What is the design principle of UHPC substrate materials

1. What is the design principle of UHPC substrate materials?

Tightly packed. This is one of the fundamental principles of designing all dense powder materials. The high density and good working performance of UHPC make the surface in contact with the template have a high smoothness. It is difficult for harmful external media to penetrate into UHPC, and the colorants and other components in UHPC are also difficult to precipitate outward. By utilizing this feature, UHPC can be used as an exterior decoration material for buildings.

2. How to choose fibers for UHPC?

Considering cost-effectiveness, metal fibers can be preferred, followed by non-metallic fibers. When mixing different fibers, it is necessary to carefully test before selecting them reasonably.

3. Why not recommend using large-sized aggregates for UHPC?

This involves material fracture mechanics issues, including the size of the original crack and the density of defects; It also involves issues of material homogeneity, such as the spatial distribution of large particles; It also involves issues in porous materials. Unless necessary (or if the cross-sectional size of the component is large enough), it is generally not advisable to use aggregates>5MM (unless it is indeed necessary, such as reducing shrinkage, cooling, reducing costs, etc.)!

4. What occasions is UHPC suitable for?

Where conventional concrete cannot meet the requirements! Places with high requirements for impermeability, frost resistance, and salt erosion; In places with high requirements for earthquake resistance, explosion resistance, and crack resistance, UHPC's high tensile strength and corrosion resistance properties can be used to manufacture oil and gas pipelines to replace expensive large diameter thick walled steel pipes, significantly improving pipeline durability and reducing costs; Large span structures, large shell structures, curved structures; The repair and reinforcement of old structures, such as UHPC, have now been used as the outer protective layer of steel structures on offshore oil platforms, which can greatly improve the service life of pillars in water level fluctuation zones; Used in the military and security fields to manufacture anti explosion and anti impact devices.

5. How to ensure the basic quality of UHPC?

The compressive strength and tensile strength of a cube (100MMX100MX100MM) without fiber substrate material shall not be less than 150MPA and 5MPA, with a permeability two orders of magnitude lower than C80, and no visible bubbles; These are also entry-level quality requirements. In addition, the common deterioration problems of conventional concrete (including HPC), including steel corrosion, freeze-thaw failure, alkali-aggregate reaction, and sulfate attack, should be exempted, so that UHPC can deserve the title of true UHPC; If we are still troubled by these deterioration phenomena, it is not worthy of being called UHPC.