Masham & Colsterdale - Tony Wright shows how to build viaduct's and bridges
The M&C has existed as a basic short oval for a few years. A new challenging extention has been planned which needed an embankment and overbridge in a tight space. Shuttering has been installed with the top set to trackbed height. Plastic pipe piles have been driven into the foundations to help stablize the structure.
A concrete mix has been poured, compacted thoroughly and screeded level to the shuttering top. The mix is two parts pea gravel, one part sharp sand, one part cement and half a part black cement dye plus plasticier. I am trying to recreate millstone grit stone work hence the dye but you can omit or use yellow or red.
When the mix has set but is still soft, very very carefully remove the shuttering. Oiling the shuttering before pouring helps to get a clean separation. Then with a scrubbing brush and plenty of water scrub the face of the concrete to remove the finings and exposing the pea gravel. Once happy with the result cover and leave for a good three days. Give the face another scrub to remove the last of the cement from the gravel, allow to thoroughly dry out and them seal with a patio sealer.
photos © Tony Wright