Solar Decathlon 2017
CRETE house construction in Denver
CRETE house is a model for advanced building technology, resiliency, and livability. The project is designed as a demonstration of integrated innovative precast concrete panelized system used in single-family homes, as a compelling alternative to traditional wood light frame construction. High Performance precast concrete structures are inherently resilient, protecting against fire, moisture and mold, insects, seismic events, extreme weather conditions and man-made phenomena such as blasts, force protection and acoustic mitigation.
Team WashU’s CRETE house developed from the belief that innovation comes from a holistic perspective on building technology, resiliency, and livability. This approach starts with a building enclosure system that is inherently protective of its inhabitants. Our choice of UHPC (Ultra High Performance Concrete) on the outside face of the wall panels allows for a longer life cycle than typical construction materials; it utilizes a wall section which cuts down on material usage and weight, allows a faster and more accurate construction process, and gains flexibility in design.
Additionally, the design of the house focuses on self-sufficiency in terms of energy, water and food production, supporting a hydroponic system built within the gutter system of the house. CRETE house maximizes the performance of the concrete mass in terms of its thermal, system integration, structural and aesthetics properties. This house uses durable and insulated robust precast concrete panels manufactured in a factory and assembled on-site.
For Crete House, Team WashU developed a precast concrete sandwich panel for the exterior walls, which consist of 4” of standard concrete for the interior wythe of the assembly, 5” of insulation and 1.25” ultra-high-performance-concrete (UHPC) exterior wythe. The thin exterior layer provides the possibility of unlimited configurations with geometries and variable thicknesses, which are not possible with traditional concrete panels. It also significantly reduces the overall thickness and weight of the wall as compared to traditional precast sandwich panels which lowers the overall embodied energy as well as the cost and energy related to shipping and handling the panels to the jobsite.
We developed a system using Ductal, a specific Ultra-High-Performance-Concrete (UHPC) with exceptional mechanical properties and characteristics adapted specifically to the building envelope. Ductal is a very dense, high quality cementitious material and it is defined by its exceptional high strength and durability. The material provides compressive strengths up to 29,000 pounds per square inch (psi) and flexural strengths up to 7,000 psi. It is six times stronger in compression, when compared to traditional concrete. This allows thinner and lighter structures. In addition, UHPC’s inherently waterproofing characteristics makes it a very viable alternative for exterior layer of the building’s envelope. UHPC performs well in terms of abrasion and chemical resistance, freeze-thaw, carbonation, and chloride ion penetration. “Based on ion transportation predictive modeling, it would take 1000 years for UHPC to have the same level of chloride penetration as high-performance concrete would have in less than 100 years. The potential for building façades with a millennium-long design life (along with little to no maintenance and less environmental impact over time) is a huge paradigm shift from the way sustainable infrastructure is viewed today.”
For this project, Washington University in St. Louis has collaborated with the Precast/Prestressed Concrete Institute (PCI) and specifically the following PCI Members: Gate Precast, Ductal Lafarge North America Inc., Dukane Precast, St. Louis Prestress Inc., Wieser, Lambard, Rocky Mountain Prestress, EnCon United/Stresscon Corporation, Ben Hur and Gibbons Erectors.
Yin, Hongxi / Faculty Project Leader
Moyano Fernandez, Pablo / Faculty Project Designer
Ryan Abendroth: Faculty Project Manager
Michels, Tim / Faculty Building Systems Specialist
Henry, Chad / Financial Manager
Meyer, Debbie / Corporate Relations Specialist
Student team for construction at Denver
Callahan, Dylan Weber
She, Ke (Kathy)
Erb, Sarah Beth
 G8WAY DC, Ultra-high performance concrete has it covered, by Kelly A. Henry and Bill Henderson.