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The presented study aims to describe the seismic vulnerability of a sample made by 90 masonry one-nave churches, subjected to the Valle Scrivia Earthquake, 2003, Piemonte, Italy. In particular, the...

Foamed concrete is a special lightweight concrete characterized by the presence of a stable preformed foam in the mix proportion that give rise to the development of a system of air voids in the material. Its physical and mechanical properties are strongly influenced by microstructural properties, in turn linked to various parameters such as the amount of foam, the presence of mineral additions or chemical additives, the characteristics of the mixing process and so on. Since ultra-lightweight foamed concrete is characterized by excellent functional properties (thermal insulation, sound absorption, fire resistance) but very poor mechanical properties (compressive strength), in this contribution three different ways to improve the compressive strength of this material without worsening its lightness are discussed. More specifically, the three different strategies (improve the consistency of the fresh lightweight cementitious paste through the addition of a viscosity enhancing agent, add silica fume and increase the rotational speed of the vertical mixer) lead to appreciable improvement in the compressive strength of the produced foamed concrete. The most significant increases in compressive strength are associated with the addition of silica fume in the mix, in proportion to 10% of the cement weight.

The organic waste management is a most current topic, because its processing and degradation it is responsible for emissions of methane and other greenhouse gases, leading to serious environmental problems. Limited oxygen thermochemical processes, such as pyrolysis or gasification, have demonstrated the energy recovery potential of the treated biomass and its environmental benefits. However, the solid part of the process -Biochar- it is considered as a waste, as only its coarse ash can be used as soil improvers. Nevertheless, several researchers have explored its potential application as green filler in order to reduce the carbon footprint both of cement production and cement-based construction materials. In this work, Biochar microparticles were used both as a filler inside the cement paste and mortar composites and as a substitute for the cement powder inside the mixes. Based on previous work, this investigation has a twofold objective: to understand the full influence of the use of an optimized percentage of Biochar (2% with respect to the weight of the cement) either as a filler in the mixture or as a substitute for cement, while guaranteeing an improvement in the strength without losing ductility. The results showed that 2 wt% of Biochar’s particles are sufficient to increase the strength and toughness of the cement and mortar composites and, in place of the cement in the mixture, can maintain the mechanical properties equal to those of the reference samples.

The high seismic vulnerability of the Italian territory and its ancient building heritage require attention regarding planning interventions on existing buildings. In fact, they show both structural and technological design deficiencies mainly due to the period of construction, the lack of design to withstand horizontal forces and the type of material used, which is mainly masonry and reinforced concrete. Therefore, it is extremely difficult to intervene with solutions of seismic improvement or adjustment also concerning the economic point of view. This work suggests an advanced approach to address the problem employing the innovative concept of an external self-supporting steel system: the exoskeleton technology. It has been applied to guarantee the seismic adjustment of an existing structure that aims at reaching higher safety targets as well as new aesthetic and sustainable features. Due to the overcoming of lifespan limit of 50 years, the explored residential construction no longer complies with the current technical standards; the issue has been solved connecting the two structures by a non-dissipative rigid link to create a coupled system whose floors show an in-plane rigid behaviour while maintaining separated their response to seismic actions. Initial explanations of the internal and the outer constructions advance the dynamic analysis, which allows to highlight the main seismic properties of the whole model such as frequencies and periods of vibration, floor displacements and shear forces. Following outcomes do not just focus on how the exoskeleton can take base and floor shear forces but also the way it manages to strongly reduce displacements and deformations of the primary building, so that it can bear earthquake actions preventing not only collapse but also reducing non-structural elements damage.

The attention on the use of raw materials, the energy consumption as well as carbon dioxide production of cement factories are boosting the experimentation on innovative and sustainable materials in concrete technology. In recent years, biochar has become an emblematic material with a thousand facets. Mainly investigated up to now as amending in the agricultural field, biochar can be explored as a building material due to its innumerable properties. Indeed, several applications have been studied to use it as a filler to modify the nanogranular nature of the cement matrix, or as a substitute for clinker, aggregates and clay, reducing the carbon footprint and the emissions of greenhouse gases linked to the production processes of cementitious materials. In this paper, nano/micro-particles of biochar, the solid by-product from the gasification process of biomass derived from wood waste, has been used in different cement composites aiming at determining the optimal percentage of addition while trying to guarantee an improvement of mechanical properties. The results showed that an optimized percentage of biochar nano/micro-particles can increase the strength and toughness of the composites.

Innovative cementitious composite materials are drawing considerable interest due to their substantially improved mechanical properties as compared to ordinary cement-based materials. Their enhanced ductility is promising and particularly suited to structural applications under severe dynamic loading conditions. Cyclic response is essential to understand the effects of loading and unloading on the material, as well as to understanding how it behaves in the transition from tension to compression. It is also fundamental to identify its properties in terms of energy dissipation and strain-rate sensitivity. This paper presents the first part of an ongoing research project which aims to develop the constitutive relationship in innovative cementitious composites and its numerical implementation. Results from this research will facilitate the investigation of the ductility and durability of existing buildings. In this paper, an experimental set-up for uniaxial cyclic loading is described. It was developed to study reversed cyclic compression/tension loadings of innovative cementitious composites. To set the cyclic loading process, cylindrical specimens of concrete were tested. All the tests were performed on a Zwick testing machine with 50 kN load cell. The machine was customised with accessories specifically designed to meet test requirements, avoiding instability and bending moments during the alternating phases of uniaxial compression and tension. Strain gauges were used to measure lateral deformations. The customized machine has shown good performance so far. In order to test specimens with a higher number of cycles and a higher loading rate, improvements to the machine are currently under development. These tests will allow greater insight into the ductility of innovative cementitious composite materials.

An exoskeleton is an external steel self-supporting system rigidly linked to an existing building that need to be safeguarded against seismic actions in order to comply with the current technical standards. Its application can guarantee an innovative seismic adjustment that combines structural and safety goals with sustainable properties. The present study deals with the performances of the developed coupled system under seismic actions when a suitable exoskeleton structure is applied to a real construction. It is designed with an in-plane rigid behaviour at each floor and a non-dissipative rigid link connects the primary building to the external structure. Early descriptions of the inner and the external constructions forerun the dynamic analysis, which allows to understand seismic response of the system especially in terms of frequencies and periods of vibration, floor displacements, stiffness and shear forces. Ensuing outcomes highlight the capability the exoskeleton has in taking base and floor shear forces as well as in reducing displacements and deformations of the primary building, so that it is protected from a potential earthquake collapse.

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, biochar is added as micro-nano particles in different cementitious composites, i.e. cement pastes and mortars, as a function of filler or partial substitute of cement. The main mechanical properties of biochar-based materials are then investigated to determine the optimal percentage of biochar addition.

A ferrous tie rod, which was retrieved from a 17th century masonry building, has been examined. The chemical composition and the microstructure of the tie-rod are consistent with the technology of ...

The fracture behavior of lightweight foamed concrete (LWFC) is significantly influenced by microstructural properties, which are ascribed to the arrangement of air bubbles and pores as well as to the presence of different hydration products. In this contribution, an experimental investigation on the fracture behavior of LWFC is performed. Notched beams made of LWFC were tested in three-point bending to determine the fracture energy based on the load-CMOD (Crack Mouth Opening Displacement) curve. The influence of the dry density is explored considering one density for non-structural purposes (equal to 800 kg/m3) and another density for structural applications (1600 kg/m3). Moreover, two curing conditions are considered (air and water). The load-CMOD curves reveal that for lower dry densities the fracture behavior of LWFC is particularly affected by the curing conditions, with better results achieved in air curing conditions, but this influence decreases with higher dry densities. The improved performance in air curing conditions for lower dry densities is also observed in terms of flexural strength, but is not particularly evident for the compressive strength. Micrographs across the crack surface determined via Scanning Electron Microscopy (SEM) are finally presented to analyze the experimental findings and justify the results in terms of microstructural configuration of the specimens.

In the last four years, Italy experienced the collapse of five road bridge: Petrulla viaduct (2014), Annone (2016) and Ancona (2017) overpasses, Fossano viaduct (2017) and Polcevera (2018) bridge. 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 as-built 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.

In recent years, a scientific shift has been observed towards the use of carbon based nano materials in different composites to enhance their mechanical and electrical properties. However, carbonaceous nano/micro inert particles synthesized through pyrolysis of agricultural and industrial wastes offer a very cost effective alternate to the commercially available carbon based materials such as carbon fibres, carbon nanotubes, graphene and graphene oxide. A comprehensive survey of reported data on the synthesis of carbon particles is presented in this article. The utilization of synthesized carbon particles as reinforcing material has also been explored together with an attempt of proposing future novel applications of synthesized carbon particles in cement based systems. In this paper, meticulous efforts have been made to overview the potential beneficial effects of synthesized carbon particles intrusions to cementitious systems for modifying/improving their mechanical characteristics.

Unlike ordinary concrete, lightweight foamed concrete (LWFC) has the benefit of decreasing the self-weight of constructive elements while ensuring an efficient thermal insulation and acoustic absorption as well as high fire resistance. A novel version of LWFC has been recently developed by the authors, with the unique property of “extrudability” in a wide density range, meaning that its production process can be carried out without formworks and exploiting innovative 3D printing technologies. The present contribution is focused on the rheological behaviour of this innovative extrudable LWFC (ELWFC). The rheological behaviour in terms of yield stress of the ELWFC is studied via a rotational rheometer in two different modalities, namely constant shear rate and increasing shear rate. Comparison of the rheological behaviour between ELWFC and classical LWFC is also presented. Additionally, the dimensional stability of the cementitious paste at the fresh state having a given yield stress is assessed through an extrusion test. In particular, the experimental investigation is focused on a target dry density of 800 kg/m3, which is identified as a good compromise between insulating features and mechanical strengths. The experimental results show that the considered ELWFC, characterized by a zero slump in the extrusion test, has a yield stress of around 150 Pa (constant shear rate) and 130 Pa (increasing shear rate).

This contribution focuses on the design and the characterization of innovative mix designs of high consistency mortars with biochar additions in different percentage with respect to the cement weight. Biochar is a by-product material that gives the cementitious mix a sustainable connotation from an environmental point of view. The mix designs presented here are characterized by a good dimensional stability in the fresh state, peculiarity that gives them the possibility to be extruded and so, to be used in automated construction processes. In addition to the mechanical properties (flexural and compressive strength), the assessment of the CO2 emission of representative mixes is presented. Different biochar content and maximum diameter of the aggregate are studied, obtaining interesting indications on these parameters to optimize mechanical properties. Finally, on the basis of the CO2 emission assessment, certain venues for future research work to minimize CO2 emissions are reported.

The present study concerns the experimental investigation of foamed concretes with 1600 kg/m3 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.

Portal-frame reinforced concrete precast industrial facilities built in Italy between 1960 and 1990 have shown high vulnerability during recent seismic events interesting Emilia region. Post-earthquake damage observations have shown that most of collapses interested portal-frame structures arranged with dry beam-to-column friction joints because of the loss of support due to sliding of beams with respect to columns. At the same time severe damage to column base cross-sections was recognized even in the case of portal-frame systems with beam-column connection devices (fixed joints). The paper investigates the dynamic behaviour of portal-frame precast industrial facilities, especially addressing the inelastic displacement demand as function of the generalized mechanical response of beam-to-column joints. Portal-frames are idealized as 2D inelastic single degree of freedom systems. A framework based on a parametric model developed in OpenSees is defined to build inelastic spectra of maximum relative beam-column displacement demands and maximum column top displacement demands. Inelastic displacement demand spectra are defined for four different sites in Italy (Messina, Mirandola, Naples and Turin), characterized by different seismic hazard. Analytical expressions of spectra approximating numerical results are finally derived to be used for rapid displacement capacity/demand assessments of portal-frame industrial buildings with friction joints or fixed joints. The approach can account vertical component of seismic excitation in a simplified way and can be also used to assess the effectiveness of retrofitting interventions.

In tall buildings, central cores composed by reinforced concrete shear walls linked by coupling beams provide an efficient structural system to resist earthquake loads. However, building codes and design recommendations are most appropriate for smaller buildings with stand-alone shear walls and fail to adequately address slender 3D linked cores composed of “I”, “L” or “T” shapes. This leads to overly conservative and rigid design solutions with low dissipative behavior when subjected to seismic loads. The present paper aims to propose a new rational methodology for design of these lateral-force resisting systems. Linear and nonlinear prototype models based on the Skidmore, Owings & Merrill LLP project, the 500 Folsom Tower, are built to investigate the widely used central core consisting of linked “L” shape shear walls. Nonlinear Response History Analyses (NRHA) are performed in order to validate the new design methodology, according to the Performance-Based Seismic Design (PBSD) approach.

In recent years, researches concerning cement-based materials has been focused not only on the strength and the toughness but also on the durability. In fact, the interest on concrete's self-healing process is increasing, due to the rapidly deterioration of that material which tends to crack and thus quickly deteriorate. In this paper, a new self-healing technology for cement-based materials is proposed. This technology is based on the encapsulation method of repairing agent inserted in randomly distributed shell inside the material during its preparation. Two different kind of shells were used: glass spheres and pharmaceutical capsules. The material the shells are made of has to be endowed with a series of fundamental characteristics. That material has to be inert with respect to the repair agent so that it doesn't react with it, resisting to the severe stress condition that the shells undergo during the mixing, and at the same time being capable of breaking down when the crack intercept them, having a good compatibility with the cement mixture. The results demonstrate that it is possible to use this kind of shell to encapsulate the repairing agent: the crack breaks them and they release the healing agent, which allows patching up the crack.

The Bio-char, the solid sub-product of pyrolysis process, has several applications in the cement and concrete green technology. In this research, the utilization of Bio-char such as nanoparticles has been analysed. Two types of pyrolyzed agro-food waste, coffee powder and hazelnut shells, have been investigated as carbon nano-aggregates, in different percentages of addition with respect to the weight of the cement. Results have demonstrated that small amount of both pyrolyzed materials improves the mechanical properties of cementitious composites, as they are capable of increasing not only the flexural and compressive strength, but also the fracture energy with a more tortuous crack path which increases the final fracture surface.

Interest in biochar, a sub-product of biomass pyrolysis, has increased enormously in the last few years, finding applications in a wide variety of fields. In the present work, a standardized biochar was used as a nano/micro-filler in cement-based composites, ensuring the reproducibility of cement mixtures. Although, in terms of flexural strength and fracture energy, results were inferior compared to the previous studies conducted at Politecnico di Torino. Nonetheless, an overall enhancement of mechanical properties was recorded with the introduction of standardized biochar in cementitious composites. This paper attempts to show that some parameters of biochar processes, e.g. production, temperature, heating rate or pressure, as well as some biochar features such as carbon content, particle size distribution or porosity dramatically influence the enhancement of mechanical properties of cementitious composites. This result is extremely important, because it indicates that, even if the parameters are not optimal, biochar can be used to create new green building materials because of its effectiveness in cementitious composites.

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 properties were also evaluated, both at 7 and 28 days, through three point bending and compression tests. The results of the mechanical tests showed a promising improvement in strength and toughness. This study is a first step towards developing a CO2 circular economy.

In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut (PS) and hazelnut (HS) shells are presented. These materials were characterized by Raman spectroscopy and field emissionscanning electron microscopy (FE-SEM). When added to cement paste, up to 1 wt%, these materials led to an increase of the cement matrix flexural strength and of toughness. Moreover, with respect to plain cement, the total increase in electromagnetic radiation shielding effect when adding 0.5 wt% of PS or HS in cement composites is much higher in comparison to the ones reported in the literature for CNTs used in the same content.

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 explain the increase of toughness in the composite samples.