What Precast Delivers

The importance of residential housing for both university and student is demonstrable. Today’s student housing has to offer not only a place to sleep and study, it also must facilitate community and offer a range of top-class amenities. It must balance privacy and security with the ability to craft fellowship. For the purposes of both longevity and budget, housing is saddled with the need to use space flexibly. Yet in the face of these heavy demands lies the opportunity to improve campus housing.

Adaptable Housing Design Calls for an Adaptable Material

William Pollard also said, “Those who initiate change will have a better opportunity to manage the change that is inevitable.” The versatility of precast concrete and its attributes makes a perfect partner in this demanding arena, both via life-cycle performance and aesthetics. Precast brings with it a range of abilities, allowing housing projects to successfully capture structural assets like durability and resiliency, while also realizing innovative design visions.

Precast concrete is the fastest building system available, thereby minimizing negative effects at the project site. As a high-performance material, precast concrete is manufactured off-site so it contributes to the overall sustainability of a building during construction. Using precast concrete means site efficiency: minimal site disturbance, waste, and accelerated construction.

Photo courtesy of Dukane Precast

Precast panels are installed on-site. Using precast means efficiency during construction, as panels are delivered fully ready for installation, minimizing site disturbance and the potential for waste, and keeping schedules on time.

Precast inherently provides a high level of resiliency that protects against multiple hazards, such as fire, severe storms, explosions, and even earthquakes. Besides offering superior hazard management, like storm and blast resistance, concrete also enhances life safety and health by bolstering indoor environmental quality and offering passive fire resistance.

Concrete as a product offers use versatility: it is recyclable and is compatible with deconstructive or adaptive reuse. It provides energy and water conservation, safety, security, durability, and accessibility; and it meets cost-benefit, productivity, sustainability, functionality, and operational considerations.

Precast’s Aesthetic Versatility Means Beauty and Sustainability

Aesthetics play an important role in sustainability.

In addition to its high-performance attributes, precast concrete as a solution allows designers to create a wide range of aesthetic effects and colors to affordably incorporate historic elements and to integrate a diverse array of facade elements into a single precast panel.

Precast concrete facilitates this tremendous range of design options through the use of formliners, aggregates, brick, terracotta, stone, and pigmentation. An assortment of finishing techniques is available, such as acid etching, abrasive blasting, polishing, and burnishing, offering a wide range of final surface finishes from which to choose. Precast concrete comes in almost an unlimited array of forms from radius to straight and everything in between.

Precast concrete is available in an endless color palette. Concrete color begins with basic ingredients or natural materials to which a powdered, granular, or liquid pigment dispersion is placed into the admixture. To achieve optimum results, it is important to use high-quality, consistent materials and processes. Color can be created by natural materials, such as aggregates like stone and sand, or via cements and colored pigments, or from a combination of both, depending on the finishes selected.

Designers can create intricate bullnose detailing, reveals, and custom castings. Designers also can embed or veneer traditional materials, such as clay brick, terracotta, or natural stones, into precast panels to utilize their natural beauty. Precast also provides an affordable way to provide historic facade elements. Precast producers can mimic natural stone and window/door surrounds, for instance, to provide historical context on a budget. Thin-brick is real brick, engineered to fit in forms that allow for arched openings, corbels, and numerous other masonry effects.

Photo courtesy of Cipher Imaging/Brian J. Rotert

Precast allows the seamless integration of a variety of beautiful finishes and architectural elements, as showcased at Jackrabbit Grove, South Dakota State University.

With precast, all looks, textures, and forms are integrated, and the panel arrives ready to install. This reduces the number of trades required, cutting costs. Precast panels also have less joints and flashing to maintain, reducing maintenance. Less complexity equals less risk.

CASE STUDY: COMSTOCK GRADUATE HOUSING PROJECT, STANFORD UNIVERSITY, 2015 PCI HARRY H. EDWARDS INDUSTRY ADVANCEMENT AWARD WINNER

Photo courtesy of Bernard Andre Photography

Precast concrete allowed the general contractor to deliver the Comstock graduate housing planned for Stanford University within one academic school year. The buildings became the first vertically posttensioned, precast concrete panel buildings in Northern California.

The 2015 Harry H. Edwards award winner exemplifies how precast concrete can bring durability, performance, and efficiency to student housing.

At Stanford University, new housing was urgently needed—within the span of a single school year—including the replacement of nine low-rise, two-story buildings that provided 79 beds. In addition, four new buildings were called for to accommodate more than five times as many students. The new structures also had to include student meeting and social gathering spaces, laundry facilities, computer clusters, music practice rooms, game rooms, and other amenity spaces.

To meet those needs within the allotted schedule, the designers chose precast concrete over wood, says Mark Palmer of Clark Pacific, the precast concrete producer for the project. “With the speed of erection, the general contractor was able to deliver the student housing within one school year, getting students in quicker and allowing the university to start bringing in revenue earlier.”

The buildings feature architecturally finished, structural precast concrete; unique vertically posttensioned, precast concrete walls for seismic resistance; and, a first-ever in this region, a pre-topped plank system for the flooring. The floor system consists of pre-topped, prestressed concrete planks; these planks span from exterior wall to exterior wall, over interior bearings walls, and result in a two-span plank. “The integration of the performance of a structural system with the finish of an architecturally clad precast concrete product saved time and money for everyone involved,” Palmer says.

By prefabricating the components off-site, installation crews were able to keep the crowded campus clear of extra materials using just-in-time delivery, allowing cranes to lift the precast concrete pieces directly from the trucks and immediately install them. “Installation crews were able to set an entire floor of wall panels and floor planks above every three days, allowing other trades to follow quickly behind once the precast was installed,” Palmer says. The general contractor noted how the benefits of the prefabricated precast allowed other trades to follow quickly behind once the precast was installed.

A medium sandblast was used on all of the panels to match existing colors of the other buildings on the campus, while green and brown accent colors were used at the top of each building to add visual interest and contrast. Formliners also were used on the fourth-story panels to create a ribbed texture that wrapped around the upper floor of the dormitory buildings.

Along with meeting schedule and aesthetic goals, the precast concrete design delivered a more durable solution that will require minimal maintenance and meet seismic design requirements. Using vertically post-tensioned, precast concrete rocking wall panels, developed as part of the multi-year Precast Seismic Structural Systems Research (PRESSS) research project, walls are designed to rock at their base, with special energy dissipating rebar developed into the foundation and debonded up into the wall panel, in accordance with the 2010 California Building Code. “One of the most interesting aspects of this system is its ability to move like a hybrid moment frame,” Palmer says. “After a seismic event, the building will pull itself back to its original position.” Construction on the housing complex began in April 2013 and was completed in June 2014, well in advance of the academic year. Palmer says, “It was exciting to see how quickly a complete system like this could be built.”