Concrete over asphalt?

[Jim Benante]

I am pouring a small pad to act as the first step to my front porch. Half the step will land on the driveway and half in the dirt. I will dig out and lay gravel in the dirt area, but was wondering if I can pour concrete right on top of the asphalt or do I need to cut it away?

[Russ Filtz]

I would bet it's best to cut out the asphalt and prepare the whole area the same. Otherwise you might get differential settling.

[Mike Langford]

I agree with Russ.....Cut the asphalt! That way there's no chance the concrete will crack with uneven settling and/or from temperature changes.



my .02 cents :)

[Jim Benante]

Can I use an abrasive blade with my circular saw or is there a better way?

[Jim O'Dell]

Unless you have a saw you're willing to throw away, I'd go rent an electric jack hammer with a wide spade bit. Should get a fairly straight cut. Jim.

[Bob DiGiacomo]

Buy a 7 1/4 concrete blade or as called diamond blade for your circular saw and cut a straight line in the asphalt. Then take a pick axe and chop away the asphalt. You can use the small pieces of asphalt anything less than an inch an a half as the base for your concrete make sure you tamp it down with a tamp.:cool:

[Chuck Saunders]

Dig out the dirt, fill with rock, compact well, pour pad over asphalt and rock. This is a pad for foot traffic not a driveway. If the pad is uniform thickness it is not going to crack, at worst it would rock.

[Cliff Rohrabacher]

IN NJ the road Dept regularly patches old concrete roads with asphalt. It's great stuff~!! Only destroyed one of my cars when a boat size chink came un-moored in an ice storm and ripped my undercarriage out.

Asphalt and concrete don't work and play well together.

[Chuck Saunders]

Well Cliff, you best keep your car off Jim's patio. There is probably a different set of criteria covering overlayment on the highway than a slab resting on pavement.

[Leigh Costello]

We used to live in the 'burbs. One of our patio improvements called for some new concrete steps. The contractor poured over asphalt. Several years later, and foot traffic only, the step would rock. Not a problem, we thought. Until someone stepped onto the rocking step and fell. Thank God for a family tree that is sprinkled with lawyers! I will always recommend cutting through and removing the asphalt. HTH

[Jim Benante]

Since it is a small section I guess I'll play ultra safe and cut it out. I think I am going to try to score the asphalt with a circular saw and abrasive blade and then use a rotohammer to finish it off. I probably only need to cut about 5-6 lineal feet total.

Hey thanks for the help.

Someday I'll post some pics if I can ever finish this year long addition and front porch project.

[Rob Russell]

Seems to me that a Sawzall would work well here - just put a masonry blade in it.

[Ron Jones near Indy]

I was going to make a suggestion, but I see Rob beat me to it. Sawzall!:cool:

[Jim Benante]

Off to the Depot to find a masonry blade for the sawzall. Hadn't thought of that and I always enjoy using the sawzall. I didn't know they even had masonry blades for them. Thanks for the tip.
I have been procrastinating a little with this step in the process and have used my time to install the decking. Ipe is beautiful and hard. My abs are sore from the pressure required to drill the countersunk plug holes. Cool to see it smoke after each hole is drilled though!

[Chris Kalkowski]

Hire someone.

[Jim Benante]

Well I tried the sawzall and it cuts, but would have taken about a week. Advice for those wanting to cut asphalt.... rent a concrete cutting saw like I did and it is easy work. Unless you have a lot of cutting to do the disposable abrasive blades work well and at $6 bucks a piece you can buy almost ten for the price of one diamond saw.

Anyway I cut the asphalt and then used a iron breaker bar to bust it up. I have nice clean lines.

[Rob Russell]

Good to know - thanks for the followup post with what worked (and didn't work).