The paper presents an experimental program carried out to check the load bearing capacity of a steel fibre reinforced concrete (SFRC) floor in northern Italy. The extensive mechanical ...characterization focused on the suitability of 3 non-standardized test methods for quality control and tensile constitutive curve assessment was performed, this consisting of: uniaxial tensile test (UTT), double edge wedge splitting test (DEWST) and double punching test (DPT) to characterize the post-cracking mechanical properties of the material. The joint experimental programme, carried out at the Politecnico di Milano and at the Universitat Politècnica de Catalunya, included the flexural characterization of four shallow beams (1.5 × 0.5 × 0.25 m
3
) and six standard notched beams (0.55 × 0.15 × 0.15 m
3
). All the samples were produced from the same batch and with the same SFRC mix which was applied for the floor. After that, 192 cores were drilled from the shallow beams and subjected to either UTTs, DEWSTs or DPTs. The stress level, the scatter and the constitutive curves derived from the non-standardized tests were identified and analysed. The calculated constitutive curves were used to predict the behaviour of the shallow beams.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the context of the evaluation of the load-bearing capacity of a steel fibre reinforced concrete (SFRC) elevated slab recently built in northern Italy, this paper presents the study addressing the ...effects of fibre distribution and orientation. An extensive experimental programme was carried out in a collaboration between Politecnico di Milano and Universitat Politècnica de Catalunya. The programme included mechanical tests on four shallow beams and six notched standard beams. Additionally, uniaxial tensile tests (UTTs), double edge wedge splitting tests (DEWSTs) and double punching tests (DPTs) on 192 drilled core samples extracted from the shallow beams were performed. Inductive tests, measuring the self-induction change that occurs when a SFRC sample is placed inside a coil, were performed on all samples subjected to DPTs to assess fibre distribution. This paper compares direct and indirect tensile tests for the definition of the FRC post-cracking constitutive law, highlighting advantages and disadvantages of each test type. A comparison between standard and non-standard mechanical tests is also presented. Mechanical and non-destructive tests on drilled core samples extracted in different directions and at different locations have allowed the evaluation of the effects of fibre distribution and fibre orientation which provide an estimation of the possibility of using these tests as simplified tests for production control.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Discarded polyethylene terephthalate (PET) bottles have damaged our ecosystem. Problems of marine fauna conservation and land fertility have been related to the disposal of these materials. Recycled ...fibre is an opportunity to reduce the levels of waste in the world and increase the mechanical performance of the concrete. PET as concrete reinforcement has demonstrated ductility and post-cracking strength. However, its performance could be optimized. This study considers a statistical-experimental analysis to evaluate recycled PET fibre reinforced concrete with various fibre dose and aspect ratio. 120 samples were experimented under workability, compressive, flexural, and splitting tensile tests. The results pointed out that the fibre dose has more influence on the responses than its fibre aspect ratio, with statistical relation on the tensional toughness, equivalent flexural strength ratio, volumetric weight, and the number of fibres. Moreover, the fibre aspect ratio has a statistical impact on the tensional toughness. In general, the data indicates that the optimal recycled PET fibre reinforced concrete generates a superior performance than control samples, with an improvement similar to those reinforced with virgin fibres.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Infrastructure plays a pivotal role in a nation’s economic and societal progress. However, due to the substantial expenses and the constraints of a limited government budget, the need to assess the ...condition of each infrastructure and identify those requiring utmost attention has become imperative. To address the challenge of assessing and prioritizing infrastructure, national civil engineering associations have developed infrastructure report cards (IRCs) following diverse methodologies. The objective of this paper is to present and compare the existing IRCs, analysing their key characteristics and comparing them through the developed comparison guidelines. The findings offer valuable insights into IRCs, encompassing general knowledge, diverse practices, and areas for improvement. Furthermore, it provides guidance to civil engineering associations in nations lacking an infrastructure report card, as well as to governments and national infrastructure planners. Recommendations highlight the importance of government collaboration without direct control, transparent methodology explanations, and accessible results presentation. Enhancing IRCs based on these recommendations can facilitate structured, rational, realistic, and sustainability-based decision making. The study acknowledges limitations, including the challenge of assessing IRCs’ real impact and the limited dataset. Despite these limitations, this paper provides a crucial step toward improving IRCs and fostering informed infrastructure decisions.
Narrow trenches are a common technique for the installation of utility pipelines of small diameter. The excavated soil is not always appropriate as landfill and, in those cases, an appropriate soil ...from somewhere else (ex. a borrow pit or another construction site) should be used instead (classical solution, CS). Another common solution is to use a controlled low-strength (cementitious) material (CLSM) as backfill instead of compacted soil. However, both solutions lead to increased raw material consumption, waste generation, need for transportation, and CO2 emissions. In an attempt to address these issues, researchers developed an eco-trench (ECO) that reuses the excavated soil of narrow trenches to produce a controlled low-strength material to be used as landfill. Although technically viable, the sustainability of this solution versus the traditional solution has not been properly addressed. Hence, this paper aims to develop a method for the sustainability assessment of trenches. The Sustainability Index of Trenches (SIT), based on the MIVES decision-making method, enables the assessment and prioritisation of different types of trenches according to sustainability criteria. Criteria, indicators, weights and value functions were specifically defined based on seminars with experts in the field of utility services and construction. A case study was performed in which four types of trenches (CS, CS with recycling CS + R, CLSM and ECO) were assessed and prioritised according to SIT. ECO resulted in the most sustainable alternative with a SIT of 0.80 out of 1 followed by CS + R, CS and CLSM with SITs of 0.63, 0.40 and 0.38 respectively. The sensitivity analysis showed consistent results in different scenarios. These findings demonstrate the capability and reliability of SIT as a decision-making tool for the evaluation of the sustainability of different construction processes for trenches and the prioritisation of the most suitable solution for different situations.
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•A Sustainability Index for Trenches (SIT) is defined.•SIT is based on MIVES multi-criteria decision-making method.•SIT enables the assessment and prioritisation of different types of trenches.•Four type of trenches including the new eco-trench have been evaluated with the SIT.•The sensitivity analysis proved the method to be robust and repeatable
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Slabs reinforced with macro-plastic fibres were tested under hyperstatic configuration.•The slabs showed a ductile behaviour, keeping high load level after cracking.•The tests were numerically ...simulated using a finite element method (FEM) program.•The predictions provided by RILEM and EHE, clearly overestimate the experimental results in all cases.•This finding suggests the need to adjust the constitutive equations for PFRC.
This paper focuses on the study of the structural response of hyperstatic concrete flat suspended slabs reinforced only with structural plastic macro-fibres. First, the experimental program is described and then the results obtained are presented. The slabs tested maintained a high load level after cracking showing a ductile behaviour with great stress redistribution capacity. Next, the tests were simulated by means of a finite element software with constitutive models according to the specifications of RILEM and the Spanish Structural Concrete Code (EHE). The numerical results in terms of load/mid-span deflection were compared with the experimental results. The predictions provided by the codes and guideline models clearly overestimated the experimental results, which suggests the need to review the constitutive models used for plastic fibre-reinforced concrete.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Environmental issues are becoming increasingly important, and researchers are developing new technologies and models to reduce environmental impact. The circular economy is a production and ...consumption model that involves sharing, borrowing, reusing, repairing, reconditioning and recycling existing materials and products for as long as possible. This study focuses on the concept of reuse and, specifically, how to reduce waste generated by pandemics through recycling and reusing facemasks made of polyamide fabric. Facemasks can be reused to refurbish buildings in low-income contexts. To assess the reutilization potential of recycled bulk polyamide fiber, thermal, acoustic, and fire performance properties were assessed experimentally. The results show that they are comparable to commercial insulation materials such as glass wool and mineral wool in terms of thermal conductivity, while also demonstrating good sound absorption performance at medium and high frequencies (greater thickness and density will increase the amount of insulation and sound absorption). The material's fire performance is similar to that of other synthetic insulation materials, such as EPS. However, the performance is worse than for common organic insulation materials, such as cellulose. Finally, a low-cost, self-portable insulation panel concept designed for indoor installation was tested for material performance. Considering these properties, this solution may represent a significant opportunity to enhance thermal and acoustic comfort in vulnerable energy-poor households, bringing clear environmental benefits and positive social implications.
•Recycled cloth facemasks residue was studied as a low-cost insulation material.•Its thermal, acoustic and fire performance was experimentally assessed.•Acoustic & thermal results are comparable to that of commercial insulating material.•Fire results are similar to other synthetic insulations but worse than organic ones.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
From a construction point of view, neighborhoods with residents living at or below the poverty threshold are characterized by low energy efficiency buildings, in which people live in acoustic ...discomfort with no viable options for home improvements, as they usually can not afford the materials and labor costs associated. An alternative to this is to use low-cost insulating elements made of non-conventional materials with acceptable acoustic properties. Given that household materials at their end-of-life (EoLHM) are free of costs and available also to the more disadvantaged population, they can be used to build acoustic panels for such contexts. This approach embraces several benefits since it reduces the amount of waste produced, the footprint deriving from the extraction of new raw materials and, by highlighting the potential of the EoLHM, discourages the abandonment of waste. In this paper, the acoustic properties of EoLHM, such as cardboard, egg-cartons, clothes, metal elements and combinations of them, are investigated by means of the impedance tube technique. The measured sound absorption coefficient and transmission loss have shown that EoLHM can be used for the realization of acoustic panels. However, since none of the analyzed materials shows absorbing and insulating properties at the same time, EoLHM must be wisely selected. This innovative approach supports the circular economy and the improvement for the living condition of low-income households.
► A summary of the worldwide applications of steel fibres in precast segment linings. ► A methodology to assess the optimum reinforcement configuration for precast segments. ► Reduction up to the 70% ...of rebars by using 25
kg/m
3 of steel fibres in two tunnels of Barcelona.
This paper presents the most outstanding experiences regarding the use of fibres as the main reinforcement in precast segmental linings in the metropolitan area of Barcelona. It is known that the addition of structural fibres improves, on the one hand, the mechanical behaviour of the structure during its construction, especially in cases such as the thrust of the jacks, and on the other hand it leads to a reduction of the global costs by reducing the conventional passive reinforcement. The aim of this paper consists in presenting three real experiences that are representative of the application of FRC in urban tunnels and a design methodology to take into account the structural contribution of the fibres. Two particular cases of the application of this design method are presented. In the first case, the use of 25
kg/m
3 of fibres has led to a reduction of 70% of the conventional reinforcement initially proposed in the project. In the second one, which was planned to employ fibres but without considering its structural contribution, the parametric study reflected the possibility of reducing up to a 38% of the rebars adding 25
kg/m
3 of steel fibres in the concrete mixture. In light of good results, construction companies in Spain have become aware of the advantages of using fibres in these structures and have carried out experimental stretches. This attitude has also been influenced by the approval of the new Spanish Code, which includes the FRC as a construction material with design purposes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Specimens drilled from slabs are tested to qualitatively assess fibre orientations.•Plastic fibres tend to be oriented parallel to the formwork walls.•Plastic fibres tend to be oriented ...perpendicular to the flow direction for a free surface.•CT-scan can be used to identify the dispersion and orientation of plastic fibres.
This paper focuses on the study of the influence of flowability and wall-effects of the formwork in the orientation pattern of macro-plastic fibres. In order to identify the preferential orientation of fibres caused by the geometry of slabs, pairs of specimens drilled from PFRC slabs with different width/length – ratio are tested using the multidirectional double punch test (MDPT). The results show that plastic fibres tend to be oriented parallel to the walls or surfaces of the formwork and perpendicular to the flow direction for a free surface flow. The side walls slightly redistribute the fibre orientation, as the transverse dimension of the slabs is reduced. Additionally, a computed tomography (CT-scans) was, for the first time, successfully applied to assess the amount of macro-plastic fibres as well as its distribution and orientation in a prismatic core.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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