Sample of colloidal concrete of 1878 removed from road at West Arthur Place, Edinburgh in 1972.
Used for urban road construction. Edinburgh’s City Roads Surveyor DC Proudfoot was at the forefront nationally of this type of construction and was responsible for constructing some 5 miles of cement-grouted whin stone aggregate roads in the city.
The concrete was formed on a blinded and rolled stone bottoming 6 in thick as follows: a 4.5 in thick layer of 1.5 in whin road metal was spread uniformly over the bottoming and grouted with a mixture of fine gravel riddled out of Fisherrow gravel and Robin & Co’s best (Portland Cement). The cement used was to be capable of sustaining a tensile strain of 600 lb on the superficial area of 2.25 in of the standard test block after being immersed 7 days in water. The grout was mixed in a patent steam mixing machine and then spread beaten and “equalised” into the road surface “in a most careful and tradesmanlike manner” (from specification).
A photograph of a similar concrete road surface on High School Yards, Edinburgh is shown as Image 3 (Note 1 shilling coin in centre).