Nano-Materials Enhanced Protectants for Natural Stone Surfaces

Abstract

Natural stones undergo wet weathering, bowing and dissolution and suffer irrevocable degradation. Self-cleaning is an effective approach to stone protecting. Herein, nanomaterial enhanced protectants for Marble, Qingshi and Hedishi was developed. Inherent microscale cracks and holes exist on the polished natural stone surfaces. When modified by commercial protectant, 101S, the surfaces showed hydrophobic but not superhydrophobic. Superhydrophobicity was achieved through modification by 101S emulsions containing Al 2 O 3 and SiO 2 nano-powder. Meanwhile, the cracks and holes were reserved. The principle of the protectants prepared in this work is permeation and consolidation on the stone surfaces as well as the inner surfaces of the cracks and holes. The reservation of the micro cracks and holes on the stone surfaces is important since the breathability of the stones is remained. The superhydrophobic surfaces showed good thermal stability below 250 ºC.