scholarly journals Performance Study of Eco-Concrete Based on Waste Demolition as Recycled Aggregates

2020 ◽  
Vol 2 (2) ◽  
pp. 123-130
Keyword(s):  
Mechanical Response ◽  
Negative Impact ◽  
Research Work ◽  
Physical And Mechanical Properties ◽  
Substitution Effect ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Performance Study

Aggregates are considered as essential constituents in the composition of ordinary concrete or special concretes. The use of recycled aggregates is of great interest from the economic and environmental point of view. This study concerns the use of aggregates issued from the waste of crushing of the old concrete as a substitution for natural aggregates. An experimental program plan includes the study of the behavior of recycled aggregate concretes (RAC) at replacement of 0 %, 30 %, 50 %, 70 % and 100 % of recycled aggregates respectively. The objective of the present research work is to study the substitution effect of recycled aggregates (RA) on the physical and mechanical characteristics of a local recycled concrete. The non-destructive test methods NDT (Rebound hammer and ultrasonic velocity) were adopted to assess the mechanical response. The correlation of these tests had been considered for the different properties of tests to see wither; they are reliable to characterize a local recycled concrete, in this particular case of study. The results obtained showed that there is a negative impact of replacement ratio of recycled aggregate on the physical and mechanical properties mainly higher air content, lower density, greater absorption and decrease in strength in comparison with reference crushed aggregate concrete (CAC). Further, low correlation coefficients were registered to predict the due compressive strength in this case regarding the effect of aggregate type.

scholarly journals Recycled Precast Concrete Kerbs and Paving Blocks, a Technically Viable Option for Footways

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7007
Author(s):  
Andrés Juan-Valdés ◽  
Desirée Rodríguez-Robles ◽  
Julia García-González ◽  
María Isabel Sánchez de Rojas ◽  
Manuel Ignacio Guerra-Romero ◽  
...  
Keyword(s):  
Water Absorption ◽  
Circular Economy ◽  
Precast Concrete ◽  
Research Work ◽  
Lower Class ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Durability ◽  
Conventional Concrete

The linear economy paradigm in place to date has to be seriously challenged to give way to a new school of thought known as the circular economy. In this research work, precast kerbs and paving blocks made with recycled concrete (RACC-mixture) bearing 50 wt% mixed recycled aggregate (masonry content of 33%) and an eco-efficient cementitious material as 25 wt% conventional binder replacement were evaluated to assess their intrinsic potential to replace traditional raw materials, in keeping with circular economy criteria. Therefore, precast products were subjected to mechanical strength, durability and microstructure tests and were compared to conventional concrete units (CC-mixture and commercially available precast elements). Although a class demotion was observed for water absorption and some decreases in flexural strength (26%), splitting tensile strength (12.8%) and electrical resistivity (45%) and a lower class water absorption were registered, and the recycled mixture also exhibited a greater performance in terms of compressive strength (6%), a better abrasion resistance classification and a comparable porosity and microstructure, which ensures a good concrete durability. In any case, the results showed that precast pieces were European standard-compliant, thus supporting the viability of the mixed recycled aggregates and eco-efficient cementitious replacement in footways.

scholarly journals Effect of recycled materials and hybrid fibers on the properties of self-compacting concrete

2021 ◽  
Vol 19 (1) ◽  
pp. 262-269
Author(s):  
Eethar Dawood ◽  
Maysam Al-Heally
Keyword(s):  
Fly Ash ◽  
Negative Impact ◽  
Strength Properties ◽  
Fiber Content ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Dry Density ◽  
Self Compacting Concrete ◽  
Recycled Materials

Self-compacting concrete (SCC) has many properties comparing to conventional concrete and represents a good choice towards sustainability. The use of different recycled materials contributes to seize the negative impact of huge amount of waste on the ecosystem. In this study, locally available materials have been used as partially cement replacements. Such materials including ceramic waste powder (CWP) and glass powder (GP) in addition to fly ash with total cement replacement of 30%(12%CWP+8%GP+12%Fly ash) have been found to increase the compressive strength by about 7% compared to the control SCC. Normal aggregate was replaced by recycled aggregate with different recycled aggregate which are Recycled Concrete (RC), Crushed red brick (REB) and Crushed ceramic (CER.) The percentages of replacements are: 25%, 50%, 75% and 100%, for each type of aggregate. The results show that the increase of the amount of recycled aggregates decreases the strength properties of SSC and effect on workability of SSC also the result show a reduction in oven dry density. The combination of different type of recycled aggregate shows a reduction in SSC strength. The use of fibers shows better performance of SSC compared to combination aggregate mix without fiber but reduce the workability of SCC. However, the fiber content of 1.0% shows the best result of the mechanical properties, whereas, fiber content up to 1.5% affects negatively on concrete properties. The use of hybrid fiber also increases the strength properties of concrete.

scholarly journals Mechanical behavior of recycled lightweight concrete using EVA waste and CDW under moderate temperature

2009 ◽  
Vol 2 (3) ◽  
pp. 211-221 ◽  
Author(s):  
E. Q. R. Santiago ◽  
P. R. L. Lima ◽  
M. B. Leite ◽  
R. D. Toledo Filho
Keyword(s):  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Lightweight Concrete ◽  
Recycled Concrete ◽  
Raw Material ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Demolition Waste

Many benefits can be achieved by using recycled waste as raw material for construction. Some of them are the reduction of the total cost of the construction, the reduction of the consumption of energy and the decrease in the use of natural materials. The construction sector can also incorporate the waste of the other industries, like the waste of the shoes industry, the Ethylene Vinyl Acetate (EVA). EVA aggregate is obtained by cutting off the waste of EVA expanded sheets used to produce insoles and innersoles of the shoes. In this work two types of recycled aggregate were used - construction and demolition waste (CDW) and EVA. The aim of this work was to study the influence of the use of these recycled aggregates, as replacement of the natural coarse aggregate, on mechanical behavior of recycled concrete. The experimental program was developed with two w/c ratio: 0.49 and 0.82. Four mixtures with produced with different aggregates substitution rates (0, 50%EVA, 50%CDW and 25%EVA-25%CDW), by volume. Compressive tests were carried out to evaluable the influence of recycled aggregate on strength, elastic modulus and Poisson coefficient. In addition, it was evaluated the effect of the moderate temperatures (50, 70 and 100º C) on stress-strain behavior of concretes studied. The results demonstrated that is possible to use the EVA waste and RCD to produces lightweight concrete. The influence of temperature was more significant only on elastic modulus of the recycled concrete with 50%EVA.

Critical Analysis of Recycled Aggregate and Concrete with Recycled Aggregate

2011 ◽  
Vol 99-100 ◽  
pp. 1274-1280
Author(s):  
Neela Deshpande ◽  
S.S Kulkarni
Keyword(s):  
Compressive Strength ◽  
Critical Analysis ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Waste Materials ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Mix

One of the construction sector's major contributions to the preservation of the Environment and sustainable development is the reuse and recycling of the waste materials it generates (reducing, reusing, recycling and regenerating the residues that originate the constructive activity). With this view an experimental program was undertaken which helped in judging the effectiveness of using Recycled aggregate in concrete ,by assessing the properties of Recycled aggregates – Coarse and Fine. Further with the guidance of IS 10262:2009 ,Concrete mix was designed for 28 day compressive strength as 25N/mm2 using conventionally used aggregates and Recycled aggregates. From economy perspective an attempt was made to use superplasticser to reduce cement consumption. With reference to the experimental results, analysis of important properties of both the types of concrete is done and the suitability of use of recycled concrete aggregate for new concrete is judged.

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

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.

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

Crystals ◽  
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.

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

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.

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

2014 ◽  
Vol 894 ◽  
pp. 45-49 ◽  
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.

Recycling of Waste Concrete and Fly Ash for Recycled Aggregate Concrete: Fundamental Characteristics Evaluation

2009 ◽  
Vol 620-622 ◽  
pp. 255-258 ◽  
Author(s):  
Cheol Woo Park
Keyword(s):  
Fly Ash ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Recycled Concrete Aggregate ◽  
Aggregate Concrete ◽  
Waste Concrete

As the amount of waste concrete has been increased and recycling technique advances, this study investigates the applicability of recycled concrete aggregate for concrete structures. In addition fly ash, the industrial by-product, was considered in the concrete mix. Experimental program performed compressive strength and chloride penetration resistance tests with various replacement levels of fine recycled concrete aggregate and fly ash. In most case, the design strength, 40MPa, was obtained. It was known that the replacement of the fine aggregate with fine RCA may have greater influence on the strength development rather than the addition of fly ash. It is recommended that when complete coarse aggregate is replaced with RCA the fine RCA replacement should be less than 60%. The recycled aggregate concrete can achieve sufficient resistance to the chloride ion penetration and the resistance can be more effectively controlled by adding fly ash. It I finally conclude that the recycled concrete aggregate can be successfully used in the construction field and the recycling rate of waste concrete and flay ash should be increased without causing significant engineering problems.

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

2018 ◽  
Vol 68 (332) ◽  
pp. 168 ◽  
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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