{"title":"Effects of dry and wet mixing times on the quality of asphalt concrete","authors":"Jia-Ruey Chang, Yi-Ting Lo, Yi-Yu Lo","doi":"10.1016/j.conbuildmat.2025.143788","DOIUrl":null,"url":null,"abstract":"<div><div>The quality of asphalt concrete is affected by dry and wet mixing times, which often rely on the operator’s experience. This study was conducted at an asphalt plant to examine batch size (1, 2, 3 tons), dry mixing time (5, 10, 20 s), and wet mixing time (35, 40, 50 s) on dense-graded asphalt concrete with a 19.0 mm nominal maximum aggregate size and 4.8 % asphalt content. For dry-mixed aggregates, visual uniformity assessment, sieve analysis, and regression analysis of gradation degradation were conducted. For wet-mixed mixtures, visual uniformity assessment, sieve analysis of extracted aggregate, and asphalt content measurement were conducted. For Marshall specimens, stability and flow were measured, and asphalt film thickness was analyzed. The results indicated that for dry-mixed aggregates, longer dry mixing time improved aggregate uniformity in small batches but caused gradation degradation. For wet-mixed aggregates, extending the wet mixing time in small batches compensated for shorter dry mixing times, showing that gradation degradation primarily results from the dry mixing phase. Larger batches showed limited impact on gradation with longer wet mixing time. However, in full batches, dry-mix-induced gradation degradation increased fine aggregate content and asphalt content variation. Results from the stability, flow, and asphalt film thickness analyses showed that increasing batch size and wet mixing time improved stability, reduced the range of stability values, and decreased the standard deviation of asphalt film thickness. The study identified the most suitable combinations of operational parameters and recommended the most appropriate production quantity for achieving the best mix quality. Overall, the experimental process presented in this study serves as a reference framework for selecting the appropriate dry and wet mixing times under different mixers, aggregate gradations, or production needs.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"497 ","pages":"Article 143788"},"PeriodicalIF":8.0000,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Construction and Building Materials","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S095006182503939X","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
The quality of asphalt concrete is affected by dry and wet mixing times, which often rely on the operator’s experience. This study was conducted at an asphalt plant to examine batch size (1, 2, 3 tons), dry mixing time (5, 10, 20 s), and wet mixing time (35, 40, 50 s) on dense-graded asphalt concrete with a 19.0 mm nominal maximum aggregate size and 4.8 % asphalt content. For dry-mixed aggregates, visual uniformity assessment, sieve analysis, and regression analysis of gradation degradation were conducted. For wet-mixed mixtures, visual uniformity assessment, sieve analysis of extracted aggregate, and asphalt content measurement were conducted. For Marshall specimens, stability and flow were measured, and asphalt film thickness was analyzed. The results indicated that for dry-mixed aggregates, longer dry mixing time improved aggregate uniformity in small batches but caused gradation degradation. For wet-mixed aggregates, extending the wet mixing time in small batches compensated for shorter dry mixing times, showing that gradation degradation primarily results from the dry mixing phase. Larger batches showed limited impact on gradation with longer wet mixing time. However, in full batches, dry-mix-induced gradation degradation increased fine aggregate content and asphalt content variation. Results from the stability, flow, and asphalt film thickness analyses showed that increasing batch size and wet mixing time improved stability, reduced the range of stability values, and decreased the standard deviation of asphalt film thickness. The study identified the most suitable combinations of operational parameters and recommended the most appropriate production quantity for achieving the best mix quality. Overall, the experimental process presented in this study serves as a reference framework for selecting the appropriate dry and wet mixing times under different mixers, aggregate gradations, or production needs.
期刊介绍:
Construction and Building Materials offers an international platform for sharing innovative and original research and development in the realm of construction and building materials, along with their practical applications in new projects and repair practices. The journal publishes a diverse array of pioneering research and application papers, detailing laboratory investigations and, to a limited extent, numerical analyses or reports on full-scale projects. Multi-part papers are discouraged.
Additionally, Construction and Building Materials features comprehensive case studies and insightful review articles that contribute to new insights in the field. Our focus is on papers related to construction materials, excluding those on structural engineering, geotechnics, and unbound highway layers. Covered materials and technologies encompass cement, concrete reinforcement, bricks and mortars, additives, corrosion technology, ceramics, timber, steel, polymers, glass fibers, recycled materials, bamboo, rammed earth, non-conventional building materials, bituminous materials, and applications in railway materials.