Understanding the influence of properties of fine recycled aggregates on recycled concrete

With increasing urbanisation, new approaches such as the Circular Economy (CE) are needed to reduce resource consumption. In Switzerland, Construction & Demolition (C&D) waste accounts for the largest portion of waste (84%). Beyond limiting the depletion of primary resources, implementing recycling strategies for C&D waste (such as using recycled aggregates to produce recycled concrete (RC)), can also decrease the amount of landfilled C&D waste. The use of RC still faces adoption barriers. In this research, we examined the factors driving the adoption of recycled products for a CE in the C&D sector by focusing on RC for structural applications. We developed a behavioural framework to understand the determinants of architects’ decisions to recommend RC. We collected and analysed survey data from 727 respondents. The analyses focused on architects’ a priori beliefs about RC, behavioural factors affecting their recommendations of RC, and project-specific contextual factors that might play a role in the recommendation of RC. Our results show that the factors that mainly facilitate the recommendation of RC by architects are: a senior position, a high level of RC knowledge and of the Minergie label, beliefs about the reduced environmental impact of RC, as well as favourable prescriptive social norms expressed by clients and other architects. We emphasise the importance of a holistic theoretical framework in approaching decision-making processes related to the adoption of innovation, and the importance of the agency of each involved actor for a transition towards a circular construction sector.

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Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

Sustainability ◽

10.3390/su13137498 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7498

Author(s):

Tan Li ◽

Jianzhuang Xiao

Keyword(s):

Mechanical Properties ◽

Stress State ◽

Strain Curve ◽

Confining Pressure ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Aggregate Model ◽

Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

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Characterisation and Life Cycle Assessment of Pervious Concrete with Recycled Concrete Aggregates

Crystals ◽

10.3390/cryst11020209 ◽

2021 ◽

Vol 11 (2) ◽

pp. 209

Author(s):

Adilson C. Paula Junior ◽

Cláudia Jacinto ◽

Thaís M. Oliveira ◽

Antonio E. Polisseni ◽

Fabio M. Brum ◽

...

Keyword(s):

Environmental Performance ◽

Treatment Plant ◽

Recycled Concrete ◽

Pervious Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Positive Contribution ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates

The search for environmental preservation and conservation of natural resources gives rise to new concepts and viable technical solutions on the path to sustainable development. In this context, this study’s main objective is to analyse the influence of recycled concrete aggregates (RCAs) on the development of pervious concrete, whose use as a floor covering represents an excellent device to mitigate the urban soil sealing phenomena. For this, mechanical and hydraulic tests were carried out, in addition to microstructural analyses and the assessment of its environmental performance. The results obtained were compared to reference studies also involving the incorporation of recycled aggregates. A pilot-scale case study was conducted, involving a parking space lined with pervious concrete moulded “in situ”. In laboratory tests, permeability coefficients and mechanical strengths compatible with the literature and above the normative limit for light traffic were found. The case study demonstrated higher permeability than in the laboratory, but the flexural strength was lower, being indicated only for pedestrian traffic. The environmental assessment showed that the RCA represents a positive contribution to the environmental performance of pervious concrete. Still, attention should be given to the recycled aggregate transport distance between the concrete plant and the RCA treatment plant.

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Strength and Water Absorption of Sustainable Concrete Produced with Recycled Basaltic Concrete Aggregates and Powder

Sustainability ◽

10.3390/su13116277 ◽

2021 ◽

Vol 13 (11) ◽

pp. 6277

Author(s):

Ibrahim Sharaky ◽

Usama Issa ◽

Mamdooh Alwetaishi ◽

Ahmed Abdelhafiz ◽

Amal Shamseldin ◽

...

Keyword(s):

Water Absorption ◽

Edge Length ◽

Recycled Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Partial Substitution ◽

Small Reduction ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Sustainable Concrete

In this study, the recycled concrete aggregates and powder (RCA and RCP) prepared from basaltic concrete waste were used to replace the natural aggregate (NA) and cement, respectively. The NA (coarse and fine) was replaced by the recycled aggregates with five percentages (0%, 20%, 40%, 60% and 80%). Consequently, the cement was replaced by the RCP with four percentages (0%, 5%, 10% and 20%). Cubes with 100 mm edge length were prepared for all tests. The compressive and tensile strengths (fcu and ftu) and water absorption (WA) were investigated for all mixes at different ages. Partial substitution of NA with recycled aggregate reduced the compressive strength with different percentages depending on the type and source of recycled aggregate. After 28 days, the maximum reduction in fcu value was 9.8% and 9.4% for mixtures with coarse RCA and fine RCA (FRCA), respectively. After 56 days, the mixes with 40% FRCA reached almost the same fcu value as the control mix (M0, 99.5%). Consequently, the compressive strengths of the mixes with 10% RCA at 28 and 56 days were 99.3 and 95.2%, respectively, compared to those of M0. The mixes integrated FRCA and RCP showed higher tensile strengths than the M0 at 56 d with a very small reduction at 28 d (max = 3.4%). Moreover, the fcu and ftu values increased for the late test ages, while the WA decreased.

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Effect of mixed recycled aggregates on mechanical properties of recycled concrete

Magazine of Concrete Research ◽

10.1680/macr.14.00217 ◽

2015 ◽

Vol 67 (5) ◽

pp. 247-256 ◽

Cited By ~ 18

Author(s):

Desirée Rodríguez-Robles ◽

Julia García-González ◽

Andrés Juan-Valdés ◽

Julia Ma Morán-del Pozo ◽

M. Ignacio Guerra-Romero

Keyword(s):

Mechanical Properties ◽

Recycled Concrete ◽

Recycled Aggregates ◽

Mixed Recycled Aggregates

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Ultrasonic Test on Recycled Concrete: Relationship among Ultrasonic Waves Velocity, Compressive Strength and Elastic Modulus

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.894.45 ◽

2014 ◽

Vol 894 ◽

pp. 45-49 ◽

Cited By ~ 1

Author(s):

Luisa Pani ◽

Lorena Francesconi

Keyword(s):

Compressive Strength ◽

Elastic Modulus ◽

Ultrasonic Wave ◽

Ultrasonic Test ◽

Ultrasonic Waves ◽

Recycled Concrete ◽

Recycled Aggregates ◽

Experimental Program ◽

Static Modulus ◽

Cylindrical Samples

In this paper an experimental program has been carried out in order to compare compressive strength fcand elastic static modulus Ecof recycled concrete with ultrasonic waves velocity Vp, to establish the possibility of employing nondestructive ultrasonic tests to qualify recycled concrete. 9 mix of concrete with different substitution percentage of recycled aggregates instead of natural ones and 27 cylindrical samples have been made. At first ultrasonic tests have been carried out on cylindrical samples, later elastic static modulus Ecand compressive strength fchave been experimentally evaluated. The dynamic elastic modulus Edhas been determined in function of ultrasonic wave velocity Vp; furthermore the correlations among Ed, Ec, fce Vphave been determined. It has been demonstrated that ultrasonic tests are suitable for evaluating different deformative and resisting concrete performances even when variations are small.

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Stress-strain curve of concretes with recycled concrete aggregates: analysis of the NBR 8522 methodology

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952017000300002 ◽

2017 ◽

Vol 10 (3) ◽

pp. 547-567 ◽

Cited By ~ 2

Author(s):

D. A. GUJEL ◽

C. S. KAZMIERCZAK ◽

J. R. MASUERO

Keyword(s):

Test Procedure ◽

Strain Curve ◽

Recycled Concrete ◽

Load Test ◽

Recycled Aggregates ◽

Elastic Behavior ◽

It Use ◽

Stress Strain Curve ◽

Stress Strain ◽

Brazilian Standard

ABSTRACT This work analyses the methodology "A" (item A.4) employed by the Brazilian Standard ABNT 8522 (ABNT, 2008) for determining the stress-strain behavior of cylindrical specimens of concrete, presenting considerations about possible enhancements aiming it use for concretes with recycled aggregates with automatic test equipment. The methodology specified by the Brazilian Standard presents methodological issues that brings distortions in obtaining the stress-strain curve, as the use of a very limited number of sampling points and by inducing micro cracks and fluency in the elastic behavior of the material due to the use of steady stress levels in the test. The use of a base stress of 0.5 MPa is too low for modern high load test machines designed do high strength concrete test. The work presents a discussion over these subjects, and a proposal of a modified test procedure to avoid such situations.

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Comparative study of the influence of three types of fibre in the shrinkage of recycled mortar

Materiales de Construcción ◽

10.3989/mc.2018.07817 ◽

2018 ◽

Vol 68 (332) ◽

pp. 168 ◽

Cited By ~ 5

Author(s):

P. Saiz-Martínez ◽

D. Ferrández-Vega ◽

C. Morón-Fernández ◽

A. Payán de Tejada-Alonso

Keyword(s):

Negative Impact ◽

Polypropylene Fiber ◽

Capacitive Sensor ◽

Recycled Concrete ◽

Construction And Demolition Waste ◽

Moisture Loss ◽

Recycled Aggregates ◽

Fiber Types ◽

Demolition Waste ◽

Recycled Concrete Aggregates

Construction and demolition waste can be used as a substitution of natural aggregate in mortar and concrete elaboration. A poorer quality of recycled aggregates generally has negative impact on mortar properties. Shrinkage is one of the properties that experiences worse outcome due to the higher absorption of recycled aggregates. This research evaluates the potential shrinkage of mortars elaborated with recycled concrete aggregates both with and without fibres addition, as well as the relation between moisture loss and shrinkage caused by mortar drying process using a capacitive sensor of the authors’ own design. Two different mortar dosages 1:3 and 1:4 and three fiber types: polypropylene fiber, fiberglass and steel fiber, in different proportions were used. Obtained results show that the use of polypropylene fiber improves the recycled mortars performance against shrinkage in 0.2%. Moreover, a clear relation between dry shrinkage and moisture loss was observed.

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Laboratory Evaluation of Hot Asphalt Concrete Properties with Cuban Recycled Concrete Aggregates

Sustainability ◽

10.3390/su10082590 ◽

2018 ◽

Vol 10 (8) ◽

pp. 2590 ◽

Cited By ~ 6

Author(s):

Debora Acosta Alvarez ◽

Anadelys Alonso Aenlle ◽

Antonio Tenza-Abril

Keyword(s):

Asphalt Concrete ◽

Aggregate Size ◽

Asphalt Mixtures ◽

Recycled Concrete ◽

Construction And Demolition Waste ◽

Recycled Aggregates ◽

Laboratory Evaluation ◽

Maximum Aggregate Size ◽

Demolition Waste ◽

Aggregate Fraction

Recycled Aggregates (RA) from construction and demolition waste (CDW) are a technically viable alternative to manufacture of asphalt concrete (AC). The main objective of this work is to evaluate the properties of hot asphalt mixtures that have been manufactured with different sources of CDW (material from concrete test specimens, material from the demolition of sidewalks and waste from prefabrication plants) from Cuba. Dense asphalt mixtures were manufactured with a maximum aggregate size of 19 mm, partially replacing (40%) the natural aggregate fraction measured between 5 mm and 10 mm with three types of RA from Cuba. Marshall specimens were manufactured to determine the main properties of the AC in terms of density, voids, stability and deformation. Additionally, the stiffness modulus of the AC was evaluated at 7 °C, 25 °C and 50 °C. The results corroborate the potential for using these sources of CDW from Cuba as a RA in asphalt concrete, thereby contributing an important environmental and economic benefit.

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Distresses In CRCP Due To Horizontal Cracking: A Parameter Analysis

10.33593/jdp3cxsf ◽

2021 ◽

Author(s):

Luc Rens ◽

Anne Beeldens

Keyword(s):

Recycled Concrete ◽

Parameter Analysis ◽

Recycled Aggregates ◽

Ultrasonic Tomography ◽

Concrete Pavements ◽

Crack Control ◽

Recycled Concrete Aggregates ◽

Preventative Measures ◽

First Case ◽

New Type

Continuously reinforced concrete pavements are known for their durability and longevity as well as for the driving comfort, thanks to the absence of transverse joints. The strength and weakness of CRCP is situated in the network of fine transverse shrinkage cracks whose spacing distance and opening width are determining the pavement behaviour. The most commonly known distress is the punch-out: a fragmentation of the concrete over full depth. During the last decade, a new type of distress was encountered at Belgian worksites. It is characterised by a delamination at the level of the longitudinal reinforcement, a partial fragmentation of the pavement, mostly positioned under the wheel tracks. The first case was the worksite "N49 at Zwijndrecht", where severe distresses were observed after three years of service. An examination with the technique of ultrasonic tomography detected the presence of horizontal cracks at the level of the reinforcement. The use of recycled concrete aggregates was supposed to be the cause. A significant indicator was also the presence of widely opened cracks. In the period 2011-2018 other cases were observed in Belgium, some of them leading to early degradation and others not. Also in other countries (South-Korea, U.S., Japan, ...) distresses due to horizontal cracking were reported. Based upon observations an analysis is made of the main parameters that may cause the wide initial cracks: the use of recycled aggregates, temperature and temperature changes during construction and concrete quality. Preventative measures such as active crack control will be presented.

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