S.L. 10.11 ст. 3Composition of hydraulic cement - concrete. Cap. 10.

The hydraulic cement-concrete mentioned in article 97 (c)

(iii) of the Code of Police Laws shall be made as follows: eight parts of hard stone spalls, three of lime and three of Roman pozzolana; or four parts of hard stone spalls, one of Portland cement and two of sand. In either case, the layer must have a minimum thickness of ten point one six centimetres.