Drainage beads

Abstract

Polystyrene drainage heads having optimized shapes to provide increased specific gravity and void volume at a given bulk density. Expanded forms of such drainage beads may be used as a geosynthetic aggregate in pre-assembled drainage units. Such pre-assembled drainage units may be used as foundation drains, septic drainage fields, or for other applications.

1 - 27 . (canceled) 
     
     
         28 . An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise a central spine including a first side and a second side opposite the first side and a plurality of legs-extending from the central spine and defining a plurality of first channels between the first legs and a plurality of second channels between the second legs; and wherein the aggregate of expanded polystyrene drainage beads further comprise a specific gravity and a bulk density such that a ratio of specific gravity to bulk density is greater than 2.3. 
     
     
         29 . The aggregate of drainage beads of  claim 28 , wherein the ratio of specific gravity to bulk density is greater than 2.4. 
     
     
         30 . The aggregate of drainage beads of  claim 28 , wherein the ratio of specific gravity to bulk density is greater than 2.5. 
     
     
         31 . The aggregate of drainage beads of  claim 28 , wherein the first channels are wider than the first legs. 
     
     
         32 . The aggregate of drainage beads of  claim 28 , wherein the first side comprises at least three first legs. 
     
     
         33 . The aggregate of drainage beads of  claim 32 , wherein the second side comprises at least three second legs. 
     
     
         34 . The aggregate of drainage beads of  claim 28 , wherein the central spine defines a spine width extending between the plurality of first and second legs and wherein the plurality of first and second legs each define a leg length extending away from the central spine; wherein the ratio of the leg length to the spine width is greater than 0.75. 
     
     
         35 . The aggregate of drainage beads of  claim 34 , wherein the plurality of first and second legs each define a leg width; wherein the ratio of the leg length to the leg width is greater than 1.35. 
     
     
         36 . The aggregate of drainage beads of  claim 34 , wherein the plurality of first legs includes a central leg that is longer than the other first legs. 
     
     
         37 . The aggregate of drainage beads of  claim 28 , further comprising a perforated sleeve enclosing the plurality of drainage beads. 
     
     
         38 . The aggregate of drainage beads of  claim 37 , further comprising a pipe extending from a first end of the perforated sleeve to a second end of the perforated sleeve. 
     
     
         39 . The aggregate of drainage beads of  claim 28 , wherein the central spine defines a spine width extending between the plurality of first and second legs and wherein the plurality of first and second legs each define a leg length extending away from the central spine; wherein the ratio of the leg length to spine width is greater than 2. 
     
     
         40 . The aggregate of drainage beads of  claim 28 , wherein at least some of the drainage beads further comprise a first arm extending from a third side of the central spine and a second arm extending from a fourth side of the central spine. 
     
     
         41 . The aggregate of drainage beads of  claim 40 , wherein the first and second arms extend in substantially perpendicular directions to the first and second legs. 
     
     
         42 . The aggregate of drainage beads of  claim 28 , wherein the central spine and first and second legs are substantially planar. 
     
     
         43 . The aggregate of drainage beads of  claim 28 , wherein the second channels are wider than the second legs. 
     
     
         44 . The aggregate of drainage beads of  claim 33 , wherein the central spine defines a spine width extending between the at least three first and second legs; wherein the at least three first and second legs each define a leg length extending away from the central spine; and wherein the ratio of the leg length to spine width is greater than 0.8. 
     
     
         45 . The aggregate of drainage beads of  claim 44 , wherein the at least three first and second legs each define a leg width; wherein the ratio of the leg length to leg width is greater than 1.4. 
     
     
         46 . An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise a central spine including a first side and a second side opposite the first side and a plurality of legs-extending from the central spine and defining a plurality of first channels between the first legs and a plurality of second channels between the second legs; and wherein the aggregate of expanded polystyrene drainage beads further comprise a specific gravity and a bulk density such that a ratio of specific gravity to bulk density is greater than 2.3 and less than 2.875.