US2341518A

US2341518A - Grouting system

Info

Publication number: US2341518A
Application number: US343100A
Authority: US
Inventors: Ray L Allin
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-06-29
Filing date: 1940-06-29
Publication date: 1944-02-15
Anticipated expiration: 1961-02-15

Description

Feb. 15, 1944. R, L, A| `|N l 2,341,518

' GROUTIN'G SYSTEM Filed June 29, 1940 s sheets-sheet 1 INVENTOR.

Feb. 15, 1944.

` R. L. ALLIN GROUTING SYSTEM Filed Jun 29, 1940 3 Sheets-Sheet. 2

Feb. 15, 1944. R. L. ALLIN GROUTING SYSTEM Filed Jude 29, 1940` Patented Feb. 15, 1944 UNITED STATES f PATENT OFFICE GROUTING SYSTEM RayL. Allin, .San Francisco, Calif;y Application June zo, 1940, serai No. 343,100

s'olaims. (c1.4 fz-eide) My invention relates toa new System and apparatus for introducing suitable grout into -contraction join-ts of concrete `structures in the course of their erection, or, preferably after t-heir completion, and to provide a direct method, of

forcing the grouting material into and along the contraction joints, and to avoid the attendant dilculties,uncertainties, vpoor quality of grout, and great expense caused by the use vof the present methods and available equipment.v

Concrete .contracts insetting and as it dries out and Icools oil it shrinks .to such eXtentt-hat large concrete structures will .develop cracks that may :form at such positions and locations as to be dangerous to the stability of the structure. By locating contraction joints vin the structure at frequent intervals and atproper positions -and locations, .the development of dangerous cracks can be entirely eliminated.. To .strengthen the concrete structure due to the weakening effect of the contraction joints, ythe contraction joints are lled with Portland cement grcut or other suitablecementing material, forced into and along the contraction joint under pressure, preferably when the structure isat its lowest temperature and when `the structure has 'the lleast external load to be carried by it. The Agrouting of the Vertical, normal contraction joints in concrete structures, such as retaining walls and dams,- is very important, and-in such structures varched in plan and depending on vvarch action for fstability,-grouting of 'the vert-ical radialra'nd cir cumferential" joints is of "the greatest "importance; and it lis vadvisable to 'do vthe grou-ting at anl estimated pressure such'that when the-'maxi'- mum loads'are imposed on thestru'cture, there will be practically no tensil lstresses remaining-'inthe structure. In grouting thel contraction-joints of such. structures it is very important to pro-- vide means for the direct removal of Water,-for eign matter and the advancing sheet ofjgrout which usually vgets 4so mixed with lforeign matter that it loses "its strength-and becomesof ajchalky weak character unsuitedfor binding the structure together as a monolith. vBy 'providingmeans tov withdraw this Apoor .grade of 'grout from `all parts of the `joint and continuing to -force good grout into'the Vjoint until onlygoodgroutemerge's from the4 joint vent system; insuresthat thejoiiit has only good grout in it over its entire area; This method of grouting of the contraction joints between the various parts of such structures, cef ments the parts into amonclithic s'tructure'whicn will .transmit 4archthrusts to the rock abutments on eachside of the canyon with lpractically no tension stresses in the structure.

During the grouting of any contraction joint in the structure it is Very important to force water into all joints not already grouted, and to maintain the water in these joints at the con'- stant pressures at which they wi11 later `be grouted. Myinvention contemplates the use of any system'of voperative procedure 'in the accomplishmentof these results and any arrangement of open conduits attached to the face ofthe concrete. forming 'the contraction joint, and by any system of open conduits which provides means for forcing the cementing liuid in one group Iof open 4conduits to be designated the injection conduits', and withdrawing or venting lthe fluid after it has passed into and through the contraction joint opening and on into and through another group of open conduits to be designated thevent conduits; the two groups so located and so4 arranged as tol insure the forcingr in and retaining of good grout in all parts of the contraction joint. f

The .obj ects of Vmy nventionlare: First;- to provide l'an open conduit system and apparatus for Agrouting `the contraction joints which 'will occur between different parts of a.

concrete structure of large dimensions such'as a massive concrete dam or retaining wall in which- 'one or more parts or units of the structure are ybuilt up progressively to partial or full height and allowed Vto harden in advance of the other parts or units of the structure, which are later poured against the formed faces of the partsor units first built.

Second; to provide an open conduit system and' apparatus for grouting concrete structures where= by the'shrinkage and temperature openings or cracks designated `as contraction joints develop` ing between the different parts or units of the structure, which have been poured at different times, are grouted under pressure with cement grout and strongly bonded-to form them vinto one integralwhol'e. Y Third; to provide a simple, inexpensive, easily erected grouting system of vsuiiciently rigid -construction to remain in placeV while theconcrete structure 'is being poured and will 'be' effective `in thoroughly lling the opening in all contraction joints when the pressure grouting Operationis performed.

"Fourthj toprovide an open .conduit supplying, injecting', distributing, venting, grout system 'and apparatus 'can .beV progressively installed unit by unit as the forms for each successive vertical increment of a large concrete unit are erected upon and above the concrete previously poured and hardened, and thereby avoiding any necessity of following any special erection and construction programs from those which would be followed were a grouting mechanism not used.

Fifth; to provide a plurality of open injection and venting conduits communicating independently between Apredetermined :positioned points into the space to be grouted or 'filled and the outside source of supply where the grouting material is introduced under pressure, with said plurality of communicating open conduits entirely embedded between the face of the concrete first poured and hardened, and the face of the second its connection to the vent riser conduit, the lower header pipe and its connection by T to the vent riser pipe and lap-joint.

Figures 1 and 7A are Side views of a structural concrete unit, Figure 'l representing a typical grout panel at the bottom and Figure '1A a typical grout panel at the top of the structure, showing the injection header conduits I, the injection riser conduits 2, riser vent conduits 3, injection pipe. connections', ventheader conduits 5, injecti'onris'er pipes 6. upper pipe header 1, vent riser pipes 8, lower pipe header 9, vent pipe connections Y I0 to the surface of the concrete, and grout stops II, the unit having the appearance it presents pour; the corrugations of the vconcrete in the two concrete' units or parts of the concrete strucjoint in the first pour protecting the injection and venting conduits from injury during the making of the second pour.

' Other objects and features ofadvantage'will be apparent during the course of thefollwing description.'

In the accompanying drawings" forming` 4part of this specification andfin which like"'nu merals` are employed to designate like parts'throu'ghout the same,

Figure 1 is a vertical sectional view, showi n'g 'a portion of the formed concrete face of thecontraction joint forming a unit or part of thecon--4 crete structure,'inconne'ction with a grout supplying open header conduit I, anopen ris'er conduit 2,v through both of which grout is forced into and along the contraction joint.

'Figure' 2 isa vertical sectional view of a portion of two finished and hardened concrete units, showing the contractionjoint'opening H between the units, and the separated open header conduit and open riser conduit through which and out of which the grout can flow at all points along the open conduits into and alongv the contraction joint Figure 3 is a horizontal sectional view of a portion of the finished and hardened concrete unit; showing the vopen riser'conduit 3 attachedto the formed concrete faceof the rst pour'ed concrete.` *This View is typical of a section taken normal to the axis of the open conduits used in the injection and venting conduits. Figure l is a side View of a portion of a str,uc'` tural unit, showing a portion of the injection header -conduit I, injection riser condui t' '2, and pipe connection 1I le'adingto the surface ofthe concrete passing to onefside o f grout stopj'I' This view inverted is also typical of the 'side' view of a vent header conduit andfv'ent riser conduit and vent piper connection. f

Figure '5 is a horizontal sectional View of a portion ofY th'nished and hardened concrete unit, showing an injection header conduit I, Iand an injection pipe 4 leading'to the surface. of the concrete passing toone side of the grout stop I I; This View is'also typical of a horizontal sectional view of the vent header conduit and vent pipe leading to the surface of the concrete.

Figure 6 is a vertical sectional vie'w of aport'ion of the finished and hardened concrete unit, showing an injection riser conduit 2an'ejection riser pipe 6, and its connection to the open conduit I8, the upper header pipe 1 and its connection by T-22 to the injection riser pipe 6, and a 11g inch fillet welded lap-joint 3U showing method of con# nectionat a reductionin size of angle conduits 2. Thi'svertical sectional view inverted is also typical of the vent riser conduit, a vent riser pipe and.

when ready for the pouring of an adjoining unit or 4part of the concrete structure.

Figures 8 and 9 are plan views of portions of ture showing the lower portion of the grouting system installed and fastened in place after the first and lsecond units have hardened.

lFigure 10 is a plan view of a portion of one concrete unit -a a higher elevation than shown in Figures' 8 and '9, showing the open conduits fastened to the concrete surface of one of the concrete units thatY has hardened.-

Figure 11 is a plan view of a portion of one'of the concrete units., showing the typical configura.'- tion of one of the side faces thereof in the central portion of the unit; these configurations are suppressed near the horizontal grout stops.

Figures 12 and 12A are vertical sectional views ofa portion of the finished and hardened concrete unit, Figure 12 representing a typical sectional view of the bottomgrout panel or panels, and Figure 12A a typical sectional view of the top grout panel or4 panels'of the structure, showing the injection header conduits I, injection riser conduits` 2, riser vent conduits 3, vent header conduit 5,'injectionriser pipes 6, upper header pipe 1, vent-riser pipe 8, lower header pipes 9, and grout stops I I; these views also show the typical congurationjof one ofj the side faces of a concrete unit, with configurations suppressed near the horizontal grout stops. Figure 13 is -a horizontal sectional view of a fragment of a concrete-holding form, showing a metal strip secured to one side thereof which later closes the contraction joint opening between two adjoining vconcrete units.

Figure V-14 isa horizontal sectional view of a portion of two hardened units and the joint-clos.. ing Y metal strip partially embedded therein.

Figure 15 is aplan view of fragments of two hardened units, showing' the contraction joint opening between them andthe joint-closing strip partially embedded in each unit; and a plastic filler stripinserted in the U of the joint-closing strip. Y

Referring now to vthe drawings, the apparatus I employ to accomplish the objects of my inven-L tion, vconsists of an opengrout injection header conduit I which is placed horizontally Vcrapproximately so, near thelower confines or bottom edgeportion of each of the contraction joints, bein g set preferably perauei thereto, and to this 11ijectionheader conduitfL'I secure at predetermined distances apart; along its length, the lower ends of injection riser conduits 2, which extend up vertically against yand attached tothe face of the concrete unit or block of concrete along whichthe contraction joint is to occur to the top surface'of the completed structure. In the pref'v ferre'd construction of the injection andv venting conduits', any suitable vopen conduits may be used',

the. header conduits are' preferably made .of` '2' inch by' Zivinch` by 1/8 inichsmallsteel anglesandv the'v riser conduits are preferablyv made off'llly, inch by 11A inchby. 1inicio-.small steel angles in the lower half ofthei riser, reducing in the upper halt of, the riser to l. inch by 1. inch by 1A; inch small steel angles and are made in anypredetermined length, the header and riser conduits communicate. through a suitable opening, preferably a triangular opening I2 inthe leg of the header angles I and 5 respectively, Aand placing the bevel-cut endk of. the

riser angles

2 and 3 respectively'over'the respective. out openings, and. joiningtlre: two angles respectively by any suitable means that will. prevent the entry of mortar. at the joint, preferably by 11e inch continuous fillet wells I3. ontheoutside.I surfaces of contact of the angles, the header and riser conduits held firmly against thesmooth` surface III' of the previously poured and hardenedunit of theiconcrete structure.

My 1 invention contemplates the securing of these header andriser anglesagainst the smooth surface I4 ofthe concrete by. any suitable means; but I preferablysecure them to the concrete face with. l0penny nails embedded in the previously poured concrete or similar suitable attachments substantially as shown in the accompanying drawings at; A. Ipreferably have the vertical riser angles made in a` number of units whose equalky lengths are each equal. to', or multiples of the vertical depths of concretev to be poured. Theends. of two adjacent units being joined by any suitable means thatv willy prevent the' entry of mortar at the joint, preferably by le inch continuous iillet welds. on` the outside surfaces off contact of theangles. l

This unit method of; assembly and emplace ment is particularly Well adapted to structures. of the largest size andk also permits making the lengths of the units composing the riser angles such that,.if thestructures wherein they are used be so great as to necessitate several successive pouringsv of concrete inl vertical sequence one above the. other, these lengths will either-.singly or in multiples equal the` amount that the con--v crete is raised in.these.progressivesteps/of pourings required to reach the'nal completed height of the structure. I hold.V the angles rmly against the smooth surface I 4'. of the concrete by any suitable means, preferably'by 'steel wire ties I5, the looped ends of whichv are placed over the bent nail ends A and wire ties twistedA together over theheelof'theV angle by means of ay wire tying: brace',- or by twisting a` nail inserted inf the tie wire loops or other suitable means which presses the angles rmly against the smooth surface I4 and makes a strong rigid con-- struction for the purpose intended, which can` be built up readily as fast as the `concrete is poured and hardened, and will remain Xed in the predeterminedly selected vand erected positions while the concrete is poured against the.

smooth surface I4 of the concrete unit and against the injection and venting lconduits attached' to the hardened` concrete surface I 4.

My invention also contemplates-the securing and' anchoring these injection and venting conduits to the concrete poured against the smooth surface IIIv of the concrete' by any suitable means, preferably by steel straps IS Whichare prefer-Y ably l inch wide by le inch thick'and 3 inches long, attached to the steel angles at about 6 inch centers on alternate legs of the angles by any suitablemeans, preferably by 11g inch fillet weldsr IT'for- 1/2, inch along the-.Ledges cri the: straps:v

and theI joint opening-H widens, the: small steel angles are rigidlyrheldi to the concrete unit in.l Whichzthe anchorV straps I'6 are embedded', thev wire ties used are' much,l weaker and less rigidthan thek anchor' strapsi I6, thus. the wirey ties stretch, elongate and break,` and' ani opening occurs along/the edgesi of the angle-equal to the opening Hof the joint, thus providing an opening for the groutfto o'w from theinj'ection` conduits, out, into, and along thejo'int opening, and out of, the jointropen-in'g and". into and along theA ventconduits until. only-good grout remains in the joint openinglwh'en under! fulll final' grout pressure.

My invention. alsocontemplates the making thep connections between the open conduits andi the pipesby any suitablev meansthat 1 will" prevent the entry of mortar into the openv conduit or pipe attheir connections; I preferably use al1/8 inch plate I8 cut to t the outside dimensions of the section of the endothe conduit, usually cut on a bevel, andA attached thereto lby any suitable .v means, preferably 'by a le inch continuous Weld into the conduit or pipe, preferably by al le inch continuous WeldiZI atvthe outside surface of contact of the plateand the pipe. The riser pipes,-

preferably lqinch inediame'ter, are connected to the header pipes; preferably 1 inch indiameter chored- `to. the hardenedfconcrete forming. the

outer surfacev-ofithe corrugations by means or' nails embeddedliinl thefconcrete, and wire ties similar to the'method used in attaching the angle conduites to the concrete-surface I4;

In laying outa` unit of concrete, I preferablyform its-.borderoutline along its sides intoa continuous succession of equal corrugatio'ns 23` except near-the sloping surfaces' of the structure where the height is reduced to t in each panel boundedby groutfstops If-I the corrugations' being' formed' by projecting thecOncrete-Out, in, Aor at suitable angles from the pla-ne surfacestrips I4, the width of thersmooth surface strips I4 being made equal to the Width of` the at projecting arear23. I embedsheet metal!J strips II,V calledy grout stops (except at the; upstream face where they are usually called water' stops), or other suitable material having a U shaped fold IIA along the central portion of their widths, with their folded portion temporarily resting against the contraction jointforming faceof the form of the first pour of concrete, then after the form isremovedr the grout `stop is bent out into its final position for embedment in` the second pour of` faces to the exterior surface of the structure'forA its entire height.

'Ihe corrugations I4 and 23 inthe formed concrete units C and D of Figures 8 and 9 that are' opposite to each other, forma continuous tongue and groove surface throughout practically' their length and height' except where the corrugations are suppressed to facilitate forming and placing" the horizontal grout stops II; andiassumng that' the two units C and D have been poured and have hardened, then by closing up the opposite ends F' andG ofthe space'E, thisspaceior unit E canbe poured and when itis poured the concrete flows into the vertical groove members against the surfaces 23 and I4, that define the depth of these grooves; and this tongue andgroove vconstruction of new units between hardened units results in the new units being locked by these numerous tonguelike keys that enter the hardened units, against any movements except the small vertical and horizontal movements due to shrinkage and temperature change; and after the concrete unit E has also hardened, cooled, and the open joints H grouted, the new units are rigidly locked by these numerous tonguelike keys, against any possible movement whatever from pressures acting in a downstream direction that are caused by the pressure of water or other material against its upstream end, as the units in dam construction are placed transversely across the length of the dam, but the units can be arranged in any other predetermined positions relative to the length and breadth of other kinds of concrete work.

After the concrete has been poured and has set, the forms are removed in the usual manner, and the point ends of the embedded nails are now left protruding from the concrete.

I now bend the protruding ends 24 of the nails A over as indicated in Figure 3; I then place the grout injection and vent conduit and pipe systems and grout stops in position and secure them firmly in place against the hardened face of the concrete units by means of wire ties as indicated in Fi-gure 3, and by fillet welding and threaded connections to connect the portions of these systems together. 'I'hese materials are preferably installed in units equal to the depth of pour of the concrete with the upper ends of the conduits and pipes left protruding above the top of the next lift or depth of concrete to be poured with the upper ends temporarily plugged and capped to prevent them from becoming clogged during the pouring of concrete. Prior to the pouring of the next lift of concrete above described the edges of the open conduits, preferably angles, are coated with cement mortar or other suitable material and let set to prevent the entrance of mortar into the conduits during they pouring and vibrating of the fresh concrete. After the pouring of the fresh concrete and prior to the time of the concretes initial set the open conduits are flushed with water to Wash out any mortar that may have found its way into the conduits during the concrete pouring operations.

, When the fresh concrete above described is first poured and while still in its workable senilliquid and plastic condition, it is in intimate contact with the contraction joint faces of the seasoned and hardened concrete on either side previously poured, but as it begins to set and harden, consider-able rise in temperature in the interior of the mass occurs, and as the process of hardening and setting enters into its final stages, this temperature becomes less and less, and in thick masses of concrete, this heat of hydration of the cement is carried out of the mass by the circulation of cooling water and refrigerating water through preferably one inch pices embedded in the concrete at the top of each 5 foot lift or pour of concrete with the pipes spaced at about 5 foot centers horizontally, and the resulting drop in temperature produces a reduction or shrinkage in the mass of the concrete and its physical dimensions, thus causing its outer confines to contract towards its center, and thoselportionsl originally in contact with the faces of contraction `ioints previously poured on, either side .recedesjor pulls. away from those faces, leavingy an opening Hl between them, and inasmuch as the open .conduits are rigidlyanchored by straps I6 in this new contracting concretethey alsorecede or pull away from the faces of the concrete units.

previously poured, so that. this receding movement produces two continuous lines of opening,

one along each leg of the :open conduit toy the. open space betweenthe faces ofthe concrete.4

When thisV receding movement between 'the open conduits ,and the concrete face occurs,:it

is resisted only by the wireties I5 looped over the bent nails A, and these wire ties I5v and. loops 25 are straightened, stretched and broken.-

by the relative movement of, the two `units of concrete, as shown in Figure 2 toaccommodate this movement.

In Figures 1, 3, 4, 5, 7, 7A, a, 9, -10, 12 and 12A,

I illustrate a complete uid grout injectionand venting system set up and attached to a formed and hardened face of a contraction joint-and held in place .by wire ties connected to bent over nails, the headand portion of the shank of which have been previously embeddedin .the concrete of the first pourwhich then hardened.

In Figure 2, I illustrate the condition after the A concrete of the third pour has been placed..

against the hardened concrete face of the first pour, and the concrete ofthe third pour has. hardened, cooled and shrunk away fromy thez hardened face of the rst pour of concrete, theny the open joint H is ready to receive the grouting material between the two masses 4of concrete.

for filling the contraction joint opening H with cement grout. This is accomplished by forcing and pumping the grout into the injection pipev the edges of these conduits I. and 2 into andv along the opening H in the contraction joint directly across the groovesld and the corrugations 23, forcing the air, water, and foreignmatter in the open joint H ahead of the grout,

and to, into and along and down into the vent riser pipes 8 andthe lower pipe header 9 and out of the open control valvevZIi until good grout of proper consistency is discharged, whenthe control valve 26 is closed,l and the additional grout pumped into the pipe I is forced along the opening H directly across vthe grooves I4 and the corrugations 23, forcing the air, water and foreign matter in the open joint H ahead of the grout, and to, into, and along the riser vent conduits 3 and the vent header conduit 5, ony

through the vent pipe connection I0, and out of the control valve 28 until good grout of Vproper consistency isy discharged, when the control valve 28 is closed, and the required additional,`

pressure over the entire joint is appliedv and maintained by closing the control valve 29, yor by a pressure control chamber or other suitable means, until the grout has hardened. .This

illustrates the grouting of the contraction joint if shown in Figure 8. In a similar manner vthe contraction joint shown in lFigurgfi is grouted When the entire concrete structure has. thus been completed, I have incorporated in the structure and provided a direct communication.

2,341,518 and the grout let harden. When this process of grouting has been continued over all the grout panels from bottom to top and from downstream face to upstream face of the dam, the concrete units or masses of concrete are then integrally united into one monolithic structure of concrete.

The same procedure of pumping grouting media of any suitable material under pressure into the bottom header conduits of each of the remaining joints in turn until each system has been entirely nlled progressively from the bottom to the top, is followed until all the joints are grouted. The work of grouting can be performed at any time after the concrete has hardened upon both sides of the joint or joints, but the best resuits are obtained when the concrete has a temperature below normal and has attained maxirnum contraction as in winter or by cooling or refrigeration as herein described.

When using cement grout, I preferably force Water and air and water mixed under pressure through each space that forms the contraction joint opening H, washing out laitance and other deleterious materials that prevent the bonding' of the grout to the concrete faces of the open joint H. After the washing out of the joint,`I ll all the open joints H full of clear water for several days before starting to introduce the grout, as this fills the interstices of the adjoining concrete with water, and meistens all surfaces which the grout is required to bond, and insures that the grout will reach all portions of the voids in the open joint with its proper free flowing consistency, which it would not otherwise retain were it progressively coming in contact with dry concrete and losing its moisture content by absorption therein.

From the foregoing it will be observed that the filling or bonding mixture is introduced directly into the open joint along predetermined lines progressively from the bottom of the structure towards the top, and the Venting of the open joint along predetermined lines parallel to, opposite to, between and above the grout injection lines, so that the bonding mixture must pass directly through and across the open joint between the injection and vent systems before it can be discharged out through the vent system, thus insuring free escape of the air upwards and the water out of the joint from the ascendingbonding mixture, avoiding any possibility of entrapped or imprisoned air, gases, water, inert grout and laitance, or other poor quality bonding mixture, forming pockets or gaps where bonding could not otherwise occur; that the conduit system supplying the predetermined lines of entry into the joint and lines of vent out of the joint are directly in contact and open to the joint opening along their entire lengths, on each side of the open conduits, thereby making certain the delivery of the bonding mixture to all parts of the joint surfaces to be bonded.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same, and

though it refers particularly to contraction joint openings as being the type that are in a vertical plane, the invention can be equally used in any contraction joint in any other plane, including warped surfaces, and in any type of structure to which the principle of the invention can be applied, and that variations relative to the material, size, shape and arrangement of the elements involved can be resorted to without departing from the spirit of the invention `orthe scope of the subjoined claims.

Having described my invention7 what I claim as new and desire to secure by Letters Patent is:

1. Apparatus for grouting the contraction jointl between two concrete units, comprising open header and open riser conduits in a grout injection system and a grout Venting system, the grout injection conduits being in the form of a channel with the edges of the open side thereof positioned against the contraction joint face of the first poured unit of hardened concrete, means yieldingly secured to said conduits and to the contraction joint face of the first poured unit of hardened concrete for enabling an opening to form between said edges and face by the shrinkage of the concrete whereby grout is permitted to flow into the contraction joint, means associated with said conduits for fixing the same in the second poured unit of concrete, means connecting the ends of said open conduits for the injection and venting of grout in these open conduits, and means for closing the ends of the open contraction joints.

2. The invention as set forth in claim 1, wherein the said means connecting the ends of said open conduits comprise injection and vent riser pipes connected to the ends of the open injection and vent riser conduits respectively and leading to an upper injection header pipe and a lower vent header pipe respectively and thence these header pipes lead to the surface of the finished concrete structure.

3. Apparatus for grouting the contraction joint between the two concrete units, comprising means for closing the ends of the contraction joint, a lower grout injection open header conduit and connected thereto a plurality of open grout injectionriser conduits and located opposite to and approximately half Way between and above these injection conduits, -a plurality of open grout Vent riser conduits and connected thereto an upper grout Vent open header conduit, means for flexibly holding the open side of said conduits against; the smooth vface of the concrete unit first poured, pipe connections from said open header conduits leading to the surface of the concrete structure and including a plurality of small pipes connecting rfom the upper ends of the grout injection riser conduits to an upper header pipe that leads to the surface of the concrete structure; and a plurality of small pipes connecting from the lower ends of the grout vent riser conduits to a lower header pipe that leads to the surface of the concrete structure.

RAY L. ALLDT.