Mass Concrete Production Tie Fabrication

Pouring Concrete into the Forms

Above:  This small mixer bought at Loew's Home Improvement is ideal for mixing small batches of concrete when pouring concrete ties.

Below:  Brad Grounds is mixing the concrete using pre-measured amounts of sand and stone.  I could get techinical here and talk about weights, yields and slump, but instead I will keep it simple as this does not have to be complicated.

The mix used is made up of 1/3 washed #11 crushed limestone, 1/3 masonry sand and 1/3 portland cement.   No you don't wash the stone. That is done as a process of production at the stone company.  I just wanted to point out that stone with dust is not to be used.  Gravel is not suitable for this type of project.  #11 washed stone is about the size of small beans and has been washed to elimate limestone dust from the product.  Masonry sand is a clean sand used in mixing mortar for laying block and brick. Portland cement is raw cement bought in 94 lb. bags.  The strength of any concrete mix is determined by the water cement ratio.  The wetter you want to pour it, the more cement you will need to use. This 1/3, 1/3, 1/3 mix we are using is a very rich mix and will provide great strength even though it will be poured wet.  You want this mix to look like pancake batter when it is done. If you get it too wet, add more cement.

We pre-measure all of the ingredients in 1 gallon buckets for ease.

Mixing 1 batch:     Turn the mixer on.  First put 1 gallon of water into the mixer.  Then add 2 buckets of the stone.  Next slowly added two buckets of the portand cement.  (If one gallon of water is not enough initially you can adjust that amount.  If it has rained and your stone and sand pile is wet you might even need to use less than a gallon intitially.)  You must add the cement slowly or the cement will clump and stick to the mixer paddles.  If at anytime you need to add water, add it very slowly.   Then slowly add the two buckets of sand.  Once again, if you need to add water, do it very slowly.  You want the finished product to look like pancake batter. 

Left.  Begin pouring the mix into the forms trying to spread it evenly in many forms at once.  That keeps the sides of the forms from bulging and making irregular shaped ties. 

Right:  Wearing rubber gloves, take you fingers and adjust the amount of concrete in each tie mold by removing or adding concrete.  Keep the mix down 3/16 or so from the top of the forms.  That will allow room for the displacment of the mix when the rebar is added without over flowing the form.  Also keeping the mix down from the top of the form makes getting the hardened tie out of the mold easier.  Do not learn this the hard way.

Left.  While waiting for the next batch of concrete we are putting the 14" long rebar into the molds that have enough concrete mix in them.  The last step is to take a hammer and tap on the plywood all around the ties.  This will help consolidate the concrete mix and helps level the concrete.  No smooth finish is required.  Remember, the part you see is really the bottom of the finished tie. It does not need to be pretty. You will just be wasting you time trying to make them look smooth and nice looking.

Below:   This shows the placement of the rebar in relationship to the inserts.  The photo on the left is using a #3 rebar 14" long.  The Photo on the right is using a #4 rebar.  Either size will work fine.  The rebar should not be put in the forms before the concrete.  If you do that, then the rebar will be laying directly on the forms bottom, which is actually the top of the tie.  The rebar will be too close to the top surface if you that and will start rusting and showing on the tie.  Idealy the rebar should be floated in by hand, after the concrete is poured.  That is another reason for the rubber gloves.  Remember cement harm your skin after continued physical exposer.  No it is not dangerous, but protect your skin. 

                               New Unionville and Western Railroad