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The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century BC includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY-GC/MS. Therefore, the possibility of the use of 'a secco' techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X-ray diffractometers do not detect them. Synchrotron radiation -high-resolution X-ray powder diffraction has allowed identification with only a few micrograms of sample.a rcm_478 286..307

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Two polycarboxylate ether copolymers were assessed as superplasticizers (SPs) for hydrated lime pastes modified with two reactive compounds, nanosilica (NS) and ceramic metakaolin (MK). Characterization of the molecular structure of the SPs by Size Exclusion Chromatography, XRD, FTIR and MALDI-TOF (Matrix Assisted LaserDesorption Ionization Time-of-Flight) mass spectrometry was performed. The structures of the polymers were seen to be star-and worm-like shapes. A close relationship was found between the molecular architecture and the flowability of the pastes, being the star-shaped plasticizer the most efficient. Zeta potential assessment allowed us to elucidate a steric hindrance as the main action mechanism for these polymers. The large specific surface area of nanosilica led to a large SPs consumption as compared with metakaolin with lower surface area. However, SPs in MK-lime samples were attached favourably on the C-S-H and aluminate hydrates, so that the dispersing action was greater with respect to NS-lime suspensions.2

39The effect of individual and combined addition of both nanosilica (NS) and 40 polycarboxylate-ether plasticizer (PCE) admixtures on aerial lime mortars was studied. 41The sole incorporation of NS increased the water demand, as proved by the mini-spread 42 flow test. An interaction between NS and hydrated lime particles was observed in fresh 43 mixtures by means of particle size distribution studies, zeta potential measurements and 44 optical microscopy, giving rise to agglomerates. On the other hand, the addition of PCE 45 to a lime mortar increased the flowability and accelerated the setting process. PCE was 46shown to act in lime media as a deflocculating agent, reducing the particle size of the 47 agglomerates through a steric hindrance mechanism. Mechanical strengths were 48 improved in the presence of either NS or PCE, the optimum being attained in the 49 combined presence of both admixtures that involved relevant microstructural 50 modifications, as proved by pore size distributions and SEM observations. 51 the technical characteristics of the final product and/or addressing environmental issues 58 [3][4][5]. The addition of nanosilica (NS) has attracted increasing interest because of the 59 filling effect, which improves the particle size distribution, thus reducing porosity, and 60 the pozzolanic reaction between NS and calcium hydroxide (CH) yielding calcium 61 silicate hydrates (C-S-H). These actions result in enhanced mechanical strength [6][7][8]. 62The filling of the interparticle space leads to a denser packing and reduces the water 63 demand, as there is no need to fill the space with water. In this case, the use of a 64 superplasticizer is required in order to guarantee workability [9]. Furthermore, the 65 strong tendency of NS to agglomerate also may make it necessary to use a dispersing 66 additive in order to overcome this problem and to ensure enough reactive surface for the 67 filling effect and C-S-H formation [7,10,11]. Dispersing additives are the so-called 68 plasticizers or superplasticizers, which have a water reducing action on cement 69 materials. When superplasticizers are added, workability at a constant water/cement 70 ratio is improved. Alternatively, the same workability as that of plain cement paste can 71 be reached with an outstanding reduction in water content. In the latter case, cement 72 materials with higher mechanical strengths can be obtained. The adsorption of the 73 plasticizer molecules on the solid particles, either by modifying the surface charge (zeta 74 potential) of the particles, thus increasing the electrostatic repulsion, or by steric 75 hindrance, causes a dispersing action, which has been claimed to be responsible for the 76 increase in fluidity of the cement paste [12]. The interaction between the 77 superplasticizer and the particles of the binder could be affected by the presence of 78 4 mineral additions (such as NS, silica fume or fly ash), which means that the 79 compatibility between them needs to be studied [13]. 80 81The interest in usi...

Illuminated Arabic manuscripts have been studied, employing two laboratory-made X-ray diffraction (XRD) systems developed recently in the C2RMF laboratory. The validity of the micro-XRD and XRD portable systems for the study of this type of artworks has been demonstrated. A common observation in all the analyses is the presence of calcite and rutile; also, hematite, goethite, cinnabar, brass, anatase and barite were detected in the various colours. Differences between the results obtained by both techniques due to acquisition mode are discussed. In addition, other techniques such as X-ray fluorescence (XRF) and micro-Raman were used for the complete characterization of the manuscripts.

The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60ºC/100% RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.