Use of cementboard or Hardibacker for roadbed??

[imrnjr]

Good morning all, my wife and are new to large scale, and in process of building our first layout (my first train in fourty years), and we have a mountain of questions about almost all aspects of the hobby.  We live in the country, and have a variety of critters, large and small, domestic and otherwise that may be able to step on the track. 

I've read several different threads on roadbed construction methods; HPDE ladder, treated lumber, floating, concrete etc., but has anyone utilized cementboard or Hardibacker as a roadbed?  Seems to me that it would be pretty impervious, easily cut/shaped, with limited expansion/contraction issues (average temps range from 15 to 100 where we live in West Central Texas), and easily leveled utilizing techniques similar to the HPDE ladder.  The first things I'm unsure of are sag/distance between support stantions/anchors, and moisture/freeze durability. 

Our primary considerations are naturally cost, and materials availability.  A 3'x5' sheet of 1/2" cement board is approximately $10, which would yield about 30' to 37' of straight roadbed depending on width.  Curves naturally reduce the yield, but have not don the math on that yet.  We welcome ideas/comments/experience on this?  

[Anonymous]

For road bed I'd use Turkey Grit, it's crushed granit and float the track. It can expand and contract with the weather, and once it settles it's not going anywhere!!!

Be careful when cutting/sawing Hardibacker, it's dust is known to cause cancer. Of course everything causes cancer in California.....but still, where a mask. I's use the cement board and Hardibacker as a base for the structures.

This is what I'm doing and it's working great.

http://rides.webshots.com/album/547283539pPilnH

I started last February, click on the link to see the pics.

good luck
dan

[imrnjr]

Thanks for the reply, and yes a dust mask is a requirement. 

As soon as I figure out how to post a picture I'll put a couple up. 

I'm thinking about doing a test with a piece of I/2" cement board and a piece of 1/4" Hardibacker screwed together with 1" PVC stantions on 48" and 54" centers to check the sag/flex.

 

thanks again

mr

[Anonymous]

Yes I have used cement board for a base.  I live in New Zealand, so I am making a major assumption that the cement board we get here is similar to what you call cement board.

The thickness I have used is about 6mm which was determined because it was free - well remains left by the builder who did work on our house.  (so I guess we did actually pay for it anyway). :-)

That thickness is not strong enough to support track on its own, so I have wood under it.  I started out doing 1 layer of wood (old fence posts - because they were free too), with 2 layers of cement board on top.  I found that 2 layers was overkill, and 1 was enough, so later stuff was done with just one layer.  The reason I used cemenet board was it made a good wide strip to support the track and it provided some protection to stop the wood soaking up water from rain going through the ballast.

I painted the cement board with grey paving paint before laying track, so if the ballast gets thin you don't see white under the track.

Some of it has been sitting out in the sun for a two years now, as I am only just getting around to putting down ballast, and it is going brittle and can snap easy if not supported underneath.

However once holding the pballast up I don't forsee any problems.

You might be able to see some photos of it in the Whats New page on my website:

www.trainweb.org/nzgr

Regards,

Glen Anthony

Rocky Creek Railway, New Zealand

[Mike Dorsch CJ&M r.r.]

Are you building your track on the ground or elevated ? If its on the ground I would think that the floating method on some kind of gravel / ballast would be best . I'll leave the elevated method to the experts who have done that to answer those questions . I have cement board on my railroad garden , but it is used as a barrier to save my cedar fence from dirt being piled against it . Its held up well in the 3 years outside here in Chicago .

[CandCRR]

Like stated earlier I would worry about it snapping unless well supported.  Most of my track is floating and has held up well the past two years.  I live in the woods and have had cats and dogs, squirrels and chipmunks, skunks and the like walking across with little damage.  This spring a moose even visited and walked across the layout.  The only damage was a couple broken plastic track ties.

Jaime

[FJ and G]

all of my garden 7/8n18 switches are mounted on hardiboard; here's photo of construction putting it together indoors to take out



Now,I'm mounting my outdoor 7/8n2 on twin battans instead

[imrnjr]

Thanks to all for the input.  The track will be in a raised bed, on the ground for the most part, so support shouldn't be a problem.   The use of the cement board was an idea to minimize future grade maintenance and provide me a reasonable way to make up the the line.  I have had some trouble finding chicken grit locally and thought this might be a way to reduce the total volume of crusher fines/grit I had to have.  I still need to compare cost of grit/fines versus the Hardibacker, but bulk delivery of sand/gravel is expensive, at about a $1.50 per ton mile with minimums.  I would expect the fines to be close to that with an approximate 50 mile haul from the quarry.  More to come......  still need to finish moving dirt into the raised bed (30-35 cubic yards added to the 60 already placed) and the raised bed back wall (about 300 retaining wall pavestone blocks at 22 pounds each).

[Capt Bob Johnson]

I did the call the factory about the Hardiboard about 2 years ago and explained that I wanted to use it for something it wasn't for!  Had a discussion with somebody from their engineering dept.   He said it would be ideal for garden railroading in many uses; the main thing being to paint it with el cheepo exterior house paint to keep it from weathering even longer!   Check out some of the older postings, some guys use it under switches and others build structures out of it!  There have been several threads about it in the past couple of years.

On the grit thing, try contacting your local manufaccturer of concrete block about the stuff they use for the coarse aggregate in the cement block.   Wonderful stuff for track ballast!  Even better for scal and locking in than chicken or turkey grit!   Shouldn't be too expensive to get a couple of tons delivered, or use your pickem up truck to get some to try.

[imrnjr]

appreciate the input Captain.... but the nearest cement block plant (if it's still open) is 110 miles away, and the next one after that is maybe 250.  Is the material called 1/4 minus? Then I think its it's the same as what is used in 7000 lb concrete mix   and some of the local concrete companies may have it.

 

mr

[ttrigg]

  The use of the cement board was an idea to minimize future grade maintenance and provide me a reasonable way to make up the line.  ......  still need to finish moving dirt into the raised bed (30-35 cubic yards added to the 60 already placed) and the raised bed back wall (about 300 retaining wall pavestone blocks at 22 pounds each).

IMRNJR;

Since you are doing a lot of back filling, unless you are doing some serious compacting you will be experiencing some "future grade maintenance".  The small amount of fill I put in five years ago is still settling and it was only a small hill, ten wheel barrows full of dirt, compacted with a "hand pounder" between every load.  My track "floats" on a gravel bed (crushed rock) and I just add a little more ballast when making adjustments for ground settling.  If you use any kind of boards you will find yourself trying to squeeze the dirt in under the boards.

[Anonymous]

I have been of the opinion that going to too much trouble with the foundations for your track is a waste of time. I just put down quarry fines and it works ok for me.

However different strategies are required for different areas and what works for me may not in another area,

Rgds ian 

[imrnjr]

Thanks for the input ....Ian... what temp[erature ranges do you experience?  I expect a range from 5F to 105 F  I really am concerned about expansion and movement.... as well as critters.

 

mr

 

[Anonymous]

Mate i live in a metric country and i am not allowed to make non metric statements, nor am i allowed to ener into non metric converstaions.

The nearby Coral Sea has a temperature range of 20 deg to 30 Deg C year round and the air temperature never gets much more than 5 deg C either side of that. It rains heavily during monsoonal time but mainly of a night time.

Rgds ian

[imrnjr]

How about that..... metric only......so lets see..... is the conversion 5/9's or 9/5's.... have to go look it up............5/9's it is....  -15C  to 40.5C  at maximums and most of the time we stay in between 3-4C winter to 32-35C summer with a temp swing of  25 to 35F or approximately 15C low to high during both winter and summer....

Now given that your temps are much mor moderate I doubt you have expansion issues.

 

mr

[Anonymous]

No mate i don't have an expansion issue but from what i aheard from the best brains in this business is that this matter is greatly overestimated and it is much less than you would think. In any case you can get an expansion rail joiner. If you put ypour track down on fines or similar as ballast and have it float this should suffice.

By best brains i am referring to Jack Verducci who is anAmerican and he puts down layouts for a living all over USA.

Rgds ian  

[ttrigg]

Imrnjr;
Here in sunny San Diego, we have a temp range for 40 ~ 110 Degrees F.  The only time I have experienced any expansion problems was when I had put up a temporary section of 2x4's to test the proposal of having "bridge work" from ground level to the top of my waterfall.  That section moved quite a bit considering it was screwed to the wood ever foot.  The roughly 500 ft of track that "floats" on a gravel bed has experienced no problems with expansion.  The way I see it, the more you attach the track to a "hard" surface the more the problem of expansion will occur.

[Anonymous]

Well Tom th good book agrees with you on that. They even reckon it is better to tie the rail down and leave the sleepers (ties) float.

It is definitely a no no to screw your sleepers down.

rgds ian 

[Anonymous]

In Christchurch, New Zealand, the temp goes from about -8C (in a frost) to high 30'sC in summer.

I have used the board and not had a problem with expansion. And I do screw through the sleepers to fasten track down.  As long as you put down the track on the hotest day and almost butt the rails together, the cold will take care of itself. Well it has worked for me anyway.

Glen.