Pore Structure and Water Transfer in Pietra d’Aspra Limestone: A Neutronographic Study

Luciana Randazzo,Giuseppe Paladini,Domenico Majolino,Valentina Venuti,Giuseppe Montana,Michela Ricca,Vincenza Crupi,Frédéric Ott,Mauro Francesco La Russa,Natalia Rovella

doi:10.3390/app10196745

Abstract

Neutron radiography (NR) was here applied to study the effects of two different commercially available consolidants on the water absorption properties in a particular type of limestone (biocalcarenite), known as Pietra d’Aspra stone, which is one of the most extensively used lithotypes in Sicilian Baroque buildings. Our attention was mainly focused on the evaluation, using a fast and nondestructive visualization of water motion through capillarity, of the effectiveness of such layers as consolidating agents in view of preserving and maintaining both old and modern structures. The biocalcarenite was treated with nanosilica (Nano Estel®) and nanolime (CaLoSil®) by brushing it until full saturation, and then artificially weathered by salt crystallization and temperature/relative humidity jumps. Liquid distribution and height of the water front were monitored as a function of time. Significant differences in the water suction behavior among all the investigated samples were highlighted, which allowed us to gain insight into the coating/substrate interaction mechanisms which regulate the fluid mobility inside the porous network of the limestone.

Highlights

IntroductionThe presence of water inside the porous matrix of building materials, whether artificial (concretes and mortars) or natural (stones), plays a main role in determining their mechanical performance and stability
The presence of water inside the porous matrix of building materials, whether artificial or natural, plays a main role in determining their mechanical performance and stability
A neutronographic investigation was carried out on Pietra d’Aspra limestone, a particular type of lithotype extensively used in Baroque buildings of Palermo city (Sicily, Italy)

Summary

Introduction

The presence of water inside the porous matrix of building materials, whether artificial (concretes and mortars) or natural (stones), plays a main role in determining their mechanical performance and stability. Salt crystallization and transportation of unwanted substances through water penetration can lead to the formation of cracks and plane distortions, strongly affecting the structural integrity of the construction itself. Restoration treatments aimed at “conservation” should preserve the original material while slowing down the decay process as much as possible. Stone durability is a term describing how well the material retains its original physical and mechanical properties. As a consequence, it concerns several aspects such as texture, structure, and mineralogical composition, as well as methods of quarrying and handling, applied loads, and environmental conditions to which.

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