Definition and development of high performance concrete

Ultra-high performance Concrete (UHPC), because generally need to incorporate steel fibers or high-strength polymer fibers, Also known as ultra-high performance Fibre Reinforced Concrete (UHPFRC). UHPC is different from the traditional high-strength concrete (HSC) and steel fiber concrete (SFRC), and is not the high strengthening of the traditional "high performance concrete (HPC)", but a new type of cement-based structural engineering material with clear performance indicators. In 1999, Professor Qin Weizu of Tsinghua University published an article "A kind of ultra-high performance concrete - Reactive powder concrete", which introduced UHPC early, and so far, the name "reactive powder concrete (RPC)" is still widely used in China. RPC is a French company's patented product name, more publicity and introduction and widely known. In 1994, the French scholar DeLarrard and other new materials called UHPC, because UHPC or UHPFRC name has no commercial color, and can better express the superior performance of this cement-based material or concrete, gradually widely accepted and adopted.

The typical definition or characteristics of UHPC are as follows:

It is a cement-based composite material which is the best gradation of the particles of the well-taught component material in the cement-based composite material; The water-binder ratio is less than 0.25, and the proportion of micro-fine and micro-short steel fiber reinforcement materials is high; Compressive strength not less than 150MPa; It has the toughness of tensile state, and still maintains the tensile strength of not less than 5MPa (France requires 7MPa) after cracking, compared with traditional concrete and high performance concrete, it has a non-connected non-porous structure, and has a high resistance to gas and liquid immersion ability, compared with traditional concrete and high performance concrete, it has a high resistance to gas and liquid immersion ability (HPC). Durability can be greatly improved.

UHPC is a modern advanced material, innovative cement-based materials (concrete or mortar) and fiber, steel, steel (rebar or high-strength prestressed steel) composite mode, greatly improve the strength utilization efficiency of fiber and steel in concrete, so that the overall performance of cement-based structural materials have made leap-forward progress. UHPC can be used to construct lightweight, high-strength and high-toughness structures, and completely change the "fat beam and fat column" state of concrete structures. Its structure has the durability and working life, far beyond steel, aluminum, plastic and other all steel, aluminum, plastic and other structural materials.

UHPC manufacturers originated in Denmark in the late 1970s, eight, 90 Denmark originated in the late 1970s, the 1980s and 1990s in Europe carried out more systematic and in-depth research, and began to apply products in small engineering and products. In this century, in Europe, the United States, Japan and South Korea and many other countries have UHPC as a new type, the future will enter the UHPC France and Japan as a new or strategic engineering material research and development, France and Japan, the first to develop design guidelines. At present, the preparation, production, construction and prefabrication technology of UHPC has become mature, the structural performance and design specifications are in the process of development and improvement, the application of engineering structures and products continues to make new progress, and international UHPC/UHPFRC seminars are held regularly for academic exchange.