K/Na-silicate, ethyl-silicate and silane nano-molecular treatments in the restoration of high porous limestone

Carbonate sedimentary rocks (i.e., limestones) have been frequently used in historical times due to easy availability and workability. These latter depend primarily by petrophysical characteristics (porosity, bulk density) that influence the mechanical strength. However, the limestones with high porosity (>30%) and a poorly cemented carbonate-matrix show chemical alteration (i.e., dissolution) and physical decay (e.g., decohesion). In this work it was taken as case study a biomicritic limestone belonging to the carbonatic miocenic series (lower Tortonian) of Cagliari (southern-Sardinia, Italy). This limestone has a low-medium cementing matrix containing hygroscopic clay and sea-salt phases, which make the rock degradable. To limit the decay it can intervene with consolidating products (K-Na-silicate, ethyl-silicate) and protective-chemicals (silane nano-molecular gel-coat) to reduce the porosity and permeability to the liquid aqueous phase. Results highlight an increase of strength after consolidation and a decrease of gas-permeability after protection-treatment, maintaining in both cases a good permeability to the vapor-phase

Building pathology and environment: Weathering and decay of stone construction materials subjected to a Csa mediterranean climate laboratory simulation

Building stone materials have to satisfy long-term durability requirements in different environments in terms of mechanical strength and resistance to aggressive conditions. Several studies and field observations show that weathering on geo-materials is related to average annual precipitation and temperature. The decay also depends on salts air/soil concentrations and biological agents, but the more harmful impact is given by greenhouse gas (e.g. CO2, SOX, NOX, O3). These last induce the acidification of the rain and runoff waters. Nowadays, decay prediction is required in order to estimate the behaviour of stone materials over time. This research represents a second part of a previous work where the response to weathering of some construction materials used in ancient and contemporary architecture and cultural heritage has been evaluated by a labo- ratory simulation of hot-summer Csa Mediterranean climate. Simulation consists of accelerate ageing test on climate chamber by reproducing macro (e.g. daily and seasonal cycles of temperature, relative humidity, CO2 air concentration) and micro (e.g. rain, soil capillary rising) environments. Some non-destructive testing were executed to evaluate some physical–mechanical “decay markers” before and after the ageing. Test caused both decreasing and increasing of Leeb D hardness, decreases of permeability and a general decrease of ultrasonic speed, mainly due to the formations of patinas, crusts and efflorescences on the surfaces

Degrado, danni e difetti delle pietre naturali e dei laterizi

Il manuale descrive e analizza le patologie dei materiali lapidei naturali e dei laterizi per fornire al lettore preziose indicazioni utili per il loro corretto utilizzo, soprattutto nella prevenzione delle possibili patologie. L’opera è arricchita con immagini, tabelle, grafici e casi studio. A corredo, una copiosa bibliografia rimanda a specifici approfondimenti dei temi discussi. Viene fornita la descrizione chimica, fisica e meccanica dei materiali lapidei naturali, quindi delle rocce utilizzate come pietre da costruzione, trattando anche l’influenza della finitura superficiale sulla suscettibilità al deterioramento e i difetti più frequenti manifestati dalle pietre utilizzate come rivestimento. Un corposo spazio è dedicato alla caratterizzazione dei laterizi, materiali lapidei artificiali che meritano attenzione poiché ampiamente utilizzati sia nell’edilizia storica sia contemporanea. Non manca una sintesi delle principali tecniche diagnostiche e della normativa di riferimento vigente. Infine, il lettore troverà riassunti, in forma di schede illustrative, i meccanismi di danno e i difetti di cui sono state trattate le cause nel testo. Si tratta quindi di un volume pressoché unico nel campo della diagnostica, utile al professionista, al patologo edile e al progettista, che vogliano approfondire i fenomeni patologici che si verificano a carico dei materiali lapidei

Micro Destructive Analysis for the Characterization of Ancient Mortars: A Case Study from the Little Roman Bath of Nora (Sardinia, Italy)

In this work, a protocol of a partially invasive sampling for the archaeometric characteri- zation of ancient mortars from the little Roman Bath of Nora (Sardinia, Italy) is presented. Optical microscopy and different analytical techniques such as X-ray diffraction, X-ray fluorescence, thermo- gravimetric analysis, and physical/mechanical tests have been carried out on the mortars. These analyses were performed to investigate the chemical composition, alteration products, and binder pozzolanic activity. An innovative method of image analysis has been tested to obtain information about the size and shape of both the mortar aggregates and the binder/aggregate ratio. This new particle-size analysis has two different advantages: (i) it saves a huge volume of material compared to a classic granulometric classification through its use of a sieve and (ii) is eco-friendly in respect to the environment by saving a large volume of liquid waste derived from the acid attack for the separation of the insoluble aggregate from the soluble binder, as would be done for a common sieving. Results show a local provenance of the aggregates. The use of two different limestones for the mortars’ binder production was detected and probably this raw material belongs to the nearby Roman town of Karales (current day Cagliari)

Accelerate ageing on building stone materials by simulating daily, seasonal thermo-hygrometric conditions and solar radiation of Csa Mediterranean climate

The maintenance plan of ancient and contemporary buildings today takes on strategic importance and should include the identification of climatic environment where the structures are located. Researcher are trying to evaluate the response to weathering of the building materials by accelerated ageing tests. This technique often consists of the ‘‘aggravations practice”, by subjecting materials to extreme climate parameters not representative of the real environment conditions. For this reason, this type of ageing pre- sents a lot of criticisms. This research addresses the lacking of literature about the realistic simulation of a determinate environment/climate on building stone materials. The aim of this research is to understand if it is possible to recreate in laboratory the pathologies observed on building stones of ancient monuments from Sardinia (Italy) by simulating the climatic context of location. To do so, samples were undergone to accelerated cycles of thermo-hygrometric conditions and solar radiation for simulating realistic param- eters of Csa Mediterranean climate. Monitoring of some physical/mechanical properties before and after ageing indicates an overall decohesion of samples, the appearance of decay patinas and a slight worsen- ing of mechanical resistances. A mathematical equation relates the ageing test duration (6 months) with the hypothetical outdoor exposure quantifiable in %18 years for samples evolved to temperature and humidity cycles while %3.7 years for the samples subjected to only solar radiation. However, the test should to be reproduced in the natural outdoor environment to correlate and verify the reliability of the obtained data (test the test)

Hydrophobic Coatings’ Efficiency and Limestones’ Resistance to Salt Crystallisation

Funding Information: Carla Lisci gratefully acknowledges Roberto Madorno (PhD, Chemistry Engineer) for the support. Fabio Sitzia gratefully acknowledge FEDER (alentejo2020): Recursos Humanos Altamente Qualificados—ALT2059-2019-24. Vera Pires gratefully acknowledges the Contrato Programa entre FCT e a Universidade de Évora no âmbito do concurso estímulo ao emprego científico institucional 2018. The authors gratefully acknowledge the following funding sources and all the companies involved in INOVSTONE4.0 with reference POCI-01-0247-FEDER-024535), Portugal 2020, co-financed by Fundação para a Ciência e Tecnologia (FCT) under the project UID/Multi/04449/2013 (POCI-01-0145-FEDER-007649). The authors gratefully acknowledge the European Union: Sustainable Stone by Portugal, Call: 2021-C05i0101-02—agendas/alianças mobilizadoras para a reindustrialização—PRR (Proposal: C632482988-00467016). Publisher Copyright: © 2024 by the authors.Stone deterioration is significantly influenced by the process of salt crystallisation. The expansion of salt crystals on a porous framework exerts pressure on the solid fraction, causing the stone to deteriorate when the internal pressure of salt surpasses the stone’s strength. Protective coatings are employed to effectively hinder or substantially reduce the penetration of water and saline solutions. This study attempts to evaluate the effectiveness and long-term durability of limestones protected with hydrophobic coatings, focusing on their resistance to salt damage. The investigation followed the specifications set by the standard EN 12370:2019 and EN 14147:2003, which assesses the resistance of natural stone to salt crystallisation. The findings of this study indicate the conservation of physical–mechanical properties after ageing tests. In parallel, measurements of the static contact angle and the measurement of quality indexes revealed that the coatings maintained a certain level of hydrophobicity even after undergoing salt weathering tests, maintaining the good quality of the stones.publishersversionpublishe

Microscopia e Microanálise no Estudo de Pedras Ornamentais Carbonatadas

A crescente competitividade de economias emergentes tem criado dificuldades aos países Europeus produtores e exportadores de Pedra Ornamental. Para acrescentar valor, estes países terão que adicionar tecnologia aos seus produtos. São apresentados três casos de como as técnicas de microscopia e microanálise permitem antecipar e compreender o comportamento das rochas, em diversas condições climatéricas. Estas metodologias podem ser usadas em rocha de obra nova, eventualmente seguindo as normas vigentes ou em objetos património

Advances Technologies for natural stone| Inovstone 4.0 important results from a research project on natural stone construction material selection and performance analysis

The natural stone as a building material has been revealed to have much lower life cycle costs than other materials as concrete, glass and steel. For this reason, it has a positive impact on the environment. However, several incidents with different pathologies on distinct lithologies has led to an increase in maintenance costs. The lack of knowledge on a stone performance over time and the frequent absence of a solution has a significant negative effect on the entire stone trade. Therefore, less sustainable, and less durable construction solutions are used as an alternative. The work-package “Tools for value” of the Inovstone 4.0 project (Advanced Technologies and Software for Natural Stone) addresses the need to highlight the dynamic capacity of the Portuguese Ornamental Rocks Sector (RO) based upon in-depth knowledge on natural stone performance regarding dissimilar testing conditions and, at the same time, strengthen its competitiveness in relation to the new digital procurement model, namely in the context of the Building Information Modeling (BIM). This paper provides a comprehensive overview of the main project findings. The main objectives were: i) Classifying the stones by petrographic, mineralogical and geochemical analysis; ii) To understand and explain the mechanisms of the loss of strength caused by thermal ageing cycles; iii) To study the effect of biodeterioration on marbles, slates and limestones; iv) To develop a concept for assessment of Portuguese natural stone products, including a monitoring system to predict strength development and improve safety and reliability; v) To address quality control issues to optimize the production conditions. The research was performed on twenty-five different lithotypes, from various locations in Portugal. Project results eased the development of Portuguese natural stone construction products selection, performance guidelines and critical influence factors. Biosusceptibility and colour evaluation have been performed in the laborator

Mineralogical, petrographic and physical-mechanical study of Roman construction materials from the Maritime Theatre of Hadrian's Villa (Rome, Italy)

This paper presents the study of various Roman materials used in the construction of the Maritime Theatre, one of the main buildings in the Hadrian’s Villa complex, a designated UNESCO World Heritage Site located in Tivoli (Rome, Italy), dating to the first half of the II century A.D. The plaster layers (arriccio and intonachino) and overlying original Roman paintings that form the concave wall of the portico as well as some bedding mortars of the pyramidal stone elements (i.e. cubilia) of the circular masonry have been studied in particular. In addition, the acid volcanic rocks of the cubilia have been investigated, aiming to understand their state of alteration and geological origin. By mineralogical-petrographic microscopy (OM), diffractometry (XRPD), Raman spectroscopy, Point Load Tests (PLT), helium pycnometry, and particle size analysis, the composition and granulometric distribution of the aggregate, type and characteristics of the binder, and various physical-mechanical properties (density, porosity, water absorption, imbibition and saturation indices, mechanical resistance) of mortars and stones were defined. In addition, through digital image analysis of thin sections, the binder/aggregate ratio and some geometric characteristics of the aggregates (e.g. circularity) were determined. The research aims to improve the knowledge of the constructive technologies of the Maritime Theatre through the analysis of its materials

DETECTION OF FRACTURE PLANES BY GEORADAR IN A GRANITE QUARRY

No sector da extração de pedra natural, em particular no granito, mármore e calcário, vive-se um bom momento económico. Contudo, face às novas exigências técnicas, ambientais e de segurança, é necessário que sejam disponibilizadas informações úteis e em tempo útil, de modo a responder às necessidades dos profissionais do sector. Neste sentido, é fundamental o desenvolvimento de métodos e metodologias científicas que permitam a monitorização constante do recurso natural sem colocar em causa a operacionalidade da atividade extrativa. O georadar é uma técnica não invasiva e não destrutiva que permite detetar diferenças na composição geológica das estruturas soterradas. Este método tem sido aplicado com sucesso em diferentes áreas, nomeadamente, geotecnia, arqueologia, ou monitorização ambiental. O objetivo deste trabalho visa a aplicação do método de georadar em detetar descontinuidades, como fraturas, falhas, diaclases e veios de quartzo na frente de uma pedreira de granito, localizada em Évora, e representar essas descontinuidades num modelo digital 3D. Este trabalho foi complementado com mapeamento 3D com recurso a drone