MPA Explained

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MPA Explained

Concrete Strength

Concrete is measured by its strength capacity. MPa (megapascals) is the metric measurement for psi or pounds per square inch. The BC Building Codes require a minimum MPa for specific concrete projects. Please refer to the table to choose the appropriate MPa when calculating your volume and price.

Concrete Location	BCBC Minimum Strength (MPa)	BCBC Maximum W/C* Ratio	BCBC Air Content	Suggested Strength (MPa)	Maximum W/C Ratio	Optimum Air Content Range
Footing, walls, foundations	15	0.70	n/a	20 - 25	0.55 - 0.60	3-5%
Interior flatwork	20	0.65	n/a	25 -28	0.50 - 0.55	3-5%
Garages, carports	32	0.45	5-8%	32	0.45	5-6%
Exterior flatwork	32	0.45	5-8%	32	0.45	5-7%

BCBC = BC Building Code 2006: Housing and Small Buildings

Notes:

Concrete is mixed with the correct “air-entrainment” (optimum air content). The following are some general guidelines.

For garages, carports and any exterior flatwork that will be troweled, keep air in the low range - close to 5%. This will help reduce “crusting“ of the surface and blistering.
For exterior flatwork that will not be troweled (broomed, exposed, etc.), keep air around 6% for freeze-thaw durability.
For interior flatwork that will be troweled, keep air around 4%. This will help control bleeding and not cause blistering.

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