Over the clay there shall be spread a course of concrete, to be four and one-half (4½) inches in depth after compression. The material and mixing for this concrete shall be done as specified in section 17-73 et seq.
After being laid, the surface must be struck off and trowelled with a wooden trowel until the sand and cement mortar appears on top. After the surface has been trowelled until it is uniform and even, it shall be brushed with a large size paint brush by swinging the brush parallel to the strips, so that all markings of the brush shall be reasonably uniform and even and in the same direction.
All joints and edges shall be finished the same as for two-course pavement.