March 29, 2010

CONCRETE PROCESSING AND POLISHING TECHNICAL INSTITUTE

The move to sustainability has brought changes to the composition of concrete.

Concrete and Masonry

Best materials can’t compensate for shoddy concrete work

DAN O’REILLY

correspondent

New product developments and technical advances in technology aside, the traditional emphasis on communication remains paramount to produce high-quality concrete floors, says an industry expert.

That communication — involving floor contractors and owners and their representatives — starts right at the tender stage, said Geoff Kinney, executive director of the Concrete Floor Contractors Association, which recently made the move from a provincial to a national non-profit organization representing contractors and suppliers.

Speaking at an annual industry seminar, Kinney told an audience of owners that ensuring high quality begins with naming of trades on the tender form to avoid problems caused by the last-minute award of work. This allows sufficient project planning time, proper scheduling of work, ordering of specified materials and ensures pre-qualification compliance.

“It also allows you (the owner) to understand what you are buying and eliminates an opportunity for bid shopping,” he said.

Despite new technological product developments, mixing good materials with poor workmanship will still result in a poorly performing floor, he said.

“Workmanship is commonly the weak link. A worker may possess skills, but not the essential knowledge to build good floors that are in compliance with CSA (Canadian Standards Association) standards.”

The new CSA A23.1-09 Concrete Materials and Methods is now the updated standard for concrete materials and methods of concrete construction, he pointed out.

Of course, the combination of cheap materials and good workmanship won’t produce any better results. Not all materials are equal in cost or performance, warned Kinney, who recommended a regular inspection program to eliminate the use of unapproved material substitutions.

“There is no such thing as normal concrete anymore,” said Kinney, noting that cement content is being increasingly replaced with flyash byproducts for concrete production.

While this is being done for environmental sustainability reasons, the use of those substitutes is creating unique protection, finishing and durability concerns.

Lower cement content, for example, creates longer drying periods for applied finishes and lower wear resistance.

“Use of these materials requires greater handling and protection requirements,” said Kinney, explaining that a major problem now being encountered in floor construction is plastic shrinkage.

Avoiding new problems and long existing ones, such as curling at the floor joints, isn’t easy considering the very nature of construction where schedules are short, site conditions vary significantly and planning time can be almost non-existent due to those last minute awards.

Nevertheless, with project co-ordination and precautions, those challenges can be met.

While the concrete flooring contracting industry has become more sophisticated and involved in the actual floor design compared with 20 or 30 years ago, the main point of communication on the project still has to be between the flooring contractor and the main contractor, he said.

Touching on the need for planning, Kinney also said that preconstruction meetings need to be held at least one month before the actual pour.

This ensures the owner’s expectations are understood and provides an opportunity for contractors to express any concerns prior to the actual construction.

Critical material for those meetings is floor mock-ups and the shop drawings.

“It’s very important that the specification writers ensure what’s going into the project is exactly what was specified,” he said.

Critical to the project’s success is the inspection process both during construction and after it has been completed.

“I’m a huge fan of inspection,” Kinney said.

“We (contractors) do go back to make sure the floor is performing well.”

But it is also incumbent on owners to conduct their own inspection to report any problems. Some owners only do that to “varying degrees.”

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