|the concrete ties are cast 5 up in molds with 1/2 inch rebar cut 21"
long and 4 2-1/2x5/16 bolts jig wielded at the correct spacing for the
tie plates and 15" gauge. the ties are 24" wide, 3-1/2" high, 3" at the
top and 4" at the base. a mold of 5 ties requires 1 cubic foot of
cement. a 92# bag of portland cement, along with sand and gravel
will make 15 ties.
tie costs: cement:$0.73, sand/gravel:.05, rebar:0.33, bolts/nuts:0.28,
wielding rod and electricity :0.05, for a total cost of:$1.44 each (with
time to make a stack of 20 ties is about 2-1/2 hours. the tie at the
top right shows a chip on one end caused by unmolding after only
36 hours. a full cure of 48 to 72 hours is better.