Abstract
This report is a compilation of the characterisation methods and results performed at different institutes and companies to analyse four different fillers employed in a subproject
Case study Velde in COIN FA2.3 High Quality manufactured sand for Concrete.
Here, the application of different methods for characterizing four different fillers which were manually sieved to obtain particle size below 125μm is highlighted. The parameters measured were: thermo-stability, mineral/phase compositions, specific surface areas, particle size distribution, particle shape profile and flow resistance ratio. The first three parameters were measured by thermogravimetric analyssi (TGA), qualitative X–ray diffractometry (XRD) and BET method. For particle size distribution, 4 different conventional methods were employed to determine the best measurement method in determining this factor. The methods include: laser diffractometry by Beckmann Coulter Analysis LS13 120 (dry method) and Mastersizer 2000 (wet method), sedigraphy by Sedigraph 5100 and imaging analysis by PartAn analysis for fine powders. For shape profiling, PartAn image analysis was also employed. For the last investigated parameter, FlowCyl test was employed to study the flowability of the matrix containing different fillers.
For all the fillers, it was found that despite having similar mineral composition, the amount of these phases differed from filler to filler, which affected the particle size distribution and thus specific surface areas of the filler samples. In general, asphalt fillers were the most XRD amorphous, attributing to the high amount of fine particles which cannot be detected in the XRD analysis. This was confirmed by BET measurements and PSD determination, where a very high surface area (~30% higher than the filler possessing the lowest surface area) and contain up to 30% particles with sizes lower than 10μm. Fine filler possessed the second highest surface area and fine particles content, but it contained the highest fraction of mica, which can contribute to the adsorption of water when fillers are added to the matrixes. In the case of medium filler, it contained the lowest amount of mica and thus possessed the lowest surface area and highest particle sizes. Finally, sand filler lies in between that of medium and fine fillers. The shape profiles of all fillers were relatively similar, and thus this factor was dismissed as an influencing factor here in the dispersion of matrixes in the presence of fillers.
The characterization of fillers confirmed results from FlowCyl test, whereby matrixes with fine fillers displayed the highest flow resistance, followed by asphalt fillers, sand and finally medium. The trend can be attributed mainly to the fineness of the particles. In the case of fine fillers, the high content of water retaining mica further reduced the flow of matrix, thus causing matrixes containing fine fillers to display the highest flow resistance ratio.