264 PARKS 



surfaces should be protected from heavy rains for at least twelve hours, 

 and during exceedingly hot weather in open exposure to the sun's rays the 

 surface should be sprinkled freely subsequent to the end of one day, during 

 one week. Covering the surface with a two-inch layer of sand or loam will 

 protect it against undue evaporation until the concrete has set. Freezing 

 conditions are apt seriously to injure new concrete. New walks should be 

 protected during late fall by a covering (4 to 6 inches deep) of straw or 

 stable litter, or by tar paper, which should be kept in place for a period of 

 two or three weeks if freezing conditions prevail. 



(of) Macadam walks with tarvia-bound surface (foundation course and 

 wearing surface}. The foundation course of slag or crushed stone (passing 

 a 2^-inch screen) should be put in place in a single layer to a depth of 

 four inches when rolled. This foundation course of stone should be thor- 

 oughly bound with one-half-inch screenings only sufficient to fill the voids. 

 The foundation course should be thoroughly watered and tamped or rolled. 

 On this course should be spread a layer of crushed stone passing a one and 

 one-half-inch screen. If the walk area is wide and of considerable extent 

 this course as well as the foundation course may be rolled with a two or 

 three-ton drum wheel roller. This wearing course should be rolled but once 

 in order to detect any depressions before the tarvia is applied. The tarvia 

 should then be applied in accordance with standard specifications for com- 

 pleting wearing surfaces of tarvia-bound macadam roads, with the exception 

 that the quantity of tarvia used per square yard of walk will be at least 

 25 per cent less than for road work. The success in completing a tarvia- 

 macadam walk will depend largely upon the selection and application of a 

 desirable and interesting type of washed gravel or one-fourth-inch stone 

 screenings for the surface, as this decides the color and texture. 



(ag} Macadam walks with water-bound construction (foundation course 

 and wearing surface}. The total depth of the foundation course and wearing 

 surface for water-bound macadam walks should approximate six inches at 

 the side of the walk. With the subgrade properly prepared and drained, 

 crushed stone or slag, passing a one and one-half-inch screen, should be put 

 in place to a depth of five inches when rolled. On this foundation course a 

 one-inch layer of crushed stone or slag (passing a %-inch screen) should be 

 carefully spread, watered and tamped or rolled. Crushed stone screenings 

 (passing a 3^-inch screen) should then be applied to the surface of the walk 

 only in the quantity necessary to fill the voids and thoroughly bind the 

 surface of the walk into a permanent condition. It is very desirable slightly 

 to crown the surface of water-bound macadam walks. 



(ah} Gravel walks (foundation course and wearing surface}. The sub- 

 grade should be prepared as shown in figure 6, Plate no, with a minimum 



