February 2000 Table of Contents

Features Fast-Track Forming

Using a combination of forming systems-a modular hand-set system and flying form tables-the concrete contractor for the new twin-tower Diplomat Hotel in Hollywood, Fla., was able to top out the reinforced-concrete structural frame in only 19 months. Read more

Features Stronger, Faster

When determining the true cost of a concrete repair project, owners must consider the financial impact of shutting down a structure to perform the work. Read more

Features Specification Report Card

Over the years, we've had many contractors describe what they believed to be inferior specifications, but it was hard for us to tell if the problem was widespread. To evaluate a broad sampling of concrete specifications, we visited plan rooms in Baltimore, Denver, Detroit, San Diego, and Seattle and did an in-depth review of 50 specifications. Read more

Features Steel-Free Bridge Decks Defy Corrosion

The cancerous corrosion of reinforcing steel in highway bridge decks exposed to salt-laden air or deicing salts leads to ongoing problems of maintenance, repair, and even deck replacement. Read more

Features Crane Quandary

When lifting tilt-up panels, should you operate the crane on or off the floor slab? A general contractor tackling his first tilt-up job discusses how difficult it is to evaluate the pros and cons of each option. Read more

Features Not Gone with the Wind

In tornado-prone areas, safe rooms-located either inside or outside a home-can save lives. The Federal Emergency Management Agency (FEMA) recommends building these windowless shelters using high-strength materials, such as reinforced concrete or masonry, so they can resist winds of up to 250 mph. Read more

Features Lowering the Field, with Concrete

To make room for 9,000 additional permanent seats in Ohio State University's famous horseshoe-shaped football stadium, a construction team had to lower the field area within the stadium 14 feet, eliminating the running track and replacing it with 10 tiers of seats. The work involved surrounding the playing field with a 50-foot-tall concrete wall. Read more

Features Composite Rebar: Bit Player or Rising Star?

Although composites, or fiber-reinforced polymers (FRPs), have been used for many years in the aerospace and sports-equipment industries, only recently have they been considered seriously for widespread use as reinforcing steel in concrete. Read more

Features Troubleshooting: D-Cracking

D-cracking--a series of cracks roughly parallel to joints, edges, or transverse and longitudinal cracks--is typically found in pavements or other flatwork. Read more

Features Sweat the Small Stuff

Stress-management experts suggest that we not worry about the "little" things in life. "Don't sweat the small stuff," we are advised. But most concrete contractors who do residential or light commercial construction or repair will tell you: "If you don't sweat the small stuff, you may not have enough of the large stuff to keep you in business." Read more

Concrete Basics Isolation and Expansion Joints

Slabs on grade may contract, expand, or settle under service conditions. If these movements are restrained, slabs can crack or buckle. Read more

Problem Clinic Crack Around Columns

We placed concrete for the footings and floor slab of an industrial building. The interior column footings are 18 inches deep and contain a bottom and top mat of reinforcing bars. The 6-inch-thick floor slab contains welded wire fabric. Read more

Problem Clinic Removing Curing Compound

We mistakenly used curing compound on a large floor that was to receive a glued-down floor covering. We tried to remove it with a solvent recommended by the curing-compound manufacturer, but it wouldn't come off. Are there any other ways to remove a curin Read more

Problem Clinic Overlay on Flexible Substrate

We're converting an old building for use as apartments. We want to use a thin, polymer-modified, acid-stained concrete overlay on the concrete floors but we're concerned with noise transfer through the floor. To control this, we hope to use an acoustic un Read more

Problem Clinic Adding Air-Entraining Admixture at the Jobsite

If the air content is, say, 3% when the specifications call for 5% to 7%, can an air-entraining agent be added at the jobsite to increase the air content? Or should we just reject the load? Read more

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