CA2531705A1 - Dowel assembly for concrete slabs - Google Patents
Dowel assembly for concrete slabs Download PDFInfo
- Publication number
- CA2531705A1 CA2531705A1 CA 2531705 CA2531705A CA2531705A1 CA 2531705 A1 CA2531705 A1 CA 2531705A1 CA 2531705 CA2531705 CA 2531705 CA 2531705 A CA2531705 A CA 2531705A CA 2531705 A1 CA2531705 A1 CA 2531705A1
- Authority
- CA
- Canada
- Prior art keywords
- dowels
- assembly
- concrete slab
- joint
- slab
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Landscapes
- On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)
Abstract
An assembly (10) to be at least partially embedded within a concrete slab (30), the assembly (10) including: a first bar (12) to be embedded within the concrete slab (30) and located on a first side of a joint (40); a second bar (14) to be embedded within the concrete slab (30), the second bar (30) extending substantially parallel to and transversely spaced from the first bar (12), the second bar (14) to be located on said first side of said joint (40); and a plurality of dowels (16) extending substantially parallel to and transversely spaced from each other, the dowels (16) being attached to the dust and second bars (12, 14) so as to be substantially perpendicular thereto, the dowels (16) being provided to extend across said joint (40).
Description
Dowel Assembly for Concrete SIabs held of the invention The present invention relates to a dowel assembly for concrete slabs on ground.
s )gackground of the invention Newly laid concrete shrinks as it matures. Hardened concrete expands and contracts with moisture and temperature changes. Theca volume oVangas can prodLtoe cracks in a concrete slab unless provxsior~s aze taken to allow for such volume changes.
to Such provisions include control joints, which are straight grooves formed in the concrete slab surface to "control" the cracking. The groove depth can be 1/$'~'to the full length of the slab tl~xc~ass, as required. ?he control joints can be formed with a tool during concreto hardening or sawcut soon after the slab has hardened.
Control joints are pla,eed at regular intez~~als in th.e slab, typically at 6 to $ meter ~s regular intervals in both- longitudinal and tran~verso directions, thus forming a grid (see control joints 40 in slab 30 of Fig. 3). The resulting slab panels (42 in Fig.
3) between control joints are kept as square as possible. The control joints provide a zone of weakness beeween slab panels where the forces which are pulling on the slab panels will relieve themselves. This substantially prevents the concrete cracking On itS
owz~, in an Zo uncontrolled manner. Ideally, the concrete will ztot crack between the joints, but such unaesthetic cracks do happen.
Control joints typically include dowels to increase slab strength in the jøint.
Such dowelled joints include stool dowels, embedded within the cor~ctote at half the slab depth, and extending across a cozttrol joint (perpendicular thereto) to connect slab paa~.els as on both sides of a control joint. The dowels are spaced at regular intervals along the length of the control joint, parallel to each other. The dowels impzove load transfer across the conixol joint and maintain the veztic3l alignment of adjaacnt slabs.
The dowels are typically steel round bars with a bond breaker (such as grease, shrink wrap or plastic sleeve) applied to oz~e and. The dowels arc placed at half tho ao required slab height across the expected location of the control joint, prior to pouring of the concrete to from the slab. Hurimg hardening of the concrete or shortly thereafter, the control jozz~t is formod. ThE bond bzeakers at one end of the dc~vveis larovide a debonding effect to the Concrete of the slab panel at that end, whilst the other end of the dowel is Irt u.muywos.~oc.ror bonded to the concrete of the adjacent slab panel. This allows one end of the dowels to be movable within the slab panel, allowing expansion of the slab panels relative to each other without generating stresses within the slab panels.
Recently, square cross-section dowels, #lat bar dowels azxd plate dowels have s also been used as they provide a greater load transfer capability than round bar dowels.
The difficulty rx~ith, dowelled joints is that the dowels must be instahed in a single plane, aligned and parallel with each other if they are to work as intended.
Any misaligned dowel oz a dowel which is eat parallel to the others along a control joint will usually result in s 'locked' joint and the slab panel will often crack between the control to joints along one end of the dowels. Generally, stresses in the slab paxaels will be concentrated between the unparallel dowels which results in undesirable anaesthetic cracks {see for example crack SS in Fig. 3b).
Several manufacturers are now providing dowels in pre-fabricated cradles or cages to overcome the majority of the problems associated with installation.
Such dowel is cradles/cages include a fabricated wire-frame which rests on the ground and supports dowels on one side and bond breakers (sleeves) at ttxe other side. The cradles position the dowels and sleeves at the correct half slab height and ensure that the dowels remain substantially parallel to each other at the correct dowel intervals. They are hawever expensive. rurthcr, the prefabricated dowel cradles do not allo~ov far installation of the zo cradles px~.or to the use of a 5omero Laser Screed machine as shown in Fig.
4 (from So~r~ero Enterprises, www.somero.aozn).
Referring to Fig. 4, the Somero Laser screed machine 50 is a self propelled four wheel drive unit vvhicl~ has a telescoping boom 52 with a scxveding/compacting head 54.
When forming a slab floor, concrete is dischargEd in strips fo match the width of the zs screeding/eompaciing head 54, up to a height approximately 1" higher than the hr~al slab thickness required. The Somero machine 50 moves info position and the telescopic booze 52 is extended over the discharged concrete. The screeding/cornpacting head 54 is then lowered to the slab thickness required as detennined by a laser-level transmitter.
Retraction ofthe boom 52 causes the screed head 54 to be drawn across the fresh concrete ~o which is leveled and compacted in a single pass. Once a pass is com~plated, the machine SU is moved to a position for forming the adjacent slab panel rwith some overlap on the previously screeded concrete.
(Ry,IHU,J16~69 Joc.FDP
s )gackground of the invention Newly laid concrete shrinks as it matures. Hardened concrete expands and contracts with moisture and temperature changes. Theca volume oVangas can prodLtoe cracks in a concrete slab unless provxsior~s aze taken to allow for such volume changes.
to Such provisions include control joints, which are straight grooves formed in the concrete slab surface to "control" the cracking. The groove depth can be 1/$'~'to the full length of the slab tl~xc~ass, as required. ?he control joints can be formed with a tool during concreto hardening or sawcut soon after the slab has hardened.
Control joints are pla,eed at regular intez~~als in th.e slab, typically at 6 to $ meter ~s regular intervals in both- longitudinal and tran~verso directions, thus forming a grid (see control joints 40 in slab 30 of Fig. 3). The resulting slab panels (42 in Fig.
3) between control joints are kept as square as possible. The control joints provide a zone of weakness beeween slab panels where the forces which are pulling on the slab panels will relieve themselves. This substantially prevents the concrete cracking On itS
owz~, in an Zo uncontrolled manner. Ideally, the concrete will ztot crack between the joints, but such unaesthetic cracks do happen.
Control joints typically include dowels to increase slab strength in the jøint.
Such dowelled joints include stool dowels, embedded within the cor~ctote at half the slab depth, and extending across a cozttrol joint (perpendicular thereto) to connect slab paa~.els as on both sides of a control joint. The dowels are spaced at regular intervals along the length of the control joint, parallel to each other. The dowels impzove load transfer across the conixol joint and maintain the veztic3l alignment of adjaacnt slabs.
The dowels are typically steel round bars with a bond breaker (such as grease, shrink wrap or plastic sleeve) applied to oz~e and. The dowels arc placed at half tho ao required slab height across the expected location of the control joint, prior to pouring of the concrete to from the slab. Hurimg hardening of the concrete or shortly thereafter, the control jozz~t is formod. ThE bond bzeakers at one end of the dc~vveis larovide a debonding effect to the Concrete of the slab panel at that end, whilst the other end of the dowel is Irt u.muywos.~oc.ror bonded to the concrete of the adjacent slab panel. This allows one end of the dowels to be movable within the slab panel, allowing expansion of the slab panels relative to each other without generating stresses within the slab panels.
Recently, square cross-section dowels, #lat bar dowels azxd plate dowels have s also been used as they provide a greater load transfer capability than round bar dowels.
The difficulty rx~ith, dowelled joints is that the dowels must be instahed in a single plane, aligned and parallel with each other if they are to work as intended.
Any misaligned dowel oz a dowel which is eat parallel to the others along a control joint will usually result in s 'locked' joint and the slab panel will often crack between the control to joints along one end of the dowels. Generally, stresses in the slab paxaels will be concentrated between the unparallel dowels which results in undesirable anaesthetic cracks {see for example crack SS in Fig. 3b).
Several manufacturers are now providing dowels in pre-fabricated cradles or cages to overcome the majority of the problems associated with installation.
Such dowel is cradles/cages include a fabricated wire-frame which rests on the ground and supports dowels on one side and bond breakers (sleeves) at ttxe other side. The cradles position the dowels and sleeves at the correct half slab height and ensure that the dowels remain substantially parallel to each other at the correct dowel intervals. They are hawever expensive. rurthcr, the prefabricated dowel cradles do not allo~ov far installation of the zo cradles px~.or to the use of a 5omero Laser Screed machine as shown in Fig.
4 (from So~r~ero Enterprises, www.somero.aozn).
Referring to Fig. 4, the Somero Laser screed machine 50 is a self propelled four wheel drive unit vvhicl~ has a telescoping boom 52 with a scxveding/compacting head 54.
When forming a slab floor, concrete is dischargEd in strips fo match the width of the zs screeding/eompaciing head 54, up to a height approximately 1" higher than the hr~al slab thickness required. The Somero machine 50 moves info position and the telescopic booze 52 is extended over the discharged concrete. The screeding/cornpacting head 54 is then lowered to the slab thickness required as detennined by a laser-level transmitter.
Retraction ofthe boom 52 causes the screed head 54 to be drawn across the fresh concrete ~o which is leveled and compacted in a single pass. Once a pass is com~plated, the machine SU is moved to a position for forming the adjacent slab panel rwith some overlap on the previously screeded concrete.
(Ry,IHU,J16~69 Joc.FDP
The dowel cradles mentioned have to be placed in a grid azzarlge,rnent corresponding to the control joints to be formed. As these cradles include a wire frame for locating the dowels and sleeves at the correct height, a Sorr~sro machine cannot be driven oven these czadles without damaging them. It is thus necessary to remove the s cradles to allow the Somero machine to move onto the adjacent slab panel to be fon~xed, or to place the dowel cxadles only iznu~ediately pziar to forming of the slab panel. This signifleantly slows forming of the slab floor.
Further (referring to Fig_ 3b) such cradles are only available in 3m Iangths, which requires the use of two dowel cradles 44 fez each coz~tral joint of a 6rra x 6zx~ slab to panel 42. This allows the possibility that the dowels of cradles along the same control joint 40 will be misaligned and increases the chance of undesired cracks forming in the slab panr3l.
It is the abject of the present invention to substantially overcome or at least ameliorate one or more of the prior art disadvantages or at least provide a useful i s alternative.
Summary of the Invention The present invention provides an assembly to be ac least partially embedded within a concrete: slab, the assembly including:
io a fizst bar to be embedded within the concrete slab and located on a first side of a joint;
a second bar to be embedded within the concrete slab, the second bar extending substantially parallel to and transversely spaced trom the first bar, the second bar to be located on said first side of said joint; and zs a plurality of dowels extending substatitiahy parallel to and transversely spaced from each other, the dowels being aitaahed ~to the first and second bars so as to be substantially perpendicular thereto, the dowels being provided to extend across said joint.
hi the preferred e~~nbodiment, the first and second bars are sub$tantially co~
extensive with each other. The dowels are ;also pzeferably substantially co-extensive with 3o each other.
The dowels are preferably spaced at regular intervals along the first and second bars. Preferably, the dowels include a sleeve covering the dowel portions to extend [A 1LISLL) 16405.doeFDP
Further (referring to Fig_ 3b) such cradles are only available in 3m Iangths, which requires the use of two dowel cradles 44 fez each coz~tral joint of a 6rra x 6zx~ slab to panel 42. This allows the possibility that the dowels of cradles along the same control joint 40 will be misaligned and increases the chance of undesired cracks forming in the slab panr3l.
It is the abject of the present invention to substantially overcome or at least ameliorate one or more of the prior art disadvantages or at least provide a useful i s alternative.
Summary of the Invention The present invention provides an assembly to be ac least partially embedded within a concrete: slab, the assembly including:
io a fizst bar to be embedded within the concrete slab and located on a first side of a joint;
a second bar to be embedded within the concrete slab, the second bar extending substantially parallel to and transversely spaced trom the first bar, the second bar to be located on said first side of said joint; and zs a plurality of dowels extending substatitiahy parallel to and transversely spaced from each other, the dowels being aitaahed ~to the first and second bars so as to be substantially perpendicular thereto, the dowels being provided to extend across said joint.
hi the preferred e~~nbodiment, the first and second bars are sub$tantially co~
extensive with each other. The dowels are ;also pzeferably substantially co-extensive with 3o each other.
The dowels are preferably spaced at regular intervals along the first and second bars. Preferably, the dowels include a sleeve covering the dowel portions to extend [A 1LISLL) 16405.doeFDP
across said joint. The dowels are preferably attached to the first and seoond longitudinal bars by welding.
Each dowel preferably includes a first end and a second end and the first bar is attached adjacent the dov~rel first ends. Preferably, the distance between the first and s second bars is less than half the length of each dowel. The first and second bars and the dowels are preferably steel bars, of a round, square or rectangular cross-section.
1n another aspect, the present invention provides a concrete slab having the assembly t~f the above at least partza~lly embedded therein. The slab is preferably a slab on ground. 'fhe bars ~d dowels are preferably substantially parallel to a top surface of said )o concrete slab. The assembly is preferably embedded within the concrete at a depth lower than 40 mm from the top surface of the concrete slab, and bigher than 40 mm from the lower surface of the concrete slab. The assembly is preferably embedded at half the concrete slab thiclrness.
[s Brief flesc~p~tian of the Drawings Preferred forms of the present invention will now be described by way of examples only, with reference to the accompanying drawings, wlxexeiz~:
Fig. I is a perspective view of an assembly according to a preferred embodiment of the present invention;
xo Fig. 2 is a cross-section of a floor slab with the assembly eel' Fig. 1 embedded therein, the cross-section being along line 2-2 of Fig. 3;
Fig. 3a is a schematic top view of pan of a slab panel having control joints and with assemblies according to Fig. 1 embedded therein;
Fig. 3b is a schematic top view of part of a slab panel having control joints and zs with prior art cradle assemblies embedded therein; ~d Fig. 4 is a photograph of a commercially available Sor~aexo Laser Screed machine.
betailed rleaerlption of tire 1'relk'erred Embodiments 3U fig. 1 shows an assembly 10 according to a prefer~d embodiment of the present invention. The assembly 10 includes a first bar 12, a second bar 14 and a plurality of dowels 16. The first and second bars 12 and 14 extend substantially parallel to and [A~L18LL)t4W5 doc:l~P
transversely spaced from each other. The first and second bars 12 and 14 are also substantially co-extensive with each other-The dowels 16 extend substantially parallel to and transversely spaced from each other. The dowels 16 are also substantially co-extensive with each other and each dowel s 1G includes a fZZSt ex~d 1.9 and a second ez~d 20- The dowels 1G are attached to the i;lrst and second bars 12 and 14 at regular distance intervals 21 by welding as indicated at 17, and are substantially perpendicular to the first and second bars 12 and 14, as indicated at 18. The first bar 12 is attached adjacent the dowel first ends 19, such that each dowel 16 extends ;from the fizst bar 12 and past the second bar 14. 'T'he distance 22 between the ~o first and second bars 12 and 14 is less than half the length 24 of each dowel 1E.
The first and second bars 12 and 14 and dowels 16 are preferably steel bars, of a round, srluare or rectangular cross..section_ The use of the assembly 10 will now be described with reference to Figs. 2 and 3a. The assemblies 10 are placed an the ground prioz to °pouring of the concrete at is locations specified by engineers. The assemblies 10 are located such that the first and second bars 12 and 14 will be located on one side of a (to be formed) control joint 40 and substantially parallel thereto. The dowels 16 are located to extend across the (to be formed) control joint 40 and substantially perpendicular thereto. The dowel second ends 30 are inserted into individual plastic sleeves 25 which will act as coxacrete bond breakers.
zo E~.einforcement mesh 32 is then placed aver the assemblies 10 and the assemblies axe tied by wire to the reinforcement mesh 32. Workers and the Somero Laser Screed machine can then walk or dive veer the mesh 32 and assembly 10 without substanti al risl~ of damaging or moving the bars 12 and 14 and dowels 16 out co aligzunent. Prior to pouring a:f coztcxete for forming a slab section, the mesh and assembly 10 are 'chaired up' zs (raised via spacers to (preferably) about half the slab depth) as one Lulit. The actual height the unit is chaired up is determined by engineering requzrexxaents, but is generally at a depth lower than 40 mm from the top surface of the concrete slab, and higher than AO n~~m from the lower surface of the concrete slab. Concrete is then poured and the Somero machine is used to screed the laid concrete to compact and level same as described above.
3a In fiber reinforced concrete which does not include the reinforcement mesh 32, the assemblies 10 are chaired by themselves prior to pouring of the concrete.
During hardening of the concrete, the bars I.2 and 14 and dowel first ends 19 are bonded to the concrete of slab panel 42a whilst the sleeves 25 are bonded to the slab panel [R ~L18LL11G905 ~ac:FDP
42b. 'The slight shrinking of the concrete during hardeung z~~oves the sleeves 25 slightly away from the bars 12 and 14. This creates a small space between the second end 20 of the dowels 16 and the closed end of the sleeves 25, which allows the dowels 16 to move longitudinally inside sleeve 25. This allows expansion of the slab panels 42a and 42b s relative to each other without generating stresses within the slab panels 42a and 42b. The sleeve 25 can be made of metal, plastics material or shxinlt wxap. The assembly 10 will be typically supplied with the sleeves 25 installed over the dowel second ends 20. During or after hardening of the concrete, the control joint 40 xs ~Farcned.
The cross-section shape and dimensions of the bars 12 and 14 and dowels 16, ]o length 24 of dowels 16, distance 22 between the bans 12 and 14 and distance 21 between the dowels 16 are determined by an engineer depending on the environment and expected leads of the floor slab to be Laid. The distances 21 and 22 can be set at any from 10 mm to five rrae~ers, and the dowel length 24 can be set at any from 10 mm to one meter, as specified by an engineer. The present invention allows flexibility to the engineer's l s requirements for any such distances 21 and 22 and dowel length 24.
The assembly 10 provides accurate dowel spacing and alignment and maintains this accuracy even after being wallcEd on or driven over by a Somero machine.
The dowels can be placed in their intended position in conventional or fiber reinforced slabs, prior to the use of the Somero machine. The Somero machizie can be driven over the zo assemblies 10 without causing damage andlor misalignment of the dovxrels 16. This, decreases the ~~slc of cracking in the slab pa~.~:~ls due to dowel ~ixisalignxnent. The present invention can be used with a Somcro machine or with conventional methods of concrete pouring aJ.ld f1I11Shlrig.
The assemblies 10 are typically stacked inside a rectangular steel frame, which 2s allows for a greater mobility around the building site. The assemblies 10 are thus easier to haa-~dl~ than the dowel cradles presently available.
The assembly 1 p k~as been primazily described above with reference to control joints. The assembly 10 can however also be used for othex types ref concrete joints, such as stop work joints, expansion joints and edge joints-3o Slop warlf joints are formed at an edge of a laid concrete slab. Edge boards are erected to support the laid concrete on such edges, and the assembly 1 U is located such that the bars 12 and 14 will be embedded in the laid concrete, with the sleeved dowels 16 extending thxough l~Ql~s formed in the edge board. Once the concrete slab hardens and (R~1LTALL]l frt05.doeF~p the cdge board is removed, an adjacent slab embedding the sleeved dowels 16 can be laid.
An e~cpansion joint is similar to a stop work joint, with the addition of 2t corxapressible board material between the slabs. Moles are provided in the material for the dowels 16 to extend through.
s An edge joint is formed at an edge of a laid concrete slab adjacexrt a structure, such as a wall. Zn this case, hales are formed in the str<tet<tre for the dowels 16 to be inserted into prior to pouring concrete. The bars 12 and 14 are then embedded in the laid concrete.
The assemblies 10 can be fabricated in standard six (6) meter lengths but can be to varied to suit any required control joint and or saw cut specifications, providing flexibility to tailoring the length of the assembly 10 to each individual requirement. The standard six (6) zr~eter lengths also provides higher accuracy of dowels remaining parallel over longer distances, resulting in less craclting, where compared to the 3 meter dowel cradles described.
[ s The assembly I O is fabricated off site by welding the doweis 16 to the bars 12 and 14 by a qualified welder to the required engineering dimensions. They are then transported to site for installation only, ~rrithout reqttiz~ng ;further assembly, Welding of the dowels to the bars 1~ and 14 substantially guarantees that the dowels 15 will remain substantially perpendicular to the bars 12 and 1~4, and that the dowels 15 will remain zo substantially parallel throughout ilea placement process and the pouring of concrete. This also lessens the chance of having unparallel dowel by human installation error. Further, efficiency on site is improved as no further assembly is required, thus requiring less labor.
Accurate placement and installation of the dowels becomes easier.
as The preferred ernbodimex~t of tl~e present invention thus provides the following advantages.
~ Tinno saving on dowel installation and placement;
~ No far assembly required;
Significant cost savings in comparison to other prefabricated dowel so cradle systems;
~ Somero machine can be driven over assezzxblies 10, which etumot be done to other prefabricated dowel cradle systsn~s;
~ The assemblies 10 can be stacked;
[R ~L18LLJ1~03 decPD!
g ~ The assemblies 10 remain stable under concrete placement.
~ Easier handling of dowels an site leading try fewer injuries as less work is required.
No need for wire cage as opposed to pae~abricated dowel cradle systems [R.uJHL1]1N03 doc,1=pP
Each dowel preferably includes a first end and a second end and the first bar is attached adjacent the dov~rel first ends. Preferably, the distance between the first and s second bars is less than half the length of each dowel. The first and second bars and the dowels are preferably steel bars, of a round, square or rectangular cross-section.
1n another aspect, the present invention provides a concrete slab having the assembly t~f the above at least partza~lly embedded therein. The slab is preferably a slab on ground. 'fhe bars ~d dowels are preferably substantially parallel to a top surface of said )o concrete slab. The assembly is preferably embedded within the concrete at a depth lower than 40 mm from the top surface of the concrete slab, and bigher than 40 mm from the lower surface of the concrete slab. The assembly is preferably embedded at half the concrete slab thiclrness.
[s Brief flesc~p~tian of the Drawings Preferred forms of the present invention will now be described by way of examples only, with reference to the accompanying drawings, wlxexeiz~:
Fig. I is a perspective view of an assembly according to a preferred embodiment of the present invention;
xo Fig. 2 is a cross-section of a floor slab with the assembly eel' Fig. 1 embedded therein, the cross-section being along line 2-2 of Fig. 3;
Fig. 3a is a schematic top view of pan of a slab panel having control joints and with assemblies according to Fig. 1 embedded therein;
Fig. 3b is a schematic top view of part of a slab panel having control joints and zs with prior art cradle assemblies embedded therein; ~d Fig. 4 is a photograph of a commercially available Sor~aexo Laser Screed machine.
betailed rleaerlption of tire 1'relk'erred Embodiments 3U fig. 1 shows an assembly 10 according to a prefer~d embodiment of the present invention. The assembly 10 includes a first bar 12, a second bar 14 and a plurality of dowels 16. The first and second bars 12 and 14 extend substantially parallel to and [A~L18LL)t4W5 doc:l~P
transversely spaced from each other. The first and second bars 12 and 14 are also substantially co-extensive with each other-The dowels 16 extend substantially parallel to and transversely spaced from each other. The dowels 16 are also substantially co-extensive with each other and each dowel s 1G includes a fZZSt ex~d 1.9 and a second ez~d 20- The dowels 1G are attached to the i;lrst and second bars 12 and 14 at regular distance intervals 21 by welding as indicated at 17, and are substantially perpendicular to the first and second bars 12 and 14, as indicated at 18. The first bar 12 is attached adjacent the dowel first ends 19, such that each dowel 16 extends ;from the fizst bar 12 and past the second bar 14. 'T'he distance 22 between the ~o first and second bars 12 and 14 is less than half the length 24 of each dowel 1E.
The first and second bars 12 and 14 and dowels 16 are preferably steel bars, of a round, srluare or rectangular cross..section_ The use of the assembly 10 will now be described with reference to Figs. 2 and 3a. The assemblies 10 are placed an the ground prioz to °pouring of the concrete at is locations specified by engineers. The assemblies 10 are located such that the first and second bars 12 and 14 will be located on one side of a (to be formed) control joint 40 and substantially parallel thereto. The dowels 16 are located to extend across the (to be formed) control joint 40 and substantially perpendicular thereto. The dowel second ends 30 are inserted into individual plastic sleeves 25 which will act as coxacrete bond breakers.
zo E~.einforcement mesh 32 is then placed aver the assemblies 10 and the assemblies axe tied by wire to the reinforcement mesh 32. Workers and the Somero Laser Screed machine can then walk or dive veer the mesh 32 and assembly 10 without substanti al risl~ of damaging or moving the bars 12 and 14 and dowels 16 out co aligzunent. Prior to pouring a:f coztcxete for forming a slab section, the mesh and assembly 10 are 'chaired up' zs (raised via spacers to (preferably) about half the slab depth) as one Lulit. The actual height the unit is chaired up is determined by engineering requzrexxaents, but is generally at a depth lower than 40 mm from the top surface of the concrete slab, and higher than AO n~~m from the lower surface of the concrete slab. Concrete is then poured and the Somero machine is used to screed the laid concrete to compact and level same as described above.
3a In fiber reinforced concrete which does not include the reinforcement mesh 32, the assemblies 10 are chaired by themselves prior to pouring of the concrete.
During hardening of the concrete, the bars I.2 and 14 and dowel first ends 19 are bonded to the concrete of slab panel 42a whilst the sleeves 25 are bonded to the slab panel [R ~L18LL11G905 ~ac:FDP
42b. 'The slight shrinking of the concrete during hardeung z~~oves the sleeves 25 slightly away from the bars 12 and 14. This creates a small space between the second end 20 of the dowels 16 and the closed end of the sleeves 25, which allows the dowels 16 to move longitudinally inside sleeve 25. This allows expansion of the slab panels 42a and 42b s relative to each other without generating stresses within the slab panels 42a and 42b. The sleeve 25 can be made of metal, plastics material or shxinlt wxap. The assembly 10 will be typically supplied with the sleeves 25 installed over the dowel second ends 20. During or after hardening of the concrete, the control joint 40 xs ~Farcned.
The cross-section shape and dimensions of the bars 12 and 14 and dowels 16, ]o length 24 of dowels 16, distance 22 between the bans 12 and 14 and distance 21 between the dowels 16 are determined by an engineer depending on the environment and expected leads of the floor slab to be Laid. The distances 21 and 22 can be set at any from 10 mm to five rrae~ers, and the dowel length 24 can be set at any from 10 mm to one meter, as specified by an engineer. The present invention allows flexibility to the engineer's l s requirements for any such distances 21 and 22 and dowel length 24.
The assembly 10 provides accurate dowel spacing and alignment and maintains this accuracy even after being wallcEd on or driven over by a Somero machine.
The dowels can be placed in their intended position in conventional or fiber reinforced slabs, prior to the use of the Somero machine. The Somero machizie can be driven over the zo assemblies 10 without causing damage andlor misalignment of the dovxrels 16. This, decreases the ~~slc of cracking in the slab pa~.~:~ls due to dowel ~ixisalignxnent. The present invention can be used with a Somcro machine or with conventional methods of concrete pouring aJ.ld f1I11Shlrig.
The assemblies 10 are typically stacked inside a rectangular steel frame, which 2s allows for a greater mobility around the building site. The assemblies 10 are thus easier to haa-~dl~ than the dowel cradles presently available.
The assembly 1 p k~as been primazily described above with reference to control joints. The assembly 10 can however also be used for othex types ref concrete joints, such as stop work joints, expansion joints and edge joints-3o Slop warlf joints are formed at an edge of a laid concrete slab. Edge boards are erected to support the laid concrete on such edges, and the assembly 1 U is located such that the bars 12 and 14 will be embedded in the laid concrete, with the sleeved dowels 16 extending thxough l~Ql~s formed in the edge board. Once the concrete slab hardens and (R~1LTALL]l frt05.doeF~p the cdge board is removed, an adjacent slab embedding the sleeved dowels 16 can be laid.
An e~cpansion joint is similar to a stop work joint, with the addition of 2t corxapressible board material between the slabs. Moles are provided in the material for the dowels 16 to extend through.
s An edge joint is formed at an edge of a laid concrete slab adjacexrt a structure, such as a wall. Zn this case, hales are formed in the str<tet<tre for the dowels 16 to be inserted into prior to pouring concrete. The bars 12 and 14 are then embedded in the laid concrete.
The assemblies 10 can be fabricated in standard six (6) meter lengths but can be to varied to suit any required control joint and or saw cut specifications, providing flexibility to tailoring the length of the assembly 10 to each individual requirement. The standard six (6) zr~eter lengths also provides higher accuracy of dowels remaining parallel over longer distances, resulting in less craclting, where compared to the 3 meter dowel cradles described.
[ s The assembly I O is fabricated off site by welding the doweis 16 to the bars 12 and 14 by a qualified welder to the required engineering dimensions. They are then transported to site for installation only, ~rrithout reqttiz~ng ;further assembly, Welding of the dowels to the bars 1~ and 14 substantially guarantees that the dowels 15 will remain substantially perpendicular to the bars 12 and 1~4, and that the dowels 15 will remain zo substantially parallel throughout ilea placement process and the pouring of concrete. This also lessens the chance of having unparallel dowel by human installation error. Further, efficiency on site is improved as no further assembly is required, thus requiring less labor.
Accurate placement and installation of the dowels becomes easier.
as The preferred ernbodimex~t of tl~e present invention thus provides the following advantages.
~ Tinno saving on dowel installation and placement;
~ No far assembly required;
Significant cost savings in comparison to other prefabricated dowel so cradle systems;
~ Somero machine can be driven over assezzxblies 10, which etumot be done to other prefabricated dowel cradle systsn~s;
~ The assemblies 10 can be stacked;
[R ~L18LLJ1~03 decPD!
g ~ The assemblies 10 remain stable under concrete placement.
~ Easier handling of dowels an site leading try fewer injuries as less work is required.
No need for wire cage as opposed to pae~abricated dowel cradle systems [R.uJHL1]1N03 doc,1=pP
Claims (19)
1. An assembly to be at least partially embedded within a concrete slab, the assembly including:
a first bar to be embedded within the concrete slab and located on a first side of a joint;
a second bar to be embedded within the concrete slab, the second bar extending substantially parallel to and transversely spaced from the first bar, the second bar to be located on said first side of said joint; and a plurality of dowels extending substantially parallel to and transversely spaced from each other, the dowels being attached to the first and second bars so as to be substantially perpendicular thereto, the dowels being provided to extend across said joint.
a first bar to be embedded within the concrete slab and located on a first side of a joint;
a second bar to be embedded within the concrete slab, the second bar extending substantially parallel to and transversely spaced from the first bar, the second bar to be located on said first side of said joint; and a plurality of dowels extending substantially parallel to and transversely spaced from each other, the dowels being attached to the first and second bars so as to be substantially perpendicular thereto, the dowels being provided to extend across said joint.
2. The assembly of claim 1 wherein the first and second bars are substantially co-extensive wish each other.
3 The assembly of claim 1 or 2 wherein the dowels are substantially co-extensive with each other.
4. The assembly of any one of the preceding claims wherein the dowels are spaced at regular intervals along the first and second bars.
5. The assembly of any onto of the preceding claims wherein the dowels include a sleeve covering the dowel portions to extend across said joint.
6. The assembly of any one of the preceding claims wherein the dowels are attached to the first and second longitudinal bars by welding.
7. The assembly of any one of the preceding claims wherein each dowel includes a first end and a second end and the first bar is attached adjacent the dowel first ends.
8. The assembly of any one of the preceding claims wherein the distance between the first and second bars is less than half the length of each dowel.
9. The assembly of any one of the preceding claims wherein the first and second bars and the dowels era steel bars, of a round, square or rectangular cross-section.
10. A concrete slab having the assembly of any one of the preceding claims at least partially embedded therein.
11. The concrete slab of claim 10 wherein the slab is a slab an ground.
12. The concrete slab of claim 11 wherein the bars and dowels are substantially parallel to a top surface of said concrete slab.
13. The concrete slab of claim 11 or 12 wherein the assembly is embedded within the concrete at a depth lower than 40 mm from the top surface of the concrete slab.
14. The concrete slab of claim 11, 12 or 13 wherein the assembly is embedded within the concrete at a depth higher than 4.0 mm from the lower surface of the concrete slab.
15. The concrete slab of any one of claims 10 to 14 wherein the assembly is embedded at half the concrete slab thickness.
16. The concrete slab of claim any one of claims 10 to 15 wherein the joint is a control joint, an edge joint, a stop work joint or an expansion joint.
17. The concrete slab of claim any one of claims 10 to 16 wherein the bars are substantially parallel to said joint and the dowels are substantially perpendicular to said joint.
18. An assembly substantially as hereinbefore described with reference to Figs. 1 to 3a of the accompanying drawings.
19. A concrete slab substantially as hereinbefore described with reference to Figs. 2 and 3a of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2004242538A AU2004242538C9 (en) | 2004-12-31 | 2004-12-31 | Dowel assembly for concrete slabs |
| AU2004242538 | 2004-12-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2531705A1 true CA2531705A1 (en) | 2006-06-30 |
Family
ID=34578167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2531705 Abandoned CA2531705A1 (en) | 2004-12-31 | 2005-12-28 | Dowel assembly for concrete slabs |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU2004242538C9 (en) |
| CA (1) | CA2531705A1 (en) |
| NZ (1) | NZ544392A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116356634A (en) * | 2023-04-07 | 2023-06-30 | 南通大学 | Solar-energy-based electric heating geogrid pavement device and construction method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU712389B2 (en) * | 1995-11-15 | 1999-11-04 | Daniel Charles Underwood | Concrete joint and method |
| AU8422998A (en) * | 1997-10-14 | 1999-05-06 | Connolly Key Joint Pty Ltd | Improvements in dowels for slabs |
-
2004
- 2004-12-31 AU AU2004242538A patent/AU2004242538C9/en not_active Ceased
-
2005
- 2005-12-23 NZ NZ54439205A patent/NZ544392A/en not_active IP Right Cessation
- 2005-12-28 CA CA 2531705 patent/CA2531705A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116356634A (en) * | 2023-04-07 | 2023-06-30 | 南通大学 | Solar-energy-based electric heating geogrid pavement device and construction method |
| CN116356634B (en) * | 2023-04-07 | 2023-11-28 | 南通大学 | Solar-energy-based electric heating geogrid pavement device and construction method |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2004242538C9 (en) | 2008-02-07 |
| AU2004242538C1 (en) | 2007-11-08 |
| NZ544392A (en) | 2007-06-29 |
| AU2004242538B1 (en) | 2005-05-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8312683B2 (en) | Method for constructing precast sandwich panels | |
| AU2017360985B2 (en) | Load transfer plate pocket and method of employing same | |
| US7381008B2 (en) | Disk plate concrete dowel system | |
| US7338230B2 (en) | Plate concrete dowel system | |
| US4226060A (en) | Floor plate for forming a foot path and method of laying a walking surface on a roof | |
| US7314333B2 (en) | Plate concrete dowel system | |
| RU2418917C2 (en) | Structural elements and methods of their application | |
| NL1003858C2 (en) | Wing floor element made of concrete. | |
| NL8101210A (en) | FLOORING SYSTEM. | |
| CA2531705A1 (en) | Dowel assembly for concrete slabs | |
| CN101666143B (en) | Construction method of polyurethane thermal insulation system by taking large-size face brick as finishing coat | |
| JP7051358B2 (en) | Precast synthetic slabs, widening plates, and floor structures with precast synthetic slabs, as well as buildings. | |
| CN112095876A (en) | Prefabricated laminated slab suitable for laying floor heating pipeline and preparation process | |
| EP1422356B1 (en) | Prefabricated insulated panel with heating pipes embedded in concrete and method of manufacturing | |
| NO312041B1 (en) | Factory-made joists | |
| JP5991843B2 (en) | Laying structure of floor plate for track surface laying | |
| SK105797A3 (en) | Process for the production of heat insulation panels for large panel construction | |
| KR20040009569A (en) | Joint structure and construction method of RC beam and slab for slim floor system | |
| US20040111998A1 (en) | Building planks and boards | |
| KR200337465Y1 (en) | Table form estabishment apparatus for building | |
| JP3781425B2 (en) | Construction method of structure | |
| KR20000032637A (en) | Method for constructing aggregate of wall-type structural apartment | |
| FI93668C (en) | Wet room element and method and apparatus for manufacturing the element | |
| EP0974436A1 (en) | Facade, method for manufacturing a facade, table for use in the method and assembly of section elements for use in the method | |
| GB2250537A (en) | Formwork for the formation and repair of surfaces |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |
Effective date: 20130625 |