Effect of the methylene blue value of manufactured sand on performances of concrete

Abstract

The methylene blue value (MBV) is an important index that reflects the quality of manufactured sand (MS). The relation between MBV of MS and its limestone fines content, clay content and clay characteristics was investigated and the effects of MBV ranging from 0.35 to 2.5 on the performance of MS concrete were tested. Results showed that MBV of MS is affected not by the limestone fines content, but by the clay content and the liquid limit index of clay. With an increase in MBV, the workability, flexural strength and 7d compressive strength of the MS concrete decreased, while the 28d compressive strength was notaffected. Moreover, the increase of MBV promoted plastic shrinkage and drying shrinkage cracking of the concrete, and remarkably accelerated freeze-thaw damage and abrasion loss.It was concluded that the critical MBV was 1.4, a value below which MS concrete performances are not significantly diminished. Copyright © 2011 Japan Concrete Institute.