Variation of Mechanical and Chemical Properties of Old and New Clay Bricks

Clay bricks are a popular building material, especially in historical structures. Understanding the chemical and mechanical properties of bricks is vital in historical structure rehabilitation attempts, because discrepancies in the material could lead to accelerated degradation and structural failure. This research focuses on understanding the mechanical and chemical properties of clay bricks used in the world heritage city of Kandy, Sri Lanka, over the chronological period of the 18th to the 21st centuries. Chronological analysis of brick properties reveals that optimal mechanical properties in bricks are closely related to the water absorption rate and are found to be between 10% and 18% in the analyzed specimens. Further, regional mineralogical properties, such as high concentration of calcium and inclusion of barium (Ba), potassium (K), strontium (Sr), and titanium (Ti) as trace elements, were visible in most samples regardless of the year the brick was produced. The analysis also identified revealed that the inclusion of ferrous (Fe) increases performance. Assuring similar chemical characteristics in restoration material is important to avoid chemical imbalances leading to accelerated deterioration due to the presence of reactive metals in the brick composition.

Automated summary

Clay bricks, popular in historical structures, need to be analyzed for their mechanical and chemical properties to prevent degradation and structural failure. This research focuses on clay bricks used in the heritage city of Kandy, Sri Lanka, from the 18th to the 21st centuries. The analysis reveals that optimal mechanical properties are related to water absorption rate and that regional mineralogical properties, such as high concentrations of calcium and trace elements like barium, potassium, strontium, and titanium, are present in most samples. The inclusion of ferrous also improves performance.