IMPROVED MICROSTRUCTURE BY OPTIMIZED WATER REQUIREMENTS
In everyday construction practice concrete is often produced applying water amounts inexcess of what intrinsically is needed for appropriate workability and complete hydration.This is especially true for high slump and self-compacting concretes (SCC). For an increasedrobustness of concrete to water overdose the building chemistry sector supplies viscositymodifying admixtures (VMA), which would not have been needed when the amount ofmixing water was optimized beforehand. Therefore, in this research the spread-flow test has been analyzed in more detail. In thisway new measures are derived which contribute to a deeper understanding of wet granularmixtures at the onset of flowing. The deformation coefficient which is derived by the spread-flow test was confirmed to correlate with the product of Blaine surface and intrinsic density ofthe individual powders when the mixture is flowing only under its own weight. Similarly,correlations with equal accuracy have been found with a computed specific surface based onmeasured particle size distributions instead of the Blaine surface. Using simple flowexperiments it was furthermore possible to derive an overall factor for assessing the non-spherical shape of the powder particles. A good correlation of this computation algorithm wasderived compared to the standard Blaine method. Finally, a constant water layer thickness around the powder particles was derived for allpowders at the onset of flowing. This implies the possibility to predict flow behavior ofmortar and concrete mixtures only based on the knowledge of their granular characteristics.This water layer thickness is of different nature and size as the well-known ITZ.
M.Hunger H.J.H.Brouwers
Department of Construction Management & Engineering,Faculty of Engineering Technology,University of Twente,The Netherlands
国际会议
南京
英文
51-60
2008-10-13（万方平台首次上网日期，不代表论文的发表时间）