January 2002 Table of Contents

Features Spring Training

Believe it or not, spring training for professional baseball is not far away. It seems like just yesterday that the Arizona Diamondbacks unseated the New York Yankees as World Champions. Wouldn't it be nice if we in the concrete industry could have our own "spring training"? Read more

Features Self-Compacting Concrete

A concrete that places itself? Self-compacting concrete (SCC), or self-consolidating concrete, as some prefer to call it, comes close to doing just that. Well-proportioned SCC can flow under its own weight through and around congested reinforcement, filling forms completely and producing a void-free mass with little or no mechanical vibration. Don't confuse it with the other "flowing" concretes that are subject to segregation problems and require vibration to achieve compaction. Read more

Features It Won't Happen to Me

Early one fall morning, a concrete formwork crew was building a machine base in a new industrial plant, using gang forms to encase the mass concrete and tons of reinforcing steel. High placing accuracy was needed because huge base anchor bolts to secure the machine had to line up precisely. A crane was available to handle heavy loads. Read more

Features Electronic Monitoring

The technology used to monitor the health of structures isn't new. It was used even before the mid-'70s when monitoring devices were built for specific job locations and installed to track certain events. Technicians then visited the structure periodically to record data, evaluate it, and produce reports for the owner. But today there's a wide range of "off-the-shelf" sensors, hardware, and software available. Thanks to the Internet, cell phone technology, miniaturized computers, and PDAs, information can be transferred more conveniently. Sensing devices can be installed either during construction or anytime after. Today several companies install and report data in this way. Read more

Features Admixture Innovations in Concrete Construction

"How can I do this job better and faster?" is a question I've heard many times in over 40 years of concrete construction experience. In concrete construction, as in many other areas of business and life, getting things done faster is often more cost-effective. Concrete construction professionals know that time, which is related to manpower, equipment, and materials, affects profitability. One way to save time and reduce cost is using new admixture technologies to influence concrete performance. Read more

Features Why Do I Have to Be Certified?

Why would you want to be certified as a concrete flatwork finisher? What can ACI certification offer you? Do you feel that you know all there is to know about concrete from your own field experience as a contractor, finisher, producer, or project engineer? Read more

Features Slaying the Curling Dragon

Installation of interior slabs on grade for large distribution centers can be both simple and complex: simple in that slabs are large, open areas, flat and generally free of obstructions; complex in the difficulty of maintaining an aggressive schedule, controlling the placing environment, and ensuring consistency in materials and workmanship. Through careful planning, communication, and attention to detail, the project team for the new Ace Hardware Distribution Facility in Loxley, Ala., installed a high-quality slab at a blistering pace. Read more

Features Concrete Contractors and the Internet

By now, the demise of many dot-com's—including a variety of construction-related Web sites—is well known and has been highly publicized. As founder and president of The Concrete Network (www.concretenetwork.com), I have spoken with hundreds of concrete contractors over the past couple of years about their businesses and how they use the Internet. I also have another perspective from being a principal in High Grade Form Inc., a $30 million per year foundation contractor in Riverside, California. Read more

Features Cold Weather

Dan Ellery director of research at Consumers Concrete Co., Kalamazoo, Mich., says that the most common cold weather question he hears from contractors is, "What can I do so that I can place concrete in the winter the same as I do in July?" His answer is, you can't! Ellery tells concrete contractors to think of concrete the same way they think of their own welfare: "If you are cold and need a jacket, the concrete is also reacting to cold conditions and may need cover." Read more

Features The World Trade Center

For decades, industry professionals have debated the performance characteristics and benefits between steel frame structures and concrete frame structures in mid- and high-rise buildings. Until the tragic events of September 11, 2001, specifically those involving the terrorist attack on the World Trade Center, such debates had revolved primarily around theories. As terrible and tragic as the destruction of the WTC is, we, as industry professionals, have the responsibility of looking deeply into the performance of our building structures to reasonably and responsively prevent such immediate destruction and catastrophic failure from happening in the future. The following discussion is not intended to capitalize on this tragedy but to analyze several key factors surrounding the structural failure of the WTC and consider whether a concrete frame would have performed differently. Read more

Features Concrete Innovations

Even as the pace of the construction economy slows, the pace of innovation in materials and equipment seems to accelerate. Remarkable new materials solve problems and create new applications. Tools and equipment allow faster, safer construction and let us look deeply into hardened concrete. The following are brief overviews of only a few of the innovations that we've found. Throughout this issue are other innovative materials and methods, and many more will be featured at the World of Concrete. Read more

Features Innovations for Durable Floors

Innovations in the concrete construction industry are making the difference between the ordinary and the exceptional in floor quality and durability. Distribution Plus Inc. (DPI), specializing in large food distribution centers, has high expectations for quality in its constructed facilities. That's why DPI specified shrinkage compensating concrete (SCC) slabs with a traprock surface hardener for a state-of-the-art distribution facility in Upper Marlboro, Md. Read more

Concrete Basics Concrete Mix Design

Concrete mixes are designed by following a sequence of steps that take advantage of the qualities of the available materials to make a mixture suitable for the work. The goal of mix design is to estimate the required batch weights of each material that will go into a cubic yard of concrete. Selecting proportions involves balancing economy and meeting the requirements for strength, consistency, placeability, density, appearance, and durability. These characteristics are governed by the intended use of the concrete, expected conditions at the time of placement, and job specifications. Job specifications also may dictate requirements for strength, slump, air content, maximum water-cement ratio, minimum cement content, and maximum size of aggregate. Read more

Problem Clinic Metrics and Sieve Sizes

What is the metric equivalent of the #4, #8, and #16 stone and the #467 blend in a recent Concrete Perspectives in Concrete Construction, August 2001? Read more

Problem Clinic Milky Spots

I am having trouble sealing my exposed-aggregate driveway. Read more

Problem Clinic Removing Lime Stains

What is the best way to remove the white calcification from my colored concrete patio? We have very hard water here, and the sprinklers spray onto the patio. Read more

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