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Benefits
Design
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Performance
Appropriate construction techniques are necessary to ensure the performance of pervious concrete. It has a relatively stiff consistency, which dictates its handling and placement requirements. The use of a vibrating screed is important for optimum density and strength. After screeding, the material is usually compacted with a steel pipe roller. There are no bullfloats, darbies, trowels, etc. used in finishing pervious concrete, as such tools tend to seal the surface. Joints, if used, may be formed soon after consolidation or installed using conventional sawing equipment (however, sawing may induce raveling at the joints). Some pervious concrete pavements are placed without joints. Curing with plastic sheeting must start immediately after placement and should continue for at least seven days. Careful engineering is required to ensure structural adequacy, hydraulic performance, and minimum clogging potential. Click here for more information on these topics.
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ConcreteAnswers for Architects, Engineers and Developers:
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About NRMCA
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Privacy Statement © 2008, National Ready Mixed Concrete Association
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The
creation, placement, and curing of concrete are all done
on-site, rather than in a factory under uniform conditions.
Although pervious concrete can be mixed by the same
suppliers and delivered by the same trucks as dense
concrete, its unique physical characteristics require a
contractor with specialized experience. The structural
dissimilarities between pervious and impervious concrete
call for different installation processes, neither of which
is more difficult or time-consuming than the other. However,
the quality and performance of pervious concrete are
dependent upon the installer’s familiarity with the
constructional impact of its properties. This can be gained
only through hands-on experience with the substance, which
is not a commonly-used building material in all locales.
After
placement, pervious concrete has a textured surface which
many find aesthetically pleasing and which has been compared
to a Rice Krispies® treat. Its low mortar content and little
(or no) fine aggregate content yield a mixture with a very
low slump, and with a stiffer consistency than most
conventional concrete mixtures. In spite of the high voids
content, properly placed pervious concrete pavements can
achieve strengths in excess of 3000 psi (20.5 MPa) and
flexural strengths of more than 500 psi (3.5 MPa). This
strength is more than adequate for most low-volume pavement
applications, including high axle loads for garbage trucks
and emergency vehicles such as fire trucks. More demanding
applications require special mix designs, structural
designs, and placement techniques.
