The strengthening and retrofitting of existing reinforced concrete structures against
blast or projectile loadings is a pressing problem in the current political environment.
The usual approach to protect sensitive structures is generally in the form of
establishing a barrier line away from the structure. Although this approach can be
quite effective, it still does not address the problems associated with long-range
projectiles hitting the structure. Current research aims at solving this problem by a
new strengthening technique using protective non-metallic geogrids applied on the
existing concrete surface. Results of initial impact loading studies will be presented to
demonstrate that non-metallic grid retrofits provide significant improvements in the
impact resistance capacity of reinforced concrete slabs. In particular, slabs retrofitted
with polyethylene grids show better performance compared to those retrofitted with
other materials.