Restoration of cultural heritage masonry structures damaged by the 2009 Abruzzo earthquake: Materials and methods

This research is aimed at developing a methodology for the Emergency stabilization and restoration of historic buildings damaged by the 2009 Abruzzo earthquake, by means of on-purpose modified injection grouts based on hydraulic binders. Several portions of multi-leaf stone masonry walls from buildings in the towns of Onna, Tempera and Sant’Eusanio Forconese, all located in the province of L’Aquila, were selected for carrying out injection tests with six grouts. Before and after injection, a comprehensive experimental program, including chemical and microstructural tests on original and repair materials and mechanical tests on the masonry walls, was performed. The present contribution describes the tests carried out at the various levels and discusses the main results obtained

Degradation processes of reinforced concretes by combined sulfate--phosphate attack

A novel form of alteration due to the interaction between hydrated cement phases and sulfate and phosphate-based pollutants is described, through the characterization of concrete samples from an industrial reinforced concrete building. Decalcification of the cement matrices was observed, with secondary sulfate and phosphate-based mineral formation, according to a marked mineralogical and textural zoning. Five alteration layers may be detected: the two outermost layers are characterized by the presence of gypsum–brushite solid solution phases associated with anhydrous calcium sulfates and phosphates, respectively, while a progressive increase in apatite and ammonium magnesium phosphates is observable in the three innermost layers, associated with specific apatite precursors (brushite, octacalcium phosphate and amorphous calcium phosphate, respectively). The heterogeneous microstructural development of secondary phases is related to the chemical, pH and thermal gradients in the attacked cementitious systems, caused by different sources of pollutants and the exposure to the sun's radiation

Early exploitation of Neapolitan pozzolan (pulvis puteolana) in the Roman theatre of Aquileia, Northern Italy

: The paper reports the results of the analyses on mortar-based materials from the Roman theatre of Aquileia (Friuli Venezia Giulia, Northern Italy), recently dated between the mid-1st Century BCE and the mid-1st Century CE. Samples were characterized by Polarized Light Microscopy on thin sections (PLM), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and Quantitative Phase Analysis by X-Ray Powder Diffraction (QPA-XRPD). Pyroclastic aggregates (mainly pumices and scattered tuffs), incompatible with the regional geology, were found in two samples from the preparation layers of the ground floor of the building. Their provenance was determined by means of QPA-XRPD, SEM-EDS, X-Ray Fluorescence (XRF) and Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS). Mineralogical and geochemical analyses demonstrated their provenance from the Bay of Naples, thus recognizing them as pulvis puteolana, a type of pozzolanic aggregate outcropping around the modern town of Pozzuoli and prescribed by Vitruvius (De Architectura, 2.6.1) in mortar-based materials to strengthen masonries and produce hydraulic concrete for harbor piers. This evidence represents the oldest analytically-established case of pulvis puteolana exploitation in Northern Italy up to now, and an early use of the material out of Campania adapted for civil constructions in a non-strictly maritime-related environment. Indeed, the theatre was built in the low-lying Aquileia's deltaic plain, prone to water infiltrations that are typical in lagoon-like environments. The data highlight the craftsmen's resilience in adapting and reinterpreting the traditional use of the Neapolitan volcanic materials to deal with the geomorphological challenges of Aquileia's lowland

Highly Porous Polymer-Derived Bioceramics Based on a Complex Hardystonite Solid Solution

Highly porous bioceramics, based on a complex hardystonite solid solution, were developed from silicone resins and micro-sized oxide fillers fired in air at 950 °C. Besides CaO, SrO, MgO, and ZnO precursors, and the commercial embedded silicone resins, calcium borate was essential in providing the liquid phase upon firing and favouring the formation of an unprecedented hardystonite solid solution, corresponding to the formula (Ca0.70Sr0.30)2(Zn0.72Mg0.15Si0.13) (Si0.85B0.15)2O7. Silicone-filler mixtures could be used in the form of thick pastes for direct ink writing of reticulated scaffolds or for direct foaming. The latter shaping option benefited from the use of hydrated calcium borate, which underwent dehydration, with water vapour release, at a low temperature (420 °C). Both scaffolds and foams confirmed the already-obtained phase assemblage, after firing, and exhibited remarkable strength-to-density ratios. Finally, preliminary cell tests excluded any cytotoxicity that could be derived from the formation of a boro-silicate glassy phase

Low-CO2 Binders for restoring a Pb-contaminated Soil: Improvements and Drawbacks with respect to Ordinary Portland Cement

The remediation of heavy metal contaminated soils is usually approached with binder-based techniques, like solidification/stabilization (S/S), and ordinary Portland cement (OPC) as the main binding agent. This paper reports our preliminary attempts of substituting traditional OPC with more environmentally sustainable alkali-activated cements, in the S/S of a Pb-contaminated soil. The treatment of Pb contamination is complicated by the amphoteric behavior of Pb, whose mobility is increased at high pH values, which are characteristic of cementitious systems. The use of alkali-activated cements proved to be suitable for soil remediation, with different performances depending on the formulation studied. These preliminary findings may be further enhanced by long-term investigations and further optimization of the alkaline activating solution, as first steps towards the improvement of the environmental impact of soil remediation technologies

Novel glass-ceramic composition as sealant for SOFCs

This is the pre-peer reviewed version of the following article: Federico Smeacetto, Auristela De Miranda, Andreas Chrysanthou, Enrico Bernardo, Michele Secco, Massimiliano Bindi, Milena Salvo, Antonio G. Sabato, and Monica Ferraris, ‘Novel Glass‐Ceramic Composition as Sealant for SOFCs’, Journal of the American Ceramic Society, Vol. 97 (12): 3835-3842, December 2014, which has been published in final form at https://doi.org/10.1111/jace.13219. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This work deals with the design, the characterization, and testing of a novel glass-ceramic to be used as sealant for planar solid oxide fuel cells and its compatibility with Mn1.5Co1.5O4-coated Crofer22APU. Thermal, sintering, and crystallization behavior and thermo mechanical properties of the sealant are reviewed and discussed, indicating therefore that these compositions can be deposited at 850C and provide an excellent compatibility with both the Mn1.5Co1.5O4-coated Crofer22APU and the anode-supported electrolyte. In particular, Mn1.5Co1.5O4-coated Crofer22APU/sealant/anode-supported-electrolyte joined samples have been submitted to thermal tests (in air atmosphere) from RT to 800C (SOFC operating temperature) up to 500 h. No interactions, cracks formation, or failure were observed at the Mn1.5Co1.5O4-coated Crofer22APU/sealant interface and between the glass-ceramic and the anode-supported-electrolyte after 500 h of thermal tests in air atmosphere.Peer reviewe

RILEM TC 277-LHS REPORT: A review on the mechanisms of setting and hardening of lime-based binding systems

The main objective of RILEM TC LHS-277 “Specifications for testing and evaluation of lime-based repair materials for historic Structures” is the revision, adaption and, when necessary proposal, of the test methods to accurately study lime-based binding systems and mixtures, such as mortars and grouts. The empiric use of the lime-based composites and the predominant employ of cement in the field of Civil Engineering have led to the widespread application of test methods developed for cement-based composites to test the former. However, the clear differences in composition and performance between modern cement binders and lime-based materials would advise to explore specific test methods for the latter. To undertake this task the previous knowledge on the mechanisms of setting and hardening of these binders must be revised, arranged and synthesized. Processes such as drying, carbonation, hydration and pozzolanic reaction may occur during the setting and hardening of lime-based mortars and competition between them cannot be underestimated. With the aim of underpinning the revision and proposal of test methods for lime-based systems, this review paper reports a comprehensive study of the mechanisms of setting and hardening of these binders, considering the variability of the composition, which includes pure air lime as well as lime with hydraulic properties, lime-cement and lime-pozzolan systems.authorsversionpublishe