scholarly journals Effect of the Composition of Mixed Recycled Aggregates on Physical–Mechanical Properties

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1518
Author(s):  
Antonio López-Uceda ◽  
Enrique Fernández-Ledesma ◽  
Lorenzo Salas-Morera ◽  
José Ramón Jiménez ◽  
David Suescum-Morales
Keyword(s):  
Mechanical Properties ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Percentage Error ◽  
Demolition Waste ◽  
Ceramic Particles ◽  
Bituminous Materials ◽  
Natural Aggregates ◽  
Effect Of The Composition ◽  
Masonry Mortar

Recycled aggregates (RA) from construction and demolition waste are an alternative to natural aggregates in the construction sector. They are usually classified according to their composition. The main constituent materials are separated into the following categories: unbound natural aggregates, ceramic particles, cementitious particles, bituminous materials, and other materials considered impurities, such as glass, plastic, wood, or gypsum. In this research, a large number of samples of RA were collected from three different recycling plants and their properties were studied. After that, 35 samples were selected randomly, and their RA constituents were separated under laboratory conditions. Cementitious particles were differentiated into two subcategories: masonry mortar and concrete particles. Subsequently, their physical–mechanical properties were measured. The statistical analysis carried out exhibited that the constituents had a statistically significant influence on the physical–mechanical properties studied. Specifically, masonry mortar particles had higher water absorption and worse mechanical properties than concrete and ceramic particles. Secondly, multiple regression models were performed to predict the physical–mechanical properties of RA from their composition since mean absolute percentage error (MAPE) ranged between 0.9% and 8.6%. The differentiation in the subcategories of concrete and masonry mortar particles in compositional testing is useful for predicting the physical–mechanical properties of RA.

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.

scholarly journals Evaluation of the physical-mechanical properties of cement-lime based masonry mortars produced with mixed recycled aggregates

2020 ◽  
Vol 70 (337) ◽  
pp. 210 ◽  
Author(s):  
R. L.S. Ferreira ◽  
M. A.S. Anjos ◽  
E. F. Ledesma ◽  
J. E.S. Pereira ◽  
A. K.C. Nóbrega
Keyword(s):  
Mechanical Properties ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Long Run ◽  
Lime Mortars ◽  
Binder Ratio ◽  
Mechanical Strengths ◽  
One Way Anova

This study investigated the physical-mechanical effects of cement-lime mortars containing recycled aggregate of construction and demolition waste (CDW). The natural aggregate (NA) was replaced by volume at 25%, 50%, 75% and 100% by mixed recycled aggregate (MRA) obtained from the CDW crushing. Five types of mortars were prepared with a volumetric ratio of 1:1:6 (cement, lime and aggregate) and water/binder ratio based on the fixed consistency of 260 mm. The effects of MRA on fresh and hardened mortars’ properties were analyzed. The results were analyzed using a one-way ANOVA. MRA incorporation improved most of the physical-mechanical properties of mortars tested, except for hardened bulk density, water absorption and porosity. In the long-run, mechanical strengths significantly increased in all compositions, especially those with higher percentages of MRA. The results obtained showed that the use of MRA in masonry mortars is an alternative to reduce the generation of waste and consumption of natural resources.

scholarly journals Feasibility study of cement-stabilized materials using 100% mixed recycled aggregates from perspectives of mechanical properties and microstructure

2021 ◽  
Vol 60 (1) ◽  
pp. 490-502
Author(s):  
Tao Meng ◽  
Songsong Lian ◽  
Kanjun Ying ◽  
Hongming Yu
Keyword(s):  
Mechanical Properties ◽  
Cement Content ◽  
Drying Shrinkage ◽  
Construction And Demolition Waste ◽  
Utilization Efficiency ◽  
Recycled Aggregates ◽  
Failure Behavior ◽  
Demolition Waste ◽  
Mixed Recycled Aggregates ◽  
Curing Age

Abstract The research on the highly efficient reutilization of mixed recycled aggregates (MRA) produced from construction and demolition waste has attracted significant attention globally. In this study, the feasibility of using 100% MRA in cement-stabilized materials was investigated. The mechanical properties and microstructures of cement-stabilized MRA (CSMRA) materials containing 100% MRA were systematically examined through unconfined compressive strength (UCS) test, indirect tensile strength (ITS) test, drying shrinkage test, X-ray diffraction analysis, mercury intrusion porosimetry, and scanning electron microscopy. Results showed that the UCS and ITS of CSMRA materials were significantly enhanced with the increase of cement content and curing age, and there was almost a linear relationship between the UCS and ITS. The failure behavior of CSMRA materials under load showed three typical stages: compaction stage, elastic stage, and yield stage. The increase of the cement content caused the drying shrinkage deformation of CSMRA to increase sharply when the cement content exceeded 4%. The microstructural analysis indicated that cement had both filling and binding effects on CSMRA materials. The strength growth with cement content and curing age was because of the constant hydration of cement minerals, producing more calcium silicate hydrate binders between aggregates. Moreover, the increasing cement content could reduce the porosity and optimize the pore structure distribution of CSMRA materials. The findings of this study demonstrate that the use of 100% MRA in cement-stabilized materials as a road base is feasible, which will significantly enhance the utilization efficiency of MRA.

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).

Production of Concrete Blocks with Residues for Civil Construction

2013 ◽  
Vol 690-693 ◽  
pp. 865-869 ◽  
Author(s):  
Marília Martinês de Camargo ◽  
Rosa Cristina Cecche Lintz ◽  
Luisa Andréia Gachet-Barbosa ◽  
Marta Siviero Guilherme Pires
Keyword(s):  
Value Added ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Structural Function ◽  
Demolition Waste ◽  
Original Product ◽  
Concrete Blocks ◽  
Function Blocks ◽  
Natural Aggregates

The Construction is recognized as one of the most important activities for the economic and social development, and on the other hand, behaves also as a major generator of environmental impacts, either by consumption of natural resources, the modification of the landscape or the generation of construction and demolition waste (CDW). Investing in an implementation of managed clean and healthy in the area of CDW is essential for the environment and for the economy of the cities, who are spending less resources on the collection, cleaning of drains and treatment of diseases. Nowadays, the amount of waste generated is considered large, occupying much space in landfills, and its transportation, depending on the volume and weight, is quite expensive. Recycling and reuse of these wastes are extremely important to control and mitigate environmental problems, as well as produce various materials value-added. Over 90% of waste can be recycled, reused and transformed into aggregates with characteristics very similar to the original product, thus creating environmentally friendly products such as sand, gravel, pebbles. This research concerns the study of the properties of concrete containing CDW, aiming its use in the manufacture of concrete blocks to seal without structural function. Blocks have been molded with partial replacement of natural aggregates by recycled aggregates and later were performed tests of compressive strength in accordance with the standards to prove the technical feasibility of the material for the trait studied.

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 Recommendations for the Management of Construction and Demolition Waste in Treatment Plants

Proceedings ◽  
2018 ◽  
Vol 2 (20) ◽  
pp. 1278
Author(s):  
Auxi Barbudo ◽  
Jesús Ayuso ◽  
Angélica Lozano ◽  
Manuel Cabrera ◽  
Antonio López-Uceda
Keyword(s):  
European Union ◽  
Construction Projects ◽  
Construction And Demolition Waste ◽  
Treatment System ◽  
Recycled Aggregates ◽  
The European Union ◽  
Demolition Waste ◽  
Natural Aggregates

Construction and demolition waste consists approximately of one third waste generated in the European Union. The recycling of this stream waste will provide ecological and sustainable benefits. Recycled aggregates from construction and demolition waste are clearing a path into civil constructions, as substitutes for natural aggregates. The possible applications of recycled aggregates on infrastructure construction projects will depend on the quality of the recycled aggregates mainly. This will be determined by the nature and the origin of the construction and demolition waste, and the treatment system undergone. Hence, this work proposes recommendations for the handling of construction and demolition waste in treatment plants.

scholarly journals A Critical Review on the Influence of Fine Recycled Aggregates on Technical Performance, Environmental Impact and Cost of Concrete

2020 ◽  
Vol 10 (3) ◽  
pp. 1018 ◽  
Author(s):  
Hisham Hafez ◽  
Reben Kurda ◽  
Rawaz Kurda ◽  
Botan Al-Hadad ◽  
Rasheed Mustafa ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Critical Review ◽  
Economic Life ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Extensive Literature ◽  
Demolition Waste ◽  
Technical Performance ◽  
Fine Aggregates ◽  
Natural Aggregates

The aim of this critical review is to show the applicability of recycled fine aggregates (RFA) in concrete regarding technical performance, environmental impact, energy consumption and cost. It is not possible to judge the performance of concrete by considering one dimension. Thus, this study focussed on the fresh and hardened (e.g., mechanical and durability) properties and environmental and economic life cycle assessment of concrete. Most literature investigated showed that any addition of recycled fine aggregates from construction and demolition waste as a replacement for natural fine aggregates proves detrimental to the functional properties (quality) of the resulting concrete. However, the incorporation of recycled fine aggregates in concrete was proven to enhance the environmental and economic performance. In this study, an extensive literature review based multi criteria decision making analysis framework was made to evaluate the effect of RFA on functional, environmental, and economic parameters of concrete. The results show that sustainability of RFA based concrete is very sensitive to transportation distances. Several scenarios for the transportation distances of natural and recycled fine aggregates and their results show that only if the transportation distance of the natural aggregates is more than double that of RFA, e the RFA based concrete alternatives would be considered as more sustainable.

scholarly journals VERIFICATION OF THE BASIC PROPERTIES OF RECYCLED AND NATURAL AGGREGATES

2019 ◽  
Vol 22 ◽  
pp. 67-71
Author(s):  
Karel Mikulica ◽  
Iveta Hájková
Keyword(s):  
Recycled Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Building Structures ◽  
Recycled Concrete Aggregate ◽  
Apartment Building ◽  
Demolition Waste ◽  
Concrete Mixtures ◽  
Natural Aggregates

In the future, it is planned to use up to 50% of construction and demolition waste (C&DW) for the production of new building structures. This leads us to think about how we can use recycled concrete aggregate (RCA) as a substitute for natural aggregate (NA) in concrete mixtures. This is why we compare the two typical representatives of recycled aggregates with a representative of natural aggregates. As a representative of recycled aggregates, we chose pure concrete recycled from the cutting of concrete and mixed recyclate from the demolition of the apartment building. As a representative of natural stone, we chose the extracted aggregate.

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