Most of the DST specimens were prepared using an air pluviation
technique. A limited number of tests were performed
using other techniques to allow for a comparison of the effect
of specimen preparation method. Normal stresses ranging from
about 25 to 175 kPa were used in the DST and IST tests. The
values of initial void ratio reported throughout the present paper
were determined after the normal load had been applied
and before the shear process had commenced. All tests were
conducted on dry specimens. Most tests were performed at a
horizontal displacement rate of 0.25 mm/min, except for a limited
number of tests performed at a variety of displacement
rates ranging from 0.25 to 5.08 mm/min to permit a comparison
of the effect of displacement rates. The surface roughness
of the FRP and steel specimens used in the ISTs was measured
using a Talysurf stylus profilometer.