The new CSA A23.1/A23.2 Standard has been published and is available from CSA on-line HERE.

In addition to the many changes in this standard, there is a new mandatory concrete mix requirement for concrete floors with a steel trowel finish to have a maximum 0.55 water:cement ratio.

Other important concrete floor items include:

• Steel fibres must be accompanied by a Certificate of Compliance and Test Reports in accordance with ASTM A820.
• Under-slab vapour retarders shall be installed in areas with non-breathing finishes and shall comply with ASTM E1745 and ASTM E1643.
• Granular bases shall be level to +/- 10mm prior to ordering a concrete placement (see Position Statement).
• The average slab on grade thickness shall be no more than 10mm less than the specified thickness and no local variations in excess of 20mm less than the specified thickness.
• Owners shall specify concrete mixes, curing and reinforcing as necessary to control curling to suit their needs.
• Sawcut contraction joints shall be spaced at approximately 25 times the slab thickness in metres and shall not exceed 4.5m on centre (see errata note below).
• Semi-rigid joint fillers should not be filled earlier than 120 days after slab casting (See Position Statement).
• Plastic protection procedures must be ready on site when the temperature exceeds 27C or when the water evaporation rate exceeds 0.5 kg/m2/hr.
• Surface tolerances shall be measured within 72 hours of slab casting (See Position Statement).
• The Straightedge Method and F Number System are the only approved means of measuring floor tolerances (Note: The F Number system should be employed where detailed information about the flatness and levelness of a slab surface is required).
• Levelness tolerances do not apply to cambered or unshored suspended slabs.
• F Number system FL tolerance minimum local values have been increased to 60% of the specified overall value.
• Steel trowels shall not be used on air entrained concrete.
• Concrete mixes for floors should have a slump of 100 mm at the point of placement.
• Residential concrete mixes have been added without technical update or modification (Part 9 National Building Code).
• General use cement may be modified with up to 15% inter-ground limestone dust (Type "GUL" cement).
• Table 22 is in compliance with ACI 117.
• Test method 16C permits the on-site washout of both steel and syntehtic fibres to determine the average content in concrete on site.

CSA A23.1-2009 Errata Document

The new CSA A23.1-2009 Concrete Materials and Methods of Concrete Construction will be publishing an errata document. This errata document will not include a necessary change to clause 7.3.2.1 on contraction joint spacing. The wording in this new standard includes the requirement to space contraction joints at a "maximum" of 25 times the slab thickness. This is incorrect. A contraction joint spacing of 25 times the slab thickness provides an "approximate" spacing interval to assist specifiers when determining contraction joint spacings - it should not be defined as a "maximum" spacing limit.

F Number Tolerances

The F-Number system was created in the 1970's to quantify the quality of concrete floor surfaces in terms of flatness (bumpiness) and levelness (tilt). The Canadian concrete standard CSA A23.1 includes a floor tolerance Table 22 which stipulates F-Number tolerances for a variety of concrete floor surfaces. In order to gain information on the application of the tolerance classifications listed in Table 22, the CSA A23.1 Technical Subcommittee 7 (placing, finishing & curing) welcomes the submission of anonymous F-Number data as well as any contractor or client comments for consideration. Click HERE to make a submission.

The Concrete Floor Contractors Association RPO DUNDAS NEYAGAWA, PO Box 30021, Oakville, ON, L6H 7L8 Tel: (905) 582-9825 Fax: (416) 981-3913