4D imaging and quantification of the effect of a Phosphate-Based treatment on building materials by means of synchrotron X-ray Microtomography: New insights into the dynamic of the consolidation process

Diammonium hydrogen phosphate (DAP) solutions are used as consolidants for carbonate stone materials through the crystallization whithin the original matrix of newly formed crystalline phases. However, the for- mation mechanism of the new phases within the stone microstructure, and their effects on the porous system, strongly depend on the DAP molarity, the treatment method, and the stone microstructure. In this study, we obtained real-time quantitative information on the structural evolutions induced by the treatment process on the Noto limestone, a porous carbonate stone used as a building stone since antiquity, by synchrotron X-ray Microtomography. With the aid of 4D image analysis, microstructural modifications in terms of porosity, interconnection, and pore size distribution have been demonstrated in different stadia of the consolidation process, and the influence of molarity was asserted. This study paves the way for a deeper understanding of consolidation mechanisms and the effects induced overtime on the 3D microstructural features of porous ma- terials by inorganic treatment. 1.