A place to highlight best practices and discuss key issues (security, environmental, etc.) related to transportation, including (but not limited to!) the impact of Web-based tools and mobile applications.
Could a polymer modified concrete pavement preservation material be as cost effective as a BITUMINOUS pavement preservation material?
April 28, 2010 at 5:14 pm #99349
April 28, 2010 at 5:54 pm #99355
I couldn’t tell the exact type of preservation materials the blog was talking about but offer these comments for the types I suspect it could be:
If sealcoating/slurries/microsurfacing/etc are the intent, I could never justify the cost of applying these on a local roadway. We could barely keep up with the schedule needed for overlaying/reconstruction with the amount of funds available so would have never had extra money to spend on a surface treatment. Also, for local roads, the extra life we might have gotten from these materials was also not worth the added cost. A lot of our failures seem to be structural, and I don’t believe the surface treatments would increase the structural coefficient enough to make it worth the money. As for asphalt vs. concrete materials, I would not feel either provides enough value for the money so whether one is better than the other would not matter to me.
I also have some reservations about ultra-thin whitetopping, at least in the midwest climates. Perhaps others in warmer climates have more success with these materials.
April 30, 2010 at 7:01 pm #99353
I agree fully with you that using a pavement preservation material (slurries, chip seals or microsurfacings) to replace a structural overlay would be bad practice – especially given the significant reflective cracking. Therefore, clearly, if you are stuck in a reactive maintenance program (due to limited funds) where project selection is based on worst street first, then it is really difficult to adopt a proactive strategy using preservation techniques. So again I agree with your sentiment. I suppose, if one could follow the FHWA guidelines of applying preservation techniques prior to achieving the magic 40% of the structural life, I think one could argue that they would have value from both systems. The reality is that if you are using asphalt or asphaltic surfacings, it is like buying a new car, it starts depreciating (aging) the day it is put down. Does the focus on a “worst pavement first” simply perpetuate a ever degrading network system? Why not spend a little extra and today and try some innovations to get you to try to break this spiral? The current asphalt materials were engineered with a healthy economy in mind – with little thought for age resistance. Why not challenge industry to help you make the current materials work better. For example, I think an 1/8 of an inch thick concrete surfacing (no not ultra thin white topping) could preserve a newly laid asphalt layer – arresting aging. There are great new surface coatings/emulsions that can dry solid in 15minutes and be ready for traffic. There are other emulsions set to explode on the market that also rejuvenate asphalt surfaces. What do you think – I would like your comments – given your circumstance?
TIC (Atlanta, GA)
May 31, 2010 at 12:30 pm #99351
I think a significant lack of funding for road repair perpetuates an ever degrading network system. But if we just focus on topic of pvt preservation, I am not sure it is necessary on all roads. For low-volume pavements, I have seen asphalt roads perform for 40 years with no need to do any type of surface treatment. However, on high-volume roads, I have seen new asphalt overlays begin to fail in just over a year. And for these, I am not sure a surface treatment would have much effect since the failure is usually due to traffic volume (loading). There are probably roads supporting loads between these two extremes that could perhaps benefit from a treatment.
The challenge would be to figure out which roads would benefit, apply the treatment at the right time, and have the funding to support this program. The biggest problem obviously being limited money.
But I still can’t imagine putting only an 1/8 inch thick layer of concrete over an asphalt road and have it hold up to traffic. We tried hiring a company to do something similar over a sidewalk and it exhibited multiple cracking within the first year. It would be great to be able to see photos of this type of treatment just after application then after a year or so of loading.
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