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Concrete Polishing Council Releases Chart Changes

Tuesday, November 14, 2017

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The American Society of Concrete Contractors’ Concrete Polishing Council announced last week that it has released revisions to two charts.

The Polished Concrete Aggregate Exposure Chart and the Polished Concrete Appearance Chart were both amended, the council says.

American Society of Concrete Contractors
The Polished Concrete Aggregate Exposure Chart and the Polished Concrete Appearance Chart were both amended, the council says.

Todd Sharich, ASCC decorative concrete specialist, said that changes to the Exposure Chart came after the ASCC received a high number of calls about the finished product of floors specified as Class C—or medium aggregate.

“In the attempt to reveal the proper sized aggregate, owners felt contractors were not cutting into the floor deep enough,” said Sharich, “forcing contractors to increase tooling and labor costs.”

The change eliminates the medium aggregate surface exposure and the approximate surface cut depths for all classes, the ASCC says. The new classes are:

  • Class A—cement fines: 85-95 percent cement fines, 5-15 percent fine aggregate;
  • Class B—fine aggregate: 85-95 percent fine aggregate, 5-15 percent blend cement fines and coarse aggregate; and
  • Class C—coarse aggregate: 80-90 percent coarse aggregate, 10-20 percent cement fines and fine aggregate.

The Appearance Chart had been based primarily on the finished gloss of the floor, the ASCC says, which many believe could be easily manipulated. The revised chart bases the appearance on Distinctness of Image (the sharpness of images of objects produced by their reflection in a polished surface) and haze index (the cloudiness or milky appearance of images of objects by their reflection in a polished surface).

The chart now also provides measurements for compliance and testing requirements that align with ASTM International standards.

“The founders and charter members of the CPAA kickstarted the polishing industry by creating standards to help achieve acceptance by the design/build community,” said Scharich.

“However, as polishing continues to achieve tremendous growth as a flooring option it became necessary to update these documents. The changes made to the Appearance and Exposure Charts will help contractors meet a defined expectation level. The updated standards will continue to make polished concrete a primary flooring choice that owners can count on for its durability and low maintenance.”


Tagged categories: American Society of Concrete Contractors; Concrete polishing; Concrete Polishing Association of American (CPAA); Decorative Finishes; North America; Polished concrete

Comment from John McGrath, (11/14/2017, 8:13 AM)

Thank You for the changes to the Exposure Chart. Is there a definitive way to differentiate between fine aggregate and coarse aggregate? What is the difference between a reflection that is not distinct and a reflection that is cloudy?

Comment from Jorge Servin, (1/30/2018, 10:38 AM)

This chart will help both Architects and Concrete Polishers to better define the aggregate exposure of the owner ,however concrete mix composition and placement techniques and several other factors should be considered in order to get an even distribution of the aggregates along the floor slab and have them to dry close to the surface , this becomes more relevant on class B and C levels .

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