Textile Reinforced Mortar (TRM) composite systems have recently been developed using environmentally sustainable binders, including alkali-activated mortars (AAMs). Despite their promising mechanical performance and reduced environmental impact, the feasibility of incorporating AAMs into TRM strengthening systems has not yet been fully established. In particular, the behaviour of AAM-based TRM composites, known as TRAAMs, under elevated temperatures remains poorly understood, and limited experimental evidence is currently available regarding their mechanical stability, bond performance, and failure mechanisms after thermal exposure. This study investigates and compares the performance of TRM systems manufactured with different binders (lime, cement, and alkali-activated) reinforced with coated basalt textiles, both at room temperature (20 degrees C) and after exposure to elevated temperatures (200 degrees C, 400 degrees C, and 600 degrees C). Residual properties were assessed through mechanical testing and microstructural analyses. Furthermore, the results were benchmarked against data available in the literature for comparable TRM systems subjected to high temperatures. The findings indicate that exposure up to 200 degrees C has a negligible influence on the TRM residual performance, with TRAAM systems even showing slight improvements. Conversely, exposure to 400 degrees C and above leads to a significant degradation of performance in all TRM systems.

The construction sector is under intense pressure to become more sustainable due to the significant CO2 emissions coming from cement production. A key strategy is the extensive use of alternative binders in substitution of pure cement clinker. In this regard, Limestone Calcined Clay Cement (LC3) shows great promise due to its easy adaptability on current technology. This study focuses on lightweight cementitious materials based on LC3, integrating foam and recycled carbon fibres (rCF) from end-of-life Fibre-Reinforced Polymers (FRP). The aim is to enhance the mechanical properties and foam stability as well to promote circularity. The resulting Fibre-Reinforced Foamed LC3 (FRFLC3) mix was developed to achieve a lower material density that is suitable for lightweight applications in civil engineering. The primary objective was to compare the fundamental properties (workability, density, flexural strength, and compressive strength) of foamed mix without rCF, which was considered the benchmark, and the FRFLC3 mix in their fresh and hardened states. The results confirmed that the addition of rCF successfully enhanced the mechanical properties of the composite and improved its workability for extrusion. Furthermore, preliminary extrusion trials demonstrated that the FRFLC3 mix had a satisfactory strength-to-density ratio and exhibited excellent print quality.

The Digital Image Correlation (DIC) technique is a non-contact, full-field optical method and a non-destructive evaluation approach that enables the measurement of displacements and strain fields across an entire surface during experimental tests. This technique provides high-resolution data, enabling the measurement of global strain, the detection of localized strain concentrations and crack initiation, and monitoring the evolution of dominant damage mechanisms. DIC’s ability to capture both in-plane and out-of-plane displacements makes it a powerful tool for detailed structural assessment. This paper presents preliminary results on the application of the DIC technique during diagonal compression tests of 1.2 × 1.2 × 0.25 m³ unreinforced and strengthened clay brick masonry panels. The strengthening system consists of two Textile Reinforced Mortar (TRM) layers applied on both wall sides and connected by helical stainless-steel connectors. Glass fiber bidirectional fabrics are used as TRM reinforcing meshes, embedded in a 30 mm thick lime-based mortar. A couple of CMOS cameras were used to apply the stereo-DIC algorithm and record the three-dimensional displacement field during test execution. The displacement field obtained through DIC has been compared and validated with that obtained through the more common analog Linear Variable Differential Transformers (LVDT). The comparison highlighted the benefits and weaknesses of the DIC technique.

A large share of structures worldwide cannot meet current design requirements due to updated anti-seismic guidelines, traffic growth, ageing, and severe climate change. High-Performance Fibre-Reinforced Cementitious Composites (HP-FRCC) represent an effective solution for structural strengthening; however, their widespread adoption is made less attractive by their high clinker content and reliance on virgin reinforcing fibres.This study investigates the development of sustainable HP-FRCCs based on limestone calcined clay cement (LC3) incorporating recycled carbon fibres (rCFs) recovered from end-of-life sources and brass-coated steel fibres (BSFs). Two commercially available rCFs were first characterised to identify the most suitable reinforcement before developing hybrid LC3-based composites. The incorporation of rCFs increased compressive strength by up to 25% and flexural strength by more than 30% through microstructural refinement, while BSFs governed post-cracking behaviour and energy absorption. Hybridisation enabled the replacement of one third of the steel fibre content while maintaining confinement performance comparable to that of reference steel-fibre systems. Concrete cylinders strengthened with LC3-HP-FRCC jackets exhibited compressive strength increases of up to 107% compared with unconfined specimens, together with significantly improved damage tolerance. The results demonstrate that combining rCFs with BSFs and LC3 binders provides sustainable high-performance cementitious composites for structural retrofitting.

Mixed cotton-polyester textile waste remains difficult to recycle because processes that recover synthetic polymers often leave the cotton fraction underused, while cellulose extraction methods may compromise the polyester component. This study investigates whether cotton in such blends can be converted into high-quality microcrystalline cellulose while retaining the potential value of the recovered polyester fraction. Cotton waste and cotton-polyester blends were treated using aqueous sulfuric acid at different conditions: from 15 to 20% acid concentration and from 70 to 80 degrees C for five to ten hours. The recovered microcrystalline cellulose was characterised and compared to commercial microcrystalline cellulose, while the polyester fraction was assessed using tensile testing. Enzymatic hydrolysis and a dimethyl sulfoxide co-solvent approach were evaluated as alternatives. The aqueous acid process yielded 82 to 97% microcrystalline cellulose from cotton waste and up to 51% from blended waste. The recovered cellulose showed around 10% higher crystallinity than commercial material and a similar particle size distribution, although morphology depended on the feedstock. The polyester fraction showed only minor reductions in tensile performance. The novelty of this study lies in the demonstration of a simple, ionic-liquid-free, single-reagent route that valorises both material streams from cotton-polyester textile waste.

Bio-epoxy composites were fabricated by casting a resin–hardener–filler mixture into 3D-printed molds, using different sea-originated secondary raw materials: mussel shell powder (MSP) (63–83 μm) and Posidonia oceanica short fibers (POF) (1–2 mm). Monofiller composites were prepared with 5 or 10 wt.% MSP, or 5 or 10 wt.% POF. Hybrid formulations were also produced, containing both MSP and POF in two combinations, where the total amount of filler again summed up at 10 wt.%. A subset of the samples was conditioned by immersion in a 35 ‰ NaCl solution reproducing seawater composition until saturation was reached. Characterization was carried out on unconditioned and conditioned samples by Shore D hardness and Charpy impact tests while performing three-point flexural loading only on unconditioned ones. Fracture morphology was also investigated. Adding MSP slightly enhanced resin hardness, whereas impact absorption exhibited, to a variable extent, a two-phase behavior, reproducing crack initiation and propagation. The MSP6-POF4 hybrid configuration provided the greatest improvement in absorbed energy (25–30% higher), which was retained after conditioning. The introduction of fillers, first separately, then in combination, resulted in a reduction in flexural strength to a similar extent for all unconditioned configurations. Finally, composite panels containing 10 wt.% MSP, 10 wt.% POF, and a 6MSP–4POF hybrid formulation, intended for prospective boat deck applications, were fabricated and compared with neat bio-epoxy, showing satisfactory consolidation. Density and post-molding dimensional shrinkage were measured on the panels.

Air filters are crucial components of building ventilation systems. Compared to conventional air filter media like glass fibers and melt-blown fibers, electrospinning membranes are more efficient for capturing various pollutants due to the smaller pores present on the structure. In this paper, activated carbon filters were prepared with eco-friendly polylactic acid (PLA) and microcrystalline cellulose (MCC) using electrospinning to obtain a high-quality factor (QF) fibrous mat for aerosol particle matter (PM) filtration and volatile organic compounds (VOCs) adsorption. Several configurations of the final membranes were investigated and tested for fiber morphology and air filtration performance. Filtering efficiency and adsorption properties were evaluated in a real-scale room by measuring the particle penetration of the newly synthesized and commercial filters against neutralized aerosol particles (3% NaCl aqueous solution) and VOCs (methyl ethyl ketone). The calculated depolluting efficiencies were up to 98% in terms of PM and 55% for VOCs abatement, respectively. Our results indicate that the proposed hybrid membranes represent promising materials for highly efficient and sustainable air filters for home application systems.

In the last years, considerable innovation has been made regarding bioprinting, particularly in the development of cell-loaded hydrogels. The specific properties of the bioinks are crucial for printing an adequate cell-laden hydrogel structure. In this research, we aimed to develop a 3D-printable hydrogel using a natural biocompatible polymer. The process is based on the use of sodium alginate subjected to calcium ion cross-linking for immediate stiffness after printing. Using the Cellink INKREDIBLE+ printer (Cellink Inc., Goteborg, Sweden), 3D structures were successfully produced. The developed bioink exhibited a viscosity suitable for extrusion printing while ensuring its structural integrity at the same time. Next, 3D spheroids developed by using bioinks were morphologically characterized by using light, a fluorescent microscope, and field emission scanning electron microscopy (FESEM). In conclusion, the properties of the construct obtained using the lab-formulated biocompatible polymer hydrogel suggest its potential use as a framework for three-dimensional cell culture, with possible applications in both fields of research and regenerative medicine.

Hydrogels are interesting materials with potential applications in the treatment of water contaminated by organic and inorganic toxic compounds. Among the different monomers/polymers commonly used, the natural polymer lignin is undoubtedly an attractive candidate due to its biocompatibility, biodegradability, low toxicity, and availability in high quantities as the main by-product of the pulp industry. In the present work, the synthesis and characterization of a lignin-based hydrogel are described and tested in the adsorption of the nonsteroidal anti-inflammatory drug, diclofenac, one of the so-called emerging contaminants. Due to the anionic nature of diclofenac currently used in pharmaceutical preparations, a cationic functionality is included in the polymeric backbone. The obtained hydrogel is characterized by a porous structure, thermal stability, and an elastic behavior more pronounced than the viscous one. It has a high swelling capacity and is able to efficiently remove diclofenac in batch mode, following a pseudo-second order kinetic, and adsorption could be well described by Langmuir and Sips isothermal models. For the first time, diclofenac removal by a lignin-based hydrogel is also carried out in a packed-bed column with a maximum capacity of ca. 50 mg/g, and different theoretical models are used to fit the experimental data.

Cementitious materials are the most common and effective building materials. While guaranteeing excellent performance, their production has an adverse effect on the environment in terms of greenhouse gas emissions and resources depletion. Thus, this research investigated the use of seashells, a waste product from the food industry, as a cement substitute and explored the optimal pre-treatment and mix design for preparing cementitious mortar. Seashell waste was characterized in terms of physical and chemical constitution and ground for use as a filler for the substitution of cement in mortar at 10, 20, and 30 wt%, with a 0.5 water-to-binder (w/b) ratio. The results were also compared to the reference mortar (0 % substitution) with the same w/b ratio. The fresh-state and hardened properties were evaluated. The compressive strength (Rc) showed that the performance decreased by up to 50 % when 30 % seashell waste filler was used. To mitigate this loss of performance, three different approaches were adopted: (i) the pre-treatment of seashell waste, (ii) a reduction in the w/b ratio, and (iii) the preparation of ternary mixes with blast-furnace slag as pozzolanic material and seashell waste as a partial substitute for cement. When substitution was performed with seashell waste from which the organic part was recovered, a 40 % reduction in Rc was recorded. With the reduction in the w/b ratio from 0.5 to 0.4, a super-plasticizer was added to maintain the same workability, and the decrease in Rc was 30 % when 30 % binder was used for substitution. However, when 10 % seashell waste filler was used for substitution, the reduction in Rc was negligible for both approaches. The addition of slag to the sand-cement-seashell-slag mixture at 3:0.7:0.1:0.2 wt % also permitted the recovery of Rc when compared to 30 % seashell waste filler substitution, with a reduction in Rc of about 25 % when compared to the reference mortar.

The combined need to propose new solutions for the structural reinforcement of existing buildings and for the reduction of CO2 emissions is leading to the development of more sustainable composite materials, such as those based on alkali-activated mortars (AAM). In this study, different formulations of AAM, based on metakaolin or fly ash, have been evaluated as possible matrices for Textile Reinforced Mortar (TRM) systems. Two different bidirectional textiles, made of AR glass or basalt fibers, were used as internal reinforcement. The physical-mechanical properties of TRM systems based on AAM were evaluated and compared with those of commercial systems with cementitious or lime-based matrices. Direct tensile tests on TRM coupons and shear bond tests on clay brick substrates were carried out. Then, their energy and environmental-related performance have been compared. Results showed that alkali-activated matrices can be very promising and eco-friendly alternative solutions to traditional mortars in TRM systems.

Nowadays it is pivotal to develop innovative solutions fostering sustainability and circularity in the construction sector. This paper presents a comparison between a traditional method (e.g. FTIR) and two advanced portable solutions, namely MicroNIR and HSI, to characterize materials. The former is based on Near Infrared spectroscopy and is commonly used for materials characterization; conversely, the latter is based on image analysis. In the framework of the European project RECONSTRUCT, these techniques will be applied to construction and demolition waste (CDW) field with the aim of developing a classification database, and therefore a library, that can be used for the management of wastes in a fast, reliable, and cost-effective way in view of extending sustainability and circularity models also to the construction sector, with the final aim of CDW valorization.

The need for repair and strengthening existing buildings has become fundamental in the construction sector. At the same time, the efforts to reduce global CO2 emissions are leading to the development of building materials with low environmental impact, such as those based on alkali-activated mortars (AAMs). When compared to traditional mortars, AAMs allow to reduce CO2 emissions in a range from 30

The urgent need to reduce the environmental impact of building materials has led to the recent development of low-clinker binders, such as limestone calcined clay cement (LC3). The possibility of using LC3 to produce cement-based composites with high mechanical properties and reduced environmental impact is certainly of great interest. In this study, two LC3 mixtures with different mechanical performances (low and high strength) were investigated. Chopped carbon fibers coming from end-of-life prepreg carbon textiles (rCF), recovered through pyrolysis, and virgin carbon fibers (vCF) were used to reinforce the matrices. Different fiber dosages were investigated, up to 1.5

Additive manufacturing, particularly Fused Filament Fabrication, has gained significant attraction in recent years. In order to increase the mechanical performances of several components, continuous reinforcements, such as carbon fibers, can be coextruded with a polymeric matrix. The present study relies on a specific 3D printing process, called towpreg coextrusion, which exploits continuous carbon fibers covered with an epoxy resin and polyamide (PA) as the thermoplastic matrix, thus obtaining a 3D printed two-matrix composite. Since polyamide is a highly hygroscopic material, the impact of moisture content on the mechanical properties of 3D-printed continuous composites was investigated. Tensile and flexural specimens were manufactured and tested under both undried and dried conditions. Drying treatment was carried out at a temperature of 70 °C for 2 h in oven, with weight measurements before and after for quantifying weight loss and then the moisture removal. Additionally, through thermogravimetric analysis, the thermal stability of the material was assessed. It was observed that the drying process allows for a reduction of up to 0.56% by weight of moisture in the specimens. Thus, the drying process led to an improvement in the mechanical properties of the material. Specifically, the tests reveal a 15% increase in tensile strength and an 11.5% increase in flexural strength following the drying process, reaching values of 392.78 MPa and 151.06 MPa, respectively. Similarly, an increase in the tensile and flexural moduli was noted in the treated specimens. Finally, fractured samples underwent optical and scanning electron microscopy analysis, through which different fracture mechanisms of the material and the presence of macrovoids and microvoids attributable to the 3D printing process were observed. Knowledge of deposition defects represents an important starting point for the improvement of the process and the mechanical properties obtained to date. This research provides valuable insights into optimizing 3D-printed continuous composites, emphasizing the importance of moisture control for superior mechanical performance in industrial applications.

The increase in concrete structures' durability is a milestone to improve the sustainability of buildings and infrastructures. In order to ensure a prolonged service life, it is necessary to detect the deterioration of materials by means of monitoring systems aimed at evaluating not only the penetration of aggressive substances into concrete but also the corrosion of carbon-steel reinforcement. Therefore, proper data collection makes it possible to plan suitable restoration works which can be carried out with traditional or innovative techniques and materials. This work focuses on building heritage and it highlights the most recent findings for the conservation and restoration of reinforced concrete structures and masonry buildings.

Digital image correlation (DIC) is a contactless full-field optical technique for measuring displacements that can be potentially used in place of more common linear variable differential transformers (LVDTs) to avoid instrumentation damage during destructive tests. However, despite being already adopted in several fields, its potentialities in testing full-scale masonry walls strengthened with textile reinforcing mortar (TRM) have not been fully investigated yet. In this paper, the results obtained by applying a stereo-DIC technique to compression tests of unstrengthened and TRM-strengthened tuff masonry walls (1.0 x 1.2 x 0.25 m(3)) are reported. Results showed that the presence of helical steel bars used to connect the two TRM layers caused crack localisation to the masonry wall, leading to a reduction of compression strength. Compared with the results obtained with LVDTs, the DIC technique was able to accurately monitor tridimensional displacements and cracking pattern evolution. The potentialities and limits of this technique are finally highlighted.

In hot-humid climates, porous external surfaces of the buildings with high water sorption capabilities could contribute to the surface temperatures reduction through the release of latent heat by evaporative cooling. On the other hand, compact and low permeable finishing materials could have mechanical and durability benefits respect to the underlying supports, for example reducing the permeability to degrading agents. In this paper, the properties of lime base coat renders with pore modulating additives (sepiolite and colloidal nano silica) have been surveyed to evaluate their effectiveness in water absorption, thermal performance, and the fulfilment of mechanical requirements for the application on the external side of the walls. A traditional lime–sand formulation was taken as reference. After preliminary tests on workability and shrinkage, the optimal mix designs were selected and the samples were subjected to several mechanical and thermo-hygrometric tests, before and after accelerated aging. The results allowed demonstrating that the use of sepiolite in substitution of sand, enhances the render ductility, thermal resistance and water uptake but worsens its mechanical stability, increasing the shrinkage effects and slightly reducing the ultimate strength values. The addition of colloidal nano silica, either to lime–sepiolite or to lime–sand renders, fails to produce any improvement in their either physical or mechanical behavior. Mixed formulations (lime–sand with sepiolite and nano silica) behave as simple lime–sand solutions, showing optimal compressive and flexural strength but reduced water uptake capabilities. This demonstrates that the presence of sand prevails in the performance of the render, and that the adoption of other additives doesn’t worth the cost for the benefit presented.

The benefits of recycling in the construction sector have been widely demonstrated and are unquestionable [...]

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