Modeling algae growth on masonry in hygrothermal simulations: Developing a new response indicator

Abstract

Biofilm stands as a critical issue in the deterioration of masonry construction, leading to aesthetic problems and potential structural issues. Giving the time-consuming nature of experimental work on algae, this research utilizes HAM modeling to predict and assess long-term algae growth using two mathematical prediction models: the Modified Avrami's model (MAV-Model) and Miyauchi's mathematic model (MM-Model). The analysis based on hygrothermal response develops a comprehensive understanding of how material characteristics and climate parameters interact to influence algae growth on brick substrates.

Results show that while the models exhibit distinct growth curves, they demonstrate similar sensitivities to the highest and lowest wind-driven rain. The Miyauchi's model illustrates greater sensitivity to climate parameters. Though wind-driven rain is the predominant factor contributing to algae growth, its impact diminishes when there is sufficient moisture to support development, with a critical annual accumulation of 100 mm. Moreover, instead of porosity, the brick's sensitivity to algae growth is determined and classified by pore structure and moisture retention capacity using response-based methods. This research also proposes a response-based indicator (RAG) that predicts potential algae risk based on temperature, RH and wind-driven rain on the substrate surface. This indicator reduces the time required to compute algae growth risk and can be applied to various material characteristics and climatic conditions. This research introduces an innovative approach to understand and predict the biodeterioration on masonry and advances the field of building conservation.