Let's talk track surface

#1

I have noticed that some tracks feature concrete inserts in the turn area along the line. Notably IRL Englishtown and the track I am simming on, Watkins Glen.

IRL and in game these concrete inserts accomplish the same thing: Big Grip Zone.

Since concrete makes so much more grip, I googled and found this intersting article:

I guess the question is why? It seems more expensive to put concrete inserts in an asphalt track. That appears to be doing the work twice. It can’t be just for grip.

If it’s a wear and tear thing, why not build the track out of concrete as opposed to asphalt? Weather?

#2

There are 2 car race tracks I’ve run at that had big concrete sections in the corners in the past which are Mid Ohio and Watkins Glen. Both also hosted big grip and big HP racing series in IMSA and Indy Car. My understanding was that the concrete patches in the corner were for better durability in the places where the asphalt could potentially get torn up from high cornering grip and/or putting down big power coming out of turns. I’m guessing the whole track wasn’t done in concrete exclusively due to cost where concrete is generally higher cost than asphalt.

Also worth noting both of those tracks have since been resurfaced and no longer use concrete patches (your Watkins simulation is out of date). I believe that asphalt technology when it comes to racetracks has improved and can now handle the rigors of big car racing better.

#3

Walking around GoPro last year I was surprised to see how the pavement there was getting torn up in the corners. It still drives well, but there is definitely some noticeable wear and tear which I imagine will probably require some maintenance in the not-too-distant future.

Dousman is a good track to contrast that one with, as the original track layout has concrete patches in the corners with asphalt straights. The surface in Dousman is very old at this point - I don’t think it has been repaved since before I started racing there around 20 years ago. Granted, it is probably overdue for a repave, but it isn’t showing the same surface tearing around the corners. The wear and tear there is more from cracks that have developed due to the extreme temperature changes you’ll see throughout the year in Wisconsin, which have been addressed easily enough with some filler.

Granted this is entirely anecdotal - but while concrete is more expensive to lay down, it seems like it is more likely to be able to handle the forces that come with racing compared to asphalt, resulting in more infrequent repavings and less maintenance. However, in areas that aren’t going to see cornering forces, asphalt is likely more cost effective.

But as Chis said, it seems like we’re seeing fewer tracks utilizing concrete these days, and asphalt appears to be holding up better for longer as technology advances. Even at Dousman, the track addition they paved a few years ago is all pavement. Time will tell how well it holds up, but it does seem like we are seeing fewer tracks utilizing concrete now compared to 20 or so years ago.

#4

I would agree that pouring concrete in corners appears to be wear related as opposed to grip (which is a nice byproduct). At liberator track at NJMP, the fast uphill 90 left literally has a groove worn into the asphalt of the exit line.

I am guessing concrete cracks though. I was forever getting big white chucks of concrete flying up from my wheels at etown.

Also, does the weight of the vehicles matter for wear? So, a kart track would last substantially longer than a car racetrack?

#5

I know next to nothing about paving, but isn’t concrete a lot more brittle, whereas asphalt can flex and handle torsion better? If so, it would make sense that concrete isn’t used for entire track surfaces, as it would crack and be unable to handle heaving earth during change of temp and stuff.

Just a guess based on literally no facts.

#6

Good point. Concrete probably doesn’t flex at all.

Concrete seems like it would be ideal for arid and hot locations. Think SoCal desert tracks, Dubai etc, maybe.

#7

Concrete is more rigid not brittle. Concrete has great compressive strength so it is used in corners at martinsville and all around tracks like Dover and Bristol due to the high loads of cars in the corners. Same reason runways are concrete and not asphalt. Over time the concrete will out perform asphalt just from a maintenance standpoint. Well placed and finished concrete on a well prepared sub base will last 30+ years before any potential structural issues as opposed to maybe 10-15 years with asphalt. Down side to concrete is it tougher to patch or replace and historically more expensive to install.

Concrete takes rubber differently than asphalt since it has a closed surface. The rub builds on top rather than getting worked into the surface.

Concrete is actually better than asphalt in colder climates. Less likely to crack and won’t create pot holes. One reason why some states in the north are now replacing highways with concrete.

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#8

I would have thought that the cold would make concrete brittle. That was my assumption as to why it’s not as common.

#9

Its horrific in the rain, probably because the rubber just lays on top of it, unlike asphalt where it fills in the grain.

My experience is only quickcrete being used to repair a track that’s being torn up due to excess heat and grip (we used to be able pull up the asphalt when we lifted the kart on to the stand in Portugal or Spain). But it was great in the dry, once rubber is laid down, but in the wet its like an ice rink. Fortunately because its only on the racing line typically, you can just avoid it.

Having said all that, I think you could build a track out of concrete if you grooved it which I think is possible.

#10

The wet part I hadn’t considered but it makes sense. Asphalt appears to be slightly porous whereas concrete is totally not.

I think I have seen grooved concrete road surfaces in parts of the NE. Very loud to drive on at highway speeds.

#11

As an aside, aspiring racers in sim should pay attention to these concrete patches. If you have any doubts as to the line, the concrete patches usually are right in the heart of it.

#12

No sir. With all the admixtures and plasticizers that can be added it is really the best surface for general traffic.

Nik, you are correct regarding the QUIKRETE. Concrete patches are not sufficient for loads placed on them by karts/cars. Black top can easily be cut out to full depth and patched back in. There are pros and cons to both concrete and asphalt.

A heavy broomed finish would be sufficient for grip on a kart track. Over time the finish will where off but the concrete can always be machine etched to bring back the texture

#13

First 1/8 mile of dragstrips are concrete. Dont really know what that means but Im sure its helpful in some way

#14

Jake,

GoPro is in the process of adding some cut throughs for additional track layouts, as well as reworking some curbs and adding more run offs(for the rentals). They have places to make some improvements around the facility so I am sure some track surface repair/replacement is on the horizon. The hairpin can be brutal.

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#15

I would assume that is due to the launch. 2 parts, keep the surface from tearing apart from the high torque cars, and one pro of concrete is that it retains temperature so much better than asphalt. It takes longer to heat up but once it does it maintains that heat longer. This also makes it more consistent, which now that I think about it makes a ton of sense for drag racing. Since drag racing is bracket style, a cloud cover change from pass to pass could drastically change the temp of blacktop and therefore the time it takes to hook up and launch.

That last bit isnt as crucial in oval/road course racing since everyone is on the track at the same time for the race so it’s more of an even playing field.

#16

All righty. Shane is now our go to guy for concrete and asphalt!

#17

Can’t have a full discussion on surfaces without including the grip patch sealer stuff they use at certain tracks like Pittsburgh. I love watching karts hit it. They can be drifting into the corer, then as soon as they hit that Rhinoliner grip they straighten out and shoot off the corner like a bullet.

#18

That I have no experience with. I am just speaking from a big construction background and growing up in short track racing.

#19

Than again there is also the fact that there is an inch of solid rubber on top so the grip of of the concrete itself doesnt matter. (never wear shoes you like to a dragstrip, the rubber will melt off)

#20

Elaborate a bit… is the surface of the track super sticky all the time or only when hot? What happens if you walk on the track? Shoes stick to ground?