Changes

===Pervious concrete===

===Pervious concrete===

Concerns over the resistance to the freeze-thaw cycle have limited the use of pervious concrete in cold weather environments.<ref name="Cold Weather">Vernon R. Schaefer, Keijin Wang, Muhammad T. Suleiman, John T. Kevern, Mix Design Development for Pervious Concrete in Cold Weather Climates, , Iowa State University, Ames, IA, 2006 National Concrete Pavement Technology Center. Report No. 2006-01.mix_design_pervious.pdf</ref> The rate of freezing in most applications is dictated by the local climate. Entrained air may help protect the paste like in normal concrete.<ref name="Entrained Air"/> The addition of a small amount of fine aggregate to the mixture increases the durability of the pervious concrete.<ref>J. Kevern, John K. Wang, V.R. Schaefer, Iowa State University, 2008</ref> Avoiding saturation during the freeze cycle is the key to the longevity of the concrete.<ref name="Concrete Tech">{{cite web|title=Pervious Concrete and Freeze-Thaw|url=http://www.cement.org/tech/Pervious_print.html |work=Concrete Technology E-Newsletter |publisher=PCA |accessdate=30 September 2012}}</ref> Related, having a well prepared 8 to 24&nbsp;inch (200 to 600&nbsp;mm) [[Grading (engineering)|sub-base]] and drainage will reduce the possibility of freeze-thaw damage.<ref name="Concrete Tech"/>

Concerns over the resistance to the freeze-thaw cycle have limited the use of pervious concrete in cold weather environments.<ref name="Cold Weather">Vernon R. Schaefer, Keijin Wang, Muhammad T. Suleiman, John T. Kevern, Mix Design Development for Pervious Concrete in Cold Weather Climates, Iowa State University, Ames, IA, 2006 National Concrete Pavement Technology Center. Report No. 2006-01.mix_design_pervious.pdf</ref>  

The rate of freezing in most applications is dictated by the local climate. Entrained air may help protect the paste like in normal concrete.<ref name="Entrained Air">  

The addition of a small amount of fine aggregate to the mixture increases the durability of the pervious concrete.<ref>J. Kevern, John K. Wang, V.R. Schaefer, Iowa State University, 2008</ref>  

Avoiding saturation during the freeze cycle is the key to the longevity of the concrete.<ref name="Concrete Tech">Pervious Concrete and Freeze-Thaw http://www.cement.org/tech/Pervious_print.html Concrete Technology E-Newsletter PCA 30 September 2012</ref> Related, having a well prepared 8 to 24&nbsp;inch (200 to 600&nbsp;mm) sub-base and drainage will reduce the possibility of freeze-thaw damage.<ref name="Concrete Tech"/>