13th International Conference on Fracture June16–21, 2013, Beijing, China -2There are three categories of freezes: (1) dry freeze and hard dry freeze, (2) wet freeze, and (3) hard wet freeze. Freeze-thaw rresistance of concrete depends on the permeability, the degree of saturation, the amount of freezable water, the rate of freezing, and the average maximum distance from any point in the paste to a free surface where ice can form safely. If the pressure developed exceeds the tensile strength of the concrete, the cavity will expand and split. The accumulative effect of continuous freeze-thaw cycles and interruption of paste and aggregate can ultimately cause expansion and cracking, scaling, and collapsing of the concrete [1]. The UHPC was originally developed by Bouygues construction group and is currently being marketed by Lafarge Inc. This particular UHPC is the only one currently widely available in the United States; however, other companies also have similar materials available in other markets. A new class of concrete that exhibits greatly improved strength and durability properties has recently been developed. The Federal Highway Administration (FHWA) at its Turner-Fairbank Highway Research Center (TFHRC) is currently evaluating UHPC for use in the transportation industry [2-3]. Selecting new materials for concrete structures requires an understanding of how the material behaves in both the uncured and cured states, given the anticipated service and exposure conditions. One of the greatest challenges for the successful performance of new materials is to control their dimensional behavior relative to the substrate. Relative dimensional changes can cause internal stress within the material as well as within the substrate. High internal stress may result in tension cracking, which can lead to loss of load-carrying capability and deterioration. Particular attention must be paid to select materials that properly address relative dimensional behavior so as to minimize these stresses [4-5]. UHPC has remarkable flexural strength and very high ductility: the ductility is 250 times greater than that of conventional concrete [5-7]. The m aterial’s extrem ely low porosity gives its low permeability and high durability, making it potentially suitable for retrofitting reinforced concrete structures or for use as a new construction material and precast product [8]. The Atrium is setting a new stage for UHPC precast solutions. The Atrium is a unique, seven-story, mixed-use building located in the vibrant downtown core of Victoria, British Columbia. Aptly named for the large, free-form atrium space atitscore,the building’sexteriorisclad w ith U H PC,a material at the cutting edge of innovation for new architectural applications. Thanks to its combination of superior properties, UHPC makes it possible to design and produce thin, complex shapes, curvatures and customized textures; concepts that were previously difficult or impossible to achieve with traditional reinforced precast concrete elements [9]. In recent times, a TechBrief was published by the Federal Highway Administration (FHWA) providing a final design for a full depth UHPC waffle deck system. This TechBrief highlights the results of a study aimed at evaluating the inelastic tensile response of UHPC subjected to simultaneous structural and environmental loading. Practical application of concrete in the highway infrastructure frequently subjects cracked sections to simultaneous mechanical and environmental stressors. This experimental investigation focused on the response of a UHPC beam subjected to
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