1,721,006 research outputs found
Metamateriali fonoassorbenti sviluppati via 3D printing per interventi di correzione acustica nel settore automotive
No full textIl punto cardine del lavoro è la prototipazione e caratterizzazione di un metamateriale fonoassorbente basato su un risonatore di Helmholtz a cavità irregolare implementato con filtri porosi realizzati via 3D printing, potenzialmente destinabile ad interventi di correzione acustica in ambito automobilistico. La stampa 3D offre la possibilità di modulare le caratteristiche strutturali dei filtri e quindi sintonizzare le proprietà fonoassorbenti in funzione del fenomeno sonoro da mitigare
3D Printing con malte cementizie: tecnologia innovativa e funzionalizzante
No full textIl lavoro fornisce una panoramica dettagliata dei principali aspetti tecnologico-ingegneristici relativi alla manifattura additiva applicata ai materiali a base cementizia. Gli argomenti chiave trattati sono: stato dell'arte della manifattura additiva dei materiali da costruzione, proprietà chimico-fisiche delle malte stampabili, aspetti tecnici degli apparati di stampa e vantaggi/prospettive della tecnologia nel settore delle costruzioni
Influence of waste tire rubber particles size on the microstructural, mechanical, and acoustic insulation properties of 3D-printable cement mortars
Full text link3D printing technologies of construction materials are gaining ground in the building industry. As well documented in the literature, these advanced manufacturing methodologies aim to reduce work-related injuries and materials waste, enhancing architectural flexibility which would enable more sophisticated designs for engineering and aesthetic purposes. In this framework, the development of functional and eco-sustainable printable materials represents an extremely attractive challenge for research, promoting digital fabrication to reach its maximum cost-effective and technological potentials. The use of recycled tire rubber particles in 3D printable Portland-based compounds is an exclusive contribution in this field. This line of research aims to integrate the well-known engineering performances of rubber-cement materials with the advanced peculiarities of additive manufacturing methodologies. As an innovative contribution, the authors propose here a detailed study on the possible relationship between rubber particle size and technological properties of the 3D printable mix. Specifically, two groups of continuous size grading polymer aggregates (0-1 mm rubber powder and 1-3 mm rubber granules as fine and coarse fractions, respectively) were analyzed in terms of impact on rheology, print quality, microstructure, mechanical properties, and acoustic insulation performance. Concerning the print quality, rubber aggregates altered the fluidity of the fresh mix, improving the adhesion between the printed layers and therefore enhancing the mechanical isotropy in the post-hardening sample. A remarkable influence of the rubber gradation on the compounds’ behaviour was found in hardened properties. By comparing the rubberized compounds, the fine polymer fraction shows greater interfacial cohesion with the cement paste. However, more significant mechanical strength loss was found due to a greater reduction in density and increased porosity degree. On the other hand, mortars doped with larger rubber particles tend to have a higher unit weight, finest pore distribution, minor mechanical strength drop, and higher ductility but worse interface binding with the matrix. Regarding the acoustic insulation properties, a proper balance between rubber powder and granules in the mixes allows to obtain comparable/superior performance compared to plain mortar but the effect of the aggregate size is strongly dependent on the sound frequency range investigated. Future findings revolve around applicability studies of these formulations in civil and architectural fields, benefiting from the design flexibility of 3D printing
Ground waste tire rubber as a total replacement of natural aggregates in concrete mixes: application for lightweight paving blocks
Full text linkThe use of waste materials as alternative aggregates in cementitious mixtures is one of the most investigated practices to enhance eco-sustainability in the civil and construction sectors. For specific applications, these secondary raw materials can ensure adequate technological performance, minimizing the exploitation of natural resources and encouraging the circular disposal of industrial or municipal waste. Aiming to design and develop lightweight paving blocks for pedestrian or very light-traffic purposes (parking area, garage, sidewalk, or sports surfaces), this paper presents the material characterization of rubberized cement mortars using ground waste tire rubber (0–1 mm rubber powder and 1–3 mm rubber granules) to totally replace the mineral aggregates. Considering recommended requirements for concrete paving members in terms of mechanical strength, water drainage performance, acoustic attenuation, and dynamic and energy absorption behavior, a comprehensive laboratory testing is proposed for five different formulations varying the sand-rubber replacement level and the proportion ratio between the two rubber fractions. Tests highlighted positive and promising results to convert laboratory samples into pre-cast members. The “hot” finding of the work was to prove the feasibility of obtaining totally rubberized mortars (0 v/v% of sand) with suitable engineering performance and enhanced eco-friendly features
PHYSICAL, MORPHOLOGICAL, AND MECHANICAL CHARACTERIZATION OF RECYCLED HYBRID NON-WOVEN MATS AS A CONTINUOUS FIBROUS REINFORCEMENT FOR NOVEL ECO-SUSTAINABLE PMMA THERMOPLASTIC COMPOSITES FABRICATION
No full textNowadays, global objectives have given special attention to sustainability and circular economy
in every sector, such as the composite industry. Therefore, the popularity of thermoplastic
composites reinforced with recycled non-woven fabrics has been intensified for lightweight
material fabrication. Particular attention has been given to hybrid tissues obtained from recycled
Glass and Carbon fibers. In this paper, primarily the properties of dry TNT made from recycled
Glass (GFs) and Carbon fibers (CFs) were evaluated. Afterward, these mats were impregnated
with two different types of Elium resin (Arkema Co.) and were utilized to fabricate thermoplastic
composite via vacuum infusion system in order to distinguish better impregnation. Finally, the
polymeric composites were characterized from physical, morphological, and mechanical points
of view.
ELIUM® C 040 and ELIUM® 158 O were purchased from Arkema Co. with peroxide
polymerization using two various components, BENZOCLEAN and PERKADOX. CarbonTask
Co. supplied GF/CF non-woven fabrics. In the first phase, dry hybrid GF/CF non-woven mats
were analyzed to indicate their areal density, morphology, and tensile behavior. Density
measurements were performed with METTLER TOLEDO Balance for 4cm2 samples. Tensile
analysis of dry hybrid non-woven mats was done by Zwick-Roell Z10 machine longitudinally and
transversally. In the second experimental phase, dry hybrid GF and CF non-woven
reinforcements were impregnated with two diverse types of Elium resin to produce
thermoplastic composites via vacuum infusion method. At last, the composites were cut and
examined to indicate their morphology, tensile characteristics, and flexural properties.
As dry non-woven mats were analyzed mechanically, it was revealed that due to the CF content
enhancement, the mechanical performance of the non-woven fabrics was improved. GFs and
CFs were distributed randomly through the non-woven fabrics. In the last phase of the
experimental work, the fabrics will be impregnated with two kinds of PMMA resins with various
viscosity to investigate higher reinforcement content with superior mechanical properties.
Tensile properties, flexural behavior, and morphological observations will be demonstrated.
In this work, hybrid recycled non-woven mats based on GF and CF were impregnated with two
different kinds of Elium thermoplastic resins (Arkema Co.) to investigate the composite
fabrication process and the corresponding properties. The focus of the project in the next step
is to refine the vacuum infusion method for composite production, an autoclave system to
maximize vacuum pressure will be utilized. Another option is to fabricate composites through
Resin Transfer Moulding (RTM
Green cement-based materials for 3D printing: preliminary tests and characterization
No full textIntroduction
Additive manufacturing of cement-based materials is a new challenge for the construction business. Compared to traditional manufacturing, this technology offers important advantages: design freedom, reduction of production costs and times, low pollution and safety.
Printable mixture must meet certain requirements in order to guarantee good extrudability, durability and suitable mechanical properties of the final product.
University of Marche patented a material that combines remarkable printing characteristics and excellent mechanical performances. The purpose of this work is to study the possibility of modifying the printing mix by adding recycled rubber tires to replace the sand and coarse aggregate of the mixture. This strategy aims to improve some physical-mechanical properties of the material (lightness, toughness, acoustic and thermal insulation) and promote the additive manufacturing to reach its maximum cost-effective and environmental-friendly potentials.
Material and Methods
Materials used for the experimental work are:
a) cement-based printable mixture
b) rubber grain/powder from tire recycling processes: powder (0 – 0,8 mm) and granulated (2 – 3 mm). Several rubber-concrete formulations were tested: reference, sand-powder mix and powder-granulated mix. Deposition tests were performed for each mixture in order to monitor the printing properties. From printed artifacts, normed size specimens were extracted for mechanical characterization. Microscopic analysis was performed in order to investigate the fillers distribution in the cement matrix.
Results
The replacement of the aggregates with rubber grain/powder provided a material with good printability. The type of filler affect the mix composition: in the richest formulations of granulated, it was necessary to increase the mix fluidity. Increased hydration promoted a lower shape stability of the filaments during deposition. Experimental characterizations, performed on rubber-concrete mixtures, show interesting results.
Discussion
The use of tire rubber as aggregate in cement mix shows promising results in producing an innovative building material with improved performance in terms of lightness, energy absorption and ductility. The choice of the optimal replacement ratio of rubber fillers is related to the achievement of the best compromise between mechanical strength and toughness based on field of application. Future research will concern the effect of rubber on the thermal and acoustic insulation properties of cementitious material
Optimization of tire rubber-concrete core materials for application in new sandwich-structured cementitious composites
No full textImplementing tire rubber-concrete mixtures to produce sandwich-structured cementitious composites can represent an attractive route in the perspective of lightweight design, energy efficiency, and sustainability for the building and construction industry. This work deals with a DOE multi-response optimization study on rubber-concrete mixes designed with different proportions of fine and coarse rubber aggregates to achieve the best formulation to be applied in the manufacturing of cementitious sandwich composites. The “sand-free” concrete mixture made up of 70% of rubber powder and 30% of rubber granules was optimal in terms of mechanical properties, physical characteristics, and thermo-acoustic insulation behavior. Sandwich-structured composite incorporating the optimum mix as a core layer showed significant improvement in terms of flexural performance over the monolithic rubberized materials and strength value in the range of RILEM “class II” lightweight construction materials
Tire recycled rubber for more eco-sustainable advanced cementitious aggregate
Full text linkThis research focused on using ground tire rubber (GTR) with different grain sizes as a replacement for the mineral aggregates used in a cement-based mixture suitable for extrusion-based Additive Manufacturing. The use of two types of GTR particles and the possibility to apply rubberized mixtures in advanced manufacturing technologies are the innovative aspects of this work. At the base of this strategy is the possibility of achieving cementitious aggregates, which would potentially be improved regarding some technological-engineering requirements (lightness, thermal-acoustic insulation, energy dissipation capacity, durability) and environmentally sustainable. The integration of waste tires into cement-based materials is a promising solution for the reuse and recycling of such industrial waste. In addition, this approach may involve a considerable reduction in the use of natural resources (sand, water, coarse mineral aggregates) needed for the building materials production. The purpose of the research was to investigate the effect of sand-GTR replacement on certain chemical-physical properties of mixtures (permeable porosity, surface wetness, and water sorptivity), closely related to material durability. Besides, the role of rubber on the printability properties of the fresh material was evaluated. GTR fillers do not alter the rheological properties of the cement material, which was properly extruded with better print quality than the reference mixture. Concerning chemical-physical characterization, the GTR powder-granules synergy promotes good compaction of the mixture, hinders the cracks propagation in the cement matrix, decreases the permeable porosity, improves the surface hydrophobicity and preserves optimal water permeabilit
Geopolymers vs. cement matrix materials. How nanofiller can help a sustainability approach for smart construction applications. A review
Full text linkIn the direction of reducing greenhouse emissions and energy consumption related to the activities of the cement and concrete industry, the increasingly popular concept of eco-sustainability is leading to the development and optimization of new technologies and low impact construction materials. In this respect, geopolymers are spreading more and more in the cementitious materials field, exhibiting technological properties that are highly competitive to conventional Portland concrete mixes. In this paper, the mix design, mechanical properties, microstructural features, and mineralogical properties of geopolymer mixes are discussed, investigating the influence of the main synthesis parameters (curing regime, type of precursors, activator molarity, mix design) on the performance of the final product. Moreover, recent developments of geopolymer technology based on the integration of functional nanofillers are reported. The novelty of the manuscript is to provide a detailed collection of past and recent comparative studies between geopolymers and ordinary Portland concrete mixes in terms of strength properties, durability, fire resistance, and environmental impact by LCA analysis, intending to evaluate the advantages and limitations of this technology and direct research towards a targeted optimization of the material
Extrusion-based additive manufacturing of concrete products. Revolutionizing and remodeling the construction industry
Full text linkAdditive manufacturing is one of the main topics of the fourth industrial revolution; defined as Industry 4.0. This technology offers several advantages related to the construction and architectural sectors; such as economic; environmental; social; and engineering benefits. The usage of concrete in additive technologies allows the development of innovative applications and complexity design in the world of construction such as buildings; housing modules; bridges; and urban and domestic furniture elements. The aim of this review was to show in detail a general panoramic of extrusion-based additive processes in the construction sector; the main advantages of using additive manufacturing with the respect to traditional manufacturing; the fundamental requirements of 3D printable material (fresh and hardened properties), and state-of-the-art aesthetic and architectural projects with functional properties
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