title: On the role of hydrophobic Si-based protective coatings in limiting mortar deterioration.
abstract: In order to avoid both natural and artificial stone decay, mainly due to the interaction with atmospheric pollutants (both gases such as NOx and SO2 and particulate matter), polymeric materials have been widely studied as protective coatings enable to limit the penetration of fluids into the bulk material. In the current work, an air hardening calcic lime mortar (ALM) and a natural hydraulic lime mortar (HLM) were used as substrates, and commercially available Si-based resins (Alpha®SI30 and Silres®BS16) were adopted as protective agents to give hydrophobicity features to the artificial stones. Surface properties of coatings and their performance as hydrophobic agents were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Finally, some exposure tests to UV radiation and to real polluted atmospheric environments (a city centre and an urban background site) were carried out during a wintertime period (when the concentrations of the main atmospheric pollutants are higher) in order to study the durability of the coating systems applied. The effectiveness of the two commercial resins in reducing salt formation (sulphate and nitrate), induced by the interaction of the mortars with the atmospheric pollutants, was demonstrated in the case of the HLM mortar. Graphical Abstract ᅟ.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133, Milano, Italy. giuseppe.cappelletti@unimi.it.
authors.forename: G
authors.initials: G
authors.lastname: Cappelletti
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133, Milano, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Fermo
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133, Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Pino
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133, Milano, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Pargoletti
authors.affiliation: Dipartimento di Scienza della Terra, Università degli Studi di Firenze, Via G. La Pira 4, 50121, Firenze, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Pecchioni
authors.affiliation: CNR-Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, Via Madonna del Piano 10, 50019, Sesto Fiorentino, Firenze, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Fratini
authors.affiliation: Dipartimento di Biologia, Ecologia e Scienze della Terra (DiBEST), Università della Calabria, Via Pietro Bucci, Cubo 12 B, 87036, Arcavacata di Rende, Cosenza, Italy.
authors.forename: S A
authors.initials: SA
authors.lastname: Ruffolo
authors.affiliation: Dipartimento di Biologia, Ecologia e Scienze della Terra (DiBEST), Università della Calabria, Via Pietro Bucci, Cubo 12 B, 87036, Arcavacata di Rende, Cosenza, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: La Russa
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry; D060389:Construction Industry; D003252:Construction Materials; D057927:Hydrophobic and Hydrophilic Interactions; D010087:Oxides / Q000737:chemistry; D052638:Particulate Matter / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D000393:Air Pollutants; D017610:Calcium Compounds; D010087:Oxides; D052638:Particulate Matter; C016538:lime
keywords: External exposure; Hydrophobic coatings; Mortars; Transpirability; UV ageing; Water capillarity