Few Things to Consider When Designing a Box Culvert

Deciding to use precast box culverts for your next project is only the first step. Here’s a rundown of the various options for joints and sealants, fastening mechanisms, and testing techniques, as well as other factors to consider for your project.

Will Your Project Need the Use of Restraint Devices?

In most cases, no restrictions are required to join box culverts. In projects with a lot of internal pressure or external vibration, you might want to include restraining mechanisms to keep the box pieces from shifting. If restrictions are required for your project, you have a few options: To connect the entire culvert, one method is to run cables through holes in each box portion. The cables are post-tensioned, which pulls all sections together and tightens them. This isn’t easy because all holes must line up correctly during installation.

The second alternative is to use bolts to lock two sections of the culvert together by placing them in pre-formed niches in the culvert walls and tightening them.

If Your Task Requires the Use of Different Box Sizes

Though specific projects need various box sizes, experts recommend employing as few as possible to make production and testing at the precast concrete plant as simple as feasible. Purchasing extra forming equipment to generate a wider variety of sizes is a significant investment unless businesses have already invested in adjustable formwork. Additionally, arranging the production of a range of sizes might be difficult.

Adding A Bend to Your Culvert

Contractors will often leave a small opening in one side of the joint in a few sections if a culvert requires a curve. However, extreme caution should be exercised during this procedure, as overextending the joint (more than 12″) raises the risk of a joint leak. Working with the producer to map the sequence of each box at the job site, then marking or numbering the boxes for easy identification and appropriate installation, is one technique to facilitate the installation of bent or skewed boxes.

What Is the Best Way to Place Box Pieces On the Job Site?

Suppose a contractor is unfamiliar with box section installation. In that case, a representative from the design engineering firm should be present, at least at the beginning of the project, to ensure proper processes are followed. If gasketed box sections are used, a representative from the box and gasket manufacturer can speak with the installation crew on proper joint and gasket techniques.

How Should Joints Be Examined?

ASTM C1677: Standard for joints for concrete boxes employing rubber gaskets and ASTM C1619: Standard specification for elastomeric seals for joining concrete structures should be used to specify gasketed box projects. These include the proof of design testing that producers should complete before sending box components to a job site. Joints can also be field tested with seals made by companies that specialize in joint seals. These box culverts businesses offer a variety of equipment for isolating joints and testing them under vacuum or hydrostatic pressure. These gadgets are expensive and aren’t adjustable to different box sizes, so whoever is in charge of the testing could making a significant investment.