Influence of the water and aggregate contents on the concrete mixing evolution. (30th March 2018)

• Record Type: Journal Article
• Authors: Moreno-Juez, J.; Cazacliu, B.; Artoni, R.
• Is Part Of: Construction & building materials. Volume 166(2018)
• Page Start: 280
• Page End: 289
• Publication Date: 2018-03-30
• Subjects: Concrete mixing evolution -- Effective water estimation -- Coarse aggregates wall effect -- Fresh properties control; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.12.105
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Monitoring tools employed for analysing concretes and mortars mixing evolution. The influence of water and coarse aggregate on the mixing evolution was analysed. Difference between mixtures due to the wall effect exerted by coarse aggregates. New mixture parameter defined: the "effective water-to-powder ratio in the mortar". Better estimation of the real effective water and of the fresh properties. Abstract: A new image analysis technique coupled with the power consumption were employed in this paper and proved to be a relevant method to detect the different characteristic times of the mixing evolution, i.e. the cohesion time, the fluidity time and the half-life time of the mixture evolution after fluidity. It was shown that the "effective water-to-powder ratio in the mortar" which excludes from the effective water the quantity of water needed to fill the less compact packing in the vicinity of the coarse aggregates, governed the mixing behaviour before fluidity and the interval of water content where the concrete mixture behaves as a homogenous and fluid granular suspension. It was also shown that the mixing behaviour was adversely affected by the amount of water into the mixture. The fluidity and cohesive times were faster to be obtained when the water proportion was increased. At opposite, it was more difficult to obtain the final consistency for a more fluid mixture, at given super-plasticizer proportioning. As a general remark, the behaviour seemed controlled by the mixture composition before the fluidity point and by the mixture consistency after the fluidity point. To end, the image analysis technique coupled with the mixing power technique can be employed at the end of the mixing to complete the information obtained with the other methods of analysis in order to monitor the consistency of the mixture. But, the use of the cohesion and fluidity times, easy to detect with the texture analysis, could be more efficient monitoring tools from an industrial point of view.