Behavior of reinforced concrete walls with internal plaster coating under exterior hard projectile impact

This paper presents an experimental study on the impact response of protect ive reinforced concrete structural elements that are coated with plaster on their interior faces. Even when a structural element's perforation is prev ented, impact conditions may initiate rear face scabbing due to high-intens ity reflected tensile stress waves at the element's rear face. Israeli stan dards for civil defense shelter design forbid any interior wall coating, su ch as plaster or wall tiles, as they may easily be detached upon impact and produce scabbing fragments. Following the Gulf War, a new Israeli civil de fense policy became effective, where the protective spaces have been includ ed within the dwelling units. Although plaster coating is the common finish work of the entire interior of a dwelling unit, it seems to a priori contr adict the above requirements of scabbing prevention. Further study of the p roblem and investigation under impact conditions are therefore required to better understand the behavior of the concrete-plaster composite under loca l hard projectile impact. An experimental program was conducted and include d response studies of reinforced concrete specimens to hard projectile impa ct. The specimens with plastered rear faces were impacted at the center of their front faces. The results showed different responses of various types of plaster coating and demonstrated the importance of parameters that affec t the specimens' performance under impact lends, which are mainly the plast er-background adhesion strength, the plaster density and stiffness, and the improved toughness of the plaster layer. The latter is obtained by reinfor cing the plaster with fiberglass mesh.