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Laboratory and Field Evaluation of an Alternative UHPC Mix and an Associated UHPC Bridge TR-684

项目名称：	Laboratory and Field Evaluation of an Alternative UHPC Mix and an Associated UHPC Bridge TR-684
摘要：	Over the last decade a new generation of concrete known as Ultra High Performance Concrete (UHPC) has emerged on the market. This general class of concrete has compressive, tensile, permeability, and other properties that far exceed those of conventional or High Performance Concrete (HPC). The major drawback to this material is that its cost is considerably higher too. The prospect of using this material has, in fact, prompted the Federal Highway Administration (FHWA) to invest in strategic research related to the use of UHPC. To the credit of Iowa Department of Transportation (Iowa DOT) and County Engineers in Iowa, Iowa has remained at the forefront of this research too. In fact, the first two vehicular bridges constructed with UHPC in the United States were constructed in Iowa through multi-organizational partnerships. Up to this point there has been only one major producer of UHPC - LaFarge. The LaFarge product is a highly engineered concrete mix design sold under the trademarked name Ductal. Likely at least in part due to limited competition, the price of Ductal appears to have changed very little since it was first introduced. As a result, the most recent research activities have focused on identifying ways that small volumes of UHPC can be used in very strategic manners (e.g., joint closure pours in bridges, etc.). With this philosophy, the highly desirable properties can be exploited without resulting in significantly higher bridge construction costs. In the past 12 months, engineers and researchers in Iowa have become aware that an alternative UHPC mix design, known as K-UHPC, has been developed at The Korea Institute for Civil Engineering and Building Technology (KICT). Because the material is relatively new to the market, there are many questions regarding its performance, cost, etc. However, preliminary conversations with the developers seem to point to one very important fact: the cost of K-UHPC mix may be considerably less than Ductal. Should this hold true and should it be verified that the K-UHPC material does possess the required material characteristics, there would be significant benefits to Iowa bridge Engineers. For example, the Iowa Highway Research Board (IHRB) recently invested in the development of a set of box beam bridge standards using UHPC as a joint filler material. While conventional joint materials are also being explored for applications where "lower service levels" are required, having an alternative to Ductal could mean that even the highest service level could be obtained more economically. Advanced concrete mixtures typically take advantage of special materials, such as fibers, latex, and proprietary cements, to achieve very high performance in terms of early-age setting, lifecycle durability, and long-term strength. There are a number of studies conducted on special cements and binders that can be used to produce such concrete materials. Use of rapid hardening Portland cements, rapid setting calcium sulfoaluminate cements, latex modifiers, and accelerator admixtures are among the main options that have been examined for bridge construction applications. As a matter of fact, one of the first studies on the special cements used for fast track concrete was performed by the Project Development Division of Iowa DOT (Weber and Marks, 1997). To advance the state of the art for the construction of bridges, the FWHA has carried out research on the use of UHPC, especially for closure pour connections (Graybeal, 2011 and 2012). UHPC is generally a cementitious composite material composed of an optimized gradation of granular constituents, a water-to-cementitious materials ratio less than 0.25, and a high percentage of discontinuous internal fiber reinforcement. As of today, 24 bridges (11 of those in 2013) have been constructed in the U.S. using field-cast UHPC connections (FWHA, 2014). Despite the success of these field-cast UHPC connections, the following drawbacks, which limit the use of this material, have been reported: (1) UHPC used by the FHW A is a proprietary material named under the trademark Ductal by LaFarge, (2) available UHPC is not able to deliver a sufficient high early-age strength within the first 24 hours under normal curing conditions (2.2 ksi according to Graybeal, 2007), and (3) UHPC is an expensive material as Ductal, currently the only commercially available UHPC in the U.S., is being sold for about $2,000 per cubic yard, which is about 10 to 20 times the cost of regular concrete. The objectives of the project proposed here are to aid evaluation of (1) a new cost-effective UHPC mix design and (2) evaluate the performance of a UHPC bridge design by: (a) assisting the Buchanan County Engineer in reviewing the plans for the yet-to-be constructed K-UHPC bridge; (b) characterizing the new UHPC material; (c) assessing the bond/development length for the K-UHPC material; and (d) documenting the durability and performance of a yet-to-be-constructed K-UHPC bridge over a two year period.
状态：	Completed
资金：	85792.00
资助组织：	Iowa Highway Research Board<==>Iowa Department of Transportation
项目负责人：	Goetz, Vanessa
执行机构：	Iowa State University, Ames
开始时间：	20141201
预计完成日期：	20181130
主题领域：	Bridges and other structures；Construction；Highways；Pavements；I30: Materials