This research describes the effects of two innovative aqueous polyacrylate polymers on the microstructure of porous stone materials. Such latex nanodispersions have been designed (with and without fluorination) as consolidation agents and tested on two types of sandstone, namely, Prague (Mšené) and Obernkirchen, largely used as building materials for valuable Cultural Heritage objects. Quantitative description of the polymer distribution within the specimens was obtained noninvasively by adopting synchrotron radiation computed microtomography. The propagation-based phase-contrast mode was adopted to test its effectiveness in enabling the recognition of the polymers in the two matrices, which is usually hampered by their low attenuation coefficient for X-rays. Quantitative image analysis revealed significant dissimilarities in total porosity, specific surface area of pores, connectivity density and fractal dimension as a consequence of the consolidation treatments. For instance, about 7% and 3% lower porosity values were found in the consolidated Prague and Obernkirchen sandstones, respectively, with the distribution shifted towards smaller pores. Furthermore, the simulation of water transport, based on the retrieved pore network, evidenced a decrease in water permeability and diffusivity of more than one order of magnitude in the treated samples; the effect was more pronounced along the direction of penetration of the consolidating agent. Overall, both latexes exhibited similar film-forming and pore-filling abilities. In general, the results highlighted the high potential of synchrotron-based 3D X-ray imaging for the quantitative assessments of the porous microstructure of consolidated building materials.

中文翻译：

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通过同步加速器 X 射线计算机显微断层扫描评估聚丙烯酸酯乳胶纳米分散体作为多孔砂岩固结剂的功效

这项研究描述了两种创新的水性聚丙烯酸酯聚合物对多孔石材微观结构的影响。这种乳胶纳米分散体被设计为固结剂（含氟化和不含氟化），并在两种类型的砂岩（即布拉格（Mšené）和奥伯恩基兴）上进行了测试，这两种砂岩主要用作珍贵文化遗产的建筑材料。通过采用同步辐射计算机显微断层扫描，无创地获得了样品内聚合物分布的定量描述。采用基于传播的相衬模式来测试其在两种基体中识别聚合物的有效性，这通常因其对 X 射线的低衰减系数而受到阻碍。定量图像分析显示，由于固结处理，总孔隙度、孔隙比表面积、连通密度和分形维数存在显着差异。例如，在固结的布拉格砂岩和奥本基兴砂岩中，孔隙率值分别降低了约 7% 和 3%，且分布向较小的孔隙移动。此外，基于恢复的孔隙网络的水传输模拟证明，经过处理的样品的水渗透率和扩散率下降了一个数量级以上；沿着固结剂渗透的方向，效果更加明显。总体而言，两种乳胶表现出相似的成膜和孔隙填充能力。总的来说，结果凸显了基于同步加速器的 3D X 射线成像在定量评估固结建筑材料的多孔微观结构方面的巨大潜力。