After making a series of volumetric tests of the materials it was decided to use a 1:2 

 concrete instead of a 1 : 2: 5, the proportions being based on dry sand and cinders. The concrete 

 was thoroughly mixed by machine a:i-l w.is of a . During the pouring of the slab* 



samples of the concrete were taken whi-.-h, when tested in th : forn of cylinders. 6" in diameter 

 and 18" high, gave crushing strengths of 631 and 785 Ibs. pet square inch at 33 days and 56 

 respectively. 



METHOD OF CONSTRUCTION. 



A foundation of 1 : 2: 4 gravi-1 concrete. 12 in. thick and about 3 ft. high, was first built, 

 this foundation were imbedded bearing plates which supported the I-beams of the flat arches 

 or slabs. 



, Each of the arches was of the flat type and was carried by two 12 in. 31 X Ib. I-beams spaced 6 ft. 

 on centers. These I-beams were connected by two V in. steel rods with nu; ; hat there 



was little initial tension in the rods. The length of the arches was 6 ft., the thickness at the. 

 center and haunches was 4 in. and 15 in., respect: 



The arches were all reinforced with sheets of "Steelcrete" Expanded Metal; arches O and O 

 with 3-13-075, N with 3-9-175, and P with 3-9-15. 



The cross-sections of the sheets of metal used in the arches checked these values within com- 

 mercial limits. 



The details of the arches and the position of the reinforcement are shown in Fig. 40. 



METHOD OF TESTING. 



The pig iron was piled in three separate tiers, each parallel to the I-beams in order to reduce 

 the arching effect to a minimum. Deflections were obtained at seven points, these points being 

 located at the center of tbe slab and at the center and ends of each I-beam carrying the slab. 



At these points holes were left in the concrete in which were inbedded slender wooden rods 

 carrying scales at the top. By means of a Y level these scales were read to ^ of an inch for in- 

 crements of 150 Ibs. per sq. ft.'in the loading, this unit load being based on the total area of the 

 slab which was 36 sq. ft. In order to detect any change in the heightof instrument, level readings 

 were frequently taken on a permanent bench mark entirely separate from the slabs. 



RESULTS OF TESTS. 



The detailed results are tabulated in Tables 1 to 4, inclusive. Deflections are given in 64ths 

 of an inch; negative values indicate a downward movement and positive values an upward n 

 meat of the slab. Rods. No. 1, No. 3, No. Sand No. 7 were located at the ends of the 12 in. I- 

 beams carrying the slabs, rods No. 2 and No. 6 at the centers of these I-b< 



the center of the slab, (See Fig. 40). The missing deflections are due to the fact that it was im- 

 possible to read all of the rods after the pig iron had reached a height of about 6 ft. 



