New technologies drive advancement in the way infrastructure is designed and built
By Randall W. Poston
Revitalizing existing concrete infrastructure is being addressed by the American Concrete Institute (ACI) in several ways. Working through our technical committees, ACI is able to disseminate information through consensus-based publications. Many of the most talked-about industry technological advancements are being addressed through new ACI committees – 3-D printing, Building Information Modeling (BIM), self-consolidating concrete, fiber-reinforced polymer reinforcement, and continued advances in concrete repair.
ACI Committee 562: Evaluation, Repair, and Rehabilitation of Concrete Buildings, is leveraging the Institute’s content with the historical knowledge and state-of-the-art resources on the evaluation, repair, and rehabilitation of concrete structures. ACI 562 provides minimum performance requirements that address the unique nature of existing construction, and also includes the addition of specific criteria requirements for assessment and design of repair and rehabilitation for varying levels of damage, deterioration, or faulty construction. A new version of these code requirements is expected soon.
3-D printing is a new and exciting frontier in the concrete industry. Headlines suggest that 3-D printing technologies for concrete construction are approaching fast, and the recently formed ACI Committee 564: 3-D Printing with Cementitious Materials, is working to develop and report information on three-dimensional printing and additive manufacturing with inorganic cementitious materials.
The committee is working to develop publications relating to additive manufacturing with cement-based materials, and is collaborating with other ACI committees to disseminate additive manufacturing information to determine ways it may be integrated into the concrete community. Fostering discussion on research needs and challenges preventing additive manufacturing from wide adoption in the concrete construction community is a top priority for the committee.
On a similar theme, BIM is a process that creates a data-rich digital model representing a three- (or more) dimensional building or structure, including the physical characteristics, material attributes, and other information that may be assigned to the building and its components. Constructing a structure virtually before doing so physically allows interface among building systems to be coordinated. ACI Committee 131: Building Information Modeling of Concrete Structures is working hard to develop and report information on the application of building information modeling to concrete structures.
Reduced labor and equipment costs are advantages that self-consolidating concrete (SCC) provides to the construction industry. SCC is highly flowable, non-segregating concrete that can spread into place, fill the formwork, and encapsulate the reinforcement without any mechanical consolidation. SCC provides better consolidation in congested areas; reduced noise; more detailed flexibility; smooth surfaces; and better hardened properties. ACI Committee 237: Self-Consolidating Concrete, continues collaborative work with other ACI committees to ensure alignment and accurate application of self-consolidating concrete.
Fiber-Reinforced Polymer (FRP) has evolved as a mainstream material for reinforcement of concrete structures around the globe. Research has advanced this technology both as internal reinforcements for new construction and as external reinforcements for rehabilitation of existing structures.
FRP materials are composite materials that typically consist of strong fibers embedded in a resin matrix. The fibers provide strength and stiffness to the composite and generally carry most of the applied loads. The matrix acts to bond and protect the fibers and to provide for transfer of stress from fiber to fiber through shear stresses. The most common fibers are glass, carbon, and synthetic fibers. FRP composites have very high strength characteristics and are nonconductive, noncorrosive, and lightweight.
ACI Committee 440: Fiber-Reinforced Polymer Reinforcement, works to develop and report information on FRPs for internal and external reinforcement of concrete. The committee has produced several design guides, specifications, standards, and construction practice for practitioners, plus a competition for students.
ACI’s commitment to infrastructure renewal is evident in its members hard work and dedication to produce the ACI 318: Building Code for Structural Concrete, which presents the code requirements for design and construction of structural concrete that are necessary to ensure public safety. The ACI is expected to release the new ACI 318-19: Building Code Requirements for Structural Concrete in June 2019. The new edition is the first since the reorganized format was published in 2014 and includes many new and updated code provisions along with updated color illustrations for added clarity. It is anticipated that these code requirements will be referenced in the 2021 International Building Code.
ACI is the premiere, global community dedicated to the best use of concrete and continues to support infrastructure renewal through its mission of “Always Advancing.”
Randall Poston is PhD, PE, SE, NAE, is President of the American Concrete Institute and Senior Principal with Pivot Engineers, Austin, TX.