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Mineral production continues to be necessary for economic development, consequently also the management of mining and mineral-processing wastes represent a considerable issue in terms of recycling and economic strategies for the future. One of the most promising reuses for coarse-grained mining wastes, especially barren waste rocks from coal and metal mining, is their application in the building and construction sector. An experimental research has been developed with the aim of studying the possible reuse of waste rocks – coming from mining activities-as fine aggregates in a fly ash based geopolymer: physical, chemical and mechanical tests have been carried out in order to analyze in detail the interaction between the geopolymer binder and the rock waste aggregates. All the mixtures, characterized by an aggregate/binder/ratio ranging between 0.05 and 1, showed a final microstructure characterized by a rather homogeneous geopolymer matrix embedding the mining waste rock. The geopolymeric matrix governs the overall mechanical behavior of the system, thanks also to the strong interaction at the interface between matrix and aggregates (mining waste). Moreover, all the geocomposites satisfy the prescribed limit for inert or non-hazardous waste.

In the last decades, the use of natural fibers as replacement to synthetic fibers in reinforced composites has become a trending practice due to their attractive features. The main drawbacks associated with the use of natural fibers are the hydrophilic nature and the weak interaction between fiber and binder matrix, so they are often subjected to pre-treatments before their utilization. The use of chemical treatments may improve the adhesion between fiber and matrix, but it involves a dangerous impact on the environment. In this study, biologically treated hemp fibers were proposed as reinforcement in plasterboards. The effect of the bio-treatment was evaluated by SEM, DTA, FT-IR and XRD analysis in comparison with traditional chemically treated fibers. These analyses showed that both the treatments involve in similar modifications on fiber's morphology and composition. In addition, a strong reduction of treated fibers' water absorption was measured. Three-point bending test and low impact behavior revealed an enhanced toughness and a damage reduction of the fiber-reinforced plasters, so indicating a comparable efficacy of the biologically treated fibers respect to a chemically treated ones.

Mesoporous silica nanoparticles are among the most promising nanovectors for controlled release of active compounds. In this work we design a mesoporous silica-based delivery system in which the release of the active compound is controlled by specific pore/wall interactions and can also be triggered by an external stimulus, such as the simple addition of water into the surrounding releasing medium. Due to its reversibility in presence of water, imine bond formation between amino groups and aldehydes has been proposed as a valuable approach to reach this scope. The amino-group is provided by the amino-functionalized mesoporous silica which has been obtained through the functionalization of Santa Barbara Amorphous (SBA)-15 with aminopropyltrietoxysilane. Whereas the aldehyde is represented by the active compound itself: the natural antimicrobial vanillin. The obtained particles have been embedded into PCL-based films. The amino-functionalization of mesoporous silica has been confirmed through NMR analysis and X-ray diffraction. Imine bond formation and evolution has been followed by 13C NMR before and after the contact of mesoporous silicas with water. Release kinetics of vanillin show that the diffusion of vanillin from films containing the functionalized mesoporous silica is delayed by about 20% and 75% with respect to films containing free vanillin, in water and in ethanol respectively. The most significant feature of the system is the stepwise behavior which shows that the release of the amount of vanillin bound to the NH2 groups of functionalized SBA is triggered only after the addition of water to the surrounding ethanolic solution. These findings give an important insight into the use of pristine and functionalized mesoporous silicas for the development of polymer films for active responsive packaging materials.

The management of huge amounts of waste deriving from several anthropogenic activities, such as manufacturing, construction, mining and quarrying, dredging, represents a great contemporary environmental challenge for many countries worldwide. Among the different recycling possibilities, the use of the excavated soils, obtained from operations such as tunneling, excavations, mining, dredging etc., which are generally considered as soil waste, in the production of innovative eco-sustainable building materials represents an interesting alternative to their disposal. In fact, considering especially their chemical composition, low cost and easy availability, soil wastes seem to be the ideal candidates to be used as secondary raw materials for the manufacture of geopolymer-based materials. The paper intends to present a review of the recent scientific literature regarding the use of different types of soil waste to produce geopolymeric binders. Particular attention is focused on mining waste (deriving from various types of mining industries) and dredged sediments coming from marine harbors and natural and artificial water reservoirs, in order to understand and critically discuss the limits of their disposal approach and, at the same time, show perspectives and challenges for possible future research activities in this field. The production of geopolymer-based building components, starting from mining waste and reservoir sediments, is widely discussed thanks to the numerous scientific findings, while the recycling of marine dredged sediments through geopolymerization represents a completely new and innovative trend in research activity, in fact only few related papers were found in literature. It can be strongly stated that geopolymerization can significantly contribute to a sustainable improvement of soil waste management systems.

This paper reports the characterization of Sr-, Zn- and Cd-exchanged zeolitic materials as water vapor adsorbents, in order to evaluate the influence of the extraframework species on their adsorption properties. Both synthetic and natural substrates are taken into account. Water vapor adsorption isotherms on each ion-exchanged sample have been obtained at 298, 318, 338, and 358 K and have then been modeled using the Dubinin-Astakhov equation. Focusing on the possible implementation of such adsorbents in thermodynamic cycles, an estimation of their specific heat storage densities has been expressed. Results revealed that adsorbents of natural origin are not suitable for a valid employment in thermodynamic cycles, while FAU-type zeolite X samples exchanged with Sr2+ or divalent transition metal ions (i.e., Zn2+ or Cd2+) show a significant potential as heat storage media. The same trend of the specific heat storage density with the cationic content of the adsorbent can be identified for both series of synthetic and naturally originating materials (i.e., Zn > Sr > Cd > Na), confirming how ion exchange allows effective tuning of zeolitic substrates when employed in thermodynamic cycles based on the reversible adsorption of water vapor.

The management of reservoirs for water supply is a great environmental problem, since regular de-silting operations produce huge quantities of sediments. Among the recycling possibilities, the use of clay sediments for the manufacture of geopolymer-based materials seems to be an interesting alternative to disposal, due to their low cost and easy availability. In particular, two sediments, coming from reservoirs located in Southern Italy, were firstly characterized by X-ray diffraction, differential thermogravimetry, Fourier transformed infrared (FTIR) spectroscopy and 27 Al and 29 Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy. The reactivity of raw and thermally treated clay sediments in alkaline media was also investigated. Finally, geopolymeric samples were produced and chemically, physically and mechanically characterized. The results showed that the calcined clay sediments can be suitable source materials in polycondensation reactions and that the increase of the calcination temperature from 400 to 750 °C resulted in an increased reactivity. Moreover, good mechanical properties were obtained by all the geopolymers prepared with heat-treated sediments.

In this paper artificial aggregates based on recycled plastic materials, mostly polyolefin and polyethylene terephthalate waste, were used as partial replacement of natural aggregates for manufacturing hydraulic mortars. In particular, different amounts (10–50% by weight) of siliceous sand were substituted by the same weight of the above plastic waste, to obtain six mortars with different composition. The influence of plastic addition on physical and mechanical properties (density, porosity, compressive and flexural behavior and water vapour permeability) was studied. Moreover the thermal conductivity of the obtained mortars was evaluated. Recycled plastic substitution enhances the open porosity, causing a decrease in flexural and compressive strength, with an increase in water vapour permeability. Nevertheless, the presence of plastic aggregate leads to a significant reduction in thermal conductivity, which improves the thermal insulation performances of the mortar. For this reason the addition of recycled plastic aggregate in the manufacturing of hydraulic mortars can be considered a way to reduce the growing environmental impact of polymers and, at the same time, it allows the development of increasingly eco-sustainable building materials.

In order to design binding materials able to historical buildings restoration, physical–mechanical properties and microstructure of fibre-reinforced lime-based hydraulic mortars, have been studied, in comparison with a reference hydraulic lime-based mortar with no addition. Fibre-reinforced mortars, even characterised by larger porosity and lower mechanical strength than the reference, pointed up a clear improvement in the post-cracking behaviour and, regardless of nature and concentration of fibres, turned from brittle materials to ductile materials. It was demonstrated that the addition of as low as 2% of glass fibres leads to a toughening of the mortar and jointly to an improvement of the flexural load.

Five different samples of (Ba, Sr)-exchanged zeolite A, exhibiting the same Na residual content within the experimental error, were prepared by cation exchange. These powders, with or without a previous thermal treatment, were cold pressed in an isostatic press to manufacture cylindrical compacts. Such compacts were subjected to various thermal cycles up to 1500◦C. The sintering and densification of these compacts was studied by determining linear shrinkages, mass variation, bulk density and porosity. All the compacts produced were totally composed by BaAl2Si2O8–SrAl2Si2O8 solid solutions occurring in the polymorph known as monoclinic celsian. Porosity lower than 0.1% and bulk density higher than 95% theoretical density were obtained. The problems arising in the sintering of compacts manufactured with zeolitic precursor are discussed and proper measures to solve them are suggested