Historic buildings and archaeological monuments are periodically subjected to aggressive environmental conditions such as storms, high winds and freezing winter conditions. Alterations in local environmental conditions can impact the microstructure of historic and modern building materials, eventually leading to macro-scale damage such as spalling (the detachment of fragments of material), granular disintegration (powdering) and fragmentation. Durability testing of new mortars, stones and conservation treatments attempt to predict the stresses of decades of aggressive environmental conditions through simulated accelerated weather conditions. In real-world condition, the concerns surrounding this seasons cold temperatures and snowfalls are more usually focused on what may happen now in the short-term. However, if sudden building failures in the winter months are wrongly attributed to freeze-thaw action simple because snow is present, larger, more serious and costlier problems can be overlooked.
‘Freeze-thaw’ damage is a common form of moisture-related decay of building materials, and a sub-set of how buildings handle precipitation. Along with drizzle, rain, heavy downpours and storms, in winter historic buildings and structures must also handle sleet and show, dew and ice. Freeze-thaw cycles see the transformation of water into ice, and this can exert two types of pressure on historic building materials such as stone, brick, mortar and render. Continue reading