Flexural strength of weathered granites under wetting - drying cycles: Implications to steel structures

Deterioration of stone veneer cladding panels due to environmental weathering can lead to expensive restoration work, serious risks from falling debris and compromises the performance of high-rise steel and concrete structures. The influence of wetting - drying cycles (WDC) on the flexural tensile strength of thin granite cladding panels is investigated. Forty-five specimens of Imperial Black, Calca and Grandee type Australian granite panels were used in the experimental program. Total 15 specimens served as control reference, while 30 specimens were subjected to 100 WDC in two separate stages. The wetting cycles were conducted in contact with tapwater and acidified solution of pH-4.5, while the drying cycles were conducted using a controlled drying chamber at 40 oC. Ultrasonic pulse velocity (UPV) and flexural tensile strength of the control, and weathered specimens were measured after the 50th and 100th weathering cycle of WDC. It was noticed that the thin granite cladding panels experienced limited flexural strength reduction accompanied by changes in UPV and weight loss. A correlation between flexural strength and UPV of the unweathered and weathered WDC specimens is proposed which can be useful in on-site assessment of granite cladding panels during the service life of the primary steel structure. © 2019 by The Hong Kong Institute of Steel Construction. All rights reserved.