Bruce Suprenant, P.E.

Suprenantbruce1206 10364169

http://www.bsuprenant.com

Phone:(303) 499-0264

Bruce A. Suprenant, PhD, PE, FACI, is a concrete consultant and technical direcator at the American Society of Concrete Contractors. Reach him at [email protected].

The Contractor’s Welded Wire Reinforcement WWR Dilemma

The Contractor’s Welded Wire Reinforcement (WWR) Dilemma

There needs to be an alternative to removal and replacement for WWR.

Ideally, a cambered cast-in-place slab deflects just enough to take out the camber and result in a uniform-thickness slab with the surface at the design elevation. That rarely happens.

Approach Form Camber Specifications with Caution

Cast-in-place reinforced concrete structural members deflect under load. Whatever the cause of the problem, engineers have sometimes tried to control deflection effects by requiring cambered form soffits.

Challenging the System image ASCC 14 Anchor Bolt Location 58e3ab694fae0

A Tolerance Compatibility Success

ASCC, ACI and AISC anchor bolt placement tolerances are now identical.

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Concrete Slump Should Not Be Specified

The concrete producer and contractor should determine slump requirements.

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MOE Specifications on a Project Near You!

Seek to understand before committing to modulus of elasticity requirements.

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Having Tolerance Compatibility Problems?

ACI 117.1R-14 can help.

Contractors Make Recommendations Based on Experience

Contractors citing previous experience should make their recommendations with the understanding the final decision will be made by the designer and owner.

Stop Me If You’ve Heard This One…Anecdotes Masquerading as Data

When slabs on ground are polished, non-uniform exposure of aggregate is a result of high spots cause by slab curling. Deflection of many suspended slabs exceeds the upward movement at curled slabs, so polishing may result in even larger areas that exhibit such non-uniform aggregate exposure.

Why Polishing Suspended Concrete Slabs is More Likely to Disappoint Customers

Polished-concrete specifications are based on experience with slabs-on-grade, so contractors must help project owners understand how results will likely vary when polishing suspended slabs

Whatever Happened to Engineering Judgment?

When a test result falls outside of the specified limits or other specification requirements aren’t met, engineers typically have three options for dealing with such noncompliance issues.

In this view, beams, girders and slabs (floors) are the horizontal structural members, while columns and walls are the vertical members.

Understanding ACI 117 Tolerance Language

“I have a beam and a column, what ACI 117 tolerances apply where?” To make it easier to discuss, we developed a graphical approach using an elevation and plan view of a beam and column similar to what callers see on the construction drawings.

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Why is the Acceptance of Concrete Test Results Still a Struggle?

The acceptance criteria for concrete strength tests have been the same since the early 1970s but have often been interpreted incorrectly. ACI E702 provides a step-by-step example of concrete test-result evaluation and an explanation.

Innocent Until Proven Guilty: Unless You’re a Contractor

How to Make an Irrational Inspector Rational

Learn about five ways a contractor can challenge an inspector.

Some Specifications Just Aren’t Fair

Where are the obstruction-free vertical runs of 4' x 6' minimum cross section to permit vibrator insertion?

Define Constructibility!

Figure 1 Fins and offsets can be the result of form leakage. But fins and offsets have tolerances as described in ACI 117 and ACI 301. Fins and offsets are allowed but the height of each is controlled by the tolerances. If form leakage were prevented, there should be no tolerances. The fact that the tolerances are included in both ACI 117 and ACI 347 means that form leakage is acceptable but is limited by these ACI documents.

Formwork Mortar Leakage

A concrete contractor recently had a close-out meeting with the Owner and Construction Manager, and was be surprised by the demand for a reduction in payment based on form leakage.

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Challenging the System: Need Help With A Business Question?

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Adding Calcium Chloride to Improve Cold Weather Concrete Pouring

Calcium chloride is the most effective and least expensive cold weather accelerator for concrete. But its use may be limited by building codes or prohibited by some specifications.

New ACI Code Requirements for Anchor Installation

The new ACI code requirements for concrete adhesive anchor installation will cost contractors time and money to certify personnel.

Construction schedules and contractor economics typically require concrete placements of 10,000 to 20,000 square feet or from 30,000 to 50,000 square feet when a Laser Screed is used. This figure shows a 300,000 square foot pour that was completed within 24 hours in a single concrete placement.

Specification Limits on Slab-on-Grade Placement Size

ACI 302 has stated since 1980 that a limited placement size concept has not achieved any better shrinkage results, is more expensive, and adds time to the schedule.

The penetrations required in this depressed area in an elevated floor slab make it difficult to use 10-foot straightedges and riding power trowels. Specifiers should consider these multiple obstructions to finishing operations when determining F-number values. In this case, the specifier required F-numbers in the small depressed floated area that was to receive ceramic tile for bathrooms.

The Limitations of F-Number Specifications

Contractors need to be cognizant of certain situations that make it difficult to achieve routine FF and FL requirements and know how to get those specifications changed to more reasonable requirements.

Reinforcing steel is so congested in the shear wall boundary element (right side of photo) that concrete must be placed in the less heavily reinforced shear wall section (left side of photo) and vibrated at that point to move it laterally into the boundary element.

Show Us the Data

Authoritative statements in ACI documents are often unaccompanied by any reference to published data that validate the statements. That’s a problem.

Beware of Risk Transfer: Part 2

Making contractors responsible for building code requirements.