scholarly journals Recycled Aggregates Produced from Construction and Demolition Waste for Structural Concrete: Constituents, Properties and Production

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5748
Author(s):  
João Pacheco ◽  
Jorge de Brito
Keyword(s):  
Construction Material ◽  
Mineral Resources ◽  
Heterogeneous Material ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Adequate Quality ◽  
Natural Aggregates

This paper concerns the recovery of construction and demolition waste as coarse recycled aggregates for concrete. Coarse recycled aggregates may be used as a partial or total replacement of natural aggregates, contributing to the circular economy and minimizing landfill disposals as well as the consumption of natural mineral resources. However, construction and demolition waste is a heterogeneous material with undefined quality and the processing of this waste into recycled aggregates needs to ensure that the recycled aggregates have suitable properties for concrete. This paper summarizes several aspects related to coarse recycled aggregates, specifically addressing: (i) the typical composition of construction and demolition waste; (ii) the influence of different types of constituents on the properties of recycled aggregates and recycled aggregate concrete; (iii) requirements for recycled aggregates to be used in concrete; and (iv) production methods of recycled aggregates. It is argued that coarse recycled aggregates are a suitable construction material with adequate quality, even when common equipment is used in their production and preliminary separation as a key operation for ensuring the quality of the aggregates is recommended.

scholarly journals Effects of Recycled Aggregate Resin (RAR) in Concrete Material

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Sharifah Salwa Mohd Zuki ◽  
◽  
Shahiron Shahidan ◽  
Shivaraj Subramaniam ◽  
◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Engineering Properties ◽  
Recycled Aggregates ◽  
Hardened Concrete ◽  
Demolition Waste ◽  
Split Tensile Strength ◽  
Close Proximity

This paper discussed the recycled aggregates produced from construction and demolition waste and their utilization in concrete construction. Along with a brief overview of the engineering properties of recycled aggregates, the paper also summarizes the effect and use of recycled aggregates on the properties of fresh and hardened concrete. The recycled aggregates were treated with epoxy resin to reduce the water absorptions with different percentages of resin such as 0%, 25%, 50%, 75%, and 100%. Epoxy resin is widely used in recent years owing to the enhancing of mechanical and durability of the concrete. This research also showed, recycled aggregate concrete are close proximity to normal concrete in terms of split tensile strength, compression strength and wet density. The low usage of resin was obtained good strength concrete compared to high percentage contained treated aggregates due to low bonding between material.

scholarly journals Preliminary Analysis of the Use of Construction Waste to Replace Conventional Aggregates in Concrete

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 81
Author(s):  
Fernando A. N. Silva ◽  
João M. P. Q. Delgado ◽  
António C. Azevedo ◽  
António G. B. Lima ◽  
Castorina S. Vieira
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Fine Aggregate ◽  
Demolition Waste ◽  
Fine Aggregates ◽  
Mechanical Strengths

This work aims to study the influence of using construction and demolition waste in the replacement of coarse and fine aggregate to produce recycled aggregate concrete (RAC). A moderate compressive strength concrete made with usual fine and coarse aggregate was used as a benchmark material. Compressive and split tensile tests were performed using 120 cylindrical concrete specimens with 150 mm diameter and 300 mm length. Four-point flexural tests in reinforced beams made with conventional concrete and RAC were performed. The results obtained showed that the use of recycled fine aggregates, in both percentages of substitution investigated—50% and 100%— did not generate any deleterious influence on the values of compressive strength and split tensile strength of the RACs produced. Tin fact, the mechanical strengths of RACs produced with recycled fine aggregate were equal or higher than those from the reference concrete. The same behavior was not observed, however, when the recycled coarse aggregate was used. For this case, decreases in concrete mechanical strengths were observed, especially in compressive strength, with values around 35% lower when compared to the reference concrete. Tensile mechanical tests results confirmed the excellent behavior of all RACs made with replacement of usual fine aggregates by recycled. Bending tests performed in reinforced RAC beams had as objective to evaluate the deformation profile of the beams. The obtained results showed that RAC beams with full replacement of usual fine aggregate by the recycled aggregates have presented little changes in the global behavior, an aspect that encourages its use.

A Novel Conceptual Approach for Predicting the Mechanical Properties of Recycled Aggregate Concrete

2016 ◽  
Vol 847 ◽  
pp. 156-165
Author(s):  
Marco Pepe ◽  
Eduardus Koenders ◽  
Romildo Dias Toledo Filho ◽  
Enzo Martinelli
Keyword(s):  
Mechanical Properties ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Conceptual Approach ◽  
Demolition Waste ◽  
Predictive Capacity ◽  
Moisture Condition

The construction sector is more and more committed to reduce its environmental impacts. One of the key actions undertaken in the last decade deals with the ability of turning construction and demolition waste into new raw materials. For instance, the use of recycled aggregates for producing new concrete was one of the most investigated. Thus, in the last decade, plenty of researches were involved in project on characterising the mechanical behaviour of concrete made with recycled aggregates. However, these projects were mainly experimental in nature and generally led to merely empirical formulations. Conversely, this paper is intended at providing a contribution for predicting the mechanical properties of Recycled Aggregates Concrete (RAC). Particularly, it aims at quantifying the effect of replacing ordinary aggregates with Recycled Concrete Aggregates (RCA) on the resulting compressive strength of RAC. To this end, a conceptual model considering both the relevant physical properties of regular and recycled aggregates, including the attached mortar content, and the hydration reactions of Portland cement paste is proposed. The actual predictive capacity of the proposed model is assessed through an experimental validation against experimental tests carried out on several concrete batches produced with various values for the different keys parameters, such as the nominal water-to-cement ratio, the aggregates replacement ratio and the initial moisture condition of aggregates. Both the experimental data and the theoretical formulations proposed in this paper stem out from the inter-university collaboration developed as part of the EU funded EnCoRe Project (www.encore-fp7.unisa.it).

Influence of Moisture States of Recycled Coarse Aggregates on the Slump Test

2013 ◽  
Vol 742 ◽  
pp. 379-383 ◽  
Author(s):  
Julia García González ◽  
Desirée Rodríguez Robles ◽  
Andrés Juan Valdés ◽  
Julia M. Morán del Pozo ◽  
M. Ignacio Guerra Romero
Keyword(s):  
Free Water ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Construction Sector ◽  
Inexpensive Method ◽  
Demolition Waste ◽  
Coarse Aggregates ◽  
Subsequent Elimination ◽  
Natural Aggregates

The use of recycled aggregate to produce new concretes has become increasingly widespread, and numerous studies have demonstrated that the final product performs similarly to traditional concrete. However, construction and demolition waste (CDW) presents certain characteristics which could limit its acceptance in the construction sector due to worse performance than natural aggregates. One example of this is water absorption, which in recycled aggregates reaches such high values that the amount of free water calculated for mixing the concrete is affected, consequently impacting on the concrete's properties, especially consistency. This paper reports the possibility of solving this problem with a simple and inexpensive method; pre-saturation of recycled aggregates prior to adding them to the mix. The results of two different pre-treatments are compared; one consisted of immersing the aggregates in water for 10 minutes and the other, in addition to the above procedure, included a brief period of air drying and subsequent elimination of surface water from the aggregate. Both pre-treatments were found to solve the problem of consistency.

scholarly journals Influence of Wetting and Drying Cycles on Physical and Mechanical Behavior of Recycled Aggregate Concrete

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5675
Author(s):  
Caroline S. Rangel ◽  
Mayara Amario ◽  
Marco Pepe ◽  
Enzo Martinelli ◽  
Romildo D. Toledo Filho
Keyword(s):  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Wetting And Drying ◽  
Aggregate Concrete ◽  
Wetting And Drying Cycles ◽  
The Impact

Recently, concerns have been rising about the impact of increasing the depletion of natural resources and the relevant generation of construction and demolition waste, on the environment and economy. Therefore, several efforts have been made to promote sustainable efficiency in the construction industry and the use of recycled aggregates derived from concrete debris for new concrete mixtures (leading to so-called recycled aggregate concrete, RAC) is one of the most promising solutions. Unfortunately, there are still gaps in knowledge regarding the durability performances of RAC. In this study, we investigate durability of structural RAC subjected to wet-dry cycles. We analyze the results of an experimental campaign aimed at evaluating the degradation process induced by wetting and drying cycles on the key physical and mechanical properties of normal- and high-strength concrete, produced with coarse recycled concrete aggregates (RCAs) of different sizes and origins. On the basis of the results we propose a degradation law for wetting and drying cycles, which explicitly makes a possible correlation between the initial concrete porosity, directly related to the specific properties of the RCAs and the resulting level of damage obtained in RAC samples.

The potency of recycled aggregate in new concrete: a review

2019 ◽  
Vol 19 (4) ◽  
pp. 594-613 ◽  
Author(s):  
Emmanuel Ejiofor Anike ◽  
Messaoud Saidani ◽  
Eshmaiel Ganjian ◽  
Mark Tyrer ◽  
Adegoke Omotayo Olubanwo
Keyword(s):  
Research Work ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Aggregate Concrete ◽  
Content Type ◽  
Natural Aggregate

Purpose This paper aims to review the effect of using recycled aggregates (RA) on the properties of recycled aggregate concrete (RAC) following the steady rise in global demand for concrete and the large generation of construction and demolition waste. Design/methodology/approach This study reviewed relevant literature of research work carried out by previous researchers, leading to a deeper understanding of the properties of both RA and RAC. The properties of RA and RAC reported in the various studies were then compared to their corresponding natural aggregate (NA) and natural aggregate concrete, as well as the specifications provided in different codes of practice. In addition, the mix design methods appropriate to RAC and the cost implication of using RA were reviewed. Findings Findings show that the contribution of RA to strength appears inferior in comparison to NA. The shortcoming is attributed to the mortar attached to the RA, which raises its water absorption capacity and lowers its density relative to those of NA. However, it has been reported that the use of regulated quantity of RA, new mixing and proportioning methods, the addition of admixtures and strengthening materials such as steel fibres, can improve both mechanical and durability properties of RAC. Cost evaluation also showed that some savings can be realized by using RA instead of NA. Originality/value This research serves as a guide for future works and suggests that the use of RA as aggregate in new concrete is technically possible, depending on the mix design method adopted.

scholarly journals Investigation of Properties of Concrete Produced with Recycled Aggregates

2021 ◽  
Vol 1 (2) ◽  
pp. 26-34
Author(s):  
Gökhan KAPLAN
Keyword(s):  
Acid Resistance ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Environmental Damage ◽  
Freezing And Thawing ◽  
Demolition Waste ◽  
Concrete Production ◽  
Strength And Durability

The greatest frequently applied construction substantial in the construction sector is concrete. Natural resources are mostly used in concrete production. While environmental resources are being consumed, concrete environmental pollution increases during urban transformation or reconstruction. In sustainable life, environmental damage caused by construction demolition wastes necessitates the use of recovered aggregate. Recycled aggregate is a term used to depict squashed solid, mortar, blocks or black-top from development trash that is reused in other structure ventures. Reused total is delivered by pounding annihilated waste to recover the total. For as far back as not many decades the accessibility of Construction and demolition waste has expanded so a lot of that the solid business has started using it thusly decreasing the number of totals. The goal is to examine the physical properties, (grain size distribution, density and water absorption) and mechanical properties, (for example, compressive strength, flexural strength, modulus of elasticity and splitting tensile strength) and durability properties, (for example, sulfate resistance, freezing and thawing resistance, acid resistance, high temperature effect and abrasion resistance) of recycled aggregate. It is seen that the mechanical and durability conduct of recycled aggregate concrete is optional to that of standard concrete yet with the utilizing various admixture and unique blending approach, required properties can be accomplished.

scholarly journals Construction and Demolition Waste As Recycled Aggregate for Environmentally-Friendly Concrete Paving.

2021 ◽  
Author(s):  
Manuel Contreras Llanes ◽  
Maximina Romero Pérez ◽  
Manuel Jesús Gázquez González ◽  
Juan Pedro Bolívar Raya
Keyword(s):  
Tensile Strength ◽  
Reference Sample ◽  
Production Costs ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Natural Sand ◽  
Natural Aggregates ◽  
Sand And Gravel

Abstract Recycled aggregates (RA) from construction and demolition waste (CDW) instead of natural aggregates (NA) was analysed in the manufacture of new eco-friendly concrete. Fine (FRA) and coarse (CRA) recycled aggregates were used in different percentages as substitutes of natural sand and gravel, respectively. The results revealed that the use of RA in percentages of up to 50 wt.% are feasible. Additionally, RA were used to produce paving blocks in accordance with industrial requirements. Thus, values of water absorption lesser than 6% and tensile strength upper than 3.6 MPa were obtained, which are similar to those of a reference sample. These results were achieved by reducing the incorporation of cement, thereby saving production costs and minimizing environmental impact.

scholarly journals Mechanical Strength Study on C&D Aggregates Replaced Concrete

2021 ◽  
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Steam Curing ◽  
Demolition Waste ◽  
Large Size ◽  
New Treatments

Abstract. Recycled concrete was produced to overcome the problem of disposal of construction and demolition waste and lack of availability of natural materials. To improve the characteristics of recycled concrete, new treatments and suggestions were given by the researchers. This paper investigates the compressive strength of recycled aggregate concrete having the replacement of 0, 30, 40, 50 & 60% recycled coarse aggregates. The compressive strength of recycled concrete in water curing is compared with steam curing. The compressive strength of concrete is not much affected because of the use of large size recycled aggregates. The use of saturated dried surface large size recycled aggregates improves the strength of concrete.

scholarly journals Mechanical Properties of Concrete Using Recycled Aggregates Obtained from Old Paving Stones

2021 ◽  
Vol 13 (6) ◽  
pp. 3044
Author(s):  
Ana María Bravo-German ◽  
Iván Daniel Bravo-Gómez ◽  
Jaime A. Mesa ◽  
Aníbal Maury-Ramírez
Keyword(s):  
Mechanical Properties ◽  
Environmental Impacts ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Concrete Production ◽  
Aggregate Fractions ◽  
Increasing Demand ◽  
Natural Aggregates

Nowadays, construction, maintenance, reparation, rehabilitation, retrofitting, and demolition from infrastructure and buildings generate large amounts of urban waste, which usually are inadequately disposed due to high costs and technical limitations. On the other hand, the increasing demand for natural aggregates for concrete production seriously affects mountains and rivers as they are the source of these nonrenewable goods. Consequently, the recycling of aggregates for concrete is gaining attention worldwide as an alternative to reduce the environmental impacts caused by the extraction of nonrenewable goods and disposal of construction and demolition waste (C&DW). Therefore, this article describes the effect on the mechanical properties of new concrete using recycled aggregates obtained from old paving stones. Results show that replacing 50% by weight of the fine and coarse aggregate fractions in concrete with recycled aggregate does not meaningfully affect its mechanical behavior, making the use of recycled aggregates in new precast paving stones possible. Therefore, the latter can reduce environmental impacts and costs for developing infrastructure and building projects.

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