Dec. 3, 1917 
Tests of a Large-Sized Reinforced-Concrete Slab 
507 
To provide definite points between which deformation readings might 
be taken, short brass plugs, drilled at one end with a No. 55 drill, were 
cemented in holes drilled for the purpose in the concrete, and similar 
No. 55 drill holes were made in bared sections of selected reinforcing 
rods. At points where it was planned to take deflection measurements 
steel plates were set in plaster of Paris on top of the slab. The locations 
of these deformation and deflection points are shown graphically in 
figure 1. 
Fig. i.—D iagram of slab A-25, showing location of deformation and deflection points. 
METHOD OF TESTING 
Loads were applied over an 8-inch bearing block by means of a hydrau¬ 
lic jack mounted between the slab and a specially calibrated chrome- 
nickel beam, the deflection of which, observed with the aid of an Ames 
dial, provided a means of measuring the load. This apparatus has been 
described in detail in previously published papers. 
Extensometer readings were made, between the points in both con¬ 
crete and steel, with a 20-inch Berry strain gauge. Deflection measure¬ 
ments also were taken over the steel plates by means of a special appar¬ 
atus designed for measuring the wear of concrete roads. 1 
The slab was tested first with the load applied in the center of the full 
width of 32 feet. Afterward successive sections were split off one side, 
making the width of the slab 29,25,22, and finally, 18.5 feet. As theactual 
position of the load remained unchanged, its position with respect to 
1 Goldbeck, A. T. apparatus for measuring the wear of concrete roads. In Jour. Agr. Re¬ 
search, v. 5, no. 20, p. 951-954, 1 fig., pi 66. 1916. 
