Looks like we are adding a 60' concrete pad to the Eagle Field runway for our Drag Races. What final finish sould it have? And if broom finish is reccomended what direction would you pull the broom?
Does it matter if you drag it toward the finish line or to the starting line? I really appreciate the info and we are only getting one shot at this! Rocky
Broom finish NOT! As smooth & level as you can get it. I will see if I still have specs & proper info on file. Have been involved in total track reconstruction to Nat event standards. Concrete should be continuous pour & saw cut. Not poured in separate sections. Expansion saw cut at concrete to asphalt transition. If not done, a bump will develop at concrete to asphalt transition. Vern Christy
This is exactly right. You want the surface to be as smooth as possible, for the same reason you run slicks, and not tread on racing pavement tires. Maximum surface contact.
And do NOT tamp the pour. Screed and finish. Firebird had one side come apart on the surface because it was tamped.
Forgot to mention. Do not use Concrete with fiber product in mix, as is used in some construction methods. It will leave a dust like residue as surface is used. You will never get rid of it & make it impossible for good racing surface. Know of one track that made this error & it required total replacement. Thanks Dean, someone who understands!
Good advice. Competent concrete finishers should know to avoid tamping. It's done to force the rocks down and bring a layer of "paste" to the top thus making finishing easier. However, this can result in a top boundary layer with excess bleed water which reduces durability and often results in scaling and de-lamination. I'd use a 4000 psi mix with a mid range water reducer, 3%-4% air, and placed at no more than a 4" slump. Bob
If you want it smooth, it will have to be ground afterwards. Having Penhall to come out and grind it (which leaves very small grooves) properly isn't cheap.
I wouldn't think grinding would be necessary. Look at the bare concrete floors in Lowe's, Home Depot, or other "big box" stores. Those are finished with powered trowling machines, and are plenty smooth, almost to the point of being slippery. Grinding is generally used to correct flatness profile, which shouldn't be confused with the actual surface texture. The floors in the "big box" stores are done with a laser screed, and are flat within 1/8" in any 10'. A drag strip apron doesn't need to be that accurate. Bob
I AM sure glad I asked! We are pouring a 60 x 60' starting area in the OLD air strip that we have two races a year on. Knowledge of the HAMB is incredible! Rocky
PM concreteman (Chris) http://www.jalopyjournal.com/forum/member.php?u=56896 He knows the "right" people to help you out!
I have located spec sheets provided by IHRA in my files. If you would like copies, pm me at ms132033@yahoo.ca & I will send them.
We use polypropylene fiber in our mixes when requested. I've never known it to cause dusting. Dusting is generally the results of improper finishing technique. Excessive bleed water on the surface dilutes the paste to the point that it can kill cement hydration, thus preventing proper hardening of the paste in the top boundary layer. Excessive water on the top surface during finishing can be the result of excessive slump, or water thrown onto the surface by the finisher to make finishing easier, but in either case it's detrimental to the proper hardening of the surface. The surface of a slab so affected even when fully cured, is easily scratched with a pocket knife blade and will yield a sandy powder from the scratch. Bob
I'm curious now. What finish is applied to concrete paving on a racing surface? I've poured and finished thousands of yards of concrete, but it's been many years ago and most of it was indoor flat work. Never did any real paving. I read the comment about slick finishes at big box stores. I know from experience we could produce a hard, slick as glass finish. Don't know how I'd hook up on it though, even after it's sprayed. Obviously there are some guys here with expertise. I'd love to hear about how it's done.
I'm no expert, but I've stayed at a Holiday Inn Express and I own a ready mix concrete business. We only manufacture and deliver it, but by nature usually get involved in what's going on at the jobsites because we do on site testing and job co-ordinating with the customer. Road surface requirements will no doubt vary from state to state, but the most popular finish for concrete roadways in my area (Southeast Louisiana) is a "burlaped" finish, wherein a large sheet of burlap is dragged behind the slip form paving machine, or dragged by hand when the concrete is placed manually. This yields a grainy surface finish that's lower in profile than a broom finish, but not slick like a hard machine troweled finish. Seems to me that would be the best finish for a drag strip. Bob</snip>
hey rock... make a visit to famoso. look at the concrete on either side of the groove. its nice and smooth. talk to john or blake over there.
Makes sense. The tracks I've walked weren't rough like a parking lot, but there had to be enough teeth in the surface to grab hold of the rubber. I always thought it looked like a light broom finish. Thanks.
Never heard of the burlaped finish, but it sounds ideal for a dragstrip, on the road surfaces here in Central Texas, TXDOT seems to like the very lightly broomed finish.
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