February 1997 Table of Contents

Features So You Want to Slipform Median Barriers

What's involved in producing slipformed median barriers? The scope of most barrier-wall projects requires a big investment in equipment and manpower, thorough job preparation and organization, and attention to base construction and reinforcing-steel placement. Once the site is carefully prepared, it's necessary to carefully choreograph the movements of work crews, ready mix trucks, and the paver. If a slipformer is to work properly, it needs a continuous supply of uniform concrete. Read more

Features Troubleshooting Slipform Paver Operations

The stringline is set, the paver is ready, and concrete has arrived. But even when all the preliminary work is done carefully, it's still important to check the first 15 to 20 lineal feet of paving placed each day to make sure you're on grade, line, and slope, and that the surface finish is acceptable. Read more

Features Ultra-Thin Whitetopping

Ultra-thin whitetopping (UTW) is a concrete overlay 2 to 4 inches thick, with closely spaced joints, bonded to an existing asphalt pavement. The concrete industry's newest remedy for rutted asphalt pavements, UTW combines current concrete bridge deck overlay bonding technology with early sawing of closely spaced contraction joints. This produces a bonded composite pavement, with minimized tensile stresses in the concrete layer. Read more

Features Production Paving Saws That Pack a Punch

Your job: to cut control joints in a highway's green concrete as quickly and efficiently as possible. One of the easiest ways to do that is to use a saw with a horsepower (hp) rating of at least 65. Most of today's big jobs can be cut to size with the 65- to 75-hp saws featured in this product roundup. And if you plan to tackle a monster job, be sure to check out the 112-hp saw or the 250-hp span saw also described in the article. No matter which of these saws you choose, you're sure to have plenty of power to play with on your next job. These versatile machines can be used to tackle many jobs, ranging from the full-depth removal of slabs to the shallow control-joint sawing that's the focus of this roundup. Read more

Features High-Performance Plywoods for Concrete Forming

Several manufacturers offer plywoods with durable, impervious coatings designed to substantially improve the off-the-form finish of concrete. Designed to go beyond standard high-density and medium-density overlays, these coatings resist moisture absorption, improve panel strength and stiffness, and produce smooth, mirrorlike finishes. Some of the coated panels can provide 100 or more reuses. Read more

Features Diamond Blade Basics

When properly matched to the job and to the saw being used, diamond blades provide fast, economical cuts and a long service life. But using the wrong blade for job conditions, a saw that turns the blade at improper speed, or poor sawing techniques can shorten blade life and hike cutting costs. Read more

Problem Clinic Is Craze Cracking a Terminal Illness?

We just completed a concrete floor that is acceptable in every respect except one: There are numerous craze cracks over much of the surface. Read more

Problem Clinic What Is Green Concrete?

The term green concrete is sometimes used in specifications, but it seems as if everyone defines it differently. What does the term mean? Read more

Problem Clinic Stripping Wall Forms During Cold Weather

We recently placed concrete walls in metal forms during a period when daily temperatures were around 50 F, but evening temperatures dropped to 25 F. The day after placing concrete, my foreman checked the concrete at the top of the form and found it was st Read more

Problem Clinic Patching Material for -10º F Temperatures

We need to patch some core holes in a freezer room floor. But the freezer temperature is -10 F and the room can't be warmed to allow patching. Is there a product that can be used under these conditions? Read more

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