Note 54 — PART I SPECIFICATIONS FOR STREET ROADWAY PAVEMENTS (continued 2)

It is a common practice of contractors in some cities, in the laying of both wood-block and asphalt block pavement, where a mortar bed is called for, to substitute a bed of mixed sand and cement, dampened only to such a degree as will make the mass pulverulent like damp sand, the claim being made that ordinary mortar cannot be spread and gaged properly. This claim is unfounded. The objection to the practice is that the dampened mixture does not contain sufficient water to cause the cement to set, and with the practically water-tight paving surface, does not receive, even in rainy weather, the necessary amount of water. If the weather be dry, the small quantity of moisture in the mixture quickly evaporates, leaving the so-called mortar bed not much better than a layer of sand alone. The writer has found such alleged mortar dry and unset two weeks after the pavement had been completed. If real mortar is not to be used, a layer of sand might almost as well be substituted at first.