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 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).

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.

Concrete Production of Hot Asphalt Using Recycled Aggregates CDW

2016 ◽  
Vol 881 ◽  
pp. 346-350 ◽  
Author(s):  
Luzana Leite Brasileiro ◽  
Fátima Maria de Souza Pereira ◽  
Pablo de Abreu Vieira ◽  
José Milton Elias de Matos
Keyword(s):  
Solid Waste ◽  
National Policy ◽  
Mechanical Tests ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Final Destination ◽  
Natural Aggregate ◽  
Concrete Production

Every year, there is a considerable increase in the exploitation of deposits to supply the market for aggregates. On the other hand, so does the production of solid waste from construction and demolition waste (CDW). In 2010 Brazil approved the PNRS (National Policy on Solid Waste), which sets out how the country should have their waste, encouraging recycling and sustainability. As an alternative to the above problem, this paper aims to investigate the feasibility of partial and total replacement of the asphalt concrete aggregates by recycled aggregates from CDW in order to reduce the environmental impacts caused by the operation of quarries and give an adequate final destination the residue produced by man in construction. Were carried out five (05) projects mixture of: the first (parameter of our research) used only natural aggregates (0% CDW) in the second, third and fourth replaced 25%, 50% and 75% respectively of natural aggregate by the recycled aggregate and the fifth and last, used only recycled aggregates (100% CDW). They carried out the characterization of the aggregates by means of physico-chemical and mechanical, analyzing them with reference based on specific standards paving. For mixtures, they calculated the volumetric parameters and performed mechanical tests of tensile strength and stability. The results indicate that the recycled aggregate, in a defined proportion, can replace the natural aggregate in the flexible pavements

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 Life Cycle Economic and Environmental Impacts of CDW Recycled Aggregates in Roadway Construction and Rehabilitation

2021 ◽  
Vol 13 (15) ◽  
pp. 8611
Author(s):  
Yunpeng Zhao ◽  
Dimitrios Goulias ◽  
Luca Tefa ◽  
Marco Bassani
Keyword(s):  
Life Cycle ◽  
Environmental Benefits ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Base Layer ◽  
Cement Kiln ◽  
Demolition Waste ◽  
Recycled Materials ◽  
Roadway Construction

The use of recycled materials in roadway construction and rehabilitation can achieve significant benefits in saving natural resources, reducing energy, greenhouse gas emissions and costs. Construction and demolition waste (CDW) recycled aggregate as an alternative to natural one can enhance sustainability benefits in roadway infrastructure. The objective of this study was to quantitatively assess the life cycle economic and environmental benefits when alternative stabilized-CDW aggregates are used in pavement construction. Comparative analysis was conducted on a pavement project representative of typical construction practices in northern Italy so as to quantify such benefits. The proposed alternative sustainable construction strategies considered CDW aggregates stabilized with both cement and cement kiln dust (CKD) for the base layer of the roadway. The life cycle assessment results indicate that using CDW aggregate stabilized with CKD results in considerable cost savings and environmental benefits due to (i) lower energy consumption and emissions generation during material processing and (ii) reduction in landfill disposal. The benefits illustrated in this analysis should encourage the wider adoption of stabilized CDW aggregate in roadway construction and rehabilitation. In terms of transferability, the analysis approach suggested in this study can be used to assess the economic and environmental benefits of these and other recycled materials in roadway infrastructure elsewhere.

scholarly journals Development of Concrete Incorporating Recycled Aggregates, Hydrated Lime and Natural Volcanic Pozzolan

2021 ◽  
Vol 6 (11) ◽  
pp. 155
Author(s):  
Natividad Garcia-Troncoso ◽  
Bowen Xu ◽  
Wilhenn Probst-Pesantez
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Demolition Waste ◽  
Crushed Concrete ◽  
Natural Pozzolana ◽  
Concrete Materials

Recycling of construction and demolition waste is a central point of discussion throughout the world. The application of recycled concrete as partial replacement of mineral aggregates in concrete mixes is one of the alternatives in the reduction of pollution and savings in carbon emissions. The combined influence of the recycled crushed concrete, lime, and natural pozzolana on the mechanical and sustainable properties of concrete materials is firstly proposed in this study. In this research, unconventional construction materials are employed to produce concrete: the recycled crushed concrete is used as coarse aggregate, while lime and natural pozzolana are used as a partial replacement for cement. Substitutions of 10%, 20%, 50% of gravel are made with recycled aggregates, and 2%, 5%, 10% of cement with lime and natural pozzolan. Tests on the fresh and hardened properties, destructive (compressive strength) and non-destructive tests (sclerometer rebound and ultrasound) of mixtures are carried out. It is shown that the use of recycled materials can provide an increase in compressive strength of up to 34% with respect to conventional concrete. Life cycle cost and sustainability assessments indicate that concrete materials incorporating recycled aggregate possess good economic and environmental impacts.

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 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.

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.

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