April 1983 Table of Contents

Features Post-Tensioning Systems

In post-tensioned work the concrete is cast in a way that allows the concrete to harden before the tendons are stressed. This can be done by using tendons that have been coated with grease and encased in plastic sheathing during manufacture. Read more

Features Details and Shop Drawings for Post-Tensioned Buildings

Where construction difficulties, problems, or accidents develop on a project, litigation may develop relative to liability for financial losses. Read more

Features Grouting Post-Tensioning Ducts

Bonded tendons, installed in ducts or voids within the concrete, must be grouted for protection after tensioning. The grouting of tendons tensioned to 80,000 psi or more is a demanding job that requires special skills and materials. Read more

Features Insulated Post-Tensioned Concrete Roof Is Waterproof

The post-tensioned concrete roof of the Ruth Fisher School near Tonopah, Arizona, is not finished with any roofing material. The concrete was simply left as cast. A conventional 4000-psi mix was used, but to keep cracks from forming and to keep cracks that do form watertight, the amount of post-tensioning force was increased. Instead of being stressed to the normal 140 to 150 psi, the school roof was post-tensioned to 280 to 300 psi. Read more

Features Post-Tensioned Segmental Construction

A good example of post-tensioned segmental construction is the Ely Viaduct in Wales. The highway design features a 2000-foot radius curve crossing the River Ely at an acute angle with a 538-foot-long twin-box girder. The 230-foot central span and 150-foot side spans were constructed by the balanced cantilever method. Read more

Features Inspection of Post-Tensioned Concrete: Who and Why?

While inspection is not a cure-all, it goes a long way in eliminating jobsite problems and assuring quality construction. The owner can frequently save money when post-tensioning is properly used. However, these potential savings may disappear if the structure is inadequately constructed. Read more

Features How Does Shrinkage-Compensating Cement Concrete Help Post-Tensioning?

Shrinkage-compensating cement concrete can complement the benefits of post-tensioning by reducing the normal amount of loss of prestress, reducing flexural cracking and improving durability. Read more

Features Post-Tensioning for Bell Parking Garage: Cover Story

Construction of Southwestern Bell Telephone Company's 1150-car, 11-floor parking garage at their Texas headquarters complex presented an exciting challenge for the design development team and for the contractor. Read more

Problem Clinic Pavement Buckling

Why do we occasionally run into concrete pavement buckling on hot summer days? So far as we know there is no trouble in our area with expansion from reactive aggregates. Read more

Problem Clinic Radius at Top Edge of Saw Cuts

Specifications for a food factory floor call for 15,000 linear feet of sawed joints 1/8 inch wide and 1 1/2 inch deep and another 5000 linear feet of joints 3/16 inch wide and 1 inch deep. They also require a radius at the top of the saw cuts. How can thi Read more

Problem Clinic Measuring Depth of Frost

Is there a standard way of measuring the depth of frost that still exists in the ground? We would like to know how soon we can start work again after the winter freeze. Read more

Problem Clinic Rainy Weather

In our part of the country we don't have much trouble with rain. Read more

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