Development of functionalize inorganic nanoparticles products for the consolidation of sandstones and concretes.

Abstract

This research is a development of the work presented in the bachelor’s degree thesis “Sintesi e analisi di nano-prodotti a base di silice per il consolidamento di materiali lapidei naturali”. As result of the research a Silica Nano Particles (SNP) based consolidant was synthesised and its effects on three siliceous linotypes was evaluated. Starting from the achieved results and focusing on the remotion of the observed drawbacks, further steps of the research were defined, bringing to the planning of this research of thesis. The aim is to synthesise particles bringing to the formulation of a consolidant which composition allows the complete penetration on the substrates, removing the main drawbacks showed by SNP100. The research started with the synthesis and functionalisation of the SNP. Several functionalisation methods with different typologies of reagents were performed. The composition and nature of each synthesis was analysed by the use of elemental and microscopic investigations. The acquisition of the analysis allowed to target the development of the procedures of synthesis used. As main result a consolidant based on SNP functionalised with Polydimethylsylossane was synthesised (SNP-PDMS). Comparison with a commercial consolidant called Evercrete Vetrofluid and SNP100 were made trough the application of the three consolidants on five different siliceous substrate. Two sandstones Pietra di Firenzuola and Pietra di Muggia and a granite Bianco Sardo and two type of concrete Grey Portland concrete and Vicat concrete. In order to simulate real conservation conditions and to achieve the complete comprehension of the interaction between consolidants and substrates. Two specimens of each material were subjected to different degradation process: (i)thermal shock, (ii)salt crystallisation, (iii)frost and thaw. Moreover, a new methodology of degradation was developed and applied in order to simulate, in laboratory, the effect of degradation induced by lagoonal condition. Porosimetric analysis, ultrasound and sponge test analysis were performed in order to study the textural and structural composition of the specimens. Microscopic and colorimetric analysis were applied to evaluate the aesthetical characteristic of the surface. The analysis were repeated on all the sound specimens, after the deterioration procedures and after the application of the consolidants. Thanks to the comparison of the results achieved at each steps of the research, it was possible to assess the effect of the treatments applied. The here presented research was born in 2019 and it is in collaboration with the LabCoMac section of the LAMA Laboratory of IUAV University of Venice. Thanks to the participation of LAMA to the project Venice2021 it was possible to improve aspects of the previews research to new challenging insights aimed to study the conservation of architectural materials in the lagoon.