Toward a codified design of recycled aggregate concrete structures: Background for the new <scp><i>fib</i> Model Code 2020 and Eurocode 2</scp>

Tošić, Nikola; Torrenti, Jean‐Michel; Sedran, Thierry; Ignjatović, Ivan

doi:10.1002/suco.202000512

Cited by 34 publications

(24 citation statements)

References 107 publications

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“…The provisions for RAC in EC2 are given in Annex N. An extensive background to Annex N can be found in the study by Tošić et al [10], wheras herein it will be only briefly presented. Namely, as a CEN standard, EC2 is normatively linked to other standards, in this case the standard for concrete EN 206 [11] and for aggregates for concrete EN 12620 [12].…”

Section: Annex N Of Pren1992-1-1mentioning

confidence: 99%

New Eurocode 2 provisions for recycled aggregate concrete and their implications for the design of one-way slabs

Tošić¹,

Torrenti²

2021

Građ materijali i konstrukcije

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A significant amount of research has been performed on recycled aggregate concrete (RAC), both on the material and structural level. This has enabled the formulation of material and structural resistance models that can be safely and reliably used for the structural design of RAC members and the new Eurocode 2 (EC2) will contain an informative annex detailing provisions for the design of RAC. Thus, an increased market uptake of recycled aggregate (RA) can be achieved, leading to potential sustainability improvements of concrete structures. In order to familiarize designers with the new provisions for RAC, this paper presents an example of one-way slab design using varying RA substitution ratios, as well as a parametric study on the implications of RAC provisions on slab slenderness. The results of this study show that RAC one way slabs can be successfully designed using EC2. Although such slabs might require larger depths than natural aggregate concrete slabs, their applicability in the typical slenderness range is possible.

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Section: Annex N Of Pren1992-1-1mentioning

confidence: 99%

New Eurocode 2 provisions for recycled aggregate concrete and their implications for the design of one-way slabs

Tošić¹,

Torrenti²

2021

Građ materijali i konstrukcije

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“…The technical feasibility of recycled aggregate concrete (RAC) has been demonstrated in several previous studies [ 2 , 3 , 4 ] in what concerns the mechanical and durability properties of concrete, as well as structural performance. Additionally, recent developments towards the standardization of recycled aggregate concrete (RAC) design [ 4 ] including a specific annex of prEN1992 [ 5 ] are expected to address reservations of construction agents towards RAC, contributing to its upscaling as a structural material. Moreover, under some conditions, the cost [ 6 ] and environmental impacts (EI) [ 6 , 7 , 8 , 9 , 10 , 11 ] associated with the procurement of aggregates by ready-mix plants are reduced when RAs are used instead of NAs.…”

Section: Introductionmentioning

confidence: 99%

Environmental and Economic Life Cycle Assessment of Recycled Coarse Aggregates: A Portuguese Case Study

Dias¹,

Pacheco²,

Silvestre

et al. 2021

Materials

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The incorporation of recycled aggregates in concrete not only reduces the extraction of natural resources, but also decreases landfill disposal of construction and demolition waste. Hence, environmental impacts and costs are reduced, promoting the use of recycled aggregates and circular economy. However, the impacts of transport depend on the distance between facilities and longer distances may result in recycled aggregates being more costly and having larger environmental impact than natural aggregates. This paper discusses this topic, presents a review on the use of life cycle assessment methodology on natural and recycled aggregates for concrete, and applies this methodology in a real context pertaining the procurement of coarse aggregates to ready-mix concrete plants. A case study of two Portuguese regions, Coimbra and Lisbon, is presented. For each region, a quarry, a construction and demolition waste plant, and a ready-mix concrete plant are chosen and a comparative life cycle assessment is made. Different scenarios for the supply of natural and recycled aggregates are studied and the scenarios for recycled aggregates procurement include different hypotheses for the installation (construction and demolition waste plant or quarry) processing the construction and demolition waste into recycled aggregates. For this case study and both regions, it was found that the supply of recycled aggregates produced at the construction and demolition waste plant has lower environmental impact and cost than all other scenarios, including the provision of natural aggregates, except when it is assumed that the quarry is licensed and equipped for receiving unsorted construction and demolition waste and processing it into recycled aggregates. The paper shows that transport distance is a determining factor in the comparison of the impacts of the procurement of natural and recycled aggregates. Moreover, in the Portuguese context, the environmental impacts of the procurement of recycled aggregates may be smaller than those of natural aggregates, but cost may be larger for recycled aggregates, preventing that the most sustainable option is chosen.

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“…Guidelines for RAC are needed since RAs are different from coarse natural aggregates (NAs), changing the properties of concrete. The main differences between NAs and RAs are the following: NAs are composed of particles of a single type of stone (limestone, granite and basalt are the most common), while RAs are composed of a mix of several constituents (concrete, mortar, unbound stone, ceramics, glass, and other deleterious contaminants) of different quality and properties [ 6 , 7 ]; This implies that, in general, RAs are weaker, more deformable, more porous and have larger water absorption than NAs [ 8 , 9 ]; At the same time, the mechanical and durability properties of concrete are detrimentally affected by the incorporation of RAs: for the same compressive strength, RAC is typically found to have a smaller Young’s modulus, larger creep and shrinkage and worse durability properties [ 9 , 10 , 11 ]. Fracture energy and tensile strength are also detrimentally affected, especially when the strength class of concrete is larger [ 12 , 13 ]; Regarding the structural behaviour of reinforced concrete, the use of RAs is found to result in larger short- and long-term deflections [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

“…At the same time, the mechanical and durability properties of concrete are detrimentally affected by the incorporation of RAs: for the same compressive strength, RAC is typically found to have a smaller Young’s modulus, larger creep and shrinkage and worse durability properties [ 9 , 10 , 11 ]. Fracture energy and tensile strength are also detrimentally affected, especially when the strength class of concrete is larger [ 12 , 13 ];…”

Section: Introductionmentioning

confidence: 99%

Eurocode Shear Design of Coarse Recycled Aggregate Concrete: Reliability Analysis and Partial Factor Calibration

et al. 2021

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This paper contributes to the definition of design clauses for coarse recycled aggregate concrete. One of the main reasons for scepticism towards recycled aggregate concrete is the perceived notion that the heterogeneity of recycled aggregates may increase the uncertainty of the behaviour of concrete. Therefore, the paper uses structural reliability concepts to propose partial factors for recycled aggregate concrete’s design for shear failure. The paper builds upon a previous publication by the authors, in which the model uncertainty of recycled aggregate concrete elements designed for shear, with and without shear reinforcement, was compared with that of natural aggregate concrete elements. In that paper, the statistics of the model uncertainty for recycled aggregate concrete shear design were indeed found to be less favourable than those of natural aggregate concrete. Therefore, a partial factor for recycled aggregate concrete design is needed to ensure safety. This paper presents partial factors calibrated with explicit reliability analyses for different cases of design concerning beams (in the case of shear design of elements with shear reinforcement) and slabs (for the design of elements without shear reinforcement). For full incorporation of coarse recycled concrete aggregates and the design of elements without shear reinforcement, the calibrated partial factor reduces the design value of shear resistance by 10% (design with EN1992) or 15% (design with prEN1992) in comparison to natural aggregate concrete’s design. For the shear design of elements with shear reinforcement, the partial factor decreases resistance by 5% but a sensitivity analysis showed that the reduction might be, under pessimistic expectations, of up to 20%.

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Toward a codified design of recycled aggregate concrete structures: Background for the new fib Model Code 2020 and Eurocode 2

Cited by 34 publications

References 107 publications

New Eurocode 2 provisions for recycled aggregate concrete and their implications for the design of one-way slabs

New Eurocode 2 provisions for recycled aggregate concrete and their implications for the design of one-way slabs

Environmental and Economic Life Cycle Assessment of Recycled Coarse Aggregates: A Portuguese Case Study

Eurocode Shear Design of Coarse Recycled Aggregate Concrete: Reliability Analysis and Partial Factor Calibration

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