Concrete joint technology 2

[bkengr18206]

I have been out of the highway/flatwork pavement industry for a few years. I am trying to help a long time client evaluate concrete versus asphalt pavement for a several large projects coming up. They are in the trucking business with terminals.
We are getting pros and cons from both industries.

The concrete guys say they have joint deterioration problems resolved wiith special inserts, saw cutting joints, etc. and can eliminate steel reinforcement with higher strength concrete mixes.

The asphalt guys save they can resolve swaling and rutting with several new methods.

Anyone with real life experience or good studies.

 

[Ron]

I would use a combination of the two. In the high abrasion, high concentration areas such as the truck docks and trailer staging areas, I would use concrete. Specify that sawcut joints be made the same day as placement and no more than 8 hours after finishing. Joints should be no more than 12 to 15 feet in any direction and should be cut to a depth of 1/4 of the section thickness. Make sure that the concrete thickness tolerance, both over and under is met. Use dowels in all transverse joints. I usually do not specify reinforcement for the concrete, though wire fabric, if placed properly is desirable. If no wire fabric is used, then use steel fiber enhancement to the concrete. Polypropylene fibers are worthless for this application.

The higher strength of concrete is somewhat irrelevant. Use 4000-5000 psi concrete and don't worry about it.

As for the transition between asphalt and concrete, place the concrete first and slope the face of the concrete toward the asphalt by about 15 to 20 degrees off vertical. This will help keep the interface joint sealed, because when traffic goes across the joint, it pushes the asphalt against the concrete, keeping the seal intact.

 

[Hoaokapohaku]

@Ron

In thirty years, I've never seen your concrete/asphalt joint solution before in plan or practice, but it's so obviously a good idea I don't know why it isn't always done. I'm going to put that one in my personal bag of tricks. Thanks!

 

[Ron]

Thanks, Hoa. After reading my post, I described it incorrectly, but I think you got what I meant. I should have said that I slope the concrete AWAY from the asphalt, not toward it. Just designed one today for stamped concrete golf cart paths across an asphalt roadway. I've been using this detail for about 20 years and it seems to work.

 

[Hoaokapohaku]

Ron - I like the idea because it should keep the joint sealed as you mentioned. Also, a common problem with these joints is the same problem as when there is a joint between two concrete slabs with nothing to provide load transfer between the two joints. Your design provides a degree of load transfer and support right at the location the asphalt pavement is most vulnerable.

How did you arrive at the 15 - 20 degrees? Have you experimented with a steeper angle?

 

[Ron]

Hoa...if the angle gets any steeper, the concrete will tend to break off. Keeping it only 15 to 20 degrees off vertical prevents this....sort of just enough to cause the push against the concrete, but not enough to create a ledge on the concrete.

 

[bkengr18206]

Thanks for the help Ron. I meet with the client next few days and will give them the info with my other research
Thaks again

 

[almosawy]

Ron .. good Idea from your side for this concept of joint. I think it will be useful for paths with light load but I think if we use it in high load, there are many problems will appear like creep and so it will make cracks .. thank you

 

[bkengr18206]

Thanks Ron, Hoa & Almo. This is what i needed. Tuning off thread