April 1996 Table of Contents

Features Meeting Special Design Needs with Custom Wood Forms

By definition, a custom wood form is one that is designed and built for a specific concrete structure. Many contractors find it more economical and efficient to use the prefabricated, modular forming systems now available. Read more

Features Using the New ACI 301

The American Concrete Institute has recently completed a major revision of its long-standing flagship concrete specification, ACI 301, "Specifications for Structural Concrete for Buildings," last revised in 1989. Read more

Features Using the Waviness Index to Improve Floor Flatness

Normal floor placing and finishing practices leave some variations in the finished surface in the form of small bump and dip waves. The location, length, and amplitude of these waves are determined in part by the construction methods and equipment used. Read more

Features 1996 Tilt-Up Achievement Awards

The winners of the 1996 Tilt-Up Achievement Awards provide striking examples of just how adaptable, economical, and beautiful tilt-up structures can be. Read more

Features CRSI Names 1996 Design Award Winners

The Design Award competition is held every two years by the Concrete Reinforcing Steel Institute and its co-sponsor, the American Institute of Architects, to honor outstanding cast-in-place reinforced-concrete structures from across the United States. Read more

Problem Clinic Fine, White Powder on Concrete Surface

We made a 40-cubic-yard concrete pour for a floor on ground that was to receive a machine-troweled finish. The pour started at 7 a.m., and by 10 a.m. finishers who were edging the slab noticed a fine, white dust coming to the surface. Read more

Problem Clinic Permeability of Air-Entrained Concrete

Why is air-entrained concrete less permeable than non-air-entrained concrete? Aren't the air voids permeable to water? Read more

Problem Clinic Shelf Life for Portland Cement

Is there a shelf life for portland cement, or will it last indefinitely? Read more

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