Properties of concretes bearing mixed recycled aggregate with polymer-modified surfaces

Velardo, Paula; Bosque, I.F. Sáez del; Matías, A.; Rojas, M.I. Sánchez de; Medina, César

doi:10.1016/j.jobe.2021.102211

Cited by 18 publications

(6 citation statements)

References 74 publications

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“…This table shows that mix M9, with 50% fMRA + 50% cMRA, is the cheapest, leading to a −8.03% decrease compared with natural aggregate (M1). This result is in line with the prior observations of other authors, who registered decreases of under −50% for recycled coarse aggregate replacement percentages between 50% and 100% [ 78 ].…”

Section: Resultssupporting

confidence: 93%

“…Regarding the individual incorporation of fMRA (M2 and M3), we observed that these mixes experienced a larger decrease both in maximum (Pmax) and mean (Pmed) water penetration, with the decrease ending up being between 16.1% ≤ Pmax ≤ 44.6% and 47.7% ≤ Pmed ≤ 52.9% compared with conventional concrete (M1). This greater watertightness could be connected with the pozzolanic activity of ceramic fines (<0.063 mm) of the fMRA, as well as with the hydration of anhydrous cement [ 78 ] present in the fines from fMRA mortars that give them a certain hydraulic activity and thus lead to a more sealed and tortuous pore structure.…”

Section: Resultsmentioning

confidence: 99%

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The Design and Development of Recycled Concretes in a Circular Economy Using Mixed Construction and Demolition Waste

et al. 2021

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This research study analysed the effect of adding fine—fMRA (0.25% and 50%)—and coarse—cMRA (0%, 25% and 50%)—mixed recycled aggregate both individually and simultaneously in the development of sustainable recycled concretes that require a lower consumption of natural resources. For this purpose, we first conducted a physical and mechanical characterisation of the new recycled raw materials and then analysed the effect of its addition on fresh and hardened new concretes. The results highlight that the addition of fMRA and/or cMRA does not cause a loss of workability in the new concrete but does increase the amount of entrained air. Regarding compressive strength, we observed that fMRA and/or cMRA cause a maximum increase of +12.4% compared with conventional concrete. Tensile strength increases with the addition of fMRA (between 8.7% and 5.5%) and decreases with the use of either cMRA or fMRA + cMRA (between 4.6% and 7%). The addition of fMRA mitigates the adverse effect that using cMRA has on tensile strength. Regarding watertightness, all designed concretes have a structure that is impermeable to water. Lastly, the results show the feasibility of using these concretes to design elements with a characteristic strength of 25 MPa and that the optimal percentage of fMRA replacement is 25%.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

The Design and Development of Recycled Concretes in a Circular Economy Using Mixed Construction and Demolition Waste

et al. 2021

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“…The recycled aggregates in different regions may have significant differences in their components. The complex components of MCRA lower its density [ 10 ] and flakiness index [ 11 ] and increase its water absorption [ 12 ] and crushing index [ 13 ]. Thus, it is a challenge to reuse MCRA efficiently as a conventional aggregate [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

A Study on Mechanical and Microstructural Characteristics of Concrete Using Recycled Aggregate

et al. 2022

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The objective of this paper is to provide a comprehensive study about the performance of concrete using mixed coarse recycled aggregate (MCRA) as an alternative for natural aggregate (NA) at replacement levels of 0, 30, 60, and 100%, which can greatly reduce the environmental pollution by incorporating the construction and demolition wastes in the reproduction of concrete. The focus of this study was to use the raw MCRA that was directly obtained from a recycling plant and not further processed. Initially, MCRA was studied to ascertain if its property meets the recommended Indian standards for natural aggregates. Using the slump test, the workability of freshly prepared concrete with a characteristic strength of 30 MPa was assessed. Additionally, the mechanical performance of concrete was assessed on the specimens prepared in the different forms: cubes, cylinders, and beams. Moreover, Scanning Electron Microscopy (SEM) with EDAX, XRD, and FTIR were used to study the microstructural behavior of selected optimum and control mixes at 7 and 28 days of curing. The studies revealed that a higher MCRA content improved the workability of concrete and 30% replacement of MCRA improved the compressive strength by 11.01, 6.98, 6.19, and 14.24% at 7, 28, 56, and 90 days respectively. At the same time, the 30% replacement of the MCRA mix showed an improved split tensile and flexural strength by 2.92 and 6.26%, respectively. The microstructural analysis showed that the optimum mixture had a more condensed microstructure. Therefore, 30% replacement of MCRA can be incorporated in the characteristic strength of concrete of 30 MPa. In particular, MCRA incorporation had a positive influence similar to conventional concrete on the physical, mechanical, and microstructural properties, which can increase the utilization of all kinds of directly obtained construction and demolition wastes to increase the circular economy in the construction sector.

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“…In relation to both: concretes containing MRA, and also, strategies for the enhancement of the properties of recycled aggregates, [113] implemented the surface treatment of MRA sourced from a CDW plant with a polymer solution (emulsified acrylic resin), and then, studied the impact of the full replacement of coarse natural aggregates by the treated (and the untreated) aggregates in concrete compositions. While studying the physical properties of the treated aggregates, the authors found that soaking the MRA in a 20% solution for 60 min yielded the best results and led to a 25% decline in water absorption and 31% decrease in the Los Ange-les coefficient (the upgrade in the properties was also confirmed by a two-way statistical analysis).…”

Section: Mixed Recycled Aggregatesmentioning

confidence: 99%

Advantages and shortcomings of the utilization of recycled wastes as aggregates in structural concretes

Miraldo

Lopes

Pacheco-Torgal

et al. 2021

Construction and Building Materials

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h i g h l i g h t sComprehensive, systematic review on current state of the art concerning the utilization of a wide array of wastes as aggregates, in ordinary Portland cement concrete compositions, for structural applications. Analysis of the advantages and shortcomings for each recycling material in the context of the adoption of circular patterns in the construction sector life cycle. Evaluation of alkali-activated binders as an alternative for overcoming important shortcomings of Portland cement-based structural concretes.

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Properties of concretes bearing mixed recycled aggregate with polymer-modified surfaces

Cited by 18 publications

References 74 publications

The Design and Development of Recycled Concretes in a Circular Economy Using Mixed Construction and Demolition Waste

The Design and Development of Recycled Concretes in a Circular Economy Using Mixed Construction and Demolition Waste

A Study on Mechanical and Microstructural Characteristics of Concrete Using Recycled Aggregate

Advantages and shortcomings of the utilization of recycled wastes as aggregates in structural concretes

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