Post-tensioned concrete slab with fibres

Patent metadata

Field	Value
Publication number	US-2023151611-A1
Application number	US-202117913628-A
Country	US
Kind code	A1
Filing date	Mar 24, 2021
Priority date	Mar 24, 2020
Publication date	May 18, 2023
Grant date	—

Abstract

A concrete slab (20) comprises conventional concrete and a combined reinforcement of both post-tension steel strands (22, 26) and fibres (29). The post-tension steel strands (22, 26): —have a diameter ranging from 5 mm to 20 mm, —have a tensile strength higher than 1700 MPa. The fibres (29) are present in a dosage ranging from 10 kg/m3 to 40 kg/m3 in case of steel fibres are in a dosage ranging from 1.5 kg/m3 to 9 kg/m3 in case of macro-synthetic fibres.

First claim

1 - 14 . (canceled)

15 . A concrete slab comprising conventional concrete and a combined reinforcement of both post-tension steel strands and fibres,
said post-tension steel strands
having a diameter ranging from 5 mm to 20 mm,
having a tensile strength higher than 1700 MPa,
said fibres being either steel fibres and being present in a dosage ranging from 10 kg/m 3 to 40 kg/m 3 or being macro-synthetic fibres and being present in a dosage ranging from 1.5 kg/m 3 to 9.0 kg/m 3 .

16 . The concrete slab according to claim 15 ,
wherein said conventional concrete has a characteristic compressive cube strength of 30 N/mm 2 or higher.

17 . The concrete slab according to claim 15 ,
wherein said fibres are steel fibres and/or wherein the steel fibres are present in a dosage ranging from 15 kg/m 3 to 35 kg/m 3 , preferably from 20 kg/m 3 to 30 kg/m 3 , preferably from 10 kg/m 3 to <30 kg/m 3 or further preferred from 10 kg/m 3 to 27 kg/m 3 and/or wherein the amount of steel fibers used is below or equal to 1.2 times, preferably 1.0 time, further preferred between >0 and 1.1 times, the amount of steel recommended and used for the steel bars or rebars to be replaced and/or the amount of steel fibers is below or equal 1.2 times, preferably 1 time, further preferred between >0 and 1.1 times, the amount recommend as rebar or steel bar replacement.

18 . The concrete slab according to claim 17 ,
wherein said steel fibres comprise a straight middle portion that have a tensile strength above 1400 MPa, preferably higher than 1500 MPa, preferably higher than 1600 MPa, preferably higher than 1700 MPa, further preferred higher than 2000 MPa, even further preferred higher than 2200 MPa, preferably between 1400 MPa and 3500 MPa.

19 . The concrete slab according to claim 17 ,
wherein said steel fibres comprise anchorage ends at both ends, said anchorage ends each comprise three or four bent sections.

20 . The concrete slab according to claim 15 ,
said concrete slab having a maximum crack width of 0.5 mm after hardening.

21 . The concrete slab according to claim 15 ,
said concrete slab having a length L greater than 100 m, said concrete slab having joints, said joints having a distance between neighbouring joints higher than 40 m.

22 . The concrete slab according to claim 15 ,
wherein said concrete slab is a concrete slab on ground and/or wherein said concrete slab has a uniform average density and/or wherein said concrete slab is cast in one day and/or in one go and/or be fully casted and/or wherein said concrete slab contains only the fibres and the post-tension steel strands as reinforcement elements and/or wherein conventional concrete has normal shrinkage and/or does not encompass low shrinkage concrete and/or wherein said concrete slab is free of a vapor barrier.

23 . The concrete slab according to claim 15 ,
wherein said post-tension steel strands have a distance between neighbouring post-tension steel strands or between neighbouring bundles of post-tension steel strands higher than 0.80 m and/or wherein tension is applied to the post-tension steel strands only after the concrete has been cast and the post-tension steel strands remain in place also once the concrete is completely cured/hardened and/or wherein the post-tension steel strands have a tensile strength higher 1800 MPa, preferably higher than 1900 MPa, preferably higher than 2000 MPa, further preferred between 1800 MPa and 4000 MPa and/or wherein the post-tension steel strands have a maximum breaking load of higher than 190 kN, preferably higher than 195 kN, preferably higher than 200 kN, preferably higher than 220 kN, further preferred between 195 kN and 350 kN and/or wherein the post-tension steel strands comprise anchor systems and/or ducts or sheathing.

24 . The concrete slab according to claim 15 ,
said concrete slab having a width b and a thickness h, said post-tension steel strands exercising a compression force that is 0% to 200% greater than a force according to following formula
μ o ×γ c ×b×h×L/2

where
μ o is the coefficient of friction between the concrete slab and a subbase; and

where
γc is the specific weight of concrete and/or wherein thickness h of a slab according to the invention may thereby preferably be between 4 cm and 75 cm, preferably 5 cm and 65 cm, further preferred 10 cm and 55 cm.

25 . A construction comprising the concrete slab according to claim 22 , said construction further comprising a plastic slip sheet between said concrete slab and said ground.

26 . A construction comprising the concrete slab according to claim 22 , a plastic slip sheet not being present between said concrete slab and said ground.

27 . The concrete slab according to claim 15 , wherein said concrete slab is a slab on concrete piles or gravel columns.

28 . The concrete slab according to claim 27 ,
said concrete piles or gravel columns being arranged in a regular rectangular pattern or quadrilateral shape where each set of four concrete piles or gravel columns forms a rectangle, said concrete slab comprising straight zones connecting in the two directions, i.e. lengthwise and widthwise, the shortest distance between those areas of the concrete slab above the concrete piles or gravel columns, post-tension steel strands being present in said straight zones in bundles, the distance between neighbouring post-tension steel strands within a bundle being smaller than 0.80 m.

29 . The concrete slab according to claim 28 ,
post-tension steel strands being present outside said straight zones, the shortest distance between post-tension steel strands outside said straight zones and the post-tension steel strands in said straight zones being larger than 0.80 m.

30 . A construction comprising a concrete slab according to claim 23 ,
said construction further comprising a plastic slip sheet between said concrete slab and said ground.

31 . A construction comprising a concrete slab according to claim 24 ,
said construction further comprising a plastic slip sheet between said concrete slab and said ground.

32 . A construction comprising a concrete slab according to claim 23 ,
a plastic slip sheet not being present between said concrete slab and said ground.

33 . A construction comprising a concrete slab according to claim 24 ,
a plastic slip sheet not being present between said concrete slab and said ground.

Assignees

• Bekaert Sa Nv
• Ccl Stressing Int Ltd

Inventors

• Thooft Hendrik
• Hayek Carol

Classifications

• C04B14/48

  Metal · CPC title

• C04B16/0633

  Polypropylene · CPC title

• C04B2201/50

  for the mechanical strength · CPC title

• E04C2/06

  reinforced · CPC title

• E04C3/26

  prestressed (E04C3/22, E04C3/29 take precedence; prestressing members E04C5/08) · CPC title