_Results of the Work._--More than 39,300 separate test pieces have been
made at the structural-materials testing laboratory. In connection with
the study of these, 86,000 tests and nearly 14,000 chemical analyses
have been made. Of these tests more than 13,600 have been of the
constituent materials of concrete, including tensile tests of cement
briquettes, compression tests of cylinders and cubes, and transverse
tests of various specimens.
Nearly 1,200 beams of concrete or reinforced concrete, each 13 ft. long
and 8 by 11 in. in cross-section, have been made, and, in connection
with the investigation of the behavior of these beams, nearly 3,000
tests have been made. Nearly 900 of these beams, probably more than
double the entire number made in other laboratories in the United
States, during a period of more than 15 years, have been tested.
In the section of building blocks, 2,200 blocks have been tested,
including, with auxiliary pieces, more than 4,500 tests; also, more than
900 pieces of concrete have been tested for permeability and shear. The
physical tests have numbered 14,000; tests of steel for reinforcement,
3,800; and 550 tests to determine fire-resistive qualities of various
building materials, have been made on 30 special panels, and on
miscellaneous pieces.
[Illustration: Fig. 9.