Surface biomineralization with Pythium aphanidermatum in cracked cement pastes: Limitations and perspectives

ABSTRACT This study investigates the limitations of biomineralization for the surface treatment of cracks in cement pastes. The proposed strategy involves the application of Pythium aphanidermatum spores on pre-carbonated cement matrices with induced cracks. The pastes were reinforced with polypropylene fibers, cracked via diametral compression, and subsequently subjected to a controlled carbonation process. Three treatment conditions were evaluated: water (Ref) and two biological solutions (T1 and T2) containing calcium acetate, Potato Dextrose Broth (PDB), and Pythium spores; T2 also included urea as an additional nutrient source. Treatment performance was assessed through load recovery and crack width closure. Additionally, SEM analysis was performed to detect microbial colonization along crack surfaces. The results showed limited mechanical improvement, with slightly better performance in T1 and T2. However, no measurable crack width healing (CWH ≈ 0%) was detected, and no microbial growth was observed, likely due to high alkalinity, low surface porosity, and poor nutrient retention in the treated zone. Despite the modest outcomes, the study introduces an innovative approach that combines accelerated carbonation and surface biomineralization using a non-bacterial microorganism. For future studies, it is recommended to investigate multiple treatment applications, encapsulation systems for spore delivery, surface modification to enhance microbial adhesion, and local pH monitoring to ensure optimal conditions for microbial growth and activity.