November 1999 Table of Contents

Features Placing a Foundation Mat in a Day

Thanks to a great deal of planning and coordination, winter placement of a massive foundation mat for Columbia Center No. 2, a 14-story office building in Troy, Mich., went without a hitch. The 21,000-square-foot mat was placed in November, at a time of year when Michigan weather is always unpredictable. But weather wasn't the only worry. Because the building was part of an office complex and surrounded by existing high-rise structures, parking decks, and parking lots, the concrete placement had to take place on a Saturday, when office traffic is minimal. This gave concrete contractor Simone Contracting Corp. only 1 day to place the nearly 3,200 cubic yards of concrete required for the 4-foot, 2-inch-thick mat. Read more

Features Not the Same Old Grind

According to a study funded by the National Cooperative Highway Research Program, initial pavement smoothness significantly affects future pavement smoothness, leading to pavements that remain smoother longer. But what's the best way to get better initial smoothness so that pavements last longer before requiring rehabilitation because of unacceptable ride quality? Read more

Features When to Challenge Petrographic Reports

A petrographic report is often used in construction disputes or litigation as evidence of poor workmanship by contractors. Contractors may accept these conclusions because they don't understand the limitations of petrographers' techniques. But because of these limitations, some of the conclusions should be challenged. Read more

Features Ensuring Good Vibrations

Longitudinal cracking and low air content due to excessive vibration can cause premature concrete pavement deterioration. Because vibrator frequency is a key controllable factor affecting the consolidation defects that lead to such deterioration, state DOT specifications often require paving contractors to periodically measure the frequency. However, when this requires them to slow or stop the paver and use a hand-held tachometer, it slows production. The solution: Equip the paver's hydraulic vibrators with sensors that monitor frequency and permit a continuous readout. Read more

Features Crack-Sealing Basics

Routing and sealing is a common crack-repair method in which the crack is made wider at the surface with a saw or grinder, and the resulting groove is filled with a flexible sealant. This prevents water and debris from entering the crack yet allows the crack to open and close in response to loads or changing temperatures. Read more

Features Practical Patching

Patching of corrosion-damaged concrete is by far the most common concrete repair procedure, comprising a significant portion of the total repair market. In some cases, rebar corrosion has progressed to the point where the concrete member must be replaced. But in most cases, partial-depth patching is sufficient to prevent further deterioration and extend the service life of the structure. Read more

Products Solving Problems Flatwork Grading Made Easy

For 14 years, JJ Juliano Construction has been installing large commercial and industrial floors in the state of New York. For the last 3 years, the company has been installing the floors much faster thanks to a laser-guided grader attachment for Bobcat s Read more

Problem Clinic Acceptable Rebar Rust

If reinforcing bars have been stored outside and have a coating of rust, how much rust is acceptable? Read more

Problem Clinic Correct Position for Slab Rebar

Where should we place rebar in a floor that's a slab on grade? I've heard it needs to be near the top. But to increase tensile strength, shouldn't it be near the bottom? Read more

Problem Clinic What is Shrinkage-Compensating Concrete?

We have a job calling for shrinkage-compensating concrete. Read more

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