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The monthly magazine of the American Concrete Institute. Circulated to 20,000 professionals worldwide, 80% in North America, concentrated among engineers, architects and contractors who design and build concrete structures of all kinds

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March 2009 Vol. 31 No. 3 MIXING, PLACING, AND CURING
Sustainability through Strength Integrating post-tensioned lateral systems and slag cement concrete for a model of environmental architecture by Mark Stevenson and Leo Panian Investigating Construction Methods for Longtan Dam an experimental study of surface treatments for roller-compacted concrete by Lei Yang and Jonathan J. Shi From Rheology of Fresh Concrete to Casting Processes correlating properties with field performance by Nicolas Roussel



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A Minimum Flexural Reinforcement Puzzle
Analyses of the minimum flexural reinforcement requirements in ACI 318-14 show that updates are needed. Expressions should include the effects of concrete strength, and expressions for lower strength steels should be abandoned.


Fly Ash Concrete with Low Portland Cement Content
Concrete mixtures with high volumes of fly ash can exhibit retarded setting and strength development. Various admixture and cement-fly ash combinations were evaluated to determine the impacts of cement alkali and fly ash calcium oxide contents on setting time and 1-day compressive strength.


2016 Sidney Freedman Craftsmanship Awards


From Research to Reality
A panel of experts debated the use of performance-based specifications at the 123 Forum session at The ACI Concrete Convention and Exposition – Spring 2016 in Milwaukee, WI. The general consensus was that performance-based specifications have great potential as alternatives to prescriptive specifications, rather than complete replacements.


Products & Practice Spotlight: Solving the Slab Moisture Issue
When used as a concrete admixture, sodium silicate reacts with the calcium hydroxide and the free water in the mixture to form C-S-H gel. The gel serves as an internal curing medium, bleed channels and pores are drastically minimized, and vapor transmission is dramatically reduced.


The Concrete Society Awards for 2016


2016 ACI Excellence in Concrete Construction Awards Gala Inspires Industry Members
Inspiring. Spectacular. Amazing. These are just a few of the post-event sentiments echoed by the 240 attendees of the 2016 ACI Excellence in Concrete Construction Awards Gala.


Knowledge to Practice: ACI Foundation


Concrete Q&A: Tolerances for Floors Supporting Operable Partitions
Is there an ACI tolerance for installing floors that receive operable partitions?

Shallow Embedded Anchors
Although ACI 318-14 provides design requirements for anchors in concrete, it does not apply to specialty inserts used for anchoring nonstructural elements. Background information is provided on the ACI 318 design procedure, shallow anchors and related parameters are discussed, and modification factors are proposed for ACI 318 design values.


Nano-Modified Fly Ash Concrete
Nano-modified fly ash concrete was recently used for partial-depth repair of transverse joints located on a major urban arterial road in Winnipeg, Canada. The project was the first field trial of the material, and it successfully demonstrated mixing, placement, and testing procedures as well as indicated potential for long-term performance.


Crumb Rubber Concrete Bridge Deck
In 2006, a bridge deck was constructed in China using a mixture of portland cement concrete and rubber crumbs. Although about 5% of the deck surface developed shallow shrinkage cracks shortly after placement, the rest of the deck remains crack-free. It is postulated that the crumbs create elastic joints that reduce stress concentrations near the tips of microcracks.


French Dam Technology Passes the Test
The "French Dam" is a new technology for construction of small- to medium-sized hydroelectric and water control systems. Comprising modular segments manufactured offsite in a controlled environment, the system is designed for new or retrofit projects. The fabrication, installation, and testing processes are described.


A Safe Corrosion Solution for Potable Water Reservoirs
A new potable water reservoir was constructed in Tarragona, Spain. Based on past experiences, migrating corrosion inhibitors were selected to provide long-term protection against corrosion and help meet a 50-year design life. The admixtures had no apparent negative effects on the setting time or physical properties of the concrete.


Guide to Shotcrete
This article is a reprint of a paper that originally appeared in the Summer 2016 issue of Shotcrete. It discusses updates to “Guide to Shotcrete (ACI 506R-16),” including new and expanded sections.


Concrete Q&A: ACI 318M-14 versus ACI 318-14—Eq. 18.10.4.1 and Fig. R18.7.5.2
Equation (18.10.4.1) of ACI 318M-141 looks the same as Eq. (18.10.4.1) in ACI 318-14.2 Why do the values assigned to the coefficient αc vary by a factor of 12 between the two versions of the code?


ACPA 2016 Excellence in Concrete Pavements Awards
The American Concrete Pavement Association (ACPA) has named the recipients of its 27th Annual Excellence in Concrete Pavements Awards, which recognize quality concrete pavements constructed in the United States and Canada.


ACI Concrete Sustainability Forum IX
ACI Concrete Sustainability Forum IX took place in October 2016 at the ACI Concrete Convention and Exposition. The forum featured presentations from seven experts on sustainability design, sustainability assessment systems, and new material technologies for sustainable buildings and civil engineering structures.


Revolutionary Concrete and Its Innovative Applications
Highlights of The ACI Concrete Convention and Exposition – Fall 2016.


Knowledge to Practice: ACI Foundation
CRC Announces New Research Product

Concrete Pushes Mexico to New Heights
Torre Koi, a mixed-use, 279 m (915 ft) high skyscraper in an exclusive area of San Pedro Garza Garcia, Monterrey, is currently the tallest building in Mexico. The structural design of Torre Koi was based on a combination of wind load and seismic effects. Various documents and codes on seismic design, published in Mexico as well as the United States, were consulted.


Products & Practice Spotlight: Precast Provincial
Precast concrete was used for the construction of the Champagne complex in Calgary, AB, Canada. Precast provided the clean façade with French Provincial sandstone finishes for the lower exterior walls, off-white finish with contrasting reveals for the upper floors, and delicate architectural features for the buildings. Precast also served as the primary structural material. Pre-installed windows allowed for faster enclosure of the building.


2015 Nepal Earthquake
Following the 2015 Nepal earthquakes, ACI Committee 133, Disaster Reconnaissance, deployed researchers from Purdue University, West Lafayette, IN. Assisted by 12 volunteer civil engineers from Nepal, the team surveyed low-rise and high-rise reinforced concrete buildings in Kathmandu. The survey methodology and key observations are summarized.


Decorative Concrete Council Award Winners for 2017
The Decorative Concrete Council, a specialty council of the American Society of Concrete Contractors (ASCC), announced the winners of its ninth annual Decorative Concrete Awards competition. Sundeck of San Antonio, San Antonio, TX, won the WOW! Award, best overall project, for Mission Concepcion Park, also in San Antonio. In a new category, Decorative Environmental, T.B. Penick & Sons, San Diego, CA, won 1st Place for Battery East Vista.


2016 HNA Hardscape Project Award Winners
The winners and honorable mention recipients of the 2016 HNA Hardscape Project Awards were announced at 2016 Hardscape North America. The awards are sponsored by the Interlocking Concrete Pavement Institute (ICPI), the Brick Industry Association (BIA), and National Concrete Masonry Association (NCMA). The general categories included: Combination of Hardscape Products, Concrete Paver, Segmental Retaining Walls, and Clay Brick.


ACI Names New Fellows
Members to be awarded at The ACI Concrete Convention and Exposition – Spring 2017


Notable Concrete in Greater Detroit
Recent high-profile construction projects in the vicinity


Knowledge to Practice: ACI Foundation
The ACI Foundation serves a complementary role to ACI’s consensus process.


Concrete Q & A: ACI 318—Design of Columns Not Designated as Part of Seismic-Force-Resisting System
Q. We are designing a building in a high seismic risk zone. The structural system comprises posttensioned flat slabs supported by columns and structural walls.

Successful Design of Wet-Mix Shotcrete
Although wet-mix shotcrete has proven to be an ideal alternative to conventional concrete in numerous applications, its further success is sometimes hindered by a few common misconceptions. The article discusses some of those fallacies and presents corresponding facts. It also explains why successful shotcreting requires consideration of all desired performance criteria and project needs.


Precast Concrete Pavement Implementation
Precast concrete pavement (PCP) technology is gaining wider acceptance in the United States for the rapid repair and rehabilitation of heavily trafficked asphalt and concrete pavements. Rehabilitation work using PCP is typically performed overnight over a single lane. Two applications of PCP technology are described: installation of concrete bus pads at the East Main Street Station in New Britain, CT, and rehabilitation of the SH 97 and SH 72 intersection in Fowlerton, TX.


2016 ICRI Project Awards
The International Concrete Repair Institute (ICRI) presented the 2016 ICRI Project Awards at the ICRI Fall Convention in Cleveland, OH, on November 10, 2016.


A Creative, Functional Upgrade
A team of consultants were contracted to correct a functional deficiency in a contact basin at the Sid Copeland Water Treatment Plant, Louisville, CO. The team found that although the roof structure was visibly weathered, the concrete structure was in good overall condition. To correct the functional problem, the team recommended a series of baffle walls to increase the flow distance through the basin and ensure sufficient chlorine contact time. The contractor used self-consolidating concrete to construct full-height baffle walls, solving the functional issue and providing additional support to the roof.


Computerized Project Management System
A computerized project management system (CPMS) was developed in 1980s during construction of the King Saud University campus, Riyadh, Saudi Arabia. The CPMS was built around the critical path method algorithm. The significance of the CPMS was to provide a realistic management tool for handling an enormous number of detailed activities over the nearly 10 years required to execute the project.


Products & Practice Spotlight: Repair of ASR-Damaged Piles
In 2000, severe cracking due to alkali-silica reaction was noted in piles supporting a bridge over the tidal estuary of the Barron River near Cairns, Queensland, Australia. After 14 years of searching for a system that could protect the piles and provide confinement to combat further damage, the PileMedic® system was selected. The adopted solution met these goals, could be rapidly and safely installed, and provided major savings compared to the original reinforced concrete encasement option.


Knowledge to Practice: ACI Foundation
Concrete Research Council Announces High-Strength Steel Research Product


Awards at The ACI Concrete Convention and Exposition – Spring 2017
For their outstanding achievements and service to the Institute, ACI recognized selected members at The ACI Concrete Convention and Exposition – Spring 2017 in Detroit, MI.


Concrete Q & A: Reinforcement Termination in Wastewater Concrete Containment and Designing Roads for 50+ Years
Does ACI 350-06 allow terminations of vertical reinforcing bars in a wastewater concrete containment tank wall? Is it a reasonable goal to design roads to last at least 50 years before they need to be rebuilt?

ded overlays of equal thickness. Over 30 years of Swedish research indicates that a durable bond between the overlay and the existing concrete can be achieved with proper removal, surface preparation, placement, and curing.


Composite Strengthening of a Bridge
The four-span concrete Buhung Bridge, located in Gyeonggi, South Korea, was constructed in 1960 and has since been exposed to heavy traffic from a nearby military base. One span of the bridge was recently strengthened with post-tensioned, near-surface-mounted carbon fiber reinforced polymer rods. Dynamic load tests show that the stiffness of the span has been improved significantly.


Evolution of ACI 562 Code—Part 11
The eleventh in a series discussing the 2016 edition of the ACI 562 Code, this article focuses on Chapter 8 of the Code and durability of concrete repairs. Topics include causes of deterioration, cover and equivalent cover, corrosion of reinforcing steel, and concrete cracking.


Deployment of Composite Reinforcing
Although fiber reinforced polymer (FRP) reinforcement has demonstrated great potential for improving the durability of concrete transportation infrastructure, adoption has been slowed by a lack of a unified strategy for deployment. Citing the successful introduction of prestressed concrete technology as a precedent, the authors call for development, publication, and sharing of standards and design guides for FRP applications.


Products & Practice Spotlight: Rehabbing Aging Infrastructure
Polyurea coatings and liners can provide strong, flexible, damage-resistant dampproofing in wastewater infrastructure rehabilitation projects. With the proper crack repair and surface preparation, coatings can be applied directly to the concrete over a wide temperature range. Rapid curing helps to minimize facility downtime.


Knowledge to Practice: ACI Foundation


ACI Officers for 2017-2018


ACI’s Award-Winning Papers and Articles
During The ACI Concrete Convention and Exposition – Spring 2017 in Detroit, MI, 12 authors and researchers received awards of excellence for their published work.


ACI Technical Committee Chairs Appointed
Before The ACI Concrete Convention and Exposition – Spring 2017 in Detroit, MI, the ACI Technical Activities Committee (TAC) selected Chairs for 30 ACI technical committees. These actions became effective after the convention.


Concrete Q&A: Evaluation and strengthening of members in existing structures
Q. I am the licensed design professional (LDP) for a team conducting a structural evaluation of a reinforced concrete building that was completed in the mid-1960s. We’ve determined that many elements in the floor structures do not comply with requirements in the ACI 318-14 Code.1 For example, shallow beams have stirrup spacing exceeding d/2, and deep beams do not satisfy ACI 318-14 requirements for horizontal and vertical reinforcement areas and spacing. To compound these issues, the floor live load is being increased due to a change in use. Are there any ACI Code provisions that address these issues?

The Franklin Avenue Bridge
The Franklin Avenue Bridge is an arch bridge crossing the Mississippi River near Minneapolis and St. Paul, MN. Constructed between 1919 and 1923, the bridge has been damaged by chloride-related corrosion of the reinforcement and long-term exposure to moisture and freezing-and-thawing cycles. This article, the first of a two-part series on the restoration of the bridge, focuses on the rehabilitation aspects.


Role of Rheology in Achieving Successful Concrete Performance
Concrete rheology is introduced, and insights are provided into how rheology applies to mixture design and quality control, segregation, pumping, formwork pressure, and surface finish. Basic terminology is provided along with explanations of typical measuring instruments and testing procedures used to determine rheological properties.


Inspecting Adhesive Anchors
The installation of adhesive anchors is a critical aspect of many construction projects, and special inspection of such installations is critical for safety. Guidance is provided for inspectors of new installations as well as for engineers and inspectors evaluating existing adhesive anchor anchorages.


ACI University in the Classroom
ACI University modules and certificate programs are great tools for enhancing the learning process for engineering students. Inclusion of an ACI University certificate program as part of a university course motivates students to earn resume-enhancing certificates and teaches them about benefits of being an ACI member.


Classroom Demonstrations Demonstrated
A session titled "Classroom Demonstrations Demonstrated" was held at The ACI Concrete Convention and Exposition – Spring 2017, in Detroit, MI. Presentations were designed to inspire current and future educators to enhance student learning in their classes using active learning approaches. Presenters discussed and demonstrated models they have used as teaching aids.


2016 PCI Design Awards
The Precast/Prestressed Concrete Institute (PCI) announced the winners of the 54th Annual PCI Design Awards.


ACI Board Committee Members Thanked
These ACI members have ended terms on Standing Board Committees as of The ACI Concrete Convention and Exposition – Spring 2017. Their service to the Institute is appreciated.


Concrete Q&A: Joint Deterioration Mechanism and Prevention
Q: What causes deterioration of sawcut joints in concrete pavements, and how can it be prevented?

Closure Strip Strategies
Closure strips are temporary gaps in reinforced concrete floor slabs. They are provided to allow sections on either side to undergo shrinkage independently; however, only limited guidance is available for their design. This article summarizes currently available design approaches, presents a case study of closure strip monitoring, and compares the obtained field data with predictions from the available design approaches.


Design of Reinforcement for Pile Caps
Foundations supporting pipe racks and open frame structures used in the petrochemical industry are often subjected to uplift forces. Simplified strut-and-tie models suitable for reinforcement design for pile caps subjected to axial tension or bending moment are presented. Models include the most common configurations of pile caps currently used—pile caps supported by two and four piles.


2016 PCI Design Awards
The Annual Precast/Prestressed Concrete Institute (PCI) Design Awards represent design excellence and construction quality using precast concrete. Winning projects for 2016 in the transportation design category are presented. Judging categories included bridges with spans over 150 ft (46 m), non-highway bridges, and rehabilitated bridges.


Slag Cement Association 2016 Project of the Year Awards
The Slag Cement Association (SCA) presented the Slag Cement 2016 Project of the Year Awards during the meeting of ACI Committee 233, Ground Slag in Concrete, at The ACI Concrete Convention and Exposition – Spring 2017 in Detroit, MI. Eight projects were recognized for excellence and innovation in concrete using slag cement in the categories of Architectural Design, Durability, Green Design, High Performance, Sustainability, and a new category—Innovative Applications.


Congratulations, 2017 Long-Time Members of ACI
It is our pleasure to congratulate individuals in 2017 who will have supported ACI for 25 and 45 years.


Driving Concrete Technology
Highlights of The ACI Concrete Convention and Exposition – Spring 2017


ACI Foundation Awards Student Fellowships and Scholarships for 2017-2018
Applications for the 2018-2019 awards cycle will open mid-summer 2017


Concrete Q&A: Subgrade Drag Equation in ACI 360R
Equation (6.3) in ACI 360R-921 is not included in the current version of this document (ACI 360R-102). What was the reason for this change? Also, what reinforcement percentage is needed to limit crack widths and ensure aggregate interlock?

The Franklin Avenue Bridge
The Franklin Avenue Bridge is an arch bridge crossing the Mississippi River between Minneapolis and St. Paul, MN. Completed in 1923 and last renovated in 1970, the bridge has been damaged by chloride-related corrosion of the reinforcement and long-term exposure to moisture and freezing-and-thawing cycles. This article, the second of a two-part series on the restoration of the bridge, focuses on the structural analysis and deck replacement using accelerated bridge construction (ABC).


International Exhibition on Pier Luigi Nervi
The “Pier Luigi Nervi – Art and Science of Building” Exhibition was displayed for the first time in North America at The ACI Concrete Convention and Exposition – Fall 2016 in Philadelphia, PA. The exhibition included 20 large panels with images and text, as well as videos on Nervi’s life and works. Located at the center of the convention activities, the Nervi Exhibition was seen and studied by almost 2000 convention attendees. The exhibition will be hosted next by the University of Miami, Miami, FL.


Full-Depth and Partial-Depth Bridge Deck Panels
Available options for accelerated bridge construction (ABC) include full-depth and partial-depth precast deck panels. The Nevada Department of Transportation (DOT) recently funded a survey of other DOTs throughout the U.S. regarding application and detailing of such deck panels. Data on panel connections, deck performance, and general design considerations were collected and summarized to help develop an understanding of the current state of the technology.


Measuring the Cracking Potential of Shotcrete
A recent research project was conducted to develop a suitable test method for evaluating the shrinkage cracking sensitivity of shotcrete mixtures. The experimental approach and an overview of the testing program are summarized, and the challenges of producing realistic and homogenous test specimens are discussed.


2017 International Parking Institute’s Awards of Excellence
The winners of the 2017 International Parking Institute’s (IPI) Awards of Excellence were announced at the 2017 IPI Conference and Expo in New Orleans, LA. Award categories included: Top Award for Architectural Excellence, Best Design of a Parking Facility with Fewer than 800 Spaces, Best Design of a Parking Facility with 800 or More Spaces, Best Design/Implementation of a Surface Parking Lot, Innovation in a Parking Operation or Program, Best Parking Facility Restoration or Rehabilitation, and Award for New Sustainable Parking & Transportation Facilities Excellence.


Concrete Q&A: Field- versus Standard-Cured Cylinders made from High-Strength Concrete
I’m a technician with a testing laboratory. On one of my projects, I understand that the specified strength is 10,000 psi (68.9 MPa), based on compressive tests of field-cured cylinders. For quality assurance, we are also testing standard-cured cylinders. The field-cured cylinders are consistently breaking at strengths that are 25 to 35% lower than the standard-cured specimens. Why such a difference in strength?