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Masud Rana

Whose coefficient of friction is greater on concrete, rubber or steel?

Bruce Thomson  Follow

Since you want to replace the steel I assume you wish to use a rubber tube in this project. No because rubber is elastic and will stretch easily, The sole purpose of filling the tube is to increase the lateral stability of the member and rubber is eseless for this purpose

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Anne Eastman  Follow

Can’t tell - too many unknown variables. Use .3 - no matter what the materials - you’ll be right a lot of the time

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Ayhan K. Isaacs  Follow

There are 3 kinds of friction: static, kinetic and rolling.

Rolling friction is the easiest to overcome, by far

Fr = cW where c is the coefficient of rolling friction and W = mg is the weight of the vehicle.

Steel railroad wheels on steel track, c = 0.001 – 0.002

Truck tire on asphalt, c = 0.006 – 0.010

Kinetic (“sliding”) friction is the next easiest to overcome.

μ = Ff/Fn where Ff is friction force, Fn is normal force

Cast iron sliding on greased cast iron, μ = 0.07

Teflon on steel, μ = 0.04

Steel on asphalt, μ = 0.05 – 0.20 (composition of asphalt is variable)

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David Cummings  Follow

Depends. For example, a car uses the road and has rubber compound tires, as do other forms of public roadway conveyance (bicycles, scooters, mopeds, motorcycles, trucks, ATVs). Despite this, I know you’ve heard of bulldozers with tank-like tracks, having to use a section of road to maneuver to the jobsite. Even more prevalent, perhaps, seeing enormous steel roller wheels on an asphalt roadway roller (steamroller by some’s vocabulary). You don’t see them slipping around on the road. The answer seems to rest on whether or not you will allow damage to the roadway surface, and whether you are going at a speed that will compromise traction. To be sure, even rubber- tired vehicles will lose traction given too much change in direction or acceleration for their weight and footprint area on the road. Tracked vehicles are a unique situation because they are so massive that they push against the depressions their tracks impress into the roadway, almost like meshing gear cogs. The steamroller gets away with traction because of the designed mass, the limited roadway speed it can attain, and being specified as to how much grade it can be safely used on. Tractions - yes, for one and all, but each with tradeoffs and speed limitations. In order to compare, you have to have wheels of the same diameter and footprint, applying the same amount of pressure, by spinning them in successive runs against a concrete wheel, and apply braking resistance to the concrete wheel, while driving force to the rubber or steel wheel. The wheel requiring more force to maintain it’s speed before slippage, has the greater traction.

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David Brower  Follow

No…steel is heavier. A cubic yard of concrete is around 3,300–3,500 pounds. A cubic yard of steel would be around 13,000 pounds….that’s why you never see re-bar floating on concrete.

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Brian McNellis  Follow

Friction is one of my favourite topics in Classical Physics, it's one of those borderline topics that can be explained with various levels of depth and difficulty. I'll try to raise that level, gradually.

Intuitively, friction is the that property of matter that makes it “sticky". Think for example of a solid object, for simplicity we will make it 0-dimensional (we can think it as a point), so that every force will only act on it through that only and special point. Now, what happens if I push that same object with a force [math]overrightarrow{P} [/math] ?

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Dave Saruya  Follow

Most sources will disagree on the actual coefficient of friction for materials probably because of all the variables involved . It is also dangerous to use those figures in an actual design without doing field testing on the materials to confirm the actual coefficient of friction . For concrete on concrete dry a coefficient of .8 is often used and .65 for wet . Keep in mind a factor of safety should also be used . Setting that at 2 will give .4 dry and .32 wet .

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Claude Sundae  Follow

Any two substances in contact have a coefficient of friction (actually 2, one kinetic and one static). The fact that it is rolling has nothing to do with the value of the coefficients for these two surfaces.

Or are you interested in the force of friction? That is a different question.

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