A reversible reinforcing filler for heritage building preservation fabricated by Paraloid B72 with wood fibrous filaments

Ancient Chinese wooden architecture holds significant cultural value but is threatened by biodeterioration, particularly from carpenter bees whose tunneling reduces structural load-bearing capacity. This study developed a reversible repair filler by exploiting the dissolution-solidification reversibility of Paraloid B72 and optimizing its ratio with wood fibrous filaments (WFF). The incorporation of WFF helped densify the filler and enhanced its toughness by filling voids formed during mechanical stirring. Compared to compromised wood, the B72-WFF system increased compressive strength parallel to the grain by up to 8.14% and flexural strength by up to 22.29%. In a 12-week laboratory decay test, all tested formulations (10-14% WFF) exhibited less than 5% mass loss and were classified as Class I decay resistant. These findings suggest that the B72-WFF filler may serve as a candidate material for reversible consolidation of carpenter bee-damaged historic wooden architecture.