Low Impact Development Manual for Michigan - OSEH - University ...

Figure 7.40
Open-graded, clean, coarse aggregate for
infiltration beds
Placement should be continuous and spreading
and strikeoff should be rapid. It is recommended
to strike off about ½ to ¾ inch above the forms to
allow for compaction. This can be accomplished
by attaching a temporary wood strip above the top
of the form to bring it to the desired height. After
strikeoff, the strips are removed and the concrete is
consolidated to the height of the forms.
11. Consolidation should be accomplished by rolling
over the concrete with a steel roller, compacting the
concrete to the height of the forms. Consolidation
should be completed within 10 minutes of
placement to prevent problems associated with
rapid hardening and evaporation. After mechanical
or other approved strike-off and compaction
operation, no other finishing operation is needed.
The contractor will be restricted to pavement
placement widths of a maximum of 15 feet.
12. Jointing: Control (contraction) joints should be
installed at maximum 20-foot intervals. They
should be installed at a depth of ¼ the thickness
of the pavement. These joints can be installed
in the plastic concrete or saw cut. However,
installing in the plastic concrete is recommended.
Joints installed in the plastic concrete should be
constructed using a small roller (salt or joint roller)
to which a beveled fin with a minimum depth of ¼
the thickness of the slab has been welded around
the circumference of a steel roller. When this
option is used it should be performed immediately
after roller compaction and prior to curing. If saw
cut, the procedure should begin as soon as the
pavement has hardened sufficiently to prevent
raveling and uncontrolled cracking (normally just
after curing).
Transverse construction joints should be installed
whenever placing is suspended a sufficient length
of time that concrete may begin to harden. In order
to assure aggregate bond at construction joints, a
bonding agent suitable for bonding fresh concrete
should be brushed, tolled, or sprayed on the existing
pavement surface edge. Isolation (expansion) joints
will not be used except when pavement is abutting
slabs or other adjoining structures.
13. Curing procedures should begin within 15 minutes
after placement. The pavement surface should
be covered with a minimum six millimeter thick
polyethylene sheet or other approved covering
material. Prior to covering, a fog or light mist
should be sprayed on the surface. The cover should
overlap all exposed edges and should be completely
secured (without using dirt) to prevent dislocation
due to winds or adjacent traffic conditions.
14. Porous asphalt should not be installed on wet
surfaces or when the ambient air temperature is
below 50 degrees Fahrenheit. The temperature of
the bituminous mix should be determined by the
results of the Draindown test (ASTM D6390) but
typically ranges between 275 degrees Fahrenheit
and 325 degrees Fahrenheit (as determined by
the testing and recommendations of the asphalt
supplier).
Pervious pavement should be laid in one lift
directly over the storage bed and stone base course
to a 2.5- to 3-inch finished thickness. Compaction
of the surface course should take place when the
surface is cool enough to resist a 10-ton roller.
One or two passes is all that is required for proper
compaction. More rolling could cause a reduction
in the surface course porosity.
15. Do not place Portland Cement pervious pavement
mixtures when the ambient temperature is 40
degrees Fahrenheit or lower, unless otherwise
permitted in writing by the engineer.
16. Mixing, placement, jointing, finishing, and curing
doesn’t apply to permeable paver systems. A
manual on Permeable Interlocking Concrete
Pavements from the Interlocking Concrete
Pavement Institute (Smith, 2006) offers detailed
guidance on the design and construction of
permeable paver systems.
17. After final pervious asphalt or concrete installation,
no vehicular traffic of any kind should be permitted
on the pavement surface until cooling and
LID Manual for Michigan – Chapter 7 Page 252