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Assessing the Cleanliness - Paper
Name: Assessing the Cleanliness - Paper
File: Tregger Paper Final 5-10-12.pdf
Size(MB): 0.09MB
Extension: PDF
Event: 2012 ICSC - SEATTLE
Speaker Name: Tregger, N.
Managed by: sdickens
Date Uploaded: June 13, 2012; 11:44 am
Download Count: 2402
Downloads This Month: 2402

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Historically, the use of microfines (passing the No. 200 mesh (75 microns) in concrete has been associated with high water demand, high shrinkage, and subsequent low strength. As a result, in specifying aggregate gradation limits, ASTM C33 allows a maximum of 7% microfines content (or 5% when used in abrasive environments). Based on natural sands, this limit on microfines has received greater attention with the increased use of manufactured sands in recent years. Such studies have shown that inclusion of acceptable microfines can actually improve workability, shrinkage resistance, abrasion resistance and strength. A challenge in using microfines includes the ability to distinguish deleterious fines from beneficial fines. Fines can impact concrete through their shape, gradation and cleanliness. Currently, the sand equivalency test (ASTM D2419) aims to estimate the impact of cleanliness. This paper will compare this test with the methylene blue test with regards to determining the effect of deleterious material on the performance of concrete. It is shown that the methylene blue test is more effective in identifying deleterious fines within an aggregate source.

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