15 September 1999
(15) High plasticity soil should be removed to a depth of 1 m (3 feet) below the water
barrier and 600 mm (2 feet) below the perimeter beams and replaced with non-expansive soil.
7. DRAWINGS AND SPECIFICATIONS. Appropriate sections of the drawings and
specifications should address items essential to limiting shrinkage cracking and other RRMS
details to ensure proper and complete conveyance to the Contractor. The following items
should be addressed.
a. Slab details.
(1) Slab reinforcement "t/4" (t = slab thickness in inches) clear below top of slab;
where "t/4" will not be less than 38 mm (1.5 inches) nor greater than 64 mm (2.5 inches).
Minimum slab reinforcement will be 0.5% with a maximum spacing of 230 mm (9 inches) each
(3) Capillary water barrier.
(4) Vapor barrier.
(1) Construction joint spacing and details.
(2) Place-in lanes should be a maximum of 7.6 m (25 feet) wide. For Air Force
projects lanes should be a maximum of 6 m (20 feet).
(3) Weakened plane joints in vehicular loaded slabs should be spaced a maximum of
20 to 30 times the slab thickness for adequate crack control.
(4) Details of reinforcement at re-entrant corners and around openings in the slab.
Slab reinforcing steel should be anchored into perimeter beams.
(5) Detailed foundation preparation instructions should be provided.
(6) Compressive 28-day concrete strength and yield strength of reinforcing steel.
(7) Beam size, spacing and reinforcement.
(1) The minimum 28-day compressive strength should be 21 Mpa (3.0 ksi) for RRMS
concrete. Vehicular loaded slabs require 28 Mpa (4.0 ksi) 28-day compressive strength.
Flexural strengths should not be specified.
(2) Water/cement ratio should be a maximum of 0.42.