Some things you should know
about Blue Circle Type K
The design, manufacture and placement of
Type K Shrinkage Compensating Concrete differ from ordinary portland concrete. In order to
realize all the benefits of Type K, you must adhere strictly to the practices detailed in
the American Concrete Institute's "Standard Practice For Use Of
Shrinkage-Compensating Concrete" (ACI-223).
- In order to ensure that local aggregates and admixtures complement expansion, concrete
mix designs using our Type K Expansive Cement should include the ASTM C-878 tests showing
concrete restrain expansion.
- We recommend a minimum of 612 lbs. of cement for the basic 4000 p.s.i. concrete. This is
for strength and expansion. We also recommend a minimum of 0.15% reinforcing steel in
cross- sectional areas for shrinkage compensation.
- Adequate moist curing for seven days is necessary to ensure design expansion.
- When placing Type K Concrete outside, evaporation of surface moisture can cause plastic
shrinkage cracking. To avoid this problem, precautions should be taken to protect the
surface. These include fogging, curing compound or a combination thereof.
- The width to length ratio of a slab should not be greater than 1:3 without special
design consideration.
- Where temperature changes are minimal, slabs on grade have been placed up to 150 feet
between joints with good results.
- To prevent cracking at re-entrant corners, it is advised to place additional reinforcing
at these locations.
30 years later and no cracks in this extremely heavy-duty
airlines warehouse floor at Atlanta's Hartsfield Airport (Three adjacent slabs built with
ordinary portland concrete after 1967 have been replaced twice.)
As with any concrete construction,
compliance with ACI-318 "Building Code Requirements for Reinforced Concrete-and any
other applicable codes and practices is required
