cement’s chemistry comes to life in the presence of water. Soon after the cement and water are combined, a chemical reaction called hydration occurs and the paste hardens and gains strength to form the rock-like mass known as concrete. During hydration, a node forms on the surface of each cement particle. The node grows and expands until it links up with nodes from other cement particles or adheres to adjacent aggregates. Within this process lies the key to the remarkable trait of concrete – it’s plastic and malleable when newly mixed and strong and durable when hardened. ..."

The 14th Reason is "Quality Control and Testing of Concrete Pipe."

Batching and mixing operations in the industry’s premier plants have been upgraded over the past 10 years. Characteristics of this operation of the pipe production process normally include:
• Computer controlled weighing and proportioning systems
• Computer controlled mixing systems
• Automated recording systems
• Absorption testing

Concrete PipePlant Certification

The American Concrete Pipe Association offers an on-going quality assurance program called the “Quality Cast” Plant Certification Program. (http://www.concrete-pipe.org/qcast.htm). This 124-point audit-inspection program covers the inspection of materials, finished products and handling/storage procedures, as well as performance testing and quality control documentation. Plants are certified to provide storm sewer and culvert pipe or under a combined sanitary sewer, storm sewer, and culvert pipe program.

Line Item 6.1 "Forms shall be kept clean of concrete build-up and inspected after each use."

Line Item 8.2. "Pre-Pour Visual Inspection"
For each pipe produced, visually inspect the following applicable items prior to pouring:
• Reinforcing Placement
• Handling Holes / Lifting Devices
• Tie-pin Holes
• Release Agent Application
• Form Cleanliness and Condition
• Step Holes / Plugs 

American Concrete Pipe Association

Brief History of the ACPA

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 News from the American Concrete Pipe Association

2018 Camp Fire — Reminder of Need for Fire-Resilient Infrastructure

Reinforced Concrete Pipe Replaces 20-Year Old Plastic System in Florida

Become a member of ACPA by completing a membership 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 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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