Factory formed concrete components
Precast concrete products are cast in molds in a factory setting. These products benefit from superior quality control achievable at a production plant. Cost savings are realized when shapes are duplicated. Precast products range from concrete bricks and paving stones to bridge girders, structural components, and panels for cladding.
|Photo courtesy of Opus Architects and Engineers|
In 1950, the completion of the Walnut Lane Memorial Bridge in Philadelphia signaled the beginning of the precast concrete industry in North America. Today, precast concrete structures, including buildings, parking garages, and bridges, are commonplace.
Precast concrete is widely used for:
- Multi-family housing (low, mid-rise)
- Hotels and Motels
- Retirement Homes
- Security facilities
- Office Buildings
- Manufacturing Facilities
- Storage Facilities
- Big Box Stores
- Shopping malls
- Airport Terminals
- Stadium and Arena Elements (seating, steps, pedestrian ramps, concession stands, locker rooms)
- Sound barriers (Highways, Industrial Sites)
- Security barriers (planters, walls)
Provides predictable quality and structural characteristics because of factory controlled conditions. Timeliness.
Mass production as well as off-site production shortens project timeline, allowing earlier occupancy. For example, the walls of a building can be manufactured while on-site foundations are being built.
Strength. Precast concrete is capable of higher strength which allows for long clear spans making it especially applicable to structures requiring large open spaces such as parking garages.
Safety. The concrete provides superior fire resistance and sound control for individual building elements and reduces fire insurance rates, especially useful in multi-family housing.
Durable. Provides long service for high use applications.
Secure. Acts as a strong barrier for locations where security is an issue.
|Parking Garage (PCA)|
Precast concrete has many environmental benefits during construction and for the life of the structure. See associated sustainability solutions and technical briefs (right) for more detail.
Waste Minimization. Less materials are required because precise mixture proportions and tighter tolerances are achievable. Less concrete waste is created due to tight control of quantities of constituent materials. Waste materials are more readily recycled because concrete production is in one location. Sand and acids for finishing surfaces are reused. Steel forms and other materials are reused.
Recycled Content. Recycled materials such as fly ash, slag cement, silica fume, and recycled aggregates can be incorporated into concrete, thereby diverting materials from the landfill and reducing use of virgin materials. Hardened concrete is recycled (about 5% to 20% of aggregate in precast concrete can be recycled concrete). Gray water is often recycled into future mixtures. May contribute to LEED Credit M 4.
Less Community Disturbance. Less dust and waste is created at construction site because only needed precast concrete elements are delivered; there is no debris from formwork and associated fasteners. Fewer trucks and less time are required for construction because concrete is made offsite; particularly beneficial in urban areas where minimal traffic disruption is critical. Precast concrete units are normally large components, so greater portions of the building are completed with each activity, creating less disruption overall. Less noise at construction sites because concrete is made offsite.
During the life of the structure:
Energy Performance. Energy savings are achieved in buildings by combining the thermal mass of concrete with the optimal amount of insulation in precast concrete walls. Precast concrete acts as an air barrier, reducing air infiltration, and saving more energy. May contribute to LEED Credit EA 1.
Disaster Resistant. Precast concrete structures are resistant to fires, wind, hurricanes, floods, earthquakes, wind-driven rain, and moisture damage.
Cool. Light- or natural-colored concrete reduces heat islands, thereby reducing outdoor temperatures, saving energy, and reducing smog.
Indoor Air Quality. Precast concrete has low VOC emittance and does not degrade indoor air quality.
Recyclable. Precast concrete structures in urban areas can be recycled into fill and road base material at the end of their useful life.
Standard precast products such as beams, decks, and railroad ties are shaped in one type of form that is used repeatedly. Specialty precast products are designed for the particular building, bridge, or other structure. Most precast companies have their own carpentry shops where skilled workers create forms for the specialty products. Architectural concrete is often cast specially for each new project.
During the production process, forms for concrete are well lubricated. Concrete is placed in the forms and allowed to cure. After curing, the product is carefully lifted from the form and taken to a yard for further curing before it is shipped to the project site. The form is cleaned and prepared for the next batch of concrete. Many precasters can reuse their forms every one to two days.
Exterior finishes for architectural precast concrete can incorporate a full range of colors and textures. Textures are achieved by acid-etching, retarders, or sandblasting.
|Architectural Precast Concrete, Second Edition
Precast/Prestressed Concrete Institute. Item Number: MNL-122-89
Available for $65 for member, $130 for non-members.
This manual is the second edition of a comprehensive design manual on architectural precast concrete. Design, detailing and specifying information is compiled into a practical, easy-to-use format.
*Note: To access the website for the Manual, follow the provided link to the PCI bookstore search engine. Under "Category List" select "Products, Architectural Precast Concrete" and click search. The Manual will come up in the list of materials.
Bridge Design Manual
Precast/Prestressed Concrete Institute. Item Number: MNL-133-97
Available for $245 for member, $490 for non-members.
This two-volume, 16-chapter, comprehensive design manual includes both preliminary and final design information for standard girders and most precast and precast, prestressed concrete products and systems used for transportation structures.
*Note: To access the website for the Manual, follow the provided link to the PCI bookstore search engine. Under "Category List" select "Structures, Bridge" and click search. The Manual will come up in the list of materials.
Concrete: Sustainability and Life Cycle
Portland Cement Association. Item Code: SN3011
Available for download for free
This report presents the results of the LCI of three concrete products: ready mixed concrete, concrete masonry, and precast concrete.
Manual on Design for Fire Resistance of Precast, Prestressed Concrete
Precast/Prestresssed Concrete Insitute No. MNL 124-89, Softcover 96pp
Non-member price $20, member price $10.
This design manual presents data on properties of materials at high temperatures, and procedures whereby floors, roofs, and walls can be analyzed for their fire endurance. Design information is augmented with extensive examples and design aids in the form of charts, graphs, or tables. Procedures are also given for redesigning structural assemblies for improved fire endurance. Whereas before, the only means of predicting fire endurance of structural assemblies was by standard fire tests, this manual provides an analytical and proven method of evaluating fire endurance of structures made of precast and prestressed concrete.
PCI Design Handbook
Precast/Prestressed Concrete Institute. Item Number: MNL-120-04
Available for $130 for member, $260 for non-members.
The Sixth Edition of the PCI Design Handbook (MNL-120-04) on precast and prestressed concrete provides easy-to-follow design procedures, newly formatted numerical examples, and both new and updated design aids using ASCE 7-02, ACI 318-02, the third edition of the AISC steel manual and IBC 2003.
*Note: To access the website for the Handbook, follow the provided link to the PCI bookstore search engine. Under "Category List" select "Design" and click search. The Handbook will come up in the list of materials.
PCI Manual for the Design of Hollow Core Slabs
Precast/Prestressed Concrete Institute. Item Number: MNL-126-98
Available for $65 for member, $130 for non-members.
The purpose of this manual is to bring together information that is common, that is verified by test and that can be universally applied to hollow core slabs.
*Note: To access the website for the Manual, follow the provided link to the PCI bookstore search engine. Under "Category List" select "Products, Floor & Wall" and click search. The Manual will come up in the list of materials.
Sound Transmission Loss Through Concrete and Concrete Masonry Wall
Albert Litvin and Harold W. Belliston, Portland Cement Association, Item Code RD066
Many building codes require minimum sound transmission loss values, expressed as sound transmission class (STC), of 45 to 50. Tests of sound transmission loss were made on 8-in.-thick (203-mm) concrete masonry walls and on 6- and 8-in.-thick (152- and 203-mm) cast concrete walls finished with materials intended to increase sound transmission loss. Using furring, acoustic insulation, and wallboard attachments, STC values up to 59 and 63 were obtained for the masonry and cast concrete walls, respectively. Selected STC values, reported by other investigators, for a variety of walls are included for reference.
Supplementary Cementing Materials for Use in Blended Cements
Portland Cement Association. Item Code: RD112
Available for $40.
Provides information on using fly ash, slag, silica fume and natural pozzolans in the manufacturing of blended cements and the effects of these materials on cement and concrete. This report is also found on CD019 and DVD019.
Supplementary Cementing Materials For Use in Concrete
Michael Thomas and Michelle L. Wilson. Portland Cement Association. Item Code: CD038
Available for $35.
The first of a series of interactive distance learning programs specifically designed for training individuals on cement and concrete technology. This fully-narrated CD provides an intense self-contained course on supplementary cementing materials (SCMs) and their impact on the durability, workability, economy, and sustainability of concrete.
Achieving Sustainability with Precast Concrete
VanGeem, Martha. PCI Journal, January-February 2006. 20 pages
Available for free download courtesy of the Precast/Prestressed Concrete Institute.
Sustainability is often defined as development that meets the needs of the present without compromising the ability of future generations to meet their own needs.1 While other building materials may have to alter their configurations, properties, or both to be applicable to sustainable structures, precast concrete’s inherent properties make it a natural choice for achieving sustainability with today’s new buildings. In this paper, sustainability concepts are outlined and different rating systems for evaluating sustainable design are introduced. Finally, ways are provided in which precast concrete meets or exceeds one rating system’s requirements to achieve sustainability.
Life Cycle Cost Literature Survey
Katie Amelio and Martha G. VanGeem, PCA R&D Serial No. 2484, Portland Cement Association, 41 pgs
Available for free.
Life cycle cost analysis is currently a valuable tool in the construction industry and will become more so as resources become more scarce. Selecting the materials and components of structures and pavements based on a life cycle cost analysis can significantly decrease
the lifetime cost of construction, maintenance and repair.
This literature survey gathers life cycle cost information for concrete and competing materials from a variety of sources, summarizes the results, and describes the resulting
searchable database. The database is a resourceful tool for those who would like to obtain additional information on life cycle cost analysis and results. The searchable life cycle cost
database with abstracts, in Filemaker Pro® format, is available to Portland Cement
Association (PCA) member companies, PCA staff, and cement promotion groups.
Slag Cement LEED NC 2.1 Guide
Slag Cement Association
Available for free.
This 17-page publication discusses how slag cement can help contribute to achieving 9 different points toward for LEED™-NC certification.
Sustainable Manufacturing Fact Sheet: Tire Derived Fuel
Portland Cement Association. Item Code: IS325
Available for free.
By utilizing a cement kiln's controlled combustion environment, scrap tires can be an environmentally-sound source of energy in the manufacture of cement. This fact sheet shows how the popularity of tire-derived fuel has increased over the past two decades and summarizes its environmental benefits.
The Art of Concrete
Portland Cement Association. Item Code: PL721
Available for free.
White and colored concrete made with white cement have numerous applications, from cast-in-place to precast to tilt-up. This attractive brochure highlights the benefits of this versatile material, which can be used for decorative and structural purposes.
What's Your IAQ I.Q.?
Environmental Council of Concrete Organizations, #2846
Architects, engineers, and builders are becoming more proactive in assuring the Indoor Air Quality (IAQ) of the buildings for which they are responsible. Concrete is the best building material for forestalling sick building syndrome. Concrete also reduces the outgassing of indoor air pollutants. Because concrete structures are more energy efficient, they lower emissions form furnaces. This document is available for free from Environmental Council of Concrete Organizations.
To find this article: Follow the link provided, then click "catalog" and scroll half way down the page to find the article.
Color and Texture Selection Guide
Precast/Prestressed Concrete Institute
On-line Tool for Selecting Color and Texture (also available as a publication in their bookstore)