In the construction of artificial stone or cement sidewalks, the following specifications shall be observed:
(a) Sub-base or foundation. The sub-base or foundation shall be built of “mill ashes” or granulated slag, not less than four inches deep when well and evenly tamped to a uniform degree of firmness, and shall extend three inches on each side of the walk. Ashes shall be clean and hard, and clinkers excluded or finely broken.
(b) Material. The material shall be cement of the best quality of true Portland cement. It must stand a tensile strain of 175 pounds per square inch, when mixed one part of cement in three parts of sand with a suitable quantity of water and allowed to set
one day in air and six days in water at temperature of about seventy degrees. It must also stand a test of 250 pounds under similar conditions one day in air and twenty-seven days in water. Cement will also be tested for constancy of volume and no cement failing or appearing doubtful will be accepted. Sand shall be clean, sharp sand, containing not more than eight percent of loam. Gravel and limestone must be able to pass a one-inch screen and must be free from dirt.
(c) Concrete base. The concrete base shall be not less than three inches deep and shall be made of one part of cement to six parts of sand and gravel or limestone so as to show when thoroughly mixed a surplus of mortar. Water must be used in sufficient quantity to show a mixture rather wet. Wearing surface must be put on before the base is thoroughly wet.
(d) Wearing surface. The wearing surface shall not be less than one-inch in thickness, and shall consist of one part of cement to two parts coarse screened, sharp sand; the sand and cement shall be thoroughly mixed; dry and sufficient water added that when tempered into mortar and well tamped upon the base, water will rise to the surface, after which it shall be stroked with a straight edge and floated and troweled to a true finish surface exactly to grade and slope. The sidewalk is to be put in between guide strips securely fastened to grade and line, and laid in sections four to five feet long, with a square vertical joint through the depth of the concrete; the joint is to be made by a strip of paper or equivalent means. On steep grades the walks are to be "floated" to a rough-grained surface.
(1955 Code. §303.02)