A combination of invasive and non-invasive techniques for the study of the palette and painting structure of a copy of Raphael's Transfiguration of Christ

The main objective of this study is to establish an appropriate method for the characterization of the pigments, materials and structure of the paint layers in a copy of the painting the Transfiguration of Christ by Raffaello Sanzio. A multi-technique approach that combines elemental, molecular and structural analyses and involves optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM–EDX), μ-Attenuated Total Reflection–Fourier Transform InfraRed (µATR-FTIR), μ-Raman spectrometry (µRS) and non-invasive portable diffractometer (pXRD) was used. Our results revealed that this copy of the Transfiguration was executed with a palette, which includes white lead (cerussite and hydrocerussite), lazurite from lapis lazuli pigment, red and yellow earths (goethite, hematite and lepidocrocite), lead tin yellow, cinnabar, red lake, smalt and bone black, and fillers such as calcite, baryte (an impurity associated to some pigments), and traces of colorless powdered glass. A secondary objective of this research was the application of non-invasive in situ pXRD measurements, which do not require painting sampling and helped to confirm some inconclusive results obtained with other techniques regarding the artist's palette. The results showed the crystalline nature of all the pigments identified, which were known from ancient times and available during the 16th and 17th. Lastly, the used of 14C accelerator mass spectrometry determined that the canvas date was 1451–1633 AD (with a 95% confidence level). Although the main focus of the work was to improve the analytical methodology to better understand the artist’s palette, our results will further help us to explore the authorship of the copy or the school that executed it. Graphical Abstract

An Experimental Study for Optimal Usage of Powdered Glass in Concrete as a Cement Replacement Material

The adverse effect of greenhouse emissions like CO2 leads to global warming. As per statistics, the global contribution of the cement manufacturing industry to greenhouse gas emissions is nearly 7%. To address these effects on the nature of the environment associated with cement manufacturing, it is necessary to explore sustainable binders for manufacturing concrete. Hence, extensive research is being conducted in the recent past to replace cement with various materials including waste generated from various sectors. Further, the replacement of fine aggregates and cement in concrete with various proportions of powdered glass is an engrossing topic among researchers for over a decade. The present study aims to the optimal use of glass powder in concrete as a replacement for cement and to enhance the characteristics compressive strength when compared to conventional concrete. Cement was replaced by various percentages of fine glass powder ranging from 10-50 % at an increment of 10%. The concrete cube specimens for 7 and 28 days were evaluated for their compressive strength after curing period, with that of conventional concrete. From the acquired results, it is perceptible that glass powder can be a suitable replacement for cement.

Mechanical Behavior of Modified Reactive Powder Concrete with Waste Materials Powder Replacement

Across the world, a huge amount of waste materials is deposited from different industrial or construction activities. Out of this massive waste quantity, a petite is recycled and remaining is dumped in vulnerable lands. This paper deals with the potential utilization of solid waste in reactive powder concrete, practically powdered glass originating from waste glass bottles and powdered ceramics tile from waste of construction process. First, the optimum ratio of waste pozzolanic material (ceramics to glass ratio) was obtained by pozzolinic activity test. Then, the optimal waste pozzolanic material was incorporated in reactive powder concrete at several substitution levels. The waste pozzolanic material in 5 %, 10 %, 15 %, 20 %, and 25 % were added in the reactive powder concrete mixes as fractional supplement of silica fume. Strength and water absorption of the modified reactive powder concrete were evaluated. A significant enhancement was observed in mechanical behavior of modified reactive powder concrete containing 15 % waste pozzolanic material. Results directed irrelevant raise in water absorption as increasing the waste replacement material.

A novel low temperature synthesis of sodium silicate (water glass) from silica-rich wastes using hydrothermal method

This present work aims at synthesizing sodium silicate solutions from selected industrial wastes (waste glass and rice husks) using hydrothermal method. The as-received waste glasses of different mix colors were initially washed, crushed and wet milled for several hours then sieved through 75µm mesh. The sieved recycled glasses were then oven dried at 110oC for 72 h to obtain a powdered glass (SLSG). Rice husks were also washed to remove dirt adherence and dried. The dried rice husks were thermally treated in a muffle furnace at 800oC for 1 h then left to cool to obtain whitish rice husk ash (RHA). Both SLSG and RHA were then reacted with NaOH solution at varying concentration of 3M, 4M and 5M respectively in a 250 ml Erlenmeyer flask. The mixtures were heated with continuous stirring using a magnetic stirrer at temperatures of 150oC, 170oC and 200oC respectively for a reaction period of 4 h. Analyses were carried out on the synthesized sodium silicate solutions. The results obtained from the analyses showed sodium silicate synthesized from RHA possessed high viscosity while the SiO2/Na2O ratio showed they are commercial sodium disilicates which indicates the products are all sodium silicate solutions.

Characterization of Thermochemical and Thermomechanical Properties of Eyjafjallajökull Volcanic Ash Glass

The properties of a volcanic ash glass obtained from the Eyjafjallajökull eruption of 2010 were studied. Crystallization experiments were carried out on bulk and powdered glass samples at temperatures between 900 and 1300 °C. Iron oxides, Fe3O4 and Fe2O3, and a silicate plagioclase, (Na,Ca)(Si,Al)4O8, were observed. Bulk samples remained mostly amorphous after up to 40 h at temperature. Powdered glass samples showed increased crystallinity after heat treatment compared to bulk samples. The average coefficient of thermal expansion of the glass was 7.00 × 10−6 K−1 over 25–720 °C. The Vickers hardness of the glass was 6–7 GPa and the indentation fracture toughness, 1–2 MPa √m Values for density, elastic modulus, and Poisson’s ratio were 2.52 g/cm3, 75 GPa, and 0.24, respectively. The viscosity of the glass was determined experimentally and compared to three common models from the literature. The implications for the deposition of volcanic ash on hot section components of aircraft turbine engines are discussed.