Bioreceptivity index for granitic rocks used as construction material

Area of Science:

• Geology and Material Science
• Conservation Science
• Bio-deterioration Studies

Background:

• Bioreceptivity is crucial for assessing stone susceptibility to biological colonization and biodeterioration in construction and heritage.
• No standardized bioreceptivity index (BI) currently exists for construction materials.

Purpose of the Study:

• To develop a simple, robust, and well-founded bioreceptivity index (BI) specifically for granitic rocks.
• To establish a new quality factor for the stone industry based on material susceptibility to biological growth.

Main Methods:

• A standardized laboratory protocol was employed to cultivate phototrophic biofilms on various granite types.
• Colonization was quantitatively assessed using chlorophyll fluorescence and colorimetric measurements.
• The proposed BI incorporates two components: BI_growth (biological growth extent) and BI_colour (perceptible stone color change).

Main Results:

• A novel bioreceptivity index (BI) for granitic rocks was successfully developed, incorporating growth and color change metrics.
• The BI, BI_growth, and BI_colour were calibrated to a 0-10 scale for qualitative classification of lithotypes.
• Eleven granite varieties, with varying surface finishes, were assigned BI values, demonstrating its applicability.

Conclusions:

• The developed BI provides a reliable method for classifying the primary bioreceptivity of granitic rocks.
• This index serves as a valuable decision-making tool for end-users in selecting granite for building and ornamental applications.
• The BI represents a significant advancement in quality assessment for the ornamental stone industry.