Static and dynamic elastic moduli of historical brick masonry subjected to freeze-thaw cycles and to different moisture amounts

Environment conditions and moisture presence in masonry structures may affect durability or even mechanical properties of architectural heritage. Among all the deterioration causes, the degradation of historic masonry by freeze-thaw cycles and different moisture amount are considered to evaluate their influence on elastic properties. Therefore, two experimental campaigns were carried out in the present study. The first one was performed at the Dept. of Geotechincal Engineering at Tongji University, to assess the influence of freeze-thaw cycles on elastic modulus of historic Chinese brick. The static elastic modulus was evaluated from the compressive strength test on masonry specimens subjected to different numbers of freeze-thaw cycles. Moreover, strength decay of the masonry was investigated, also analysing data obtained during ultrasonic test (UPV, non-destructive test). The aim of this step was to obtain the dynamic elastic modulus. Thanks to interpolation of the obtained data it was possible to improve the knowledge of the Elasticity modulus’ reduction of historic masonry subjected to freeze-thaw cycles. The second experimental campaign was performed at DICAM, University of Bologna, on ancient Chinese and Italian bricks, to assess the sensitivity of dynamic elastic modulus to moisture amount. In particular the influence of water presence in the material pores on the UPV measurements. The close relationship between the ultrasonic pulse velocity and the moisture content was investigated on brick cores in dry, 50% saturated and saturated conditions. Practical value and one of the main contribution of the experiments was the investigation of external factor and intrinsic properties of porous materials which directly influence the ultrasonic pulse velocity test.