Volume 32 Issue 2 - February 7, 2020 PDF
The Rise and Prospect of Ultra High Performance Concrete
Chung-Chan Hung1,2,*, Chen-Hao Yen1, Kuo-Wei Wen1
1 Department of Civil Engineering, National Cheng Kung University, Tainan 701, Taiwan
2 National Center for Research on Earthquake Engineering, Taipei 106, Taiwan
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Ultra high performance concrete (UHPC) is a new construction material that has attracted worldwide attention. Its compressive strength can reach 5-10 times that of traditional concrete, and its tensile strength can reach 100 kgf /cm2 or more. Its ultimate tensile strain can reach more than 6%, more than a hundred times that of ordinary concrete. It also has excellent crack suppression ability, subverting the definition of brittleness of concrete materials in textbooks. Due to such excellent mechanical characteristics, the traditional concrete mechanical analysis is no longer completely applicable to this new generation of high-tech concrete materials. When UHPC is used for seismic-resistant structural components, the toughness and shear capacity of the components can be greatly improved, and the use of steel confinement and shear reinforcements can be reduced. Together with its self-compacting ability, structural design and construction procedures can be simplified. In addition, the microstructure of UHPC contains high-density hydration products and has densely stacked fine particles. This enables the durability indicators of UHPC (porosity, permeability, and chloride ion diffusion rate) to be superior to conventional concrete materials and UHPC to effectively resist chemical erosion in harsh environments. These characteristics will be beneficial to sustainable design. When UHPC is used instead of general concrete, the amount of concrete materials used can be reduced by about 2 to 3 times. Not only can the load be reduced, but its excellent durability can also effectively enhance the service life of the structure and reduce future maintenance.

Table 1. Comparison of durability and strength of concrete materials

ComparisonConventional concreteUHPC
Water porosity (%)14-201.5-5
Oxygen permeability (m2)10-16<10-19
Chloride diffusion coefficient (m2/s)2.10-112.10-14
Portlandite content (kg/m3)760
Compressive strength (MPa)20-50>150

(b) UHPC
(a) Conventional high strength concrete

Figure 1. Damage of conventional high strength concrete and UHPC shear walls after strong earthquakes.
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