Drainage beads
Polystyrene drainage beads 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. An aggregate comprising a plurality of polystyrene drainage beads, wherein at least some of the drainage beads comprise:
(a) a central spine including a first side and a second side opposite the first side;
(b) at least three first legs extending from the first side of the central spine and defining a plurality of first channels between the first legs, wherein the first channels are wider than the first legs;
(c) at least three second legs extending from the second side of the central spine and defining a plurality of second channels between the second legs; and
(d) a uniform, solid cross-sectional shape along an axis of extension.
2. The aggregate of drainage beads of claim 1 , wherein the plurality of polystyrene drainage beads are expanded polystyrene drainage beads.
3. The aggregate of drainage beads of claim 2 , wherein the cross-sectional shape is perpendicular to the axis of extension, and defines a cross-sectional area and a cross-sectional perimeter, wherein the ratio of the cross-sectional perimeter to the cross-sectional area is greater than 7.7.
4. The aggregate of drainage beads of claim 2 , 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.
5. The aggregate of drainage beads of claim 4 , 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.
6. The aggregate of drainage beads of claim 4 , wherein the plurality of first legs includes a central leg that is longer than the other first legs.
7. The aggregate of drainage beads of claim 2 , further comprising a perforated sleeve enclosing the plurality of drainage beads.
8. The aggregate of drainage beads of claim 7 , further comprising a pipe extending from a first end of the perforated sleeve to a second end of the perforated sleeve.
9. The aggregate of drainage beads of claim 1 , wherein the plurality of polystyrene drainage beads are un-expanded polystyrene drainage beads.
10. The aggregate of drainage beads of claim 9 , wherein the cross-sectional shape is perpendicular to the axis of extension, and defines a cross-sectional area and a cross-sectional perimeter, wherein the ratio of the cross-sectional perimeter to the cross-sectional area is greater than 53.
11. The aggregate of drainage beads of claim 9 , 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.
12. The aggregate of drainage beads of claim 1 , 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.
13. The aggregate of drainage beads of claim 12 , wherein the first and second arms extend in substantially perpendicular directions to the first and second legs.
14. The aggregate of drainage beads of claim 1 , wherein the central spine and first and second legs are substantially planar.
15. The aggregate of drainage beads of claim 1 , wherein the second channels are wider than the second legs.
16. An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise:
(a) a central spine including a first side and a second side opposite the first side;
(b) at least three first legs extending from the first side of the central spine and defining a plurality of first channels between the first legs;
(c) at least three second legs extending from the second side of the central spine and defining a plurality of second channels between the second legs; and
(d) a uniform, solid cross-sectional shape along an axis of extension, wherein the cross-sectional shape is perpendicular to the axis of extension and defines a cross-sectional area and a cross-sectional perimeter, wherein the ratio of the cross-sectional perimeter to the cross-sectional area is greater than 8.
17. The aggregate of drainage beads of claim 16 , wherein the first channels are wider than the first legs and the second channels are wider than the second legs.
18. The aggregate of drainage beads of claim 16 , 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.
19. The aggregate of drainage beads of claim 18 , 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.
20. The aggregate of drainage beads of claim 19 , wherein the at least three first legs include a central leg that is longer than the other first legs.
21. The aggregate of drainage beads of claim 16 , further comprising a perforated sleeve enclosing the plurality of drainage beads.
22. The aggregate of drainage beads of claim 21 , further comprising a pipe extending from a first end of the perforated sleeve to a second end of the perforated sleeve.
23. An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise:
(a) a central spine including a first side and a second side opposite the first side;
(b) at least three first legs extending from the first side of the central spine and defining a plurality of first channels between the first legs, wherein the first channels are wider than the first legs;
(c) at least three second legs extending from the second side of the central spine and defining a plurality of second channels between the second legs;
(d) 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, wherein the first and second arms extend in substantially perpendicular directions to the first and second legs; and
(e) a uniform, solid cross-sectional shape along an axis of extension, wherein the cross-sectional shape is perpendicular to the axis of extension and defines a cross-sectional area and a cross-sectional perimeter, wherein the ratio of the cross-sectional perimeter to the cross-sectional area is greater than 8; wherein a perforated sleeve encloses the plurality of drainage beads.
24. The aggregate of drainage beads of claim 23 , wherein the second channels are wider than the second legs.
25. An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise:
(a) a central spine including a first side and a second side opposite the first side;
(b) at least three first legs extending from the first side of the central spine and defining a plurality of first channels between the first legs;
(c) at least three second legs extending from the second side of the central spine and defining a plurality of second channels between the second legs; and
(d) a uniform, solid cross-sectional shape along an axis of extension; wherein the central spine defines a spine width extending between the plurality of first and second legs; wherein the plurality of 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.
26. An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise:
(a) a central spine including a first side and a second side opposite the first side;
(b) at least three first legs extending from the first side of the central spine and defining a plurality of first channels between the first legs;
(c) at least three second legs extending from the second side of the central spine and defining a plurality of second channels between the second legs; and
(d) a uniform, solid cross-sectional shape along an axis of extension; wherein the plurality of first and second legs each define a leg length extending away from the central spine, and wherein the plurality of first and second legs each define a leg width; wherein the ratio of the leg length to leg width is greater than 1.4.
27. An aggregate comprising a plurality of expanded polystyrene drainage beads, wherein at least some of the drainage beads comprise:
(a) a central spine including a first side and a second side opposite the first side;
(b) at least three first legs extending from the first side of the central spine and defining a plurality of first channels between the first legs;
(c) at least three second legs extending from the second side of the central spine and defining a plurality of second channels between the second legs;
(d) 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, wherein the first and second arms extend in substantially perpendicular directions to the first and second legs; and
(e) a uniform, solid cross-sectional shape along an axis of extension; wherein the first and second arms each define arm length, wherein the plurality of first and second legs each define a leg width, and wherein the ratio of arm length to leg width is greater than 0.25.