This research aims to study feasibility of incorporation of fine fraction of recycled aggregates coming from construction and demolition waste in cement-based masonry mortar fabrication. Initially, three types of recycled aggregates: concrete, mixed and ceramic recycled aggregates, were characterized in terms of physical, mechanical and chemical properties. There were used 1:3 and 1:4 cement-to-aggregate proportions and replacement percentages of 50%, 75% and 100% respectfully for three types of studied recycled aggregates

The ferromagnetic zircon-type phase of ${\mathrm{GdCrO}}_4$ presents high values for the magnetocaloric (MC) parameters. This compound has large isothermal entropy changes $\mathrm{\Delta }{S}_T$ under the magnetic field action in a wide temperature range, from 5 to 35 K, reaching a maximum $|\mathrm{\Delta }{S}_T|=29.0\pm 0.1\mathrm{J}/\mathrm{kg}\mathrm{K}$ at 22 K, for a field increment $\mathrm{\Delta }B=9$ T. It orders ferromagnetically at $T_{\mathrm{C}}=21.3\mathrm{K}$ via the Cr-Cr exchange interaction and shows a second transition at 4.8 K due to the ordering of the Gd sublattice. The large MC effect is enhanced by the polarization of the ${\mathrm{Gd}}^{3+}$ ions by the ${\mathrm{Cr}}^{5+}$ ones via a weaker Gd-Cr interaction. This effect is an interesting feature to be considered in the search for new compounds with a high MC effect in the range of liquid hydrogen or natural gas, regarding the liquefaction of gases by magnetization-demagnetization cycles. This paper contains experimental measurements of magnetization, heat capacity, and direct determinations of the MC effect. The magnetic contribution to the heat capacity $C_m$ has been obtained after subtracting the lattice component. Approximate values for the exchange constants $J_1$ (Cr-Cr) and $J_3$ (Gd-Cr) have been deduced from $C_m$.

The present study deals with a characterization of metakaolin pozzolanic activity and its chemical character exhibited in the O rdinary P ortland C ement ( OPC ) blends by means of Transmission Electron Microscopy (TEM) and S elected‐ A rea E lectron D iffraction (SAED) techniques principally. Metakaolin sample was prepared by calcination of kaolin rock ( G uadalajara, S pain) at 780°C. Two OPC of different chemical composition from the tricalcium aluminate content point of view were chosen and P ortland cement blends series elaborated and then submitted to the pozzolanic activity test ( EN 196‐5 or F rattini test ). The main mineralogical components of the metakaolin are determined qualitatively: χ‐alumina and quartz. The chemical character of the metakaolin is described because of its final composition as well as due to its A l atoms possible coordination. The crystalline order of the material is found to be of both amorphous and polycrystalline, being an intimate amorphous mixture of alumina and silica. Finally, all the alumina capable of reacting chemically is denominated and classified as reactive alumina component, Al ₂ O ₃ ^r− , of pozzolans, as well as the aluminic chemical character of metakaolin in OPC blends is once again proved and exhibited by means of F riedel's salt formation studied already at 4 h‐age.