74 STANDARD SPECIFICATIONS 



mixed in the same proportion as the mortar of the 

 concrete. The wash shall be applied with a brush. 

 The earlier the above operations are performed the 

 better will be the result. 



(6) The tops of bridge seats, pedestals, copings, wing walls, 

 etc., when not finished with natural stone coping, shall 

 be finished with a smooth surface composed of one part 

 cement to two parts of granite or other suitable screen- 

 ings or sand, applied in a layer J to 1 in. thick. This 

 must be put in place with the last course of concrete. 



321. Waterproofing. Where waterproofing is required, a 

 thin coat of mortar or grout shall be applied for a finishing coat, 

 upon which shall be placed a covering of suitable waterproofing 

 material. 



322. Freezing Weather. Ordinarily concrete to be left above 

 the surface of the ground shall not be constructed in freezing 

 weather. Portland-cement concrete may be built under these 

 conditions by special instructions. In this case the sand, water, 

 and broken stone shall be heated; and in severe cold, salt shall 

 be added in the proportion of about 2 Ibs. per cubic yard. 



323. Reinforced Concrete. (See Part X.) 



