Powder-type SCC with crushed mineral aggregates

Design concept and flow properties of SCC – Part 1

Fig. 1 SEM scans of various 0.125/0.5 mm sands (left and center: various fluvial sands; right: crushed sand).

Fig. 1: SEM scans of various 0.125/0.5 mm sands (left and center: various fluvial sands; right: crushed sand).

Fig. 2 Model of self-compact-
ing concrete with non-spherical mineral aggregate and conversion of the particle
shapes to idealized spheres as an extension of the cement
paste layer thickness model according to [6].

Fig. 3 Test vessel for the particle-mix test (left: longitudinal section of the vessel with compaction load; right: photograph of the test vessel filled with aggregate during water discharge).

Fig. 3: Test vessel for the particle-mix test (left: longitudinal section of the vessel with compaction load; right: photograph of the test vessel filled with aggregate during water discharge).

Fig. 4 Granulometric compositions of tested aggregate mixes with ABB16 grading curve (approx. 50 m% < 4 mm). Left: calculated granulometric compositions according to the aggregate grading curves; right: test results obtained during the photo-optical particle shape analysis, measured at washed-out aggregate mixes > 0.125 mm (ABB16).

Fig. 5 Void ratios of aggregate mixes K-F; Q-F; WI-F and Q-Q in the case of grading curve variation. Tested applying the particle-mix method to the wet aggregate mix, non-compacted (V_H,KGP,unverd) and compacted (V_H,KGP,verd), as well as to the dry aggregate mix on the basis of DIN EN 1097-3 [7], non-compacted (V_{H,Schütt(EN1097)}) and compacted (V_H,Pack).

Fig. 6 Physically bound water (V_W,unverd)/volume of aggregate mix (V_KG,verd), tested with the particle-mix test (PMT) method whilst varying the grading curve.

Fig. 7 Amount of cement paste required (V_Leim,Bedarf) = void ratio in compacted condition (V_H,KGP,verd) + (V_W,unverd)/(V_KG,verd) according to Fig. 6, tested with the particle-mix test (PMT) whilst varying the grading curve.

Fig. 8 Photographs of aggregate mixes used (left: gravel (K) 4-8 mm; center: quartz porphyry chippings (Q) 5-8 mm; right: shell limestone chippings (WI) 4-8 mm).

Fig. 8b: Photographs of aggregate mixes used (left: gravel (K) 4-8 mm; center: quartz porphyry chippings (Q) 5-8 mm; right: shell limestone chippings (WI) 4-8 mm).

Fig. 8c: Photographs of aggregate mixes used (left: gravel (K) 4-8 mm; center: quartz porphyry chippings (Q) 5-8 mm; right: shell limestone chippings (WI) 4-8 mm).

Fig. 6

Dipl.-Ing. Andreas Huß,
Materialprüfungsanstalt
Universität Stuttgart, Otto-Graf-Institut (FMPA)
Geb. 1971; Studium des Bauingenieurwesens an der Universität Stuttgart Vertiefung Werkstoffkunde/Bauphysik; seit 1998 wissenschaftlicher Mitarbeiter der Abteilung Mineralische Baustoffe des Otto-Graf-Institutes (FMPA) mit Schwerpunkt
Betontechnologie; derzeit stellvertretender Leiter der Referate Betontechnologie sowie Betonkorrosion und Betoninstandsetzung.
andreas.huss@
mpa.uni-stuttgart.de

Prof. Dr.-Ing. Hans-Wolf Reinhardt, Universität Stuttgart, Institut für Werkstoffe im Bauwesen (IWB)

Although self-compacting concrete (SCC) has been regulated since 2004 as a result of the addition of the SCC Guideline [1] to the List of Building Rules, its share is still very low in Germany. Amongst other factors, this is due to the fact that the flow properties – and thus the self-compacting characteristics – are adjusted to practical requirements mostly on the basis of complex, usually empirical, mix concepts that can be transferred to other input materials only to a limited extent. For this reason, there is a continued need for practice-oriented mix concepts that take variations in the raw materials of concrete into account whilst enabling a corresponding adjustment of the fresh concrete properties in the production process.

The first part of this two-part article presents an approach to determining the volume of the cement paste required to produce SCC and discusses this approach with respect to the granulometric characteristics of the aggregate mix. The second part refers to the production of SCC mixes on the basis of the required cement paste volumes, which were determined in an experimental set-up, and outlines options to describe the rheological properties of the fresh concrete.