Fracture energy of sustainable geopolymer composites with and without the addition of slaughterhouse by-products as fibre-reinforcement: An experimental investigation

This work focuses on the development and on the mechanical characterization of geopolymer composites to be used as sustainable plasters or mortars. The starting point of the work is the synthesis of a geopolymer binder, which is subsequently used for the production of two different mortars: the first one is obtained by simply adding fine aggregates (control mortar), while in the second case, also slaughterhouse wastes (SHW) are included in the admixture. Nowadays, slaughtering industry produces a large amount of biological wastes, that are usually discarded via incineration or landfills. Among SHW, horns and hooves, which are rich in keratin, can be potentially used as additives in the manufacturing process of mortars, both in the form of fibre-reinforcement, as well as fine aggregates and fillers. In the second mortar considered in this work, 2% of SHW fibres and 2% of SHW filler are added in the admixture. The mechanical properties of the three products are experimentally investigated and compared to each other. Apart for compressive strength, close attention is paid to the flexural behaviour and to the determination of fracture energy. To evaluate the effect of SHW addition on crack propagation and width, digital image correlation technique is also adopted

Efficiency assessment of hybrid coatings for natural building stones : advanced and multi-scale laboratory investigation

The efficiency of a hybrid patented consolidant (PAASi) and two commercially available hybrid coatings (a consolidant named AlSiX and a hydrophobic product named WS3) properly modified was assessed on a calcarenite substrate. Test routines based on standard recommendations were first applied to evaluate the performances of the consolidant and protective treatments, while the investigation of additional aspects such as penetration depth and interaction with the substrate was achieved by a multi-scale approach based on classic intrusion methods (mercury intrusion porosimetry) and Drilling Resistance Measurement System (DRMS), combined with non-invasive imaging techniques (X-ray computed micro-tomography and neutron radiography) and small angle neutron scattering (SANS). A distinct interaction of the products with the pore network of the stone was quantified in the range 0.007–200 µm. Their effects on capillary water absorption were also visualized with neutron imaging. The suitability of the products on the selected substrate was discussed, highlighting also how the applied routine can support conservation material studies. The results indicated that the Al-Si-based product led to unwanted effects. Alternative application methods and/or curing procedures have to be explored to overtake these undesirable changes. On the contrary, the polyamidoamine-based product seemed to be more suitable for calcarenite substrates conservation. The performances of the hydrophobic coating, when used in combination with consolidants, were strictly influenced by the pre-consolidation of the substrate

Multi-scale laboratory routine in the efficacy assessment of conservative products for natural stones

The evaluation of conservative treatments’ efficacy on natural building stones are usually based on standard recommendation routines finalized to evaluate compatibility and harmfulness of products in turn of the substrate. However, the visualization and the quantification of products inside pore structure of natural stones is not immediate through standard tests, so that imaging and advanced techniques are recently proposed in material conservation field to improve knowledge on penetration depth, modification of pore-air interface at different scale and monitor dynamic absorption processes. Moreover, natural stones are usually characterized by complex structure, which changes due to conservative treatments have to be inspected at different scale (from micrometer to nanometer). In this prospective, the assessment of laboratory practices able to integrate multiscale methods and give back a complete overview on interaction between new conservative formulates and natural stones is of high interest. In this paper, we propose a methodological routine for efficacy assessment of conservative products, incorporating classical and innovative nondestructive techniques. Validation of the workflow has been verified on a high porous natural stone treated with new hybrid formulates appropriately customized for conservation issues. • The study intends to add new insights on problems related to consolidation of high porous carbonate stone, application methods in consolidating natural stones and methods to evaluate efficacy of new products.• A multi-scale laboratory investigation procedure is proposed by integrating standard and innovative nondestructive methods. Merits and limits of each applied method are discussed during validation.• The possibility to incorporate standard routines and/or substitute destructive testing with non-destructive ones seem to be a valid alternative to evaluate efficiency and monitor behavior of stones treated with consolidating products

Identification of Shell Colour Pigments in Marine Snails Clanculus pharaonius and C. margaritarius (Trochoidea; Gastropoda)

This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. https://creativecommons.org/publicdomain/zero/1.0/ The attached file is the published version of the article

Micro-Raman investigation of pigments and carbonate phases in corals and molluscan shells

We report the results of a micro-Raman investigation, in resonance conditions, on the pigments and on the nature of the biogenic carbonate in different species of corals and marine shells of a wide variety of colours. Corallium rubrum (Anthozoa) and Stylaster roseus (Hydrozoa) show calcite and aragonite skeletons, respectively. The shells are mostly aragonitic, with the exception of bivalves of Pectinidae family which reveal a calcite/aragonite distribution. The main Raman features of the pigments (carotenoids or polyenes) show Raman dispersion (upshift of the C=C (ν1) and C–C (ν2) stretching vibration frequencies of the polyenic chain with decreasing excitation wavelength). Partially or completely demethylated polyenes with different conjugation lengths may be responsible for the colours of Corallium rubrum and of most of the marine shells. Stylaster roseus and the dark brown colours of Gibbula sp (Gastropod class) show typical bands of carotenoids, similar to those found in canthaxanthin. Overtones and combination bands are described in terms of the four fundamental vibrations of polyenes. A constant ratio between ν1 and ν2 frequencies, nearly independent of the Raman excitation wavelength, has been determined from a large set of data for corals and shells. A simple relationship between the main Raman frequencies and the effective conjugation length N of the polyenic chains is suggested

The nature of the pigments in corals and pearls: a contribution from Raman spectroscopy

Raman measurements at 473.1nm on corals, both calcitic and aragonitic, and on pearls (aragonitic) were performed to elucidate the nature of the pigments, with the relative importance of methylated (carotenoids) or nonmethylated polyenes involved in the color associated with marine mineralized organisms still being a debated question. The resonance condition of the laser excitation enables the observation of overtones and combinations of four main vibrational modes of the polyenic or carotenoid pigment up to > 5000 cm 1. Raman spectroscopy proves to be a powerful tool to determine the biomineralized structure, the nature of the pigments, and the presence of artificial dyes

Interdependencia financiera global: equilibrios múltiples en Bretton Woods II

Se ha bautizado como Bretton Woods II a la actual interdependencia entre Estados Unidos y las economías asiáticas: el primero provee una demanda de importaciones asiáticas potente y éstas, al intervenir en los mercados de divisas para mantener sus monedas subvaluadas respecto al dólar, financian el nivel de gasto americano. Este trabajo analiza la situación como un equilibrio de Nash en un juego no cooperativo con equilibrios múltiples y describe su colapso como una crisis financiera de segunda generación con la particularidad de que vendría desencadenada por decisiones de los bancos centrales asiáticos y no de los inversores privados

WOOD PRESERVATIVE COMPOSITIONS

The invention relates to a preservative composition comprising a polyamidoamine polymer dissolved or dispersed in an aqueous solvent and/or in an organic solvent, and its use for coating wood, paper, stone and lithoid construction materials (for example travertine, calcareous stones etc.). The preservative composition, which may envisage the addition of metal cations or metal nanoparticles or boric acid, has biocidal properties (anti-fungal, anti-insect, antibacterial, anti-mould) and allows the material to which it is applied to be protected and consolidated