The main purpose of the work described herein was to study the magnitude of corrosion induced distress in brick masonry wall panels under service conditions in a structure exposed to an acid rain environment. For this purpose, some specimens were subjected to a constant sustained load during exposure testing typical of dead loading under service conditions.
Specimens consisted of nine masonry wall panels with a steel plate, representative of shelf angles used in construction, embedded in the mortar joints at the third and sixth courses. Following twelve weeks of strain readings after load application, an acid-water solution was sprayed on the face of the walls, and accelerated corrosion was electrically induced in the embedded steel plates. Corrosion was also induced in six steel plate specimens that were immersed in tubs filled with the acid-water solutions. Expansion strains and cracking caused by the corrosion of the embedded steel were recorded, and the weight loss of the steel plate specimens was measured. The corrosion products on the steel plates were analyzed under an electron microscope and using X-ray diffraction analysis.
The results show that the embedded plates do not affect the overall temperature and moisture deformation behavior of the wall panels except for local disturbances in the joints containing the plates. The plate regions in the loaded wall panels underwent larger creep strains than regions of the wall panels that did not contain embedded plates. The average creep strains for the loaded walls were 39% lower than the creep strains reported from a previous investigation using similar wall panels that did not contain embedded plates. The presence of the embedded plates appeared to decrease the magnitude and duration of creep.
The induced corrosion of the embedded steel plates caused expansion strains that were several orders of magnitude greater than the tensile strain of masonry at failure. The weight loss of the plates from the nonloaded walls generally was slightly greater than that of the plates from the loaded walls for similar exposure times and was approximately 50% less than the weight loss of the immersed plate specimens.