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All You Need To Know About Precast Box Culverts

13th April 2021

Usually, we tend to ignore the magnificence of infrastructure when we pass by it. On rare occasions, however, we look back and appreciate the magnitude of the construction and the planning that backed it up.

Precast box culverts back some of such infrastructures like bridges and tunnels. They are widely used under roads, railways and runways to allow drainage and water bodies to pass through. Box culverts are the architectural solutions for the future of 21st-century infrastructure. They offer durable, robust and economical solutions to construction projects involving bridging and water passage. 

With multiple applications, flexible design and countless benefits, precast box culverts are the go-to solutions for various civil constructions. It provides you with reasonable and practical solutions to your construction needs without the hassles of constructing on-site. Precast allows for quick and safe installation without holding the incoming traffic and disrupting other services.

These precast construction tools usually come in two shapes. One is an inverted ‘U’ on a concrete base known as a crown unit. Another is a U shaped unit with a lid called the invert unit. 

At Dallcon, we manufacture and supply custom precast box culverts to fit your needs. With over two decades of experience in the industry, we can guarantee the best quality concrete products at reasonable prices, followed by an outstanding customer service plan. 

Applications Of Box Culverts

Precast concrete box culverts are commonly used to manage storm drains, stream crossings, sewer systems, utility tunnels, etc. A wide range of construction projects use these structures for construction. Though most drainage projects tend to use box culverts, there are other applications of the structure. Here are some other fields where box culverts are employed.  

  • Water conveyance
  • Stormwater detention and retention basins
  • Rainwater harvest systems 
  • Vehicle and pedestrian tunnels
  • Utility tunnels 
  • Under crossings for wildlife, especially fishes
  • Below ground storage areas, wine cellars

What Is The Process Of Installing Precast Box Culverts? 

Once the box culverts are designed and cast in concrete, they are ready to be shipped and installed according to the project needs. Here, we have highlighted the process of installing box culverts. 

  • Bedding preparation 

The first step in the installation process starts with excavating the site and preparing a reliable foundation for the culvert. This is called ‘bedding’ for the box culverts. This area needs to house the box culvert, its content, and the loading above the box culvert while bearing its load. A trench is created with enough depth to support the heavy structure of the culvert. 

You should not assign this task to someone without experience. You need to deploy an experienced contractor who has an idea about the repercussions of faulty site preparation for this task. Since most box culverts are used in repairing old infrastructure, securing the foundation is a high priority task to reduce hazards and mishaps. 

A reliable engineer should be assigned the task of designing box culverts. For such construction, simply having experience and expertise in the field may not be sufficient; he/she must have an idea about local ground conditions. Studies on the history and soil tolerances of the area can help determine the scope of the project. 

High flowing water can sometimes sweep away the bedding area. Engineers can use dewatering methods to prevent the excavated area from relocating due to the underlying water body’s pressure. Any irrelevant material like rocks within six inches from the foundation needs to be excavated as well. The next step is to add granular backfill to support the addition of the culvert. 

  • Backfilling Method

Backfilling is the process of putting back the excavated material to secure the new installation of box culverts. It begins as soon as the culverts are placed on the trench. The filling must be monitored as it continues to fill up to the top of the box. Constant supervision is needed to ensure proper alignment of the box culverts.

Some tests must be conducted to identify the load capacity of the added box culverts.  It is advisable to avoid operating heavy vibratory machinery around the area both during backfilling and testing. Once the trench is entirely filled till the top in compact layers and the testing ends, the backfilling process ends. The box culverts are set on top after successful screeding of the backfill.

  • Conventional Lay Direction 

An ideal way to check the correct layout of box culverts is to look for the direction of used plugs. The spigot has to be facing downstream, with the bell end facing upstream. The correct way suggests starting downstream and moving upwards to lay down the box culverts. This is a general guide, whereas different states may set specific regulatory requirements. Companies must align with these rules to avoid legal roadblocks. 

  • Sealing The Joint 

Sealants play a vital role in the installation of every precast box culverts product. The choice of sealant determines the need for maintenance and ensures security as well. Since most concrete structures react to the environment factors and experience expansion and contraction, the sealant has to accommodate the movement. The operability and standard ratings for safety hazards must be evaluated before choosing one.

The most common sealant categories available in Australia are

  • High-Performance Sealants and
  • Plastic sealants
  • High-Performance Sealants

This category has two sealants: Polysulphide (PS) and Polyurethane (PU). 

For a number of years, Polysulphide was used as the first choice as a sealant for construction projects both under and over water bodies. Over time, price hike, the necessity for a primer, and slower application time contributed to its plummeting popularity. They are seldom used in the modern market. 

In most joining sealing applications, polyurethane seems to have taken the lead. It comes with a standard curve, with fire rating, potable water, acoustic and sewage certifications. This has become the standard sealant to use in masonry in most construction projects.

  • Plastic Or Plastoelastic Sealants

Acrylic sealants are one of the prefered plastic sealants as they are water-based. Over time they tend to restrict movement and shrink as well, so they cannot be applied in all construction areas. Butyl sealants and dry jointing systems are also gaining popularity nowadays with their wide use, mainly in bedding or compression seal applications.

Most people assume the sealants will be installed in ideal weather conditions, but the reality pans out differently. Correct joint design, planning, and application technique are vital to ensure the selected sealant works as desired.

Sealants need to be covered with an exterior membrane to prevent them from eroding or left open as they depend on the water flow, budget and plan of the project.

Benefits of Using Box Culverts

Numerous advantages accompany your choice of precast box culverts. We have listed some of them below. 

  • Timely delivery of superior and reliable structural solutions 
  • Feasible time-saving option
  • Off-site manufacturing ensures high-quality outputs
  • High strength endurance  
  • Minimal maintenance required 
  • High load capacity
  • A significant sustainable solution
  • Faster, uninterrupted construction 
  • The simplified and safer construction process
  • High-quality surface finishes

What Can We Offer?

Each construction project comes with its specific demands and unique requisites. Dallcon has successfully contributed to completing numerous of Western Australia’s most significant infrastructure and construction projects.

With our avid focus on professionalism, technical expertise and value-driven approach to customer service, we are proud to call ourselves the leaders in delivering high quality engineered concrete solutions. 

Customised Products 

We produce precast products for all solutions regardless of the scope of the project. When engineers outline different measurements for specific projects, Our team always makes sure they study and analyse the specification correctly to create a product that matches the requisite. Our team of experienced technicians are well-equipped with the right tools and technical knowledge to construct the required structural design for projects of all sizes. 

Reasonable Pricing 

We are the leaders in precast solution manufacturing and delivery. We have formulated a successful methodology that ensures high-quality concrete solutions reasonably through years of experience. Our prices vary according to the magnitude and requirement of each project. You can contact us to find out more about our competitive rates. 

Time-Saving Solutions

Our precast products can save significant time in a construction project by eliminating the need for on-site construction. On-site development projects usually produce uneven results and take up more time due to the complexity of ever-changing weather conditions and unmanaged workforce. With precast construction solutions, you get factory-made products built with stringent production standards. It ensures a consistent quality product ready for installation.

Reliable Service

We have a dedicated sales team in place to acknowledge and respond to client enquiries. Our sole focus is to produce and deliver excellent concrete products on time to meet our client’s requirements. We aim to provide quick and innovative solutions to diverse consumer needs, which has allowed us to thrive in a competitive industry for 20 years. The success stories from our former clients uphold our trustable reputation.

Get in touch with us today to learn more about the products and services we offer!

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