Deterioration of Sandstone in the Historical and Contemporary Sea Walls upon the Impact of the Natural and Man-Made Hazards

The contemporary sea walls built in the pedestrian seashore zone in the City of Acre, Israel, were sided with porous calcarenite sandstone, so-called ‘kurkar’. Kurkar stone has been broadly used as a durable building material in Acre and Jaffa, the Eastern Mediterranean offshore cities, since ancient times. Therefore, the contemporary urban architectural plans obligate kurkar siding in the modern structures erected beside the Old City of Acre. However, a rapid deterioration of kurkar siding had occurred in the contemporary sea walls during only a few years. In contrast, the Historic walls built of kurkar dimensional stone have been still sound. The current study has evaluated the factors and causes of kurkar deterioration in the modern seawalls. It was revealed that the main reason for deterioration was adhering the kurkar siding with cement mortar and the next exposure of adhered siding to the humid and salt-enriched offshore environment with high air pollution.