Design of an acoustic shell for Pier Maria Cantoregi Theater in Carignano (TO) Tutor by Arianna A... more Design of an acoustic shell for Pier Maria Cantoregi Theater in Carignano (TO) Tutor by Arianna Astolfi Giuseppe Ferro Eleonora Arpellino
Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural stre... more Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural strength capacity as compared to their compressive strength. Use of thoroughly dispersed carbon nanotubes in the concrete matrix is one of the possible solution for enhancing mechanical properties in tension/flexure. In the present research work, small fractions of multiwall carbon nanotube (MWCNTs) i.e. 0.05 and 0.10 wt% of cement have been integrated into the cement concrete to study their effect on the mechanical properties of the resultant concrete mixtures. The enhanced performance of the whole mix lies on a single point that MWCNTs must be thoroughly disperse in the mixture. Hence, special arrangement through usage of high energy sonication along with amended acrylic based polymer (performing as a surfactant) was made to have a uniform dispersion of MWCNTs in the concrete mix. The testing of concrete samples includes i.e., flexure, splitting tensile and compressive strengths after 3, 7, 28 and 56 days of curing. After having comparison with the control mix cured for 28 days, it was observed that the addition of 0.05 wt% MWCNTs increased the splitting
Nowadays, the environmental impact of cementitious material industry and more generally of buildi... more Nowadays, the environmental impact of cementitious material industry and more generally of building activities is matter of concern, especially in terms of their effects on climate change and consumption of natural resources. Within this context, the aim of this paper is the investigation of the role of biochar, a solid carbonaceous by-product material resulting from biomass pyrolysis/gasification of residual biomass, as a sustainable ingredient for the production of cementitious materials, combining carbon sink properties with enhanced mechanical properties. Although biochar is mainly investigated as agricultural amendment, there is also evidence that biochar may be a eco-friendly material to enhance the sustainable performance of cementitious materials. As outlined in literature, biochar can be used as filler to modify the nanogranular nature of cement matrix, or as substitute of clinker to reduce the emissions of greenhouse gases related to cement production. In this work, biocha...
There is growing interest in the use of self-consolidating cementitious systems in construction i... more There is growing interest in the use of self-consolidating cementitious systems in construction industry. The present research was conducted to enhance the mechanical performance of cement composites by the utilization of micro-sized inert particles. This paper deals with the synthesis of micro-sized inert carbonized particles from hemp hurds. The synthesized carbonized particles were characterized by field emission scanning electron microscope (FESEM). These particles were further used as additive in self-consolidating cement composites. Total of four different wt% additions (i.e. 0.08, 0.20, 1.00 and 3.00 by wt% of cement) were investigated. The cement composites containing carbonized particles inclusions were characterized by three point bending and compression tests. The results indicate that the carbonized particles additions enhanced the flexural and compressive strengths of the cement composites. It was also observed that the fracture properties and the energy absorption capa...
Fatigue & Fracture of Engineering Materials & Structures
Mortar grouting is often used in masonry constructions to mitigate structural decay and repair da... more Mortar grouting is often used in masonry constructions to mitigate structural decay and repair damage by filling cracks and voids, resulting in an improvement in mechanical properties. This paper presents an original experimental investigation on grout with added carbon nanotubes (CNTs). The samples were prepared with different percentages of CNTs, up to 1.2 wt% with respect to the binder, and underwent three-point bending tests in crack mouth opening displacement mode and compressive tests. The results showed that very small additions (up to 0.12 wt% of CNTs) increased not only flexural and compressive strengths (+73% and 35%, respectively, in comparison with plain mortar) but also fracture energy (+80%). These results can be explained on the basis of a reduction in porosity, as evidenced by mercury intrusion porosimetry, as well as by a crack bridging mechanism and by the probable formation of nucleation sites for hydration products, as observed through scanning electron microscopy. KEYWORDS carbon nanotubes, fracture energy, grouting, innovative mix design, mechanical properties 1 | INTRODUCTION Masonry is a classically built structure consisting of units, either stones or bricks, and a suitable mortar binder. The mechanical characteristics of the units and the quality of the mortar and fabric play an important role in its structural performance and durability, especially under seismic actions. 1,2
Computational Modelling of Concrete Structures, 2010
In order to investigate the average expansion of concrete members having the same percentage of f... more In order to investigate the average expansion of concrete members having the same percentage of free lime and impurities, but not the same grain diameter, a size-effect theory is introduced. More specifically, by drawing an analogy with the structural size-effect, the expansion of lime hydration must show a characteristic length, whose dimension remains constant at all scales. Thus, if a grain of CaO is assumed to be a sphere, only a thin layer on the external surface hydrates and doubles the volume. As the thickness of such layer is constant, independently of lime manufacture, the expansion of CaO is proportionally lower in grains of larger diameter. This phenomenon, confirmed by the results of a 2D finite element model, agrees with some experimental observations. For practical application, a simplified chemo-mechanical model of lime expansion is eventually proposed, to predict the consequences of uncombined lime in concrete structures.
A dimensionless formulation of the bridged and of the cohesive crack model for reproducing the co... more A dimensionless formulation of the bridged and of the cohesive crack model for reproducing the constitutive flexural response of a reinforced concrete element with a nonlinear matrix is proposed. The nonlinearity of the matrix is modelled by considering a distribution of closing forces onto the crack faces which increases the fracture toughness of the cross-section with a shielding action. The peculiarity of the models consists in the imposition of both the equilibrium and the compatibility conditions to the cracked element. The constitutive flexural response depends on three dimensionless parameters: e w w c , which controls the extension of the process zone, N P and N ð2Þ P , related to the reinforcement phases. Eventually, some experimental and numerical examples are presented and discussed in order to validate the consistence of the proposed approach.
One of the most promising application of element-free methods is the ability of analyzing crack p... more One of the most promising application of element-free methods is the ability of analyzing crack propagation problems without the necessity of remeshing the model as the crack advances. Moreover the possibility of enriching the classical polynomial basis, introducing some integrals of the WestergaardÕs solution, make the near crack tip solution accurate without requiring a very fine discretization or special treatment. In the paper the crack propagation problem is numerically analyzed by a new approach in computing the equilibrium equations. In this approach the quadrature of the variational form is not realized by introducing a background cell structure, as commonly done in literature, but by a mesh-free approach based on the partition of unity property of the shape functions. Some numerical examples illustrate the effectiveness of the method.
The present paper reviews the current state of the art of carbon nanotubes cement-based composite... more The present paper reviews the current state of the art of carbon nanotubes cement-based composites and the possible applications. The influence of carbon nanotubes additions onto cement paste mechanical and electrical properties are discussed in detail. Though promising, several challenges have still to be solved before the introduction of these new materials into the public sphere through civil infrastructures.
This work introduces a novel method for the development of CO2 recovery systems derived from the ... more This work introduces a novel method for the development of CO2 recovery systems derived from the production process of cement in order to obtain CaCO3 nanofiller in cement-based composites. Research was carried out in collaboration between the Department of Applied Science and Technology (DISAT) and the Department of Structural, Construction and Geotechnical Engineering (DISEG) of Politecnico di Torino. The objective of this method was dual. Firstly, it aimed to obtain a precipitated calcium carbonate nanoCaCO3 with a high degree of purity. Secondly, it aimed to optimize the characteristics of these nanoparticles e.g. additional percentages, morphology, particle size distribution or crystal phase, according to their use in cement-based composites. The synthesized nanoCaCO3 particles were subsequently added into the cementitious composites in different percentages according to the weight of the cement, in order to understand their behaviour within the cement matrix. The mechanical pr...
A novel cost-effective alternative in the form of nano/micro carbonized particles produced from w... more A novel cost-effective alternative in the form of nano/micro carbonized particles produced from waste bagasse fibers has been explored to modify the mechanical properties and fracture pattern of the resulting cementitious composites. Carbonized bagasse particles were produced at Politecnico di Torino and characterized by Raman spectroscopy and scanning electron microscopy. When added with cement paste up to 1 wt% in six different proportions, the carbonized bagasse particles were found effective in significant enhancement of mechanical strength as well as fracture toughness. From micro-graphical observations it is evident that these heterogenic inclusions either block the propagation of micro cracks which has to deviate from its straight trajectory and has to follow the carbon nano/micro particles contour or distribute it into multiple finer cracks. Crack contouring along the carbonized particle, crack pinning, crack diversions and crack branching are the mechanisms which can explai...
Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural stre... more Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural strength capacity as compared to their compressive strength. Use of thoroughly dispersed carbon nanotubes in the concrete matrix is one of the possible solution for enhancing mechanical properties in tension/flexure. In the present research work, small fractions of multiwall carbon nanotube (MWCNTs) i.e. 0.05 and 0.10 wt% of cement have been integrated into the cement concrete to study their effect on the mechanical properties of the resultant concrete mixtures. The enhanced performance of the whole mix lies on a single point that MWCNTs must be thoroughly disperse in the mixture. Hence, special arrangement through usage of high energy sonication along with amended acrylic based polymer (performing as a surfactant) was made to have a uniform dispersion of MWCNTs in the concrete mix. The testing of concrete samples includes i.e., flexure, splitting tensile and compressive strengths after 3, 7, 28 and 56 days of curing. After having comparison with the control mix cured for 28 days, it was observed that the addition of 0.05 wt% MWCNTs increased the splitting
High-performance and fiber-reinforced concretes are receiving growing attention because of their ... more High-performance and fiber-reinforced concretes are receiving growing attention because of their physical and mechanical properties. The appropriate mix of cementitious matrix, additives and fibers create a very large class of materials, requiring a careful design for each particular application. Typical applications of these materials include concretes for very severe environmental conditions, replacement or integration of traditional steel reinforcement, improvement of structural ductility. The large variety of these materials and the substantial absence of design guidelines for structural members is evidenced by a large number of experimental studies on high-performance and fiber-reinforced concretes, whose interpretation by a theoretical model is often nontrivial. The mix and reinforcement design of structural members for this class of materials is one of the more important difficulties to overcome for their diffusion in engineering applications. Moreover, the realization of full-scale models is often not feasible due to the very large loads required for testing. Consequently, size-effect influence has to be accounted for in the interpretation of the experimental results.
Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2016
With the development of "mega-constructions" and especially of slender components in ever-higher ... more With the development of "mega-constructions" and especially of slender components in ever-higher buildings, new concretes need to be more performing. Therefore, compressive and flexural strength, toughness and durability are finding entry in concrete technology. In recent work, to meet the challenge of "green" high-performance concrete, Ferro et al. investigated pyrolyzed particles from food waste as inerts in the cement composites [1]. In fact, EU produces about 3 billion tons of organic waste per year, and 10% of these are agro-food industry wastes [2]. Pyrolysis is a promising approach that can be used to convert biomass wastes into energy, in the form of biooil, bio-char, and syngas [3]. In this work, pyrolyzed hazelnut shells have been used. They are capable of generating high performance cement composites, by increasing the compressive strength, the peak load under bending, the fracture energy and the durability. The increment of fracture energy is due to the tortuosity of the crack path for the presence of micro carbon aggregates in the cement matrix. Moreover, having a low cost, they can contribute to produce concrete in a more sustainable way, inducing a reduction of energy consumption and reduction of CO2 emissions.
In this study, a structural optimisation problem, addressed through a stochastic multi-objective ... more In this study, a structural optimisation problem, addressed through a stochastic multi-objective approach, is formulated and solved. The problem deals with the optimal design of exoskeleton structures, conceived as vibration control systems under seismic loading. The exoskeleton structure is assumed to be coupled to an existing primary inner structure for seismic retrofit: the aim is to limit the dynamic response of the primary structure to prevent structural damage. A non-stationary filtered Gaussian white noise stochastic process is taken as the seismic input. Design variables pertain to the mechanical properties (stiffness, damping) of the exoskeleton structure. Two concurrent and competing objective functions are introduced, in order to take into account not only safety performance but also economic cost considerations. The resulting trade-off is solved searching the Pareto front by way of a controlled elitist genetic algorithm, derived from the Non-dominated Sorting Genetic Alg...
The present study concerns the experimental investigation of foamed concretes with 1600 kg/m 3 de... more The present study concerns the experimental investigation of foamed concretes with 1600 kg/m 3 density that incorporate biochar additions in the mix. A series of small notched beams are prepared to determine the fracture energy in CMOD (crack mouth opening displacement) mode and the mechanical properties in terms of flexural and compressive strength. Besides the evaluation of such properties for classical foamed concrete, the influence of the addition of biochar in the lightweight cementitious paste is comparatively investigated. Two different concentrations of biochar are analyzed, namely 2% and 4% of the cement weight, and two different curing conditions are studied, namely in air and in water at controlled temperature for 28 days. The results demonstrate that better fracture behavior are obtained with 2% biochar and air curing conditions. The biochar additions in moderate concentrations (e.g. 2%) seems to make the fracture surface more tortuous, thus justifying the numerical outcomes, and does not impair the flexural strength. Further microstructural investigation is underway to confirm the experimental observations. This research paves the way for a promising construction material that is more environmentally friendly and sustainable than traditional materials used in the building industry.
Although for deeply different reasons, the collapses occurred can all been gathered into the same... more Although for deeply different reasons, the collapses occurred can all been gathered into the same common cause: the (lack of) knowledge of the effective structural condition, a serious problem that affects existing constructions. As it will be shown in the paper, different problems such as missing of the asbuilt designs, an appropriate construction and movement precautions, a heavy vehicle checking, and a material decay monitoring can nevertheless be addressed as an inadequate knowledge of what is happening to/in the structure. In the first section, the paper will report a short description of the failures for the five bridges, while in the second part a main set of problems involved in bridge safety and maintenance will be discussed. Finally, in the third part, a review on innovative and peculiar investigation and monitoring techniques will be illustrated. The collected results can shed new light on future perspectives for the Civil Engineering sector, sector that has to be ready for facing the challenges of preservation, restoration and/or replacement of the existing infrastructural constructions, worldwide.
Design of an acoustic shell for Pier Maria Cantoregi Theater in Carignano (TO) Tutor by Arianna A... more Design of an acoustic shell for Pier Maria Cantoregi Theater in Carignano (TO) Tutor by Arianna Astolfi Giuseppe Ferro Eleonora Arpellino
Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural stre... more Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural strength capacity as compared to their compressive strength. Use of thoroughly dispersed carbon nanotubes in the concrete matrix is one of the possible solution for enhancing mechanical properties in tension/flexure. In the present research work, small fractions of multiwall carbon nanotube (MWCNTs) i.e. 0.05 and 0.10 wt% of cement have been integrated into the cement concrete to study their effect on the mechanical properties of the resultant concrete mixtures. The enhanced performance of the whole mix lies on a single point that MWCNTs must be thoroughly disperse in the mixture. Hence, special arrangement through usage of high energy sonication along with amended acrylic based polymer (performing as a surfactant) was made to have a uniform dispersion of MWCNTs in the concrete mix. The testing of concrete samples includes i.e., flexure, splitting tensile and compressive strengths after 3, 7, 28 and 56 days of curing. After having comparison with the control mix cured for 28 days, it was observed that the addition of 0.05 wt% MWCNTs increased the splitting
Nowadays, the environmental impact of cementitious material industry and more generally of buildi... more Nowadays, the environmental impact of cementitious material industry and more generally of building activities is matter of concern, especially in terms of their effects on climate change and consumption of natural resources. Within this context, the aim of this paper is the investigation of the role of biochar, a solid carbonaceous by-product material resulting from biomass pyrolysis/gasification of residual biomass, as a sustainable ingredient for the production of cementitious materials, combining carbon sink properties with enhanced mechanical properties. Although biochar is mainly investigated as agricultural amendment, there is also evidence that biochar may be a eco-friendly material to enhance the sustainable performance of cementitious materials. As outlined in literature, biochar can be used as filler to modify the nanogranular nature of cement matrix, or as substitute of clinker to reduce the emissions of greenhouse gases related to cement production. In this work, biocha...
There is growing interest in the use of self-consolidating cementitious systems in construction i... more There is growing interest in the use of self-consolidating cementitious systems in construction industry. The present research was conducted to enhance the mechanical performance of cement composites by the utilization of micro-sized inert particles. This paper deals with the synthesis of micro-sized inert carbonized particles from hemp hurds. The synthesized carbonized particles were characterized by field emission scanning electron microscope (FESEM). These particles were further used as additive in self-consolidating cement composites. Total of four different wt% additions (i.e. 0.08, 0.20, 1.00 and 3.00 by wt% of cement) were investigated. The cement composites containing carbonized particles inclusions were characterized by three point bending and compression tests. The results indicate that the carbonized particles additions enhanced the flexural and compressive strengths of the cement composites. It was also observed that the fracture properties and the energy absorption capa...
Fatigue & Fracture of Engineering Materials & Structures
Mortar grouting is often used in masonry constructions to mitigate structural decay and repair da... more Mortar grouting is often used in masonry constructions to mitigate structural decay and repair damage by filling cracks and voids, resulting in an improvement in mechanical properties. This paper presents an original experimental investigation on grout with added carbon nanotubes (CNTs). The samples were prepared with different percentages of CNTs, up to 1.2 wt% with respect to the binder, and underwent three-point bending tests in crack mouth opening displacement mode and compressive tests. The results showed that very small additions (up to 0.12 wt% of CNTs) increased not only flexural and compressive strengths (+73% and 35%, respectively, in comparison with plain mortar) but also fracture energy (+80%). These results can be explained on the basis of a reduction in porosity, as evidenced by mercury intrusion porosimetry, as well as by a crack bridging mechanism and by the probable formation of nucleation sites for hydration products, as observed through scanning electron microscopy. KEYWORDS carbon nanotubes, fracture energy, grouting, innovative mix design, mechanical properties 1 | INTRODUCTION Masonry is a classically built structure consisting of units, either stones or bricks, and a suitable mortar binder. The mechanical characteristics of the units and the quality of the mortar and fabric play an important role in its structural performance and durability, especially under seismic actions. 1,2
Computational Modelling of Concrete Structures, 2010
In order to investigate the average expansion of concrete members having the same percentage of f... more In order to investigate the average expansion of concrete members having the same percentage of free lime and impurities, but not the same grain diameter, a size-effect theory is introduced. More specifically, by drawing an analogy with the structural size-effect, the expansion of lime hydration must show a characteristic length, whose dimension remains constant at all scales. Thus, if a grain of CaO is assumed to be a sphere, only a thin layer on the external surface hydrates and doubles the volume. As the thickness of such layer is constant, independently of lime manufacture, the expansion of CaO is proportionally lower in grains of larger diameter. This phenomenon, confirmed by the results of a 2D finite element model, agrees with some experimental observations. For practical application, a simplified chemo-mechanical model of lime expansion is eventually proposed, to predict the consequences of uncombined lime in concrete structures.
A dimensionless formulation of the bridged and of the cohesive crack model for reproducing the co... more A dimensionless formulation of the bridged and of the cohesive crack model for reproducing the constitutive flexural response of a reinforced concrete element with a nonlinear matrix is proposed. The nonlinearity of the matrix is modelled by considering a distribution of closing forces onto the crack faces which increases the fracture toughness of the cross-section with a shielding action. The peculiarity of the models consists in the imposition of both the equilibrium and the compatibility conditions to the cracked element. The constitutive flexural response depends on three dimensionless parameters: e w w c , which controls the extension of the process zone, N P and N ð2Þ P , related to the reinforcement phases. Eventually, some experimental and numerical examples are presented and discussed in order to validate the consistence of the proposed approach.
One of the most promising application of element-free methods is the ability of analyzing crack p... more One of the most promising application of element-free methods is the ability of analyzing crack propagation problems without the necessity of remeshing the model as the crack advances. Moreover the possibility of enriching the classical polynomial basis, introducing some integrals of the WestergaardÕs solution, make the near crack tip solution accurate without requiring a very fine discretization or special treatment. In the paper the crack propagation problem is numerically analyzed by a new approach in computing the equilibrium equations. In this approach the quadrature of the variational form is not realized by introducing a background cell structure, as commonly done in literature, but by a mesh-free approach based on the partition of unity property of the shape functions. Some numerical examples illustrate the effectiveness of the method.
The present paper reviews the current state of the art of carbon nanotubes cement-based composite... more The present paper reviews the current state of the art of carbon nanotubes cement-based composites and the possible applications. The influence of carbon nanotubes additions onto cement paste mechanical and electrical properties are discussed in detail. Though promising, several challenges have still to be solved before the introduction of these new materials into the public sphere through civil infrastructures.
This work introduces a novel method for the development of CO2 recovery systems derived from the ... more This work introduces a novel method for the development of CO2 recovery systems derived from the production process of cement in order to obtain CaCO3 nanofiller in cement-based composites. Research was carried out in collaboration between the Department of Applied Science and Technology (DISAT) and the Department of Structural, Construction and Geotechnical Engineering (DISEG) of Politecnico di Torino. The objective of this method was dual. Firstly, it aimed to obtain a precipitated calcium carbonate nanoCaCO3 with a high degree of purity. Secondly, it aimed to optimize the characteristics of these nanoparticles e.g. additional percentages, morphology, particle size distribution or crystal phase, according to their use in cement-based composites. The synthesized nanoCaCO3 particles were subsequently added into the cementitious composites in different percentages according to the weight of the cement, in order to understand their behaviour within the cement matrix. The mechanical pr...
A novel cost-effective alternative in the form of nano/micro carbonized particles produced from w... more A novel cost-effective alternative in the form of nano/micro carbonized particles produced from waste bagasse fibers has been explored to modify the mechanical properties and fracture pattern of the resulting cementitious composites. Carbonized bagasse particles were produced at Politecnico di Torino and characterized by Raman spectroscopy and scanning electron microscopy. When added with cement paste up to 1 wt% in six different proportions, the carbonized bagasse particles were found effective in significant enhancement of mechanical strength as well as fracture toughness. From micro-graphical observations it is evident that these heterogenic inclusions either block the propagation of micro cracks which has to deviate from its straight trajectory and has to follow the carbon nano/micro particles contour or distribute it into multiple finer cracks. Crack contouring along the carbonized particle, crack pinning, crack diversions and crack branching are the mechanisms which can explai...
Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural stre... more Cement and concrete composites are inherently brittle and exhibit very less tensile/flexural strength capacity as compared to their compressive strength. Use of thoroughly dispersed carbon nanotubes in the concrete matrix is one of the possible solution for enhancing mechanical properties in tension/flexure. In the present research work, small fractions of multiwall carbon nanotube (MWCNTs) i.e. 0.05 and 0.10 wt% of cement have been integrated into the cement concrete to study their effect on the mechanical properties of the resultant concrete mixtures. The enhanced performance of the whole mix lies on a single point that MWCNTs must be thoroughly disperse in the mixture. Hence, special arrangement through usage of high energy sonication along with amended acrylic based polymer (performing as a surfactant) was made to have a uniform dispersion of MWCNTs in the concrete mix. The testing of concrete samples includes i.e., flexure, splitting tensile and compressive strengths after 3, 7, 28 and 56 days of curing. After having comparison with the control mix cured for 28 days, it was observed that the addition of 0.05 wt% MWCNTs increased the splitting
High-performance and fiber-reinforced concretes are receiving growing attention because of their ... more High-performance and fiber-reinforced concretes are receiving growing attention because of their physical and mechanical properties. The appropriate mix of cementitious matrix, additives and fibers create a very large class of materials, requiring a careful design for each particular application. Typical applications of these materials include concretes for very severe environmental conditions, replacement or integration of traditional steel reinforcement, improvement of structural ductility. The large variety of these materials and the substantial absence of design guidelines for structural members is evidenced by a large number of experimental studies on high-performance and fiber-reinforced concretes, whose interpretation by a theoretical model is often nontrivial. The mix and reinforcement design of structural members for this class of materials is one of the more important difficulties to overcome for their diffusion in engineering applications. Moreover, the realization of full-scale models is often not feasible due to the very large loads required for testing. Consequently, size-effect influence has to be accounted for in the interpretation of the experimental results.
Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2016
With the development of "mega-constructions" and especially of slender components in ever-higher ... more With the development of "mega-constructions" and especially of slender components in ever-higher buildings, new concretes need to be more performing. Therefore, compressive and flexural strength, toughness and durability are finding entry in concrete technology. In recent work, to meet the challenge of "green" high-performance concrete, Ferro et al. investigated pyrolyzed particles from food waste as inerts in the cement composites [1]. In fact, EU produces about 3 billion tons of organic waste per year, and 10% of these are agro-food industry wastes [2]. Pyrolysis is a promising approach that can be used to convert biomass wastes into energy, in the form of biooil, bio-char, and syngas [3]. In this work, pyrolyzed hazelnut shells have been used. They are capable of generating high performance cement composites, by increasing the compressive strength, the peak load under bending, the fracture energy and the durability. The increment of fracture energy is due to the tortuosity of the crack path for the presence of micro carbon aggregates in the cement matrix. Moreover, having a low cost, they can contribute to produce concrete in a more sustainable way, inducing a reduction of energy consumption and reduction of CO2 emissions.
In this study, a structural optimisation problem, addressed through a stochastic multi-objective ... more In this study, a structural optimisation problem, addressed through a stochastic multi-objective approach, is formulated and solved. The problem deals with the optimal design of exoskeleton structures, conceived as vibration control systems under seismic loading. The exoskeleton structure is assumed to be coupled to an existing primary inner structure for seismic retrofit: the aim is to limit the dynamic response of the primary structure to prevent structural damage. A non-stationary filtered Gaussian white noise stochastic process is taken as the seismic input. Design variables pertain to the mechanical properties (stiffness, damping) of the exoskeleton structure. Two concurrent and competing objective functions are introduced, in order to take into account not only safety performance but also economic cost considerations. The resulting trade-off is solved searching the Pareto front by way of a controlled elitist genetic algorithm, derived from the Non-dominated Sorting Genetic Alg...
The present study concerns the experimental investigation of foamed concretes with 1600 kg/m 3 de... more The present study concerns the experimental investigation of foamed concretes with 1600 kg/m 3 density that incorporate biochar additions in the mix. A series of small notched beams are prepared to determine the fracture energy in CMOD (crack mouth opening displacement) mode and the mechanical properties in terms of flexural and compressive strength. Besides the evaluation of such properties for classical foamed concrete, the influence of the addition of biochar in the lightweight cementitious paste is comparatively investigated. Two different concentrations of biochar are analyzed, namely 2% and 4% of the cement weight, and two different curing conditions are studied, namely in air and in water at controlled temperature for 28 days. The results demonstrate that better fracture behavior are obtained with 2% biochar and air curing conditions. The biochar additions in moderate concentrations (e.g. 2%) seems to make the fracture surface more tortuous, thus justifying the numerical outcomes, and does not impair the flexural strength. Further microstructural investigation is underway to confirm the experimental observations. This research paves the way for a promising construction material that is more environmentally friendly and sustainable than traditional materials used in the building industry.
Although for deeply different reasons, the collapses occurred can all been gathered into the same... more Although for deeply different reasons, the collapses occurred can all been gathered into the same common cause: the (lack of) knowledge of the effective structural condition, a serious problem that affects existing constructions. As it will be shown in the paper, different problems such as missing of the asbuilt designs, an appropriate construction and movement precautions, a heavy vehicle checking, and a material decay monitoring can nevertheless be addressed as an inadequate knowledge of what is happening to/in the structure. In the first section, the paper will report a short description of the failures for the five bridges, while in the second part a main set of problems involved in bridge safety and maintenance will be discussed. Finally, in the third part, a review on innovative and peculiar investigation and monitoring techniques will be illustrated. The collected results can shed new light on future perspectives for the Civil Engineering sector, sector that has to be ready for facing the challenges of preservation, restoration and/or replacement of the existing infrastructural constructions, worldwide.
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Papers by Giuseppe Ferro