Anti-weathering treatments to protect mineral surfaces: Hybrid sol-gel and biomimetic strategies

he natural weathering of stone is accelerated by the combined effects of acid rain, salt crystallization and the freeze-thaw cycles of water. This dissertation describes the development of two anti-weathering preservation treatments that are specific to limestone surfaces. The first strategy involves the application of a surface-specific, bifunctional, passivating, coupling agent that binds to both the limestone surface and to a consolidating inorganic polymeric silica matrix by a sol-gel process. The second strategy involves biomimetic process that converts the exposed limestone surface into a nonreactive calcium oxalate hydrate ceramic layer found in kidney stones and lichen deposits.;The microreactor environment of a scanning probe microscope (SPM) fluid cell was used to simulate acid rain effects on treated and untreated calcite surfaces, seen as etch pits and crystal step movement. The treatment process was also monitored at near molecular scale resolution using the SPM. Calcite crystals treated with aminoethylaminopropyltrimethoxysilane (25% AEAPS) passivating coupling agent and a silica consolidating solution (50%w/w), are resistant to the leaching action of deionized water equilibriated with atmospheric CO;Modulus of rupture strength tests on limestone cores treated with the AEAPS and silica-based consolidant showed a 25-35% increase in strength. Environmental scanning electron microscopy of treated limestone exposed to concentrated sulfuric acid showed degradation of the surface except in areas where thick layers of the consolidant were deposited.;Powder leach tests using a pH-stat apparatus yielded quantitative proof of the efficacy of the biomimetic calcium oxalate process. The dissolution rates...