Process and apparatus for manufacturing single piece railroad ties of prestressed concrete

Abstract From the Canadian patent

A process and apparatus are disclosed for production casting of railroad ties and the like to obtain maximum mold utility. The casting is accomplished by arranging tendons within a mold and subjecting them to an appropriate tensile stress. Uncured concrete is then introduced at a temperature of around 80°C - 90°C. The mold is vibrated and subsequently closed. It is then maintained at 60°C - 80°C for a time sufficient to cure the concrete such that the prestressing mechnism can be released. The mold may then be immediately re-used. One mechanism by which the molds may be closed during the curing process in a most efficient manner is to employ succeeding molds in a stacked arrangement to …