SPECIFICATIONS

File No.: FN321
Page 12
the crawl space during the non-freezing season to remove moisture
accumulations. It is desirable to design the ventilation system with vents that
may be closed with insulated covers during freezing weather.
Void form systems that rely on the decomposition of an organic void forming
material should be avoided.
5.0 SULPHATE ATTACK
No testing was conducted for water-soluble sulphate contents. As the sulphate
content is unknown, Harder Associates would recommend that the concrete be
designed for severe sulphate levels (Class S-2) with sulphate resistant Portland
Cement (Type 50) having a minimum specified 28-day compressive strength of 32
MPa and a maximum water-cement ratio of 0.45 (see Table 3 in CAN/CSA A23.1-
2009). Calcium chloride or any other admixture containing chlorides should not be
used since the sulphate resisting property of the cement would be reduced. Calcium
salts used as an accelerating admixture should also be avoided as they may increase
the severity of sulphate attack.
If Portland Cement (Type 50) is unavailable or cannot be used due to adverse
construction considerations, then Type 10 cement in combination with 30% by mass
of cement (a little less that 30% by mass of cementing materials) of a Type F or CI
fly ash, is expected to produce sulphate resistance equivalent or superior to concrete
made with a Type 50.
Such concretes have demonstrated good performance in CSA A23.1-09 Table 3 S-1,
S-2 and S-3 sulphate exposure environments. The technical basis for this practice
had its origins in work done by HBT, AGRA Limited and AGRA Earth &
Environmental Ltd in the late 1980’s for the major cement companies in British
Columbia. Referenced publications are:
Sulphate Resistance of Different Types of Portland Cements with and without
Supplementary Cementing Materials by D. Hatch and D.R Morgan
Supplying Concrete for Sulphate Conditions by Mark Stewart