Permeable traffic bearing structure

Abstract

A traffic bearing structure with a permeable pavement includes a subgrade, a base positioned on top of the subgrade, and a wear surface positioned on top of the base. The base includes aggregate compacted in a single lift, where the aggregate in the base includes different sized particles mixed together. The wear surface includes a permeable pavement. The particle size distribution of the aggregate in the base is selected to provide adequate stability and permeability for the permeable pavement.

1 . A traffic bearing structure comprising:
 a subgrade;   a base positioned on top of the subgrade, where the base includes a top lift compacted to between 90 and 95% as measured by the ASTM D 698 (07) test, where the top lift includes aggregate having varying particle sizes such that essentially all the particles will pass through a 37.5 millimeter screen, some of the particles will not pass through a 12 millimeter screen, and some of the particles will pass through a 5 millimeter screen, and where the particle size distribution is selected such that the top lift has a permeability of at least 30,000 millimeters per day as measured by the ASTM D 2434 (06) test and a California Bearing Ratio (CBR) stability of at least 40 as measured by the ASTM D 1883 (07) test; and   a wear surface including a permeable pavement positioned on top of the top lift.   
     
     
         2 . The traffic bearing structure of  claim 1  where the aggregate particles are sized such that 90 to 100% of the particles pass through a 25 millimeter screen, 60 to 90% of the particles pass through a 12.5 millimeter screen, 30 to 70% of the particles pass through a 4.75 millimeter screen, and 7 to 40% of the particles pass through a 1.18 millimeter screen. 
     
     
         3 . The traffic bearing structure of  claim 1  where the permeable pavement is selected from the group consisting of block pavers, porous asphalt, and porous concrete. 
     
     
         4 . The traffic bearing structure of  claim 1  where the base includes a lower lift comprising aggregate. 
     
     
         5 . The traffic bearing structure of  claim 4  where the aggregate of the lower lift includes particles having a larger average size than the aggregate particles of the top lift. 
     
     
         6 . The traffic bearing structure of  claim 1  where the top lift has a compaction gradient. 
     
     
         7 . A traffic bearing structure comprising:
 a subgrade;   a base positioned on top of the subgrade, where the base comprises an aggregate with varying particle sizes such that essentially all the particles will pass through a 37.5 millimeter screen, some of the particles will not pass through a 12 millimeter screen, and some of the particles will pass through a 5 millimeter screen; and   a wear surface positioned on top of the base, where the wear surface comprises a permeable pavement.   
     
     
         8 . The traffic bearing structure of  claim 7  where 90 to 100% of the aggregate passes through a 25 millimeter screen, 60 to 90% of the aggregate passes through a 12.5 millimeter screen, 30 to 70 % of the aggregate passes through a 4.75 millimeter screen, and 7 to 40% of the aggregate passes through a 1.18 millimeter screen, 
     
     
         9 . The traffic bearing structure of  claim 7  where the permeable pavement is selected from the group consisting of block pavers, porous asphalt, and porous concrete. 
     
     
         10 . The traffic bearing structure of  claim 7  where the base further comprises a compacted top lift positioned over a lower lift. 
     
     
         11 . The traffic bearing structure of  claim 7  where the base comprises one single compacted lift. 
     
     
         12 . The traffic bearing structure of  claim 7  where the lift has a permeability of at least 8,500 millimeters per day as measured by the ASTM D 2434 (06) test and a California Bearing Ratio stability of at least 25 as measured by the ASTM D 1883 (07) test. 
     
     
         13 . The traffic bearing structure of  claim 7  further comprising at least one drain line positioned within the base. 
     
     
         14 . The traffic bearing structure of  claim 7  where the aggregate is compacted to between 90 and 95% as measured by the ASTM D 698 (07) test. 
     
     
         15 . A method for installing a traffic bearing structure comprising;
 (a) preparing a subgrade;   (b) installing a loose aggregate over the subgrade, where all of the aggregate will pass through a 37.5 millimeter screen, some of the aggregate will not pass through a 12 millimeter screen, and some of the aggregate will pass through a 5 millimeter screen;   (c) compacting the aggregate into a top lift; and   (d) covering the aggregate with a permeable pavement.   
     
     
         16 . The method of  claim 15  further comprising:
 (e) installing loose aggregate over the subgrade before (b); and 
 (f) compacting the aggregate into a lower lift before (b). 
 
     
     
         17 . The method of  claim 16  where the loose aggregate from (e) is more coarse than the loose aggregate from (b), 
     
     
         18 . The method of  claim 15  where the top lift is the only lift between the subgrade and the permeable pavement. 
     
     
         19 . The method of  claim 15  where the aggregate from (b) is sized such that 90 to 100% of the aggregate passes through a 25 millimeter screen, 60 to 90% of the aggregate passes through a 12.5 millimeter screen, 30 to 70% of the aggregate passes through a 4.75 millimeter screen, and 7 to 40% of the aggregate passes through a 1.18 millimeter screen. 
     
     
         20 . The method of  claim 15  where the top lift is compacted to between 90 and 95% as measured by the ASTM D 698 (07) test, and the particle size distribution is selected such that the top lift has a permeability of at least 30,000 millimeters per day as measured by the ASTM D 2434 (06) test and a California Bearing Ratio (CBR) stability of at least 40 as measured by the ASTM D 1883 (07) test.