A review on ultra high performance concrete: Part I. Raw materials and mixture design

A comprehensive investigation into the mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC), considering various influential factors, is imperative in order to obtain fundamental information for its practical utilization. Therefore, this paper reviewed the early-age strength (or setting) development and mechanical properties of hardened UHPFRC. In connection with the latter, the effects of the curing conditions, coarse aggregate, mineral admixtures, fiber properties, specimen size, and strain-rate on the mechanical performance of UHPFRC were specifically investigated. It was obvious that (1) heat treatment accelerates the hydration process, leading to higher strength; (2) a portion of the silica fume can be replaced by fly ash, slag, and rice husk ash in mechanical perspective; (3) the use of deformed (hooked and twisted) or long straight steel fibers improves the mechanical properties at a static rate; and (4) high rate loading provides a noticeable increase in the mechanical properties. Alternatively, there are some disagreements between the results from various ‘size effect’ tests and the effectiveness of using twisted steel fibers at static and high rate loadings. Further research to reduce the production cost of UHPFRC is also addressed in an attempt to make its widespread use more practical.

Mechanical properties of ultra-high-performance fiber-reinforced concrete: A review

Effects of steel fiber content and shape on mechanical properties of ultra high performance concrete

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Carbonation of cement paste : Understanding, challenges, and opportunities

Effect of fiber content on mechanical and fracture properties of ultra high performance fiber reinforced cementitious composites

Tensile fracture properties of an Ultra High Performance Fiber Reinforced Concrete (UHPFRC) with steel fiber

Pullout behavior of inclined steel fiber in an ultra-high strength cementitious matrix

During the process of setting and hardening in concrete, the temperature profile shows a gradual nonlinear distribution due to the development of heat of hydration in cement. At early ages of concrete structures, this nonlinear distribution can have a large influence on crack evolution. It is thus important to obtain an accurate temperature history, and to do this, it is necessary to examine the thermal properties of the concrete. In this study, the convective heat transfer coefficient, which represents the heat transfer between a concrete surface and ambient air, was experimentally investigated with test variables such as the velocity of wind, the curing conditions, and the ambient temperature. For analyses using the thermal equilibrium boundary condition, it is generally noted that most of the heat release by the evaporation of moisture occurs at an early stage. To consider this phenomenon, the existing thermal equilibrium boundary condition has been modified so as to consider the evaporation quantity due to the evaporation effect. Convective heat transfer coefficients for a specific case were then calculated from the modified thermal equilibrium boundary condition using experimental results.

Experimental study on the convective heat transfer coefficient of early-age concrete

Simulation of the thermal stress in mass concrete using a thermal stress measuring device

Experimental research was performed to clarify the influence of carbonation on the rebound number and the strength evolution of concrete for three strength levels. The results reveal that the strength level dependent influence of carbonation is a source of errors in the existing equations for the strength reduction coefficient; these equations are used to compensate for the influence of surface carbonation in the rebound number method. A new equation for the strength reduction coefficient that can consider the influence of strength level was developed based on field test data extracted from technical reports of the Korea Research Institute of Standards and Science and of four universities. Over a wide range of strength levels, the equation shows good agreement with strength reduction coefficients established experimentally.

Yun Lee

Papers

Tensile fracture properties of an Ultra High Performance Fiber Reinforced Concrete (UHPFRC) with steel fiber

Pullout behavior of inclined steel fiber in an ultra-high strength cementitious matrix

Experimental study on the convective heat transfer coefficient of early-age concrete

Simulation of the thermal stress in mass concrete using a thermal stress measuring device

Effect of carbonation on the rebound number and compressive strength of concrete