Jorge Luis Almaral Sánchez

Supramolecular networks in organic–inorganic hybrid materials from perchlorometalate(II) salts and 2,4,5-tri(4-pyridyl)imidazole

Three organic–inorganic hybrid compounds have been prepared by combination of the tripyridinium imidazole of cation [2,4,5-tri(4-pyridyl)imidazole] (L) and a series of perhalometallate anions to give, namely [H3L(CuCl4)]Cl (1), [(H3L)2(PdCl4)3]·4H2O (2) and [(H3L)2(PtCl4)3]·4H2O (3), which have been structurally characterized by single-crystal X-ray diffraction analysis, showing that the hydrogen bonding interactions of the resulting 1D, 2D, and 3D networks contain at least one of the following synthons: X–H⋯ClnM− [X = C, N, N+; n = 0,1,2; M = Cu(II), Pd(II), Pt(II)] The dimensions are enhanced further by strong X–H⋯Cl− (C, N+) and OH⋯ClnM− [n = 1,2; M = Pd(II), Pt(II)] hydrogen bonds. Additional weak C–H⋯O, π–π stacking and Cl⋯Cl interactions stabilize the crystal structures further.

Chloride corrosion of embedded reinforced steel on concrete elaborated from recycled coarse aggregates and supplementary cement materials

As a result of contributive and sustainable strategies on concrete industry, researches are presently being developed, which are focused on improving durability of reinforced concrete structures as well as partially or completely replacing their components by recycled materials. In the case of steel bars, corrosion is considered as the major durability menace to reinforced concrete. The present research employed coarse aggregate from recycled concrete and supplementary cement materials, which are byproducts of industrial processes, such as fly ashes and silica fume, for the elaboration of sustainable concretes and for the evaluation of their behavior faced to chlorides exposure. Compressive resistance, electric resistivity, loading transfer resistance and ion chloride permeability resistance are the parameters which were determined from the resulting test specimens, thus specifying the minimum required properties for concrete, in accordance with regulations that guarantee its durability faced to chloride actions. From results obtained it is concluded that concrete elaborated using a 100% of recycled coarse aggregate and supplementary cement materials improves its behavior as far as resistance and durability are concerned, in comparison to conventional concrete.

New concrete additive by chemical recycling on PET

Due to the problem that represents the accelerated production of waste from the consumption of polyethylene terephthalate (PET), it becomes necessary to look for alternative solutions; chemical recycling is a suitable method for conversion into a material with potential application in concrete additive, such as unsaturated polyester resins; with the above improvements and conservation of non-renewable raw materials can reduce the environmental impact. This investigation was focused on obtaining the synthesis of a polymeric resin by the method of glycolysis, and their characterization by Infrared Spectroscopy (FT-IR); the results show that the recycled materials (PET and its processing) are similar to reagents made from primary materials so that it is considered feasible to use in the intended application.

Corrosion of Steel in Concrete with Recycled Aggregate and Pozzolanic Materials

The kinetics of corrosion was evaluated and the deterioration of the reinforced concrete made with recycled aggregate and pozzolanic materials was inferred. Four series of cylindrical specimens were made with water-binder ratio of 0.48; the reference series was made with natural aggregate and 100% Compound Portland Cement, the second series was with recycled coarse aggregate (RA) and a 100% CPC, a third series was made with RA, 30% fly ash and 70% CPC and the fourth series was made with RA, 10% silica fume and 90% CPC. Test specimens of each mixture were exposed to a 3.5% NaCl aqueous solution and the corrosion current density was obtained using Electrochemical Impedance Spectroscopy (EIS). The results show that the system of concrete with recycled aggregate and with silica fume addition has more corrosion resistance, because it presented the highest values of Resistance of charge transfer of reinforcement