Non-destructive testing for the assessment of granite decay in heritage structures compared to quarry stone.

Two non-destructive portable techniques, Schmidt hammer rebound and ultrasound velocity, were used to assess the two types of monzogranites used to construct the Our Lady of the Assumption church at Valdemorillo and the Valdamaqueda bridge, both located in the Madrid region, Spain, and rock from which the granite was originally quarried. The ultrasound velocity and surface strength as measured by the Schmidt hammer were directly related to each other and inversely proportional to the decay of the stone materials and to their porosity. The porphyritic monzogranite on the bridge and in the quarries at Valdemaqueda were both less intact than the Valdemorillo granite. There was a correlation between the indirect ultrasound measurements and the surface strength and the construction period for the church, particularly for homogeneous monzogranite, which may be used as a dating criterion for building materials exposed to similar conditions. Monumental granite decay was generally greater than quarry stone decay and the degree of alteration for both was affected by the surrounding environmental conditions.
Two non-destructive portable techniques, Schmidt hammer rebound and ultrasound velocity, were used to assess the two types of monzogranites used to construct the Our Lady of the Assumption church at Valdemorillo and the Valdamaqueda bridge, both located in the Madrid region, Spain, and rock from which the granite was originally quarried. The ultrasound velocity and surface strength as measured by the Schmidt hammer were directly related to each other and inversely proportional to the decay of the stone materials and to their porosity. The porphyritic monzogranite on the bridge and in the quarries at Valdemaqueda were both less intact than the Valdemorillo granite. There was a correlation between the indirect ultrasound measurements and the surface strength and the construction period for the church, particularly for homogeneous monzogranite, which may be used as a dating criterion for building materials exposed to similar conditions. Monumental granite decay was generally greater than quarry stone decay and the degree of alteration for both was affected by the surrounding environmental conditions.