SR146 Reactive powder concrete (2005)

This report examines the feasibility of producing high-strength reactive powder concrete (RPC) with domestically available materials.

The effect of a number of mix process variables was investigated in small-scale laboratory trials. These variables included w/b (water-to-binder) ratio, super-plasticiser dosage, curing regime and choice of silica pozzolan.

Compressive strengths in excess of 200 MPa and flexural strength of 15-20 MPa were routinely achieved using conventional concrete mixing and curing practices. Mechanical properties of hardened RPC were observed to correlate with the spatial efficiency that the dry powders' constituents could be packed together. Consequently, it is necessary for these powders to exist in distinct size classes with a wide separation between mean particle size diameters.

This places a reliance on imported silica fume as an essential component of RPC. The benefits conferred by the fume's extremely fine sub-micron particles and spherical shape are such that substitution by indigenous geothermal silica pozzolan proved impractical.