{"title":"Separation of adhered mortar from fine-recycled concrete aggregates using air winnowing","authors":"Pranav Saraswat, Bhupendra Singh","doi":"10.1617/s11527-026-03321-z","DOIUrl":null,"url":null,"abstract":"<div><p>Adhered mortar on fine-RCA can restrict its effective utilization because of its influence on aggregate characteristics. Selective removal of adhered mortar from fine-RCA is challenging due to the heterogeneous size, density, and morphology of aggregate–mortar particles. Therefore, this study investigates air winnowing as a simplified physical fractionation technique for fine-RCA based on differential particle transport under airflow. Fine-RCA processed at 450, 900, and 1300 rev/min was collected and classified into near-fan and far-fan regions based on the distance travelled by the particles. Separation performance was evaluated using particle size distribution (PSD), mass recovery, X-ray fluorescence (XRF), X-ray diffraction (XRD), loss on ignition (LOI), and image analysis method (IAM). The 450 rev/min condition provided the most effective separation, achieving 93.69% overall recovery while maintaining the near-fan fraction within the specified IS 383 gradation limits. XRF showed minor differences in bulk elemental composition, while XRD indicated similar dominant mineralogical phases with differences mainly in their relative proportions. In contrast, LOI indicated greater mass loss in the far-fan fraction. IAM quantified 38.43 ± 2.86% adhered mortar in the far-fan fraction compared with 31.96 ± 4.76% in the near-fan fraction, with the difference being statistically significant and associated with a large effect size (Hedges’ g = 1.60). The results demonstrate that controlled air winnowing can achieve the fractionation into aggregate-rich and mortar-rich fractions without complex separation equipment. This provides a simplified, low-resource technique for the processing of fine-RCA, with separation quality depending on the combined effects of recovery, gradation retention, and mortar enrichment.</p><h3>Graphical abstract</h3>\n<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":691,"journal":{"name":"Materials and Structures","volume":"59 9","pages":""},"PeriodicalIF":3.9000,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials and Structures","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1617/s11527-026-03321-z","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Adhered mortar on fine-RCA can restrict its effective utilization because of its influence on aggregate characteristics. Selective removal of adhered mortar from fine-RCA is challenging due to the heterogeneous size, density, and morphology of aggregate–mortar particles. Therefore, this study investigates air winnowing as a simplified physical fractionation technique for fine-RCA based on differential particle transport under airflow. Fine-RCA processed at 450, 900, and 1300 rev/min was collected and classified into near-fan and far-fan regions based on the distance travelled by the particles. Separation performance was evaluated using particle size distribution (PSD), mass recovery, X-ray fluorescence (XRF), X-ray diffraction (XRD), loss on ignition (LOI), and image analysis method (IAM). The 450 rev/min condition provided the most effective separation, achieving 93.69% overall recovery while maintaining the near-fan fraction within the specified IS 383 gradation limits. XRF showed minor differences in bulk elemental composition, while XRD indicated similar dominant mineralogical phases with differences mainly in their relative proportions. In contrast, LOI indicated greater mass loss in the far-fan fraction. IAM quantified 38.43 ± 2.86% adhered mortar in the far-fan fraction compared with 31.96 ± 4.76% in the near-fan fraction, with the difference being statistically significant and associated with a large effect size (Hedges’ g = 1.60). The results demonstrate that controlled air winnowing can achieve the fractionation into aggregate-rich and mortar-rich fractions without complex separation equipment. This provides a simplified, low-resource technique for the processing of fine-RCA, with separation quality depending on the combined effects of recovery, gradation retention, and mortar enrichment.
期刊介绍：
Materials and Structures, the flagship publication of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM), provides a unique international and interdisciplinary forum for new research findings on the performance of construction materials. A leader in cutting-edge research, the journal is dedicated to the publication of high quality papers examining the fundamental properties of building materials, their characterization and processing techniques, modeling, standardization of test methods, and the application of research results in building and civil engineering. Materials and Structures also publishes comprehensive reports prepared by the RILEM’s technical committees.
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