CPI - February 2011 - Working with DuctalÂ® UHPC

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CONCRETE TECHNOLOGY Lafarge North America, T2W 4Y1,Calgary, Alberta, Canada Working with Ductal Ultra-High Performance Concrete Introduced to the world in the mid-90’s, Ductal ® Ultra-High-Performance Concrete (“UHPC”) has come a long way. With its unique combination of ductility, strength, durability and aesthetics, precast elements can have thinner sections and longer spans that are lighter, more grace ful and innovative (compared to conventional concrete). Highly moldable, it replicates form materials with amazing precision. Compressive strengths reach up to 200 MPa and flexural strengths up to 40 MPa, providing improved durability and impermeability against corrosion, abrasion and impact. Furthermore, it is sustainable. UHPC structures are expected to have an extended service life, resulting in less environmental impact over time. The purpose of this article is to help precasters learn about Ductal UHPC and the potential opportunities that exist through production of innovative products and solutions that compliment their existing precast products and businesses. The following article is an introduction to UHPC and the first in a series of related articles that CPI will publish in future issues. Vic H. Perry, Peter J. Seibert, Lafarge, North America As one of the pioneers in Ultra-High Performance Concrete (UHPC), Lafarge worked closely with Bouygues in the early 90’s to explore new possibilities in ad vanced concrete technologies. After ten years of research, they produced an innovative material with unique technological performances. The main principle of this technology is based on systematic elimination of inherent weaknesses associated with conventional concrete. The ductile behaviour of this material is a first for concrete, with the capacity to deform and support flexural and tensile loads, even after initial cra - ck ing. These performances are the result of improved micro-structural properties of the mineral matrix, especially toughness and control of the bond between the matrix and the fiber. Today, Ductal is a family of UHPC products. Two types of fibers are used to make Ductal Sanderling Drive Pedestrian Overpass, Canada products: high carbon metallic or poly-vinyl alcohol (PVA) fibers. The fiber and chemical formulation is customized to best fit the application requirements. When selecting a Ductal product, determining factors include strength, ductility and rheology requirements, exposure to corrosive agents, desired aesthetics and exposure to human contact. The optimization of granulars, the fibers and admixtures provides a very low porosity in a cement-based mineral granulometric matrix. The premix components consist of granular material with a diameter less than 1 mm, and a highly reduced water-cement ratio (less than 0.25, depending on the type of Ductal formulation). Elimination of coarse aggregates, along with the granular gradation and fiber aspect ratio, facilitates a high fiber content and isotropic dispersion. There is almost no carbonation or penetration of chlorides and sulfates and a high resistance to acid attack. Its superior durability characteristics are due to a combina - tion of fine powders, selected for their relative grain size and chemical reactivity. The net effect is a maximum compactness and a small, disconnected pore structure. Ductal has almost no shrinkage or creep, making it very suitable for prestressed applications. The use of this material for construction is simplified through the elimination of reinforcing steel and its ability to be virtually self-placing or dry-cast. Overall, Ductal solutions can offer advantages such as speed of construction, im - proved aesthetics, superior durability and impermeability against corrosion, abrasion and impact – which translates to reduced main tenance and a longer structural life span. Over the years, Ductal has been subjected to a significant amount of rigorous testing and field trials. In the USA, Canada, France, Japan and Australia, several offi - cial documents now prescribe Ductal for building, infrastructure, manufacturing, artis tic and industrial designs. Today, this material is used for a variety of applications such as bridge beams and decks, joint fill, solid and perforated wall panels/facades, urban furniture, louvres, stairs and floors, pipes, piles, marine structures and others. Target markets Ductal has been used successfully by many precasters in ways that compliment their existing businesses. Due to its advanced characteristics (compared to conventional concrete) including durability, strength, reduced weight and aesthetics, Ductal has opened the door to new opportunities for precasters in the structural and architectural markets. 2 CPI – Concrete Plant International – 1 | 2011 www.cpi-worldwide.com
CONCRETE TECHNOLOGY Vic H. Perry received his Bachelor of Civil Engineering with Distinction in 1978 and Master of Applied Science in Structural Engineering in 1984 from Dalhousie University in Nova Scotia, Canada. In 1999, he was bestowed a Fellow of the Canadian Society for Civil Engineering (CSCE) and elected President of the CSCE in 2010. Since 1997, Vic has been involved in the development of Ductal (UHPC), initially as Director of Marketing (Ductal) for the Lafarge Group in Paris, France and since 2001, as Vice-President & General Manager Ductal, Lafarge North America, in Calgary, Canada. Vic.Perry@Lafarge-na.com Peter J. Seibert obtained his Bachelor of Civil Engineering from the University of Toronto in 1996, a Masters in Civil Engineering from Queen’s University, Kingston, Ontario in 1998 and an MBA from Wilfrid Laurier University, Waterloo, Ontario in 2003. Based in Calgary, Canada, Peter is the Technical Director for Ductal (UHPC), responsible for the manufacturing, supply chain, quality control and technical aspects of Ductal throughout North America since 2006. Peter.Seibert@Lafarge-na.com to their design efficiency, fast installation and low initial costs. However, the standard grouting material in the joints is often the first part of the bridge to fail due to contin - uous highway impacts causing the joints to leak. Recent applications of in-field casting of Ductal in the joints have resulted in the joints being the strongest link in the precast bridge system. This concept creates new opportunities for precasters who can now offer a new solution for bridge owners by utilizing their existing precast product offer - ing in combination with Ductal. Manufac - turing of deck panels or box girders in a precast plant results in high quality concrete elements and, when combined with Ductal joint fill, the precaster will be able to offer an innovative, extremely durable, high quality bridge deck for the bridge owner and the general public. The Atrium, Canada Structural market According to the Federal Highway Administration (FHWA) National Bridge In - ven tory (NBI) Study, approximately 156,000 bridges in the USA are structurally deficient or functionally obsolete. State, provincial and municipal engineers are seeking new ways to build better bridges, there - by reducing maintenance costs that are diverted from capital budgets required for building much needed highways and bridges. Therefore, the FHWA launched a program, “The Bridge of the Future”, to help drive new solutions for building bridges. Implementation of new technologies in the bridge sector has been a long journey due to the conservative nature of this segment. Highway bridge engineers, bestowed with guardianship of the public money and safety, have always demonstrated the technology before using it. In many applica tions, prototypes were manufactured to test and validate the bridge design concept. In addition, new bridge sections and solutions have been developed in North America. One of the best Ductal UHPC applications which utilizes existing precast products for the bridge market involves a unique joint fill solution for precast deck panels or precast box-girders. Historically, these elements were preferred by owners for bridge systems due Precast Ductal waffle panels also take advantage of the material’s high durability aspects. For this design concept, full-depth precast deck panels must be 8“ (200 mm) to ensure deck stiffness, leaving a 2.5“ (62 mm) uniform deck with 5.5“ two-way ribs. The precast panels are then jointed togeth - er in the field using Ductal joint fill. In 2010, the Iowa Department of Transpor tation requested UHPC waffle deck panels for a bridge project with UHPC joints. Innovative, new bridge girder sections made with UHPC have been developed in recent years. In particular; the pi-girder (with a cross-section that resembles the Greek symbol, “π”), resulting in a com - bined section of girder and built-in precast deck. The first bridge to use these UHPC pigirders was installed in North America in 2009. This highly optimized girder section may also open new opportunities for precasters. To date, Ductal has been used for three pedestrian bridges in Canada where the architecture of the structure was the main driver (besides strength and durability). Examples of other structural elements that have been produced in Ductal UHPC are piles, pipes and protective cladding systems for infrastructures in marine environ - ments. For each of these applications, precasters were able to use and slightly modify their existing plant equipment and formworks in order to offer a more optimized precast section which utilizes the material’s strength and durability characteristics. www.cpi-worldwide.com CPI – Concrete Plant International – 1 | 2011 3
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CPI - February 2011 - Working with DuctalÂ® UHPC

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