Concrete Rehabilitation: Slab Fracturing
If you’ve ever seen pavement before, you’ve seen damaged pavement. Even in the best weather in the world, pavement eventually develops ruts, pits, cracks, and more. As it gets worse, it can turn into potholes and uneven surfaces. Finally it crumbles and gives way. One of the bigger problems facing most cities regularly is maintaining its asphalt paving and concrete paving. There are plenty of things that can be done, such as seal coating, hot mix repair, cold mix repair, and full-depth repair. Finally, as a last measure, the pavement can be completely replaced.
One of the keys in repairing and maintaining asphalt is of course cost. Economics plays a big role in any element of construction, and asphalt paving is no different.
The present solution to asphalt repair and longevity
The current solution is asphalt overlaying. Nearly two-thirds of the Portland cement concrete (PCC) pavement in the US has been overlaid. It’s a cheap and relatively effective solution to handling asphalt damage. Portland cement concrete is the most common type of general use cement around the world. It is also the basic ingredient of concrete.
However, it has some persistent problems. The first is that cracks at joints appear in the overlay. The second problem is that cracks come through from beneath the overlay, and the overlay itself becomes cracked as well. That type of cracking is referred to as reflective cracking. This means that the solution in the end once the overlay is damaged is full-depth repair or replacement. The problems with those two forms of repair is that they are time consuming and costly.
That’s where slab-fracturing comes into play.
What is slab fracturing?
Slab fracturing is used on PCC before overlaying to increase its structural integrity. Essentially, it means that the damaged pieces of concrete that will be overlaid are further broken. This process may seem counter-intuitive, but it is effective. Damaging the underlying concrete slab helps reduce future damage to the overlay. Slab fracturing is also referred to as rehabilitating concrete.
It is based on the principle that damage to the slab below the overlay reduces stress. It does so by spreading out the load from weight across the whole surface of the concrete. This prevents extremely concentrated loads that can crack and damage individual parts of the paving. The use of slab fracturing reduces crack at joints, and reduces reflective cracking in overlay. There are three main ways that it is used.
- Crack and seat (C&S) for PCC without steel reinforcement. This is intended to reduce the slab length of PCC. It does so by producing tight surface cracks.
- Break and seat (B&S) for PCC with steel reinforcement. This method requires greater effort to break the PCC slabs, rather than simply cracking them. Additionally, the added steel increases the surface strength. It does however, cost more due to the breaking process and the added materials.
- This process is exactly what it sounds like. It involves breaking down the slabs beneath the overlay into 4-8-inch sized pieces. This method is cost effective, because the rubble remains in place after breaking. That means that there is no transport to or from the worksite.
What is the best method?
Well, beauty is in the eye of the beholder. The preferred methods are based on a combination of ease of performance and cost-effectiveness. A survey of stakeholders showed that crack and seat, and rubblization were the most popular. Most likely because they are the cheapest and still highly effective. Of course, some pavement receives extreme use by heavy machinery, construction vehicles, and loaders. This pavement will probably benefit from the steel reinforcement to ensure the overlay doesn’t crack under the weight.
Is slab fracturing it effective?
Rubblized cement with a 5-inch overlay was highly effective. It inhibited reflective cracking and had little performance differences otherwise. Surface smoothness, rut depth, and other cracking was found to be the same as other surface restoration methods. The other methods it was compared to were minimum and maximum restoration, as well as overlays with sealed and sawed joints. Researchers also discovered something else: it could be perpetual. That is, rubblized PCC could last indefinitely. It could do so under two conditions. The first was that the overlay was 8 inches or more. The second condition is that the foundation is strong enough. Of course, there would still need to be some maintenance done to seal coat and keep it protected.
It was also possible to prevent reflective cracking with the B&S and C&S methods. In the right conditions, reflective cracking would not happen at all. Even in the wrong conditions, their performance for reflective cracking was quite good.
Is your interest piqued? If you simply can’t get enough concrete slab rehabilitation, you are in luck. Here is the long form report from the NCAT. The NCAT is the National Center for Asphalt Technology. You’re welcome.
What’s the verdict?
Concrete slab fracturing is a cheap and effective way to rehabilitate concrete. It’s better than replacement and cheaper than other forms of repair. Not only is it strong and low-cost, it’s also better for the environment, requiring less outside materials. In short: rehabilitate, don’t replace.
Does your concrete need some rehab?
If your concrete paving isn’t looking so good, get it fixed reliably. Reliable Paving is a professional, experienced, and dedicated construction contractor crew. With a team of over 200 and experience paving all over the Dallas-Fort Worth area, no job is too big. Our services offered are many, including concrete maintenance, seal coating, repairs, replacement, striping, and laying asphalt. Don’t let your paving fall into disrepair any longer. Contact us today to get started on getting your pavement into tiptop shape.