Can We Lay a Concrete Surface on an Existing Bituminous Road?

Yes, it is possible to lay a concrete surface on an existing bituminous road, but with certain considerations and improper techniques, significant issues can arise. The primary concern is ensuring that the rigid concrete slab is laid on a suitable and stable foundation. This article will discuss the methods for achieving this, the process, and the key factors to consider.

What Happens When A Concrete Slab is Laid on an Asphalt Driveway?

Placing a concrete slab on an existing bituminous (asphalt) road can result in several problems, including cracking and failure. Unless the existing asphalt road is in excellent condition, it will not provide a stable and flexible base that supports the rigidity of the concrete slab effectively. As a rule, a rigid structure should not be built on a flexible foundation without appropriate reinforcement or support, as this mismatch can lead to structural failures.

Overlay Construction: A Common Solution

Fortunately, there is a standard construction practice known as overlay, which involves placing a new layer of concrete or asphalt over an existing road layer. This method can effectively strengthen and improve the overall performance of the existing road without the need to completely demolish and rebuild it.

When performing an overlay, it's crucial to ensure that the subgrade and base courses are well-compacted, as a weak or poorly compacted base can compromise the integrity of the entire overlay. The process also involves removing surface defects, properly grading the surface, and applying a well-compacted layer of asphalt or concrete. This creates a stable foundation to support the new concrete surface.

Design Considerations for Concrete Overlays

The design and construction of an overlay must carefully consider environmental factors, traffic loads, and the existing road conditions. Typically, IRC 81:1997 – Guidelines Strengthening of Flexible Road Pavements Using Benkelman Beam Deflection Technique is referred to for detailed design specifications. The Benkelman Beam, a type of deflectometer used to measure the deflection of road surfaces, helps in assessing the condition of the existing pavement and determining the required thickness of the overlay.

Proper design and execution of the overlay are essential to ensure that the new concrete surface will perform well and last for a long time. Hiring experienced civil engineers and construction professionals is advisable to achieve the best results. Additionally, maintaining and managing the road through regular inspections and timely repairs can further extend the life of the overlay.

Conclusion

While it is feasible to lay a concrete surface on an existing bituminous road, it requires careful planning and execution to ensure success. Understanding the key factors involved, such as foundation stability, proper design, and adherence to best practices, is crucial. By doing so, you can achieve a long-lasting and reliable road surface that benefits both drivers and the environment.