Hong Kong Regulations

BUILDING (CONSTRUCTION) REGULATIONS - REGULATION 57

Designed mix concrete strengths

(1) Designed mix concrete shall have the specified grade strength in
accordance with Table 5 for the particular application of the concrete except
for marine works or where the concrete is exposed to particularly corrosive
conditions a higher grade strength than that specified may be required.

TABLE 5

DESIGNED MIX CONCRETE GRADE STRENGTHS AND APPLICATIONS

Application Lowest specified grade strength of concrete permissible
Plain concrete except in carriageways 15D Reinforced concrete made with light
weight aggregate (moderate exposure condition) Piles Bond courses in masonry
retaining walls Footpaths

20D Reinforced concrete made with light weight aggregate (severe exposure
condition) Reinforced concrete made with normal weight aggregate (moderate
exposure condition) Carriageways

25D Liquid-retaining structures (moderate exposure condition) Reinforced
concrete made with normal weight aggregate (severe exposure condition)
Pre-stressed concrete with post-tensioned tendons (moderate exposure
condition) 30D Pre-stressed concrete with post-tensioned tendons (severe
exposure condition) Liquid-retaining structures (severe exposure condition)
35D Liquid-retaining structures (severe exposure condition) including those
retaining salt water Pre-stressed concrete with pre-tensioned tendons
(moderate exposure condition) 40D Pre-stressed concrete with post-tensioned
tendons (severe exposure condition) 45D

(2) The cement content of concrete shall be not less than the appropriate
amount given in Table 6.

TABLE 6

MINIMUM CEMENT CONTENT KG/M3 OF FINISHED CONCRETE MADE WITH NORMAL WEIGHT
AGGREGATES

40 mm
maximum
aggregates 20 mm
maximum
aggregates 10 mm
maximum
aggregates Reinforced concrete 260 290 340 Pre-stressed concrete 300 300 360

(3) Concrete shall be tested in accordance with regulation 58 for compliance
with the specified grade strength set out in regulation 59. (Enacted 1990)