FAQ
What causes potholes?
Possible causes of potholes include... high traffic or turning areas, asphalt that was too thin, base failure under heavy loads or poor drainage that weakens the sub-grade and base. Poor quality (segregation in the asphalt, poor compaction, chemical/diesel spillage or asphalt that was burnt or did not have enough oil mixed into it) may be a contributing factor.
What are some of the causes of asphalt failure?
Inadequate thickness of the carpark/driveway section to support the loads that travel across the asphalt, lack of maintenance, and weak or unstable sub-grade components.
Asphalt deteriorates when weather and traffic wear "fines" aggregates away. When the "fines" are worn away, there is nothing to bind the larger aggregates together and the surface begins to ravel. This weakens the pavement section and eventually allows water to penetrate the sub-grade, which leads to pavement failure.
How long should a newly resurfaced carpark/driveway last?
Depends on deflection of the original area (prior to resurfacing), how many trucks/cars use the area and the thickness of the new asphalt layer, but its been know to last up to 30 years if great care has been taken.
How thick should the asphalt be?
Asphalt carparks/driveways have defined strength co-efficients that determine their service life based on actual traffic conditions. The thicker the asphalt, the longer the area will last. For pothole patching we like to put more than what was originally installed .
In general, we use the following guidelines to determine asphalt depths:
• 25mm-30mm average for domestic use • 45mm-50mm average for commercial use
If there are budget constraints, do less area at the appropriate depth, not more area at less depth!!!
What causes the cracks in my asphalt?
All pavement failure starts with a crack. Asphalt cracking is caused primarily by the effects of sun and moisture and ground movements. Asphalt is flexible when new, but with age it becomes more rigid and is less able to tolerate vertical deflections. This causes a tension and pulling apart in the pavement and before you know it you have a crack. Once the crack is open, moisture is able to reach the asphalt subsurface and soften it. Soon the asphalt begins to deteriorate around the crack, creating a larger problem. Proper attention to the cracks will prevent the problems from spreading and double the life of the pavement. Treating the problem while it is still small will pay big dividends later by delaying costly resurfacing.
What causes crocodile cracks?
Usually crocodile cracking is caused by excessive deflection of the pavement due to an unstable base or due to repeated traffic loads heavier than what the road was built to withstand. If this cracking is not addressed then it will expand and cause more damage turning into a very costly repair.
Why can't crocodile areas be crack sealed?
When crocodile areas appear in a parking lot it means that water has penetrated the sub-grade layer and the asphalt area can no longer support the weight of the traffic. Crack sealing is not the solution at this stage.
Why are there cracks in the asphalt along the edges?
Edge cracks are usually caused because there is not enough support next to the road or the base has washed out. It is good if you can avoid driving on the edge. If you do get cracks Pothole & Co can have them filled with a rubberized crack filler. If the cracking is severe we may then have to cut it out and replace it.
Where should speed bumps/humps be installed?
Generally, speed bumps are installed in a carparks, driveways or a complex to slow drivers down and protect pedestrians. they also reduce speeding and cut through traffic. If possible, install speed bumps between islands so that cars cannot drive around them. By law in Australia shopping centres or unit complex etc must comply to a safety standard, be covered by public liability and have speed bumps installed.
When must a carpark/driveway be removed and replaced?
If the existing carpark/driveway is completely unusable due to age, neglect or change of use, then there is no other option but to remove and replace it. If the asphalt area or driveway is 60% damaged in general then it is more cost effective to remove it all and start over, opposed to continued repair patching.
How long before traffic is permitted on a newly resurfaced area?
Newly laid asphalt/bitumen will need adequate time to cure and set, its not possible to give an accurate time for this process as it will vary on materials used, weather conditions and time of year laid. Care should be taken to avoid sharp turns (especially power steering marks created by non-moving vehicles) a cover of general builders sand across the surface will stop tyres getting traction and help protect the newly laid asphalt surface.
Why are there scuff marks on new asphalt surfaces?
Scuffing of newly sealed or paved surfaces are inevitable as it is the nature of asphalt material combined with hot weather. After about a month those scuff marks are rarely noticeable. The scuffs are just the sand being displaced and will wash away. Asphalt requires approximately 6 months to fully cure and set. In the early stages the asphalt is tender and best to be a little careful. Avoid tight turns, and turning the steering wheel when the vehicle is not moving. Avoid sudden stops if you can.
Why doesn't asphalt stay that nice rich black colour?
The UV rays from the sun breakdown the carbon bonds in the asphalt oil thus causing the colour to change from black to gray. It is this oil that binds everything in the asphalt together so when it is depleted erosion starts, some sand particles at first and then larger pebbles to stones then with water infiltration it is all down hill from there. This oil is also what keeps the asphalt flexible. So when the asphalt is gray and oxidized it is less flexible and more prone to cracking.