Clustering approach for hygrothermal material properties of bricks in a tropical climate, based on three degradation risks

Architecture in Cuba has a rich and colourful history, where the colours are literally seen in the Old Havana streets. Several sites are declared World Heritage by UNESCO, such as the historical centre of Camagüey due to its peculiar urban form. Recent studies have shown that 30% of the world heritage sites in Cuba were constructed using earthly materials. Unfortunately, this number is rapidly decreasing where nowadays, only 10% is still standing and half of them show risks for biological deterioration, fungal growth, or salt crystallization. These degradation phenomena are at the root of the high collapsing rates and should be prevented at all costs. HAM-simulations have an added value in the research for renovation and restoration strategies. However, these simulations require a high accuracy for input variables. It is important to make correct assumptions for applied construction materials. For bricks, aspects as granularity, clay or sand content, compaction and firing techniques vary greatly in Cuba and have a major impact on the brick pore structures and consequently on its hygrothermal properties. In an early stage of a renovation project, exact building information is usually not provided, and in most cases a full material characterization is absent. This study investigates the potential to fill in the missing values of incomplete material data with a clustering approach for the Cuban climate. This methodology determines equivalently behaving bricks based on the impact of their properties on the hygrothermal behaviour regarding the mould growth, wood rot and salt crystallization.