FORMS FOE SPECIFICATIONS, ETC., FOE EOAD MATERIALS. 37 



heating in any part. Depending upon the nature of the oil, as usually indicated 

 by its flash, consistency at 25° O. (77° F.), and specific gravity, the operator 

 can with experience tell about what percentage it will be necessary to evaporate 

 before cooling and taking a penetration of the residue. It is sometimes neces- 

 sary to make several trials before the desired result is obtained. When the 

 required penetration is reached the residue left from evaporation is weighed 

 and its per cent of the original sample taken is computed. 



TESTS OF PORTLAND CEMENT, PORTLAND CEMENT CONCRETE, 

 STEEL REINFORCING RODS, AND VITRIFIED PAVING BRICK. 



(27) Tests of Portland Cement : 



(a) Chemical analysis, A. S. T. M. standard test C 9-17. 

 (&) Specific gravity, A. S. T. M. standard test C 9-17. 



(c) Fineness, A. S. T. M. standard test C 9-17. 



(d) Soundness, A. S. T. M. standard test C 9-17. 



(e) Time of setting, A. S. T. M. standard test C 9-17. 

 (/) Tensile strength, A. S. T. M. standard test C 9-17. 



(28) Tests op Field Samples of Portland Cement Concrete: 



Form of specimen. — The test specimen may be a cube, a prism,. or a cylinder, 

 but it is felt that a cylinder six (6) inches in diameter by twelve (12) inches 

 high will give the most satisfactory results. Molds of all types can be success- 

 fully used, from the most permanent to those which can be used only in form- 

 ing a single specimen. 



Molding specimens. — The molding should be done as near the mixer as prac- 

 ticable, and the concrete should be conveyed to the molds with as little jarring 

 or mixing as possible. The molds should be placed on a flat, nonabsorbent sur- 

 face, and the concrete should be placed in layers of inches, with slight 



puddling by means of a half-inch steel rod. 



Storing. — Specimens should be permitted to remain in position where molded 

 for a period of 24 hours. At the end of that period they may be stored on the 

 completed concrete pavement, buried in the same covering material, and mois- 

 tened at the same intervals, until ready for shipment to the laboratory ; or, if 

 not considered practicable to store on the completed concrete, they may be 

 covered at the point of molding with the same covering material as used for 

 the concrete pavement and moistened at the same intervals, until shipped to 

 the laboratory. 



Shipment. — Specimens must be suitably protected from injury during ship- 

 ment. 



Testing. — Specimens should be capped with mortar shortly after molding, or 

 with plaster of Paris just before testing, so as to provide plane bearing sur- 

 faces. The plane surface is formed by placing the specimen on a flat, non- 

 absorbent surface and pressing a flat plate on the soft mortar or plaster cap. 

 In testing, the specimens are mounted in the testing machine with spherical 

 bearing block placed on top of the specimen, the capped specimen being placed 

 in direct contact with the steel bearing surfaces. 



(29) Tests of Steel Reinforcing Rods: As given in the standard specifica- 

 tions for reinforcement bars, A. S. T. M. standard, 1916, serial designations 

 A 15-14 and A 16-14. 



(30) Rattler Tests, Vitrified Paving Brick : A. S. T. M. standard specifica- 

 tion C 7-15. 



Note. — All of the American Society for Testing Materials Methods, Tests, or 

 Specifications above referred to will be found in the A. S. T. M. Standards, 

 1916, unless otherwise noted. 



