Precast, prestressed concrete box beams, bulb tees, and voided slabs are used in short-to-medium span bridges. These bridge elements have grouted keyway sections to transfer the vertical shear forces between adjacent elements. The keyways are filled with differing types of non-shrink grouts. By definition, these non-shrink grouts do not have requirements for maximum shrinkage limits or minimum bond strength. Both properties are critical for effective load transfer. In the field, leaking keyways and vertical faulting of key-ways have been reported. A laboratory study was undertaken to compare component material tests and composite grouted keyway specimens using two different grouting materials: non-shrink grouts and magnesium ammonium phosphate mortars. Comparative composite specimens were tested in vertical shear, longitudinal shear, and direct tension. Results indicate significant differences in performance between the materials. Composite testing of the grouted keyway assemblies, rather than component materials testing, was shown to be a more accurate way to evaluate the performance of the grouting material.
