Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6718767 | Construction and Building Materials | 2016 | 11 Pages |
Abstract
In this work, the recycled concrete aggregate (RCA) friability during mixing was studied in order to better understand the evolution of this material during the mixing process and improve the recycled aggregate concrete mix-design. The influence of some important materials and process parameters was evaluated: initial abrasion resistance and initial moisture of the aggregates, mixer geometry, mixing time and mixing speed. To assess the mixing process effect on the recycled concrete aggregate friability, three different aspects were evaluated; the mass loss (mass of fraction inferior to 2.5Â mm) the grading and the angularity evolutions with mixing time of an initially 10-14Â mm aggregate. Tests were carried out in two types of laboratory concrete mixers, a planetary 30Â l mixer from Skako and an intensive 5Â l Erich mixer. The results revealed that in normal laboratory setting of the mixers configuration, the mass loss for natural aggregate (NA) is less than 1% of the coarse aggregate. This percentage reach 3% for good quality recycled concrete aggregate (MDE value of 21) and 5% for lower quality recycled concrete aggregate (MDE value of 27). The mass loss directly depends on the mixing parameters and the degradation of the recycled concrete aggregate drastically increased when the mixing speed was raised to 500Â RPM. By analyzing the grading evolution during mixing, it was shown that both cleavage (creation of intermediate size particles) and attrition (creation of small particles) mechanisms influenced the aggregate degradation. However, the configuration of mixing significantly influenced the proportion of attrition and cleavage mechanisms. To complete this work, the angularity evolution showed that recycled concrete aggregate surface becomes smoother and the edges more rounded after mixing.
Related Topics
Physical Sciences and Engineering
Engineering
Civil and Structural Engineering
Authors
J. Moreno Juez, B. Cazacliu, A. Cothenet, R. Artoni, N. Roquet,