Empirical Study on Weather Resistance of White Artificial Stones in Subtropical Island Climate

Abstract

White building components, whether decorative or the overall structure, are susceptible to extreme weathering conditions, which affect the durability of the building’s external surface. In particular, white natural stone materials can provide buildings with beauty, durability, and sustainability, but this beauty is affected by key factors determining their weather resistance, namely physical properties such as porosity and acid and alkali resistances. As indicated by a past study, marble used as the exterior wall of a building in a similar environment will exhibit tarnishing after six months of weathering. Taiwan is a subtropical island, so the weather resistance of building materials to this environment is worthy of attention. As pointed out by the study, raw stone materials containing zirconium and silica can have greater weather resistance, do not easily change color, and possess good stress resistance properties. Focusing on this, this study attempted to identify stone materials with such compositions and sent samples to SGS (Societe Generale de Surveillance S.A., New Taipei City, Taiwan) for testing of weather resistance. This paper uses Spanish artificial stones for the study and observes the changes in the surface cleanliness on two buildings in Yilan County and Taipei in Taiwan after exposure to sun and rain. The experiments were conducted over two years. The study results showed that the artificial stones displayed no change in outward appearance under both rainy and acid rain environments. In Yilan, construction of an exterior wall was carried out in February 2018. The exterior wall used the white artificial stone directly from the manufacturer, and the black artificial stone with added paint for stone protection. After two months, the black artificial stone covered with paint exhibited a change in color and stains appeared on the surface, while the white artificial stone not covered with paint maintained the same cleanliness after two years. In Taipei, white Spanish artificial stone was used for the exterior wall of an entire building block in February 2020. After the frame was dismantled in September 2020, the color was found to be unaffected, being as pure white as it was when new. Therefore, this study selected Spanish artificial stone for the design of a building’s exterior wall, as the cleanliness of the stone surface is not affected and it has good applicability in rainy and acid rain island environments.