March 2004 Table of Contents

Features Vapor Barriers: Nuisance or Necessity?

The subject of vapor barriers or retarders beneath concrete slabs on grade has long been controversial. Some justifiably argue that slabs placed in direct contact with a vapor barrier or retarder are more susceptible to curling and other slab problems than those cast on a granular base. They consider a vapor barrier or retarder a downright nuisance. Read more

Features Fast-Track Tilt-Up Construction

For many contractors and subcontractors “fast-track” is a dirty word. It often means compressing a building schedule, thereby causing conflict between trades as they scramble to finish their work. Fast-track construction can reduce the quality of a project by forcing installations before conditions are right. Read more

Features If I Can Do It, Anybody Can!

As a concrete contractor who specializes in high tolerance and super flat floors, I usually found the owner and general contractor to be ecstatic with the finished product on the day I poured and finished my floors. I would, in most cases, get paid in a timely manner. But about half the time, anywhere from 6 months to a year later, the floors would show excessive curling, cracking, shrinkage, and sometimes joint rocking. I was beside myself trying to figure out what to do to get the long-term characteristics of my flatwork to be similar to the day I poured it. Read more

Features Project of the Month

Clancy & Theys Construction Company built Saints Peter and Paul Catholic Church in Winter Park, Fla., with a focus on the highest quality construction and craftsmanship. The church required extensive attention to detail. Two major guiding values shaped the design of the church: “intimacy” and “identity.” Read more

Decorative Concrete Why Do Some Overlay Cement Applications Fail?

Overlay cement is one of today’s fastest growing decorative concrete sectors. Overlays can be sprayed very thinly or placed at up to 2 inches thick onto the surface of a slab. Placement can be by trowel or with gage rakes as a self-leveling material. Surfaces might be stamped and textured, flat and smooth, stained, sand-blasted, or multi-colored. Owners choose overlays to save money by sparing the cost of removal and replacement or when it’s important not to disrupt business or public access. But there have been failures with overlays that caused problems for everyone. Read more

Problem Clinic Hole-in-One Driveway

In a driveway that I placed recently, there is a dime-sized hole about a quarter inch deep that doesn’t want to set up. It has been this way for several days now. I’ve been pouring concrete for 15 years and have never seen anything like this. What is it? Read more

Problem Clinic Too Late to Revibrate?

We observed a concrete pour where concrete was revibrated after it had set up. The vibrator head did not “readily penetrate” the concrete as described in ACI 309. In fact the inspector relayed that “it took 15 to 30 seconds of vibrating at each pass for t Read more

Problem Clinic Forming on a Bond Breaker

I need to pour a 9-inch-thick paving slab atop a structural slab, but there is a 3-inch cement stabilized sand bond breaker required between the structural slab and the paving slab. How do I keep my formwork in place while I pour the paving slab? What sor Read more

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