scholarly journals Assessment of the Permeability to Aggressive Agents of Concrete with Recycled Cement and Mixed Recycled Aggregate

2021 ◽  
Vol 11 (9) ◽  
pp. 3856
Author(s):  
Blas Cantero ◽  
Miguel Bravo ◽  
Jorge de Brito ◽  
Isabel Fuencisla Sáez del Bosque ◽  
César Medina
Keyword(s):  
Construction Industry ◽  
Recycled Concrete ◽  
The Other ◽  
Recycled Aggregate ◽  
Transport Mechanisms ◽  
High Quality ◽  
Conventional Concrete ◽  
Reliable Assessment ◽  
Alternative Material ◽  
Carbon Dioxide Co2

Acceptance by the construction industry of recycled concrete as a sustainable alternative material is contingent upon a reliable assessment of its permeability to corrosive agents. This study analyses the transport mechanisms associated with chloride (Cl−), oxygen (O2) and carbon dioxide (CO2) ions in concrete with cement made with 10% or 25% ground recycled concrete (GRC) separately or in combination with 50% mixed recycled aggregate (MRA). The findings show that, irrespective of aggregate type, concrete with GRC exhibited lower resistance to ingress than conventional concrete due to its greater porosity. Nonetheless, O2 permeability was consistently below 4.5 × 10−17 m2 and CO2 penetration, under 4 mm/year0.5, indicative of concrete with high quality. Resistance to CO2 and Cl− penetration in the materials with 10% GRC was similar to the values observed in conventional concrete. On the other hand, the incorporation of 25% GRC increased the penetration of CO2 and Cl- by 106% and 38%, respectively. Further to those findings in normal carbonation environments, reinforcement passivity would be guaranteed in such recycled materials over a 100 year service life.

scholarly journals Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW)

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 24 ◽  
Author(s):  
Andrés Juan-Valdés ◽  
Julia García-González ◽  
Desirée Rodríguez-Robles ◽  
Manuel Guerra-Romero ◽  
Fernando López Gayarre ◽  
...  
Keyword(s):  
Precast Concrete ◽  
Recycled Concrete ◽  
The Other ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Mass Concrete ◽  
Conventional Concrete ◽  
Mixed Aggregates ◽  
Precast Elements ◽  
Mixed Ceramic

This research aimed to prove the feasibility of producing two types of precast elements widely used in construction, such as curbstones and paving blocks, using recycled concrete made with a 50% substitution of the natural gravel by recycled mixed aggregates with a significant ceramic content (>30%). In order to prove the quality of such mass concrete recycled precast elements, two different mixes were used: the first one was a conventional concrete mix provided by Prefabricados de Hormigón Pavimentos Páramo S.L., one of the collaborating companies in this study, and the other was a mixture in which wt 50% of the natural coarse aggregates were substituted for recycled mixed aggregates ceramic (RMAc). This recycled aggregate is a heterogeneous mixture of unbound aggregates, concrete, ceramic, etc., used as a secondary recycled aggregate and commonly produced in a lot of recycling plants in many European countries. This material was supplied by Tecnología y Reciclado S.L., the other collaborating company. Both mixtures were representative in order to establish the comparative behavior between them, taking into account that smaller percentages of replacement of the natural with recycled aggregates will also produce good results. This percentage of substitution represents a high saving of natural resources (gravel) and maintains a balanced behavior of the recycled concrete, so this new material can be considered to be a viable and reliable option for precast mass concrete paving elements. The characterization of the recycled precast elements, covering mechanical, microstructural, and durability properties, showed mostly similar behavior when compared to the analogous industrially-produced pieces made with conventional concrete.

scholarly journals Development of High Quality No Fine Concrete

2016 ◽  
Vol 3 (2) ◽  
pp. 277-282
Author(s):  
Dr. G. Nandini Devi
Keyword(s):  
Mechanical Properties ◽  
Construction Industry ◽  
Coarse Aggregate ◽  
High Quality ◽  
Natural Sand ◽  
Conventional Concrete ◽  
Structural Application ◽  
Alternative Material

Natural sand is being extorted at an increasing rate. Construction industry is looking for an alternative material for sand and research is going on to find new innovative concrete. No fines concrete has been generally used for paving applications, other non-structural application, such as reinforced panels, acoustic, thermal and permeability properties because of its previous nature. In this work, 12.5mm size coarse aggregate is used in place of usually used 20mm size in no fine concrete with various mix ratio of cement and 12.5mm coarse aggregate. Specimens were casted and tested for its mechanical properties. Results are compared with M25 conventional concrete.

scholarly journals A Study Based upon the Usage Recycled Aggregate to Enhance the Strength Aspects of Conventional Concrete: A Critical Review

2021 ◽  
Vol 9 (VI) ◽  
pp. 1567-1570
Author(s):  
Suhail Mushtaq Khan
Keyword(s):  
Chloride Ions ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Split Tensile Strength ◽  
Conventional Concrete ◽  
Natural Aggregate ◽  
Concrete Production

Recycled aggregates are those crushed cement concrete or asphalt pavement which comes out from the construction debris which is reused in construction. They are made from the reprocessing of materials which have been used in previous constructions. This paper discusses about the study of properties of recycled aggregates from the sources which has already been published. The results are that 100% replacement of natural aggregate by recycled concrete aggregate effect on chloride ions resistance, it plays negative effects on durability of recycled concrete aggregates, and addition of fiber in recycled aggregate concrete mixture gave more effective in the performance of concrete. On experimental study of recycled aggregate, compressive, flexural and split tensile strength of the recycled aggregate were found to be lower than that of the natural aggregate. Use of recycled aggregate in a new concrete production is still limited. Recommendation of introduction of recycled aggregates standard is required for the materials to be used successfully in future. Gaps in literature reviews are also included in this paper.

scholarly journals Bond Behavior Between Recycled Concrete Containing CDW and Different Types of Steel Bars

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Carine N. S. Reis ◽  
Paulo R. L. Lima ◽  
Mônica B. Leite
Keyword(s):  
Recycled Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Demolition Waste ◽  
Conventional Concrete ◽  
Recycled Fine Aggregate ◽  
Steel Bar ◽  
Internal Forces ◽  
Steel Rebars

The operation of reinforced concrete structures is directly associated with the adhesion between the steel bar and the concrete, which allows the internal forces to be transferred to the reinforcement during the process of loading the structural elements. The modification of the concrete composition, with the introduction of recycled aggregate from construction and demolition waste (CDW), affects the steel-concrete interface and can modify the bonding stress, which is also influenced by the type and diameter of the bar used. In this work, the influence of the recycled fine aggregate (RFA) and types of steel bar on the steel-concrete bond was experimentally evaluated using the pullout test. Conventional concrete and recycled concrete, with RFA replacement level of 25%, were produced. Two types of steel rebars (i.e.,plain and deformed) with  diameters of 10.0 and 16.0mm were considered in this paper. The results indicate a reduction in the adhesion stress with the introduction of recycled aggregate, but this trend is influenced by the diameter of the bar used. The use of ribbed bars modifies the stress bon-slip behavior, with an increase in the average bond strength, which is also observed with the reduction of the diameter of the bar.

scholarly journals ANÁLISE DAS PROPRIEDADES FÍSICAS E MECÂNICAS DO CONCRETO PRODUZIDO COM RESÍDUO SÓLIDO DE CERÂMICA VERMELHA

2012 ◽  
Vol 04 (02) ◽  
pp. 01-11 ◽  
Author(s):  
Cassio Fabian S. Campos ◽  
Giovane Bozette Mazini ◽  
Guilherme A. da Silva Neto
Keyword(s):  
Mechanical Properties ◽  
Construction Industry ◽  
Physical And Mechanical Properties ◽  
Specific Weight ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Mechanical Compression ◽  
Conventional Concrete ◽  
The Difference ◽  
Physical Changes

The construction industry accounts for the largest share of consumption of natural resources among all other areas, about 50%. Consequently is also the largest generator of waste. One of these tailings is red ceramic, which due to its fragility break easily generate large amount of debris. This project aimed to examine the possibility of reuse of waste as aggregate for concrete comparing their physical and mechanical properties, with conventional concrete. We compared the behaviors of different traits in concrete with a gradual replacement of 20% of natural coarse aggregate by recycled aggregate red ceramic to achieve 100% recycled aggregate, evaluating possible changes in density, absorption and voids, as well as the mechanical compression. The reference concrete results presented in the order of 25 MPa at 28 days of age, since the concrete produced with recycled aggregates showed lower results of the compressive strength of up to30%. The other indices also suffered physical changes as the slump that had values 4 times higher, the level of absorption and voids which increased 2-3 three times in concrete with recycled aggregate. This happens due to the difference between the densities of crushed stone and ceramics. Although the ceramic adversely affect the mechanical properties, this difference becomes lighter concrete, or decreases its specific weight, which may be favorable in some situations.

Developing Porous Concrete Interlocking Pavement Blocks Utilizing Recycled Concrete Aggregate for Rainfall Harvesting Use

2021 ◽  
Vol 28 (3) ◽  
pp. 48-60
Author(s):  
Mahdi Mahdi ◽  
Raad Irzooki ◽  
Mazin Abdulrahman
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Coarse Aggregate ◽  
Concrete Pavement ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Unit Weight ◽  
Conventional Concrete ◽  
Porous Concrete ◽  
Porous Pavement

Rainwater harvesting and flood prevention in cities are significant urban hydrological concerns. The use of porous pavement is one of the most effective solutions to handle this matter. Thus, this study aims to develop Porous Interlocking Concrete Pavement (PICP) using recycled aggregate from concrete waste. This porous pavement, then later, can be utilized in low traffic areas and parking lots to harvest water by infiltration and reduce surface runoff. First, the physical properties of the porous concrete blocks, such as density (unit weight), absorption, coefficient of permeability, and porosity, were studied. Also, the mechanical properties of concrete mixtures like compressive strength and flexural strength were tested. This study used two types of PICP, the first one with ordinary coarse aggregate (P1) and the second with recycled crushed concrete coarse aggregate (P2), and then compared their performance to the conventional concrete pavement blocks used the two types of coarse aggregate (R1 and R2). The results show that the unit weight (density) of porous types was reduced by 25% and 26%, and the total porosity increases by around 2.4 times and 18 times respectively, as compared to conventional concrete pavement types. However, the compressive strength and flexural strength of porous concrete types decreased by (55% and 71%), respectively, compared to conventional types. Overall, the infiltration test results showed that the infiltrated water through porous concrete increased by about 83% in comparison to conventional concrete. From the results, utilizing porous concrete pavement can be considered a promising material in terms of water harvesting and decreasing rainwater flooding. Additionally, using recycled concrete can bring economical and environmental benefits.

The High Quality Technical Research of Road Concrete Recycled Coarse Aggregate

2011 ◽  
Vol 346 ◽  
pp. 47-51 ◽  
Author(s):  
M. Mandula ◽  
Xiao Yu Hu ◽  
Feng Jin Chen ◽  
Wen Long Zhang
Keyword(s):  
Coarse Aggregate ◽  
Chemical Characteristic ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Cement Slurry ◽  
High Quality ◽  
Ordinary Concrete ◽  
Recycled Coarse Aggregate ◽  
Waste Concrete ◽  
Physical And Chemical

This paper studies the recycling of solid waste concrete of the foundational content. Through the experimental research on the use of recycled aggregate and recycled concrete powder, I propose recycled coarse aggregate, recycled powder of various physical and chemical characteristic and the powder mixed with cement slurry mixed with recycled coarse aggregate on the surface of the mechanical properties after treatment. The results show that the coarse aggregate crushing value after surface treatment, strength characteristics of concrete can meet the requirements of ordinary concrete.

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 Crumb Rubber in Concrete—The Barriers for Application in the Construction Industry

2021 ◽  
Vol 6 (8) ◽  
pp. 116
Author(s):  
Patricia Kara De Maeijer ◽  
Bart Craeye ◽  
Johan Blom ◽  
Lieven Bervoets
Keyword(s):  
Construction Industry ◽  
Crumb Rubber ◽  
Recycled Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Concrete Mix Design ◽  
Alternative Material ◽  
Natural Aggregates ◽  
The Cost

This state-of-the-art review was aimed to conduct a comprehensive literature survey to summarize experiences of crumb rubber (CR) application in concrete within the last 30 years. It shows that certain gaps prevent obtaining a coherent overview of both mechanical behaviour and environmental impact of crumb rubber concrete (CRC) to object to the stereotypes which prevent to use of CR in concrete in the construction industry. Currently, four major barriers can be distinguished for a successful CR application in the concrete industry: (1) the cost of CR recycling, (2) mechanical properties reduction, (3) insufficient research about leaching criteria and ecotoxicological risks and (4) recyclability of CRC. The application of CR in concrete has certainly its advantages and in general cannot be ignored by the construction industry. CR can be applied, for example, as an alternative material to replace natural aggregates and CRC can be used as recycled concrete aggregates (RCA) in the future. A certain diversity for the CR application can be introduced in a more efficient way when surface treatment and concrete mix design optimization are properly developed for each type of CR application in concrete for possible field applications. The role of CRC should not be limited to structures that are less dependent on strength.

scholarly journals Influence of Calcined Clay on the Strength Characteristics and Microstructure of Recycled Aggregate Concrete for Sustainable Construction

2021 ◽  
Vol 54 ◽  
pp. 56-70
Author(s):  
Oluwarotimi Michael Olofinnade ◽  
Isaac T. Oyawoye
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Sustainable Construction ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Hardened Concrete ◽  
Conventional Concrete ◽  
Calcined Clay

Utilization of concrete wastes as aggregate in conventional concrete is regarded as a promising way of achieving sustainability within the built-up environment. This study investigated the performance of high strength concrete produced using recycled aggregate (RCA) with the addition of calcined clay in the concrete mixes. The recycled aggregate was sourced from concrete rubbles and treated by soaking in water, while calcined clay was sourced from the pilot pozzolana plant of the Nigerian Building and Road Research Institute (NBRRI). The recycled concrete aggregates were used as a replacement for coarse aggregate at levels of 0, 20, 40, 60, 80 and 100%, using a mix ratio of 1:1:2 at a constant water-binder ratio of 0.25. Superplasticizer was added to ensure the workability of the mixes. The calcined clay was added at 15 and 20% partial replacement for cement in the mixes. Physical and chemical properties of the materials used were determined, while the workability of the concrete mixes was examined using the slump. The compressive strength of the hardened concrete was determined after 7, 28 and 56 days of curing using 100 mm cube samples. Scanning Electron Microscope (SEM) was used to evaluate the morphology of selected concrete. Results showed that soaking of the recycled aggregate in water limit the water absorption rate of the RCA aggregates in the mixes, while the addition of calcined clay was observed to slightly reduce the workability of the concrete mixes. A reduction trend in compressive strength was noticed as the percentage of recycled aggregate increases, however, a significant increase in compressive strength was observed with the addition of calcined clay at 15% cement replacement. An optimum concrete mix containing 20% recycled aggregate and 15% calcined clay showed improve performance compare to the other mixes. The implication of these results suggests that recycled concrete aggregate can be used for the production of sustainable structural concrete.

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