Introduction of White Ultra High Performance Concrete
Keywords
White UHPC, White ultra-high performance concrete, reactive powder concrete, white microsilica, silica fume, White UHPC Curtain Wall
Ultra-High Performance Concrete, referred to as UHPC, also known as Reactive Powder Concrete (RPC, Reactive Powder Concrete), is the most innovative cement-based engineering material in the past three decades. big leap.
The design theory of ultra-high performance concrete is the maximum bulk density theory (densified particle packing), in which the particles of different particle sizes of the constituent materials form the tightest packing in the optimal ratio, that is, the gaps in which the millimeter-sized particles (aggregates) are stacked are composed of micron-sized particles ( Cement, fly ash, mineral powder) are filled, and the gaps where the micron-sized particles are stacked are filled with sub-micron-sized particles (silica fume).
UHPC differs from ordinary concrete or high-performance concrete in that it does not use coarse aggregates, must use silica fume and fibers (steel fibers or composite organic fibers), a large amount of cement, and a low water-to-binder ratio.
UHPC can be regarded as the most durable engineering material. The mechanical properties of UHPC with proper reinforcement are close to that of steel structure, and UHPC has excellent wear resistance and explosion resistance. Therefore, UHPC is particularly suitable for long-span bridges, anti-explosion structures (military engineering, bank vaults, etc.) and thin-walled structures, as well as in highly abrasive and corrosive environments. At present, UHPC has been applied in some practical projects, such as long-span pedestrian bridges, highway and railway bridges, thin-walled silos, nuclear waste tanks, steel cable anchoring reinforcement plates, ATM machine protective shells, etc.
UHPC can replace external tiles and external ordinary stone, making innovative structure and decoration into one. White UHPC forms a more creative large-scale building facade decoration effect through the color, texture and shape of the concrete itself, making the UHPC components more artistic.
Composition of white UHPC materials
White cement, white silica fume, titanium dioxide, quartz powder, polycarboxylate superplasticizer, steel fiber, etc.
Formation mechanism of white UHPC appearance
After the moisture inside the concrete evaporates, many capillary pores are formed in the space filled by the unhydrated solid components in the cement slurry, and calcium hydroxide, a hydration product, is precipitated in the supersaturated alkaline solution inside the capillary pores, and the light passes through the concrete to harden the cement slurry. Various reflections and refractions will occur when the surface capillary pores, so that the color of the cement slurry and the aggregate itself can be projected into people's eyes, forming a unique and white appearance.
