The Pleasures of Life and the Praise of Wisdom in the Book of Qohelet in the Light of Medieval Jewish Interpreters

The article analyzes how the most important medieval Jewish exegetes interpreted the book of Qohelet. It is focused on some of the most controversial ideas of the text, namely, the meaning of pleasures of life and the kind of wisdom praised in the book. The question of authorship, although not controversial, is also analyzed. The interpretations of medieval Jewish exegetes on these topics were the basis for their understanding of the purpose of the book as a whole. Different explanations were given by Jewish exegetes on whether the book of Qohelet encourages asceticism or promotes the knowledge of foreign sciences.Przyjemności życia i pochwała mądrości w Księdze Koheleta w ujęciu średniowiecznych żydowskich komentatorów Artykuł przedstawia, w jaki sposób najważniejsi średniowieczni egzegeci żydowscy interpretowali Księgę Koheleta. Koncentruje się on na wybranych kontrowersyjnych koncepcjach tekstu, a mianowicie na znaczeniu przyjemności życia i rodzaju mądrości, która jest chwalona w księdze. Kwestia autorstwa, choć nie jest uznawana za kontrowersyjną, również stanowi przedmiot analizy. Interpretacje średniowiecznych egzegetów żydowskich dotyczące tych zagadnień były podstawą rozumienia przez nich celu całej księgi. Żydowscy egzegeci różnie wyjaśniali Księgę Koheleta, zastanawiając się, czy zachęca do ascezy, czy też promuje wiedzę o obcych naukach

Advanced synchrotron studies of ye'elimite-based cement pastes

Synchrotron characterization techniques [1] are being used to study Portland-based cements and recently also CSA and related cements. A key property of these techniques is that they do not require sample preparation, so the microstructures of the pastes can be preserved. The classical application of synchrotron tools is powder diffraction used to determine the crystalline phase content evolution with hydration including the overall amorphous fraction. Furthermore, other most advanced techniques are being applied to ye'elimite-containing pastes such as i) Total Scattering Synchrotron Powder Diffraction (TS-SXPD), and ii) Ptychographic Synchrotron X-ray Computed Tomography (PSXCT). All these applications will be reviewed here. TS-SXPD data coupled with the Pair Distribution Function (PDF) analysis methodology [2] allows having a better insight about the nanocrystalline/amorphous atomic arrangements in the gels. It has been very recently shown that nanogibbsite with very small particles, 3nm, is the main constituent of ye'elimite-gypsum hydration paste [2]. Nanogibbsite particles being smaller than those originated from the hydration of monocalcium aluminate. In addition, PSXCT is a tomographic technique that profits from the partly coherent nature of the synchrotron beam to provide better (smaller) resolution, which can be lower than 100 nm. It also provides the mass densities if the chemical stoichiometries are known. This technique has been applied to ye'elimite hydration to determine the microstructure and chiefly the bulk densities of nanogibbsite [3]. The microstructure evolution at early age was also followed [4]. Figure 1 shows an example of a slide of the electron density tomogram for a ye'elimite paste at 8 days of hydration and the corresponding histogram for the full volume with all phases identified.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.This work has been supported by Spanish MINECO through BIA2014-57658-C2 and BIA2017-82391-R, which are co-funded by FEDER

In-situ hydration studies of ye’elemite at early ages for understanding eco-cement performances'

Póster; ALBA User Meeting and VI AUSE Conferenc

Design and optimisation of new formulations of Belite-Alite Calcium Sulfoaluminate (BACSA) eco-cements

Belite Calcium SulfoAluminate (BCSA) eco-cements were developed as OPC substitutes since in their production release 22% less CO2 than OPC. BCSA eco-cements contain belite as main phase (>50 wt%) and ye'elimite as secondary main phase (~30 wt%). However, these materials develop low mechanical strengths at intermediate hydration ages (3, 7 and 28 days). A solution to this problem may involve the design and preparation of clinker/cement with the highest percentage of coexisting alite and ye'elimite. These materials are known as Belite-Alite Calcium SulfoAluminate (BACSA) clinkers/cements. Their manufacture may produce 15% less CO2 than OPC. Alite is the main component of OPC and is responsible for early mechanical strengths. The reaction of alite and ye´elimite with water will develop cements with high mechanical strengths at early ages, while belite will contribute to later curing times. This work is focused on the design and optimisation of all the parameters evolved in the preparation of BACSA eco-clinkers that develop mechanical strengths comparable to those of OPC with a reduction in CO2 emissions of at least 15% when compared to OPC production. These parameters include the selection of the raw materials (lime, gypsum, kaolin and sand), milling conditions of the crude, clinkering temperature (from 1280 to 1300ºC) and holding time at every temperature, and final composition. The clinker with the targeted composition (belite ~ 60 wt%, alite ~ 13 wt% and ye'elimite ~ 10 wt%) was chosen to perform the scaling-up (2 kg). BACSA eco-clinkers were chemically and mineralogically characterised through X-ray fluorescence and laboratory X-ray powder diffraction (LXRPD), the latter in combination with the Rietveld methodology to obtain the full phase assemblage including Amorphous and Crystalline non-quantified, ACn, contents. Finally, the hydration of the selected BACSA cement paste (prepared with the scaled-up clinker and anhydrite) was studied mainly through rheological measurements (at very early hydration time) and LXRPD in combination with the Rietveld methodology and G-factor method. The compressive strengths were also measured at different hydration times and were compared with OPC.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.Societ

Rheological and hydration characterization of calcium sulfoaluminate cement pastes

Calcium sulfoaluminate (CSA) cements are currently receiving a lot of attention because their manufacture produces less CO2 than ordinary Portland cement (OPC). However, it is essential to understand all parameters which may affect the hydration processes. This work deals with the study of the effect of several parameters, such as superplasticizer (SP), gypsum contents (10, 20 and 30 wt%) and w/c ratio (0.4 and 0.5), on the properties of CSA pastes during early hydration. This characterization has been performed through rheological studies, Rietveld quantitative phase analysis of measured x-ray diffraction patterns, thermal analysis and mercury porosimetry for pastes, and by compressive strength measurements for mortars. The effect of the used SP on the rheological properties has been established. Its addition makes little difference to the amount of ettringite formed but strongly decreases the large pore fraction in the pastes. Furthermore, the SP role on compressive strength is variable, as it increases the values for mortars containing 30 wt% gypsum but decreases the strengths for mortars containing 10 wt% gypsum.This work has been supported by Spanish Ministry of Science and Innovation through MAT2010- 16213 research grant, which is co-funded by FEDER, and Ramón y Cajal Fellowship (RYC-2008- 03523)

Hydration study of Belite-Alite Calcium Sulfoaluminate (BACSA) cement blended with fly ash

The main objective of this work is to understand the effect of the addition of fly ash (0, 15 and 30 wt%) in the hydration of a BACSA cement paste (water/cement=0.4) prepared with 12 wt% of anhydrite. The pastes were characterized, at different hydration ages, through laboratory X-ray powder diffraction (LXRPD) (using an internal standard) combined with the Rietveld methodology and thermal analyses. Details about the phase developments including pozzolanic reactivity will be reported and discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hydration studies of calcium sulfoaluminate cements blended with fly ash

The main objective of this work is to study the hydration and properties of calciumsulfoaluminate cement pastes blended with fly ash (FA) and the corresponding mortars at different hydration ages. Laboratory X-ray powder diffraction, rheological studies, thermal analysis, porosimetry and compressive strength measurements were performed. The analysis of the diffraction data by Rietveld method allowed quantifying crystalline phases and overall amorphous contents. The studied parameters were: i) FA content, 0, 15 and 30 wt.%; and ii) water addition, water-to-CSA mass ratio (w/CSA = 0.50 and 0.65), and water-to-binder mass ratio (w/b = 0.50). Finally, compressive strengths after 6 months of 0 and 15 wt.% FA [w/CSA = 0.50] mortars were similar: 73 ± 2 and 72 ± 3 MPa, respectively. This is justified by the filler effect of the FA as no strong evidences of reactivity of FA with CSA were observed. These results support the partial substitution of CSA cements with FA with the economic and environmental benefitsThis work has been supported by Spanish MINECO through MAT2010-16213 research grant, which is co-funded by FEDER. I. Santacruz thanks a Ramón y Cajal fellowship, RYC-2008-03523