Precast concrete box sections have been around for decades, and I am sure that if you have not produced, specified or installed them at some point, you most certainly have driven across or walked or biked through one in your lifetime. Box sections have many useful applications, some of which are listed here. If you work for a city or consulting engineering company and you have never considered using precast box sections, I highly encourage you to do so moving forward as they offer many benefits, to include:1) Rapid and simple installation, saving time and money on a project2) Superior structural integrity and quality assurance3) Readily available in just about any marketAnd 4) A broad variety of dimensions to meet virtually any need
Hamilton Kent has been selling Tylox SuperSeal gaskets for box sections for about 15 years, but the precast concrete industry has become much more creative and active in recent years in regards to how box sections, and especially gasketed box sections, are being used.In the second half of this webinar, I will be highlighting three projects that Hamilton Kent has been involved with over the last 18 months. Each of these projects provided a unique solution to problems that plague many municipalities today, primarily with regards to stormwater management. Virtually every city we visit and speak to is involved to some extent in better managing their stormwater. And there are more conferences, meetings and expositions regarding stormwater management than ever before, one of which I attended in Providence, Rhode Island last week. So this is certainly a primary reason that precasters, designers and cities are finding more applications for and success with box sections.Hamilton Kent was very fortunate that all 3 of these projects utilized our pre-lubricated Tylox SuperSeal gasket to seal the joints. No butyl sealant, no joint wrap… just a gasket. Talk about making it easy for the installers! And each required high performance joints, so quality and performance of the joints and gaskets were key for the opportunity to use gaskets in these applications.
For those of you that were not aware, ASTM recently published a new standard, C1675, which should be reviewed and utilized by all specifiers, owners, contractors and precast concrete producers. Whether already experienced with this product or just investigating them, the installation methods covered in this standard will be beneficial to everyone. You can order a copy of C1675 through ASTM’s website, ASTM.ORG.
One thing you may be wondering is if this type of formwork is readily available. The answer is yes. There are several companies who have already produced single offset joint tooling with the precision needed to work well with a gasket.Two things are really a must when considering this tooling. The first is rounded corners for the joints with a minimum of a 6” radius, and the second is formwork that allows for adjustability in the size of the box section. This formwork will represent a considerable investment by producers who purchase it, so being capable of manufacturing box sections of different dimensions will make the payback much faster. And, while I am on the topic of the investment, this also means precast plants must take great care of the tooling, as they do not want to jeopardize their investment nor the integrity of their joints.I would also like to mention that gasketed box culverts also require precise manufacturing. Some precasters are finding the use of self-consolidating concrete to work very well with a gasketed joint as they end up with few or no bugholes or voids on the joint. Quality assurance also plays a big role in this production, as these folks are the ones who ensure the joint tolerances and integrity are being met, as well as conducting any joint testing that is required, before a box section ships to the job site.
Here is a box section, one actually produced dry-cast, with the SuperSeal gasket already installed. You can see the rounded corner on the joint area allowing for use of gaskets.
As I already mentioned, the quality of the manufactured joint is critical. But equally important is selection of the joint design. We encourage any producer considering gasketed box sections to work with a gasket supplier to determine the best joint design as well as the appropriate gasket for that joint. Then comes the testing, and there are different methods for conducting this.First, sections can be brought together and then the internal chamber filled with water. This method is only viable when an engineer can calculate that the box sections can withstand the internal water pressure, as this pressure can be tremendous. We have heard about testing done in this manner where the boxes had to be buried to allow the surrounding soil to support the walls of the box sections, as would be the case when installed on a job site.Second, a joint testing device like a Cherne tester can be used, though we have seen challenges with this because of the pressure to which the tester is subjected and possibly not able to structurally withstand.Third, and the option we prefer and I will talk about more in a few minutes in regards to one of the projects, the use of an internal joint test.
INSTALL VIDEO ON THIS SLIDE (REPLACE IMAGE)This short video demonstrates installation of a gasket on a box section, which, for those who did not already know this, is done by the precaster at the plant before the box sections are shipped to the job site. Installation is definitely a two-person job even for a relatively small box section. One thing nice about a pre-lubricated gasket compared to a regular profile gasket from the producers standpoint is the stretch will not be so great that it’s difficult to install. You also are not as concerned about the equalization of the gasket for the same reason. So, once the crew has the gasket in place, they will then needto glue the gasket to the spigot of the box along the bottom and part way up each side. This ensures that the gasket will not sag on the bottom, which would prevent the box section from homing properly at the job site. Once the glue has been applied to the gasket, a board with a couple of clamps can be used to hold the gasket in place until the glue has dried.A couple of notes… First, because these gaskets are glued on at the plant days or evens weeks before installation at the job site, the gaskets must be manufactured from a rubber material that is resistant to UV and ozone. Hamilton Kent recommends EPDM rubber for any application of this type.Second, if the plant is using a pre-lubed gasket like the SuperSeal, they will want to take care to not glue the rolling tube of the gasket to the spigot. Doing this may prevent the gasket tube from rolling during homing, which would keep the joint from closing completely.
So, now let’s talk about the first of the three projects… This one is the Bond Brook combined sewer overflow in the Greater Augusta Utility District in MaineThis was a $15-million project needed to reduce the frequency of sewer overflows into the Kennebec River. The projectwas required for compliance with the Clean Water Act as administered by the Maine Department of Environmental Protection Totaling 1,400 linear feet, American Concrete Industries built 250 precast box sections to create a twin line storage system to hold 1 million gallons until such time as the water can drained from system to be treated.
Test fitting the box sections with the gasket was important, and the manufacturer found it easier to stack the box sections vertically.(ADD MORE – CHECK WITH SCOTT)
Design testing was also done prior to the job shipping and every joint was to be tested in the fieldThese boxes were wetcast and manufactured to allow post tensioning. You can probably see the holes in corner of the box section suspended by the crane. These 4 channels go through each segment allowing for cables to be run through and tensioned.The project was specified ACI 350.1 and had a specific and challenging requirement for allowable leakage
In these images you can better see the grooves in the walls and the base of the box, which is where the threaded anchors were placed to lock sections together. In this case, both options were used, but some projects allow for use of these anchors instead of post tensioning.
The second project I’d like to highlight is the Storm Water Drainage Project in Lubbock, TX. Lubbock is located in an area with a series of natural depressions and drainage patterns that collect and distribute storm water. As these playa lakes accumulate water and fill up, they drain down stream to the next lake. The City needed to transfer stormwater between holding lakes to avoid flooding, but this meant deep trenches throughout the city. Such a project would otherwise require open cutting, jacking and lateral boring, which means expensive materials.The job was deep, averaging between 32 and 38 feet of cover and basically went through a residential neighborhood within the cityThe consulting engineer originally considered Cast in Place and Fiber Reinforced Polymer Pipe, as he was concerned about box culverts due to past project issues with high repair costs and erosion due to faulty jointsIn order to satisfy the engineer, it was determined that a condition of the project was a physical joint and structure test which consisted of a hydrostatic test of 13 psi which needed to be held with no leaks for 48 hours. The test was very challenging for the producer to set up, but was ultimately very successful and won over the engineer.In the end, there were 5 sections of the installation to be carried out by tunneling and jacking of the structures. The open cut sections met up with the jacked sections using cast-in-place fittings
This project used a product in a new way. Consulting engineers were hired to rethink the use of an existing product: gasketed box culvert. They were able to modify the product to withstand extreme depths. It was a creative and cost effective solution for a large project that would have otherwise required a more expensive method. With gasketed box culverts, they made a complex drainage system go through the city. They used prefab materials instead of more expensive cast-in-place concrete and open cutting. By using an existing product in a new way, they accomplished goals and saved millions. You can see in the video a box section being lowered into place right next to the one previously set. By the way, we speeded up the video in the interest of everyone’s time… The crane operator placed the box section as close as possible to make it easier for the guys below. The installation crew then used two large hooks attached to cables and a hydraulic winch to pull the sections together in straight alignment. You can see after this step that the joints are very tight, just like you want to see for a gasketed joint. The final segment of the video shows a small portion of the line of box sections, with the final seconds showing the flowable fill that was used over and around the structure before covering with traditional fill.
Testing on this project was extremely rigorous and demandingPhysical verification of the performance of each joint and structure was required Initially, tested sections had to be buried to simulate installed sections of box culvert to ensure that the pressure did not destroy the structuresA Cherney tester was designed and developed for this project with a requirement that every joint be tested after installation. However, the Cherney tester never performed properly – it simply could not withstand the forces created during testing and resulted in inconclusive and failed tests. The consulting engineer agreed to increased external joint testing in the plant using the ASTM External Joint TestSo they tested at 5 psi for 2 hours with no allowable leaks, and they tested every 50 joints from then on instead of the field testing You can see the pressure gage on the outside of the bell in the left hand image. In the center picture you can see the SuperSeal gasket on the spigot and then a wedge shape gasket pushed up against the shoulder of the joint, which creates the pressurization cavity in between. On the right, you can see that the plant used rebar to roll the box sections into place. This ensured that the joint went together as square and easily as possible.
In the left hand picture the crew is locking the sections together with beams and threaded rods, which you must do in order to keep the joint closed against the pressure created by the water in the cavity.In the center image, you can see the pressure gage that is tapped into the joint space between the bell and spigot, and between the joint gasket and the test gasket. This space is then filled completely with water and pressurized.After pulling the box sections apart, you can see the space between the SuperSeal gasket on the spigot to the right, and then the wedge shape gasket on the left is wet, but nowhere else is, which shows another successful test.One recommendation you can consider if you decide to conduct a test of this nature on large box sections is to put the gauge on the inside of the box. You may find it a little easier to drill through the spigot of the joint in the space between the gaskets.
Finally, I want to share this video of a drainage project from Colorado where a single line of gasketed box culverts were installed in a shallow open cut trench… to demonstrate the ease of installationThis setup worked very well for the contractor as they were able to carry the box sections into the trench using a heavy duty fork lift. As you can see, installation was very fast, because of the conditions of the job and because of the gasketed connectionOnce again, the gaskets were pre-installed at the plant by the precaster so all the contractor had to do is ensure the bell and spigot of each section were cleared of debris and then lined up correctly before homing. Just a very simple process for the contractor. The crew was able to install the box sections as fast as the fork lift operator could bring the sections into the trench.
I hope that these projects have highlighted how something as simple as gasketed box sections can be used to solve a variety of project challenges.Through success in the field, many consulting engineers and owners are now looking favorably at gasketed precast concrete box section, because they are easy to install, cost effective and give high-performance results that are often superior to other materials or methods.We certainly recommend use of ASTM C1675 as a resource for future projects utilizing precast concrete box sections.And, because of the projects I have presented, the manufacturers have been able to sell more precast products. Not only on these projects, but also on new projects they have secured since the gasketed box culvert installations began. Good precast solutions!
At this time, I would like to take any questions participants might have based on the presentation. You can either use the “raise your hand” icon on the webinar menu bar or you can enter a question into the question box and send it to me. <<PAUSE FOR QUESTIONS>>Thank you for your time today. Please feel free to visit our website for more information on Hamilton Kent and our products for gasketed box sections, or contact me directly if you have any questions. Hamilton Kent wants to be a resource to anyone interested in gasketed box sections, so please do not hesitate to call or email us.We do expect to have this webinar available on demand in the next couple of weeks, so will send everyone an email in this regard shortly.Have a great rest of your day, start thinking outside of the box culvert, and we look forward to speaking to you next time!
Think outside the box (culvert): How creativity sells more precast
Thinking outside the box
How creativity is selling more precast
About Hamilton Kent
70 years supplying sealing solutions to the buried
ISO 9001-2008 Certified
Very experienced and innovative engineering and
Plants in Toronto, ON and
Head office in Toronto
Historically, applications have been:
Culverts and bridges
Utility, vehicle and pedestrian tunnels
Stacked vertically for rectangular structures
Repurposed for a variety of situations
Created new business for manufacturers
Tylox SuperSeal gaskets for watertight seal
Useful to specifiers, owners, contractors and
Beneficial to experienced and those new to use
of precast box sections
Single Offset Joint
Production tooling is available, both fixed and
Allows for a gasket – can still use butyl and wrap
Single Offset Joint Tooling
Several form manufacturers
Rounded corners with 6” radius
Flexibility is helpful – adjustable forms
Expensive, but can be worth the investment
Care for formwork is a must
Very precise manufacturing