General Discussion

Hello,

I am doing some reasearch, and will be using concrete ties on my layout with the atlas flex track, but I am needing to know do they use wooden ties for crossings and turnouts or are they concrete also.  I am figuring wood due to expansion.  Can someone help me out

 Enter "concrete" into the "Search Community" box to the right and you should get a list of many, many informative threads on this subject, one of which is this one on "Concrete ties ?" from August 2007:

http://cs.trains.com/trccs/forums/p/103502/1203241.aspx#1203241 

- PDN.

I recall readnig some information that leads me to believe you are totally correct in your assumptions.

Not cement -- concrete.  Cement is the dry powder that comes in a bag.  The instant water is added, then it's concrete.  (I know, a lot of people say "cement sidewalk" and "cement truck", but they're wrong.)

Transit and high-speed rail lines when built new usually prefer to use concrete ties throughout, if they use concrete at all. 

Class 1 railways sometimes are all-concrete including turnouts and grade-crossings, and sometimes use wood for turnouts and grade-crossings.  It depends on the individual railway's practices at that point in time, and often on the nature of the particular project and particular line segment.  It's not "incorrect" to do either on any railway.

Expansion isn't the issue -- neither wood nor concrete expand much with temperature change. 

Cost for turnouts is a very big deal, as concrete turnout ties are much more expensive, and are much more vulnerable to derailment damage, and are much harder to replace.  Also the concrete ties are all unique in a turnout, unlike wood, which can be sawn to length and kitted up however one wants on the spot.  That means one has to keep spare concrete turnout ties in inventory, and this will usually only be at a great distance from the location needed, and that's all very expensive plus it delays repair if an accident occurs.  And delaying getting the main line reopened is a very expensive proposition because if no freight moves, no income is earned by the railway.

Grade-crossings are subject to abuse from the vehicles traveling over them.  Some railways feel that concrete ties don't last long enough in a grade crossing.  Also, the greater stiffness of track with concrete ties as opposed to wood leads some to feel that it's easier and cheaper to maintain both the roadway crossing as well as the track vertical and horizontal alignment with wood ties underneath the crossing panels.

RWM

I always thought the cement + aggregate = concrete.

 You could call it "wet cement." 

And after it set up you could call it "really hard formerly wet cement."

RWM

Railway Man:

Not cement -- concrete.  Cement is the dry powder that comes in a bag.  The instant water is added, then it's concrete.  (I know, a lot of people say "cement sidewalk" and "cement truck", but they're wrong.)
RWM

Don't be too harsh on the boy.  There are 19,600 hits on Google for the song "Cement Mixer, putty, putty"

The classic qualitative simple formula for concete is: 

Concrete = Coarse aggregate (gravel or crushed stone) + fine aggregate (sand) + cement (powder) + water (liquid) [not necessarily in that order].

The quantitative aspects of concrete - the precise amounts and proportions of each constituent - vary according to the strength and other chemical and physical properties needed, and the costs and availabilty of each of these materials as well as any desired or necessary additives, etc.  Although this is a well-established science, in essence, it can be an ongoing study for each new major project or source, etc.

Where is Chris/ CopCarSS now that we need him ? ? ?

The really weird thing (to me) is that once the basic proportions are established for a particular mix ("recipe"), the major strength of the concrete - in compression - is essentially governed by the shear strength of the coarse aggregate pieces.  Which is why the concrete producers in our area of southeastern Pennsylvania love our local supplies of coarse aggregate derived from limestone, sandstone, and especially traprock (granite and other really hard rocks).

- Paul North.

There are legions of Roman engineers looking down on this and wondering if we'll ever get it right?

Paul_D_North_Jr:

The classic qualitative simple formula for concete is: 

Concrete = Coarse aggregate (gravel or crushed stone) + fine aggregate (sand) + cement (powder) + water (liquid) [not necessarily in that order].

The quantitative aspects of concrete - the precise amounts and proportions of each constituent - vary according to the strength and other chemical and physical properties needed, and the costs and availabilty of each of these materials as well as any desired or necessary additives, etc.  Although this is a well-established science, in essence, it can be an ongoing study for each new major project or source, etc.

Where is Chris/ CopCarSS now that we need him ? ? ?

The really weird thing (to me) is that once the basic proportions are established for a particular mix ("recipe"), the major strength of the concrete - in compression - is essentially governed by the shear strength of the coarse aggregate pieces.  Which is why the concrete producers in our area of southeastern Pennsylvania love our local supplies of coarse aggregate derived from limestone, sandstone, and especially traprock (granite and other really hard rocks).

- Paul North.

 

 Chris can probably explain more than I can. Hes been in the concrete business lots longer than I have.

The Recipe you speak of is referred to as a Mix Design. Some mixes may also include Fly Ash, a filler material that is sometimes used in the mix. It will generally darken the concrete a bit. Fly Ash is the ash left over from burning coal in power plants. Often the contractor likes to add in admixtures. They are chemicals that will alter the concrete to make it more workable or to give the concrete other desireable qualities. I myself have delt with admixtures that will retard the setting up of the concrete thus giving a longer working time. The sites I was on didn't like ot but we were forced to add it a couple times to prevent the concrete from hardening in the mixer and pump during an emergency blowdown. We regularly used Super Plasticizers in the summer to make the concrete more workable without adding water to the load. It is classified as a Water Recucer. And depending on the amount added will make a dry mix flow. We used this because I had a specific specification for the job that allowed me a specific Water to Cement ratio. The more water added the less strength the batch will have. Every time I wanted to add water to the load, I had to calculate my W/C ratio. Super Plasticizer helped me maintain strength while making the mud easy to work. The last really handy admixture is an accelerator. It is used in the winter to speed the setting up before it freezes. This doesnt mean that you dont have to cover it and keep it warm anyway. I have also seen it used in highway patches. You pour in copious amounts into the load, and the pour the mud where you need the patch. I have seen traffic driving on it in less that 5 hours.

 Here is a mix design that is pretty standard:

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PORTLAND CEMENT CONCRETE MIX VERIFICATION

(6 Bag Mix)

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Requirements:              4,000 psi compressive strength at 28 days laboratory cure, air entrainment, Type I/ II  Cement. 

Source of Aggregates:              Fine Aggregate – Fear Pit

                                                Coarse Aggregate – Fear Pit

Other Mix Components:         Portland Cement                                         Type I/II Ash Grove                                 Cement Co.

                                                Air Entraining Admixture                          Grace AMEX 210

                                                322N Water Reducer                                 Grace WRDA 64

            Fly Ash Bridger                                         Fly Ash, Class F  

            Non-Chloride Accelerator                          Grace Polarset

            Hydration Stabilizer                                   Grace Recover

            Superplasticizer                                         Grace ADVA 140M

            Water                                                         Potable

Mix Requirements:                  Compressive Strength, Min. at 28 days      4,000 psi

            Compressive Strength, Min. at 7 days        3,000 psi

                                                Air Content                                                5.5 percent +/- 1.5%

                                                Slump                                                        4.5 inch Nominal

Aggregate Properties:

                                                                        Percent Passing    U.S. Standard Sieve Sizes

                                    Sieve Size                    Fine Aggregate Coarse Aggregate

     1"                                      -                                 100.0

     3/4"                                   -                                   87.8

     1/2"                            100.0                                  49.8

     3/8"                            100.0                                  33.1

      #4                                98.0                                    6.8

      #8                                81.9                                    2.6

      #16                              62.0                                    2.1

      #30                              36.9                                    1.6

      #50                              14.7                                    1.3

      #100                              4.6                                    1.0

      #200                              1.5                                    0.7

      F.M.:                             3.03                                   -

      S.G.(SSD):                     2.64                                  2.61

      Absorption(%)              0.93                                  1.3

      Moisture Content(%)     5.9                                    1.3

Sulfate Soundness(%)loss   0.77                                  2.48

      La Abrasion                     -                                   25.5

ACTUAL TRIAL BATCH MIX PROPORTIONS FOR ONE CUBIC YARD OF CONCRETE

(6 Bag Mix)

                                 Computed        S.S.D. Batch          Computed Absolute        Actual Batch

                                 Volume (%)    Weights (lbs)          Volume (ft^3)                 Weights (lbs.)

Cement:Type I/II            8.52                  452.0                       2.30                            451

Fly Ash Type F               2.89                    112.0                     0.78                            113

Fine Aggregate:             28.89                  1285.0                       7.80                         1330

Coarse Aggregate:         38.44                 1690.0                     10.38                         1698

Water:                           15.78             266.0 (32.0gal)              4.26                     219 (26.25 gal)

Entrained Air:                 5.5                         -                            1.49                                 -      

TOTALS:                    100.0                  3814.0                      27.01                         3811.0

 Look through this message thread about the Union Pacific's ongoing Sunset Route double tracking project and you'll see lots of concrete ties being used for turnouts.

http://cs.trains.com/trccs/forums/t/120779.aspx?PageIndex=17 

Not to take this too far off concrete ties....

I recall reading or being told that Lackawanna had a superior mix for the concrete they used for their many concrete structures.  Apparently, however, the recipe has been lost.

 Further off-topic, the Lackawanna concrete recipe legend would fall into the Lackawanna "knife-sharp ballast" legend, too.

tree68:

Not to take this too far off concrete ties....

I recall reading or being told that Lackawanna had a superior mix for the concrete they used for their many concrete structures.  Apparently, however, the recipe has been lost.

The DL&W's concrete mix was probably OK - maybe even great - for their day, but not too much superior to anyone's then or since, judging by the amount of spalling and other superficial deterioration that I've seen on the remaining DL&W structures. 

More likely, the DL&W just went by the simple (and somewhat expensive) route of just adding another barrel (or sack) of cement to the concrete mix design.  I was told exactly that some 30 or 35 years ago about why the former Alpha Portland Cement plants and silos in Martin's Creek*, Northampton County, PA, were still standing and in good shape, when they were being converted to their present use as grain and flour storage and milling facilities for ConAgra.  As it was explained to me then, "Well, they made the stuff right here, so it didn't cost them that much more to add extra."  The DL&W of course served much of eastern Pennsylvania's "Cement Belt" - and coincidentally, ConAgra's "lower" or "A" plant on PA Route 611 that is closest to the village of Martin's Creek - so the "they made it here" part would apply pretty well to the railroad, too.  (The other plant that is still extant - now ConAgra's "upper" or "D" plant - is about 100 yds. west of Rt. 611, behind the line of former "company houses" that is now the village of Sandts Eddy.  Back in the day, that plant was served by the L&NE - another Cement Belt railroad.)

(* - on the western side of the Delaware River, about 7 miles above the City of Easton, and roughly equally far below Portland, PA and Belvidere, NJ.)

- Paul North.

mudchicken:

There are legions of Roman engineers looking down on this and wondering if we'll ever get it right?

And Henry Petroski has probably named them all in one or more of his books.