Cause and consequence: volume changes behind building material deterioration

The main reason for the deterioration of building materials is the weakening of intergranular bonds. Intergranular bonds are controlled by the nature and properties of the constituents, their interrelation (interlocking) and type of interfaces, of which the mechanical interface strength is the most important for durability. In time, due to deterioration, intergranular bonds are weakened, the material degrades and may finally decay. Physical, chemical and biogenic forces drive numerous destructive reactions. Deteriorating processes are usually associated with changes of volume—bulk volume in general and molecular volumes of constituents in particular. During any alteration, rearrangement of the fabric (structure and texture) occurs, leading to the formation of new mineral phases associated with element repartitioning and redistribution. The deterioration rate is predetermined by the reactivity of the mineral constituents and access to reactive liquids and gases. Biogenic impact significantly contributes to degradation.