Effectiveness of the anti-erosion of an MICP coating on the surfaces of ancient clay roof tiles

Abstract

Rain erosion is one of the most important factors causing the weathering of ancient clay roof tiles. Weathering damage generally proceeds from the surface to the interior; thus, protecting tile surfaces is an effective method to resist weathering. In this study, the microbially induced carbonate precipitation (MICP) technique is used to form an anti-erosion layer on the surfaces of tiles. Next, the applicability of MICP for tile surface erosion control is examined in the laboratory by the static contact angle test, capillary water absorption test, Karsten tube test, durability test, acid resistance test, water vapour permeability (WVP) test and colour change test. Moreover, the effect of the concentration of bacteria and cementation reagent on the surface erosion control is analysed. The test results show that MICP can significantly improve the water resistance of tiles by changing the microstructure of the surface. Higher concentrations of bacteria and cementation reagent allow the sediment layer to provide better protection; however, this effect is not linear. The concentration threshold reduces the positive effect of the bacterial concentration on the water resistance of the sample surface. The MICP protection layer offers favourable durability with little negative impact on the air permeability and colour of the sample. The use of an MICP protection layer can effectively relieve the weathering of ancient clay roof tiles.