Mortar-based design for self compacting concrete

TOBES, J.M.; GIACCIO, G.; BARRAGÁN, B.; ZERBINO, R.

Dubrovnik

Simposio; Concrete Structures – Stimulators of development, fib Symposium, 2007; 2007

fib Federation International du Beton

Self compacting concrete (SCC) has recently been one of the most important developments in the construction industry. It can exhibit high workability and flow into the formwork under its own weight without compaction and presenting no segregation. Then, SCC must be designed attending to achieve the mentioned characteristics. The amount of powder material is related to the particle size distribution of the aggregate and should be capable of filling the voids of the granular skeleton and reducing the interparticle friction, so fluidity can be achieved and blocking minimized. In this work, a procedure to design SCC mixes was developed based on the Slump-flow and Funnel tests on mortars to obtain the appropriated paste volume and proportions. Complementary the effect of particle size distribution of the sand on the fluidity and passing ability of mortars was analyzed. Finally, SCC was elaborated with selected mortars varying the volume of coarse aggregate. SCC was characterized by Slump-flow, J-Ring and V-Funnel tests in the fresh state, and compressive strength and modulus of elasticity in hardened state. It has been found that the proposed procedure is adequate to proportion SCC, and that an optimum paste volume exists and depends on the particle size distribution of the sand; in this study, considering various types of sands, the paste volume ranges between 50% and 63% of the mortar volume. The fluidity and cohesion values obtained on mortars seem very useful for the performance-driven proportioning of SCC.