Characterization of Demolished Concretes with Three Different Strengths for Recycling as Coarse Aggregate

Sampaio, Carlos Hoffmann; Cazacliu, Bogdan; Ambrós, Weslei Monteiro; Kronbauer, Márcio André; Tubino, Rejane Maria Candiota; Molin, Denise Carpena Coitinho Dal; Oliva, Josep; Miltzarek, Gerson Luis; Waskow, Régis Pereira; Santos, Viviane Lopes Gschwenter dos; Silva, Luis

doi:10.3390/min11080803

Cited by 6 publications

(2 citation statements)

References 24 publications

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“…the HRA product was more concentrated with low-strength concrete, whereas the CRA product had more high-strength concrete. The liberation degree of cement paste may have played a role in this trend, as reported in the recent work by Sampaio et al [28]. In their study, concretes with lower strengths showed a better liberation of aggregates from cement paste, thus facilitating their concentration in denser fractions during density separation.…”

Section: Separation Processsupporting

confidence: 60%

Production of High-Quality Coarse Recycled Aggregates through a Two-Stage Jigging Process

et al. 2022

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The use of recycled aggregates (RA) to replace natural aggregates (NA) in new concrete production has been pointed out as one of the main strategies to close the loop of construction materials. However, producing RA with properties similar to those of NA has been challenging, since current recycling methods struggle to remove contaminants like ceramics and mortar, whose presence impairs RA properties. In this study, a processing route consisting of a two-stage separation in hydraulic jig was tested, aiming to produce RA from a representative sample of Brazilian construction and demolition waste. All material streams generated in the tests were characterized in terms of composition, size distribution, density, shape index, and water absorption. The results indicated the possibility to produce a high-quality RA, containing more than 99.5% mass of concrete, with adequate properties to replace NA in new concrete production. Also, a conventional RA with suitable properties for downcycling uses (for example, base and sub-base material) could be obtained as a co-product. Finally, the results showed it was possible to recover more than 75% of the original concrete in Construction and Demolition Waste CDW, avoiding its disposal as waste.

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Section: Separation Processsupporting

confidence: 60%

Production of High-Quality Coarse Recycled Aggregates through a Two-Stage Jigging Process

et al. 2022

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“…Recycled sand is primarily used for roads, concrete and backfill applications [10]. Characteristics of recycled aggregate are important for its reuse and they are heavily influenced by the nature of CDW waste, its processing method and the presence of impurities such as sulfate, chlorides, etc., which affect aggregate quality and limit its use for structural and high-strength concrete [11,12]. For structural concrete, French standards recommend a maximum of 30% replacement of natural aggregate.…”

Section: Introductionmentioning

confidence: 99%

Stabilization and Recycling of Sand in Pedestrian Walkways

Hussain,

Zmamou,

Provost

et al. 2024

Buildings

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The production of construction and demolition waste (CDW) in urban areas is growing rapidly. While the storage and disposal of CDW waste is costly, its recovery can help to conserve natural resources. This study investigates the characteristics of recycled sand obtained from the processing of CDW waste and the possibility of its reuse for pedestrian pathways. Physico-chemical and mineralogical characteristics of the recycled sand were investigated for its reuse. The percentage of fine particles in sand (below 0.63 μm) is 2.8%. The grain size of sand fulfills the particle size requirement of French standards. The methylene blue value of sand is 0.05 g/100 g. The GTR classification of recycled sand is D2 which is insensitive to water and suitable for road applications. A mineralogical analysis of soil shows that quartz, albite and microcline are important minerals in recycled sand. XRF analysis shows that CaO and SiO2 are major oxides in the recycled sand. The characterization of sand was followed by a manufacturing of cylindrical specimens of sand to observe the compressive strength. Samples were compacted with dynamic compaction by applying the Proctor normal energy of 600 kN·m/m3. The compressive strength testing of specimens shows that non-stabilized sand samples have compressive strength around 0.1 MPa which is considerably lower for its reuse in pedestrian pathways and road applications. Due to the low bearing capacity of sand, recycled sand was stabilized with the addition of binders such as Rolac (hydraulic binder), ground-granulated blast furnace slag (GGBS) and ECOSOIL® (slag mixes) with different percentages of the binder ranging from 0 to 7% for the optimization of the binder and for economic efficiency. The compressive strength of sand samples increases with the increasing percentage of the binder. The increase in strength is more important with a higher percentage of binders (5%, 6% and 7%). At a 7% binder addition, specimens with Rolac, GGBS and ECOSOIL binders show the compressive strength of 1.2 MPa, 0.5 MPa and 0.5 MPa. At a 7% Rolac addition, specimens have a compressive strength higher than 1 MPa and meet the strength requirement for soil reuse in the foundation and subbase layers of roads with low traffic. The experimental work shows that recycled sand can replace conventional quarry sand for road applications and pathways with the addition of a local binder, which is an eco-friendly and economical practice.

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Enhancing concrete durability and strength: An innovative approach integrating abrasion and cement slurry treatment for recycled coarse aggregates

Panghal,

Kumar

2024

Structural Concrete

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This study introduces a novel approach to enhance the durability and strength of concrete by integrating abrasion and cement slurry treatments on surface‐treated recycled coarse aggregates (STRCA). Initial abrasion treatment removes aged mortar from the recycled coarse aggregate (RCA) surface, while subsequent cement slurry modification provides a fresh surface, reinforcing the bond with the concrete matrix. Through detailed material analyses including x‐ray diffraction, scanning electron microscopy, and energy‐dispersive x‐ray, microstructural changes are evaluated alongside compressive strength, drying shrinkage, electrical resistivity, and chloride ion penetration of STRCA‐based concrete. Results indicate significant improvements in mechanical properties and durability as the treatments eliminate mortar and enhance the interfacial connection with cement paste. Notably, a substantial 29.37% strength enhancement is observed at 25% replacement (STRCA 25), demonstrating treatment efficacy. While a reduction of 11.58% occurs at 100% replacement (STRCA 100), up to 75% replacement shows minimal strength loss, with optimal enhancements at 50% replacement. Additionally, STRCA concrete exhibits lower drying shrinkage (11%–20% reduction) and increased electrical resistivity (28%–36% rise), indicating improved durability at 100% replacement. Enhanced resistance to chloride ion penetration is also evident, with a 22%–28% increase at 100% replacement compared to conventional RCA. Overall, this study highlights the effectiveness of dual treatments for enhancing concrete properties using STRCA.

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Characterization of Demolished Concretes with Three Different Strengths for Recycling as Coarse Aggregate

Cited by 6 publications

References 24 publications

Production of High-Quality Coarse Recycled Aggregates through a Two-Stage Jigging Process

Production of High-Quality Coarse Recycled Aggregates through a Two-Stage Jigging Process

Stabilization and Recycling of Sand in Pedestrian Walkways

Enhancing concrete durability and strength: An innovative approach integrating abrasion and cement slurry treatment for recycled coarse aggregates

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