Innovative Construction Solutions by Hofmann Facades Group
The Hofmann Facades Group introduces Ultra-High Performance Concrete (UHPC), a groundbreaking cementitious material designed to redefine construction standards. This cutting-edge concrete boasts a minimum compressive strength of 17,000 pounds per square inch (120 MPa), along with specified durability, tensile ductility, and toughness requirements. The incorporation of fibers, such as high carbon steel, PVA, glass, carbon, or their combinations, ensures the material achieves stringent specifications.
Components and Formulation
The composition of UHPC involves a meticulous combination of portland cement, supplementary cementitious materials, reactive powders, limestone or quartz flour, fine sand, high-range water reducers, and water. This synergistic blend results in a material that can surpass compressive strengths of 29,000 psi (200 MPa), offering unparalleled structural integrity. The use of fine materials not only contributes to exceptional strength but also yields a dense, smooth surface, adding aesthetic value and precise transfer of form details.
Flexural Strength and Ductile Behavior
With the inclusion of metal fibers, UHPC exhibits flexural strengths exceeding 7,000 psi (48 MPa). Remarkably, this material showcases ductile behavior, allowing it to deform and support flexural and tensile loads even after initial cracking. The high compressive and tensile properties also enhance bond strength, enabling shorter lengths of anchor embedment. This is particularly advantageous in applications like precast balconies or façade panels.
Construction Advantages
UHPC simplifies construction through the elimination of reinforcing steel in certain applications. Its high flow characteristics make it self-compacting, streamlining the construction process. The material’s dense matrix and minimal pore structure result in low permeability, preventing the ingress of harmful materials like chlorides. This attribute contributes to superior durability, as evidenced by a chloride ion diffusion of less than 0.02 x 10-12 m²/s.
Steel-Reinforced UHPC: The Apex of Innovation
Steel-reinforced UHPC, especially stainless steel-reinforced variants, represents the pinnacle of this innovative material group. Whether through randomly dispersed steel fibers (up to 2.5% vol.) or discretely placed and staggered stainless or carbon steel mats (up to 10% vol.), these approaches, classified as UHFRC (fiber-reinforced UHPC) and UHPMRC (mat-reinforced UHPC), elevate structural possibilities. The high flexural capacity at minimal thickness makes steel-reinforced UHPC ideal for various architectural elements, including façade, roof, soffit panels, louvers, lattice systems, fins, balconies, and stairs.
Veneer-Faced Cladding: Marrying Aesthetics and Functionality
UHPC extends its versatility to veneer-faced cladding, where it harmoniously combines with materials like stone, brick, terra-cotta, ceramic, and wood. These thin UHPC elements form precast veneer-faced cladding elements, capable of spanning multiple floor heights. Integration of capillary mats facilitates the activation of facade and roof elements, paving the way for energy harvesting.
Global Recognition: Project References
The success of UHPC is echoed in prestigious projects worldwide, including the World Trade Center Vehicular Security Center and WTC Liberty Park in New York, the Bronx 40th Precinct Police Station, and WeWork Park Avenue. These references underscore the material’s reliability and efficacy in contributing to iconic and durable architectural solutions.
