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Zn and Cu interactions with three selected flavonoids (catechin, quercetin and rutin) have been electrochemically monitored. It has been shown that catechin takes 1 atom of metal per molecule; quercetin takes 2 atoms, and rutin is able to take up to 3 atoms. Not all ligands bind metals equally strong, and weakly bonded metals can be distinguished. Zn shows a sluggish kinetics and, at the same time, the highest conditional formation constants. The method could be applied to a real sample. Theoretical models are proposed for the most favourable compounds.

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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...