VITRIFIED BEICK PAVEMENTS FOR COUNTRY ROADS. 27 



slag, and sufficient water to form a quaky mass, and shall be thoroughly mixed 

 in a machine mixer of the batch type so constructed and operated that the 

 thorough mixing of the materials will be assured. The concrete shall be so 

 delivered to its place on the snbgrade as not to cause or permit any separation 

 of the materials. Wheelbarrows or other devices used for measuring the 

 materials shall be of uniform capacity. The concrete shall be deposited in place 

 immediately after it is mixed and shall be well compacted as fast as it is 

 placed. The top surface shall be smoothed by troweling with shovels or by some 

 other means approved by the engineer, and when completed shall not vary 

 more than one-half (J) inch from the proper shape and grade, as shown on the 

 plans and profiles. The concrete base shall be kept wet by sprinkling with 

 water during the first four (4) days after it is laid. No hauling over it or roll- 

 ing or tamping of brick upon it will be permitted for seven (7) days after it is 

 placed, and during this time it shall be properly protected from injury. Con- 

 crete shall not be mixed when the temperature of any of the materials is less 

 than thirty-five (35) degrees Fahrenheit. Concrete shall not be used after it has 

 begun to show evidence of setting, and no concrete which has once set shall 

 be used as material for mixing a new batch. 



Curbs. — Concrete curbs shall be built on the base as shown on the plans. The 

 concrete shall be composed of the following materials, by volume: One (1) part 

 of cement, one and one-half (1J) parts of sand, three (3) parts of gravel or 

 crushed stone, and water. The materials shall be thoroughly mixed in a machine 

 mixer of the batch type or by hand. If the mixing is done by hand, it shall be 

 done upon a water-tight platform with raised edges, in the following manner : 

 The sand and cement shall be thoroughly mixed dry and spread out upon the 

 mixing platform, and upon this dry mixture shall be spread the coarse aggregate. 

 Water shall then be poured over the aggregate in such an amount that the 

 resultant concrete will be of a quaky consistency. The whole mass shall then 

 be turned with shovels until all of the materials are thoroughly mixed. The 

 concrete for the curb shall be placed upon the base before the concrete of either 

 the curb or the base has taken its initial set, and care shall be taken, such as 

 roughening the concrete of the base and tamping the concrete of the curb, to 

 insure that the curb will be firmly bonded to the base. The concrete shall be 

 well tamped and spaded along the forms, so that when they are removed there 

 will be no open and porous places on the sides of the curb. The top surface of 

 the curb shall be floated or troweled to a smooth finish. The forms for the curb 

 shall be smooth, clean, free from warp, and of sufficient strength to resist 

 springing out of shape. They shall be well staked and braced, and the top edges 

 shall be at the same height and set true to line. To protect the curb from 

 drying out too rapidly it shall, within twelve (12) hours after it is placed, be 

 covered with gunny cloth, which shall be kept wet for five (5) days. 



Sand cushion. — Upon the base shall be spread a cushion of sand such that it 

 will have a uniform depth of two (2) 1 inches when compacted. The base shall be 

 thoroughly clean at the time the sand is spread. The cushion shall be care- 

 fully shaped to a true cross section of the roadway by means of a template 

 having a steel-faced edge, and so fitted as to be readily drawn on the curb. 

 After the cushion is so shaped it shall be rolled with a hand roller until the 

 sand is well compacted. The depressions formed by rolling shall be filled and 

 the surface of the cushion trued up with the template and rolled again. This 

 operation of filling depressions, truing up with template, and rolling shall be 

 repeated as often as is necessary to secure a well-compacted cushion true to 



*A sand cushion having a uniform depth of lg inches is frequently used and may be 

 as satisfactory as the 2-inch cushion. 



