Study on the Improvement of Freeze Resistance of Historical Architectural Bricks by Organosilicon Waterproofing Agent

Historical building bricks in cold regions are prone to chalking and spalling due to freeze-thaw cycles, reducing their durability. This paper examines chalking and spalling on walls in the ancient city of Kaifeng. We tested 0%, 1%, 2%, and 3% concentrations of organosilicon waterproofing agents, applied to old bricks via vacuum pre-pressing, to evaluate their impact on freeze resistance. The change of durability of the improved brick was analyzed and its microstructure was observed by scanning electron microscope. The results show that the organosilicon water repellent agent can change the internal microstructure of bricks, reduce the internal pores, increase the compactness between the skeleton particles, and the water repellent film formed can improve the hydrophobic properties of surface tension, which in turn can effectively improve the water resistance, mechanical properties and durability of bricks.A 3% concentration of the organosilicon water repellent can really help protect against capillary water damage and the effects of freezing and thawing cycles. The findings from this study offer a fresh perspective on how to restore ancient buildings in the Central Plains region. The results of the study provide new ideas for the restoration of ancient buildings in the Central Plains region.