Volume 31, Issue 2 (March 2008)
Influence of Test Method on Direct Shear Behavior of Segmental Retaining Wall Units
This paper reports the results of interface shear testing carried out to investigate the influence of test methodology on shear-displacement behavior of five different segmental (modular) masonry concrete block configurations. The tests were carried out in general conformance with existing ASTM and National Concrete Masonry Association test protocols. Three different normal load arrangements were investigated: (1) flexible airbag, (2) fixed vertical piston, and (3) an adjustable vertical piston. A video-extensometer camera device was used to record block deformations in the vertical plane during testing. The test results showed that the three load arrangements gave similar shear capacity failure envelopes for the frictional block system with flat concrete surfaces. For more typical block systems with concrete shear keys and trailing lips that exhibit dilatant interface shear behavior, or a system with shear pins, the most consistent test results were developed using the flexible airbag arrangement. The results of this paper can be used to guide the selection of the loading arrangement for conventional laboratory modular block shear testing.