On New Technologies for Mixing/Material Preparation of Ultra-High Performance Concrete (UHPC)

concrete mixer

countercurrent mixer

Ultra-high performance concrete/reactive powder concrete/self-leveling solidified concrete (hereinafter referred to as UHPC/RPC/SCC) is a new type of cement-based composite material developed in the past three decades. It possesses ultra-high mechanical properties and durability, as well as excellent toughness, bonding performance, impact resistance, and fatigue resistance. In recent years, with the continuous maturity of UHPC preparation technology—especially the innovation and upgrading of concrete mixer equipment—the superiority of its performance has gradually gained widespread recognition. UHPC has thus become a research hotspot in the concrete field, widely applied in structures, decoration, reinforcement, rapid repair, paving, joint filling, and other scenarios. However, due to its high cost, current domestic and international research on UHPC application technologies and pilot projects is mainly limited to bridge engineering, building exterior wall decoration engineering, and a small number of maintenance and reinforcement projects for existing concrete buildings. concrete mixer

The main application engineering categories and parts of UHPC are as follows:

(1) Bridge engineering: Including cast-in-situ bridge deck pavement, bridge wet joints, prefabricated bridge decks, bridge deck overlay, and prefabricated box girders. In these applications, UHPC’s high strength and durability can effectively extend the service life of bridge structures, and its uniform texture—ensured by precise mixing with a concrete mixer or countercurrent mixer—is crucial for structural stability.

(2) Construction engineering: Covering building exterior wall decorative panels, small prefabricated components (such as staircases and balconies), and node connections of prefabricated assembled components. The production of these prefabricated components relies on concrete mixers to achieve uniform mixing of raw materials, while the high-performance requirements of node connections further demand advanced mixing equipment like the countercurrent mixer and concrete mixer to enhance material homogeneity.

(3) Municipal engineering: Including prefabricated cover plates, prefabricated integrated pipe corridors, and structural reinforcement of infrastructure. For prefabricated integrated pipe corridors, which require high impermeability and crack resistance, the countercurrent mixer / concrete mixer plays a key role—it uses a reverse-flow mixing principle to fully blend raw materials, reducing internal voids and improving the material’s overall performance.

(4) Wind power fields: Wind power pillar castings adopt a concrete-steel-concrete integrated structure. To ensure the pillar’s ability to withstand wind and snow loads and extend its service life, the UHPC used here must undergo rigorous mixing. The countercurrent mixer, with its strong stirring capacity, ensures that steel fibers (a key raw material) are evenly distributed in the matrix, avoiding agglomeration and greatly improving the pillar’s strength and fatigue resistance.

UHPC concrete mixer typically uses the following raw materials: high-grade Portland cement, fine quartz sand, silica fume, quartz powder, high-efficiency water reducer, steel fibers (ceramic fibers, stainless steel fibers, etc.), biomass materials, polymer organic active materials, etc. The preparation process of UHPC involves measuring these raw materials, mixing them uniformly in a concrete mixer, casting into molds, and curing. Due to its strict performance requirements, UHPC raw materials must comply with extremely high standards, and concrete mixer—has undergone continuous improvement: from traditional horizontal shaft stirring to more advanced planetary stirring, and now the countercurrent mixer has become a mainstream choice for high-end UHPC production.

countercurrent mixer

Internal working of concrete mixer

concrete mixer

The countercurrent mixer differs from ordinary concrete mixers in that it generates a reverse flow between the mixing drum and the stirring blades, which not only enhances the mixing intensity but also shortens the mixing time, ensuring that various raw materials (especially micro-powder materials like silica fume and quartz powder) are fully integrated. This advanced mixing technology of countercurrent mixer not only improves the production efficiency of UHPC but also lays a solid foundation for its stable performance in various engineering applications.