Pervious Concrete: How to Properly Place and Cure by ProQuest


More Info
									Green Building                    Kimberly Johnston, Associate Editor

Pervious Concrete: How to
Properly Place and Cure
A successful concrete
pour starts with
proper placing and
curing — the same
can be said for
pervious concrete.

        pervious concrete pour is a
        three-step process — placing
        to elevation, compaction and
curing. Unlike traditional concrete
which looks for a smooth, finished
surface, pervious concrete contrac-
tors strive for compaction, aggregate
interlock and a porous surface.

The pour                                    A pervious concrete pavement placement works like an assembly line, says Dale
Like traditional concrete, there are many   Fisher, with crew members working the ready-mixed truck’s chute, members
                                            working the screed, and others following with finishing tools.
different methods and equipment for
pouring pervious concrete. However,
since pervious concrete is a low-slump      need a definite straight edge, such as      provide the same consistency of com-
mixture, it cannot be pumped into           trail pathways.                            paction that screeds can, Fisher says.
place like traditional concrete. The most      Fisher likens a pervious pour to that   Contractors also need to avoid over-com-
common methods of placement are             of a long assembly line with the only      paction when using plate compactors.
directly from a ready-mixed truck, with a   difference being the crew members            The screed is followed by the finish-
concrete buggy or by conveyor.              are working much closer together           ing crew, which has multiple jobs.
  Pervious concrete is commonly             during a pervious pour. “Everything        After screeding the pervious, it needs
poured in formed-out strips, says Dale      happens at the same time with pervi-       to be cross rolled. Typically, one crew
Fisher, CEO of PCI Systems, LLC.            ous concrete. With regular concrete        member follows behind the screed
Strips are poured every other to allow                        ”
                                            it’s spread out, Fisher says. “With        with a cross roller, rolling in a perpen-
the pervious the proper amount of           traditional concrete the whole slab is     dicular direction to the screed. Cross
curing time. Current documents spec-        placed before the finishing operation       rolling gives the finish a nice continu-
ify contractors pour strips between         even begins. With pervious concrete        ity, Fisher says.
12 and 20 feet wide. However, this          your placement, finishing and curing is       Joints are also placed during this
can be a challenge when pouring very        all done at the same time.    ”            stage. Fisher says they are placed just
large areas that have tight scheduling         Typically, there is one crew member     like traditional concrete joints by either
deadlines. New equipment, such as           near the ready-mixed truck’s chute (or     using a roller jointer while the pervious
laser screeds, allows contractors to        by the buggy or conveyor) directing the    is still wet or sawing the joints after it
pour larger areas without strips for        pervious concrete where it should go.      has cured.
situations like these.                      The screed operators are the next in         The final finishing crew members
  Some pervious concrete can be             line, screeding the pervious concrete      follow with hand floats to touch up the
placed with a concrete slipform paver.      to the proper elevation and compacting     edges. “Don’t use
To top