Prestressed pavement system

• US 6,409,423 B1
• Filed: 03/15/1996
• Issued: 06/25/2002
• Est. Priority Date: 04/29/1994
• Status: Expired due to Fees

• Current Assignee: Ran Li
• Original Assignee: Ran Li
• Inventors: Li, Ran
• Primary Examiner(s): Hartmann, Gary S.
• Application Number:
  US08/616,086
• Time in Patent Office: 2,293 Days
• Field of Search: 404/27, 404/30, 404/34, 404/43-45, 404/31, 404/67, 404/70, 404/72, 404/75, 404/49, 404/17, 522/231, 522/232, 522/236, 522/237, 522/231.4, 264/228, 264/229, 604/77, 604/78, 138/26, 138/30
• US Class Current: 404/49
• CPC Class Codes: E01C 11/14 Dowel assembly ; Design or construction of reinforcements in the area of joints coupling devices for prefabricated units E01C5/005; combined with characteristic packings E01C11/08 - E01C11/12; removable holders E01C23/045
• CPC Class Codes: E01C 2201/12 vertically interlocking
• CPC Class Codes: E01C 5/10 Prestressed reinforced units ; Prestressed coverings from reinforced or non-reinforced units prestressed concrete coverings E01C7/16
• CPC Class Codes: E04C 5/08 Members specially adapted to be used in prestressed constructions production of reinforced objects in general B28B23/00; prestressed structures produced in situ E04G21/12

Abstract

A prestressed pavement has apparatus to prestress the slabs, has slab abutments to resist the prestress force, has short-life friction-reducing medium to prevent the slab early cracking, has restraints to prevent the slab buckling, and has accumulators to control the prestress. The pavement does not need longitudinal tensile material, and can be built by continuous and one-time concrete casting. The prestressing is simple, fast, and may be delayed or made by stages. The techniques can be used to convert existing non-prestressed concrete pavements to prestressed pavements.

Claims

1. A prestressed pavement comprising:

(a) slabs on a support base,

(b) at least one hydraulic apparatus between said slabs for providing prestress on said slabs, and

(c) means for regulating said prestress, said means communicating with said apparatus and comprising hydraulic means for supplementing said prestress and damping the prestress rise.

2. A prestressed pavement according to claim 1, wherein said apparatus comprises slit-forming means for forming a slit between said slabs and slit-expanding means for expanding said slit for prestressing said slabs, said slit being a non-through slit.

3. A prestressed pavement according to claim 2, wherein said apparatus further comprises indicating sticks, said sticks exposing on the slab surfaces after said slabs form for indicating cutting position.

4. A prestressed pavement according to claim 1, wherein said apparatus comprises at least one thin flexible tube containing hydraulic fluid.

5. A prestressed pavement according to claim 1, further comprising at least one thin flexible tube to be filled with temporarily flowable material for narrowing the gap between said slabs, said tube being substantially parallel to said apparatus.

6. A prestressed pavement according to claim 4 being built by converting a non-prestressed concrete pavement to it.

7. A prestressed pavement according to claim 1, wherein said hydraulic means comprise at least one hydraulic accumulator.

8. A prestressed pavement according to claim 7, wherein said accumulator comprises at least one vessel containing fluid and compressed gas.

9. A prestressed pavement according to claim 7, wherein said accumulator is embedded underground.

10. A prestressed pavement according to claim 1 further comprising a friction-reducing medium between at least one of said slabs and said base, said medium comprising a layer of lubricating jelly, whereby before the slab gains sufficient strength, the slab cracking is prevented.

11. A prestressed pavement according to claim 10, wherein said jelly comprises means for converting its top layer, under atmospheric action, into a thin flexible tensile layer to protect said jelly during making the slab.

12. A prestressed pavement according to claim 10, wherein said medium further comprises a layer of thin flexible material between said jelly and the slab for protecting said jelly during making the slab.

13. A prestressed pavement according to claim 10, wherein the jelly base material is at least one of water and oil.

14. A prestressed pavement according to claim 10, wherein said jelly has means for disabling itself from lubricating function after said pavement is built.

15. A prestressed pavement according to claim 1 further comprising a layer of adhesive material in at least one area between at least one of said slabs and said base, said material adhering to the slab and said base, whereby when the slab area gets upward deflection, vacuum occurs in said area for preventing the slab buckling.

16. A prestressed pavement according to claim 15, wherein said area encompasses another area not having said material.

17. A prestressed pavement according to claim 15, wherein said material is ductile.

18. A prestressed pavement according to claim 15, wherein said material is one of asphalt-base material and resin-base material.

19. A prestressed pavement comprising:

(a) slabs on a support base; and

(b) at least one restraint, said restraint comprising

an upper part locked to one of said slabs,

a lower part fixed in said base,

a connection connecting the two parts, said connection allowing relative displacement of said two parts tangential but not normal to the slab plane, and

a yieldable component covering partially or entirely said connection and occupying a space in one of the slab and said base for allowing the relative displacement tangential to the slab plane,

whereby said restraint resists upward deflection of the slab for preventing buckling, but allows plane displacement of the slab for prestress transmission.

20. A prestressed pavement according to claim 19, wherein said yieldable component comprises means for lightly fixing said upper part on at least one of said lower part and said base before the slab forms.

21. A prestressed pavement comprising

(a) at least one slab on a support base, said slab bearing prestress;

and

(b) at least one restraint connecting said slab and said base, said restraint comprising;

(i) a firm component having an upper part locked in said slab and a lower part fixed in said base, and

(ii) a yieldable component covering said upper part in said slab, the vertical dimensions of said component being the same or almost same as those of said upper part, but the horizontal or plane dimensions of said component being larger than those of said upper part;

whereby said restraint restrains upward or possible upward deflection of said slab for preventing buckling, but allows plane displacement of said slab for avoiding obstructing prestress transmission.

22. A prestressed pavement comprising:

(a) slabs on a support base,

(b) at least one hydraulic apparatus between said slabs for providing prestress on said slabs,

(c) means for regulating said prestress, said means communicating with said apparatus and comprising hydraulic fluid and a pumping station, said pumping station comprising

at least one pump and power supply,

at least one fluid reservoir, and

at least one pressure-releasing valve.

23. A prestressed pavement according to claim 22, wherein said pumping station further comprises a pressure-sensitive automatic switch for switching said pump on and off.

24. A method for converting a non-prestressed concrete pavement to a prestressed pavement comprising the steps of

(a) making thin, flexible tubes;

(b) inserting said tubes into some transverse joints between some slabs of said non-prestressed concrete pavement at predetermined spacing range;

(c) pumping at least one kind of flowable material into the inserted tubes to prestress the slabs of said non-prestressed concrete pavement; and

(d) connecting the pressured tubes to hydraulic means for supplementing the prestress and damping the prestress rise.

25. A method according to claim 24, wherein said step (b) comprises the steps of

i widening a short section of a gap at one of said joints;

ii inserting at least one of said tubes into the widened section;

iii pumping fluid into the inserted tube to widen a section of said gap near the inserted tube;

iv repeating steps ii and iii until the number of said inserted tubes is enough for prestressing;

v releasing the pressure in the pressured tubes; and

vi moving a predetermined distance range and repeating steps i to v.

26. A method according to claim 24 further comprising, between steps (b) and (c), steps of:

(1) pumping at least one kind of flowable material into the inserted tubes to close the transverse joints and the possible cracks in said non-prestressed concrete pavement,

(2) processing or treating the slab surfaces to make them bondable to a later overlay, and

(3) placing and processing the overlay material; and

wherein the prestressed objects in step (c) comprise additionally said overlay.