US1318282A - Method oe and apparatus - Google Patents

Description

I N. C. JOHNSON.

METHOD OF AND APPARATUS FOR MIXING CEMENT WITH OTHER INGREDIENTS.

APPLICATION FILED MAY 29. IQIB.

Patented Oct. 7,1919.

5 SHEETS-SHEET I- THE COLUMBIA PLAN Oflfi APH c0.. WASHINGTON, c.

N. C. JOHNSDN.

METHOD OF AND APPARATUS FOR MIXING CEMENT WITH OTHER INGREDIENTS. APPLICATION FILED MAY 29. I9I8- N. C. JOHNSON.

METHOD OF AND APPARATUS FOR MIXING CEMENT WITH OTHER INGREDIENTS. APPLICATION FILED MAY 29.19I8.

1,318,282. Patented Oct. 7,1919.

5 SHEETS-SHEET 3- THE COLUMBIA WP 60-. WASHINGTON, D. C

N. C. JOHNSON.

METHOD OF AND APPARATUS FOR MIXING CEME NTWITH OTHER INGREDIENTS. APPLICATION FILED MAY 29.19l8.

Patented Oct. 7, 1919.

5 SHEETS-SHEET 4- INVENTOR N. C. JOHNSON. METHOD OF AND APPARATUS FOR MIXING CEMENT WITH OTHER INGREDIENTS. APPLICATION FILED MAY29-l9l8.

1,318,282. Patented Oct. 7,1919.

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rozwna I gei time STATES ATEN NATHAN-. G. JOHNSON, OE ENGrLEWOOD, N EW J METHOD or AND APPARATUS; r03. MIXING c vmN'r WITH OTHER I GRnDInNTs.

Specification-of Letters Patent.

Patentedflct. 7,1919.

Application filed. May29, 1918; Serial N 0. 237,216.

b all whom it may concern:

Be it known that I, NATHAN C. JOHNSON, a citizen of the UnitedStates, and a resident of Englewood, county of Bergen, and 'State of New Jersey, have invented certain new and useful Improvements in Methods of and Apparatus for Mixing Cement with other Ingredients, of which the following is a specification.

My inventionrelates to methods o-f'and apparatus for mixing cement-with other ingredients, and it is especially useful in mixin concrete.

Iere'tofore, concrete has been mixed in various ways and by different kinds of apparatus. The machine now most, generally used for mixing concrete-oonsistsof a slowly rotating horizontal or inclined drum open at each end or at one end, and carrying inner blades or blades and buckets whichcutthe mass, elevate it to a certain distance, from whence by gravity it is spilled back to the bottom of'the drum, inrepeated'cy'cle s until the mixture is adjudged made.- The unmixed ingredients are fed in at oneend and the mass is discharged either at the other end through a suitable chute moved into position to receive the mass as spilled fr'om the buckets, or through tilting of the drum. Machines of this type are slow ino peration and output and are clumsy, the actual capacities of such mixing means averaging approximately 500% greater than the actual volume of maximum batch accommodated Various other machines have been used,- such for example as one having a series-of spiraled mixing paddles which-rotate slowly in an open trough, mingling the mass .whlle conveying it through the machine, Dueto the mixing actions of such, mach nes, 1t-1s impossible with them to obtain a proper quality of concrete in the comparatively short period of time to 1 minute). allowed in practice for mixing a batch; and when concrete is thus not properly mixed, its structure is not uniform, homogeneous and dense in texture, but is, on the contrary, heterogeneous, non-uniform, porous and weak. Inas-. much as the output of a concretemixing machine directly affects the cost and speed of. building concrete structures, and as its quality determines their values and endurance,

it is important to provide mixers having not only a large output, but also those that by their mixing action shall produce material having the character desired.

The mixing of concrete by utilizing the action of centrifugal force to a greater or less degree has also been described from time to time in patents, but my invention contemplates a different kind of action and con-- stitu-tes. an improvement over these proposed devices. According to my invention, the mass of ingredients is subjected to strong centrifugal force and is moved at high velocity andis compacted, in such manner as to efi'ectinterparticle attrition and a rapid mixture of the ingredients without undue aeration, and this method of mixing the mass is carried out by very compact, simpleand inexpenslve apparatus. V

It is well understood that the inertingreclients of concrete, such as sand'and gravel, or stone, "are cemented or glued to gether by the physico-chemical actions of the cement in setting. And it is also appreciated that in gluing any substances. together, to produce thorough union, the surfaces must be clean. In the mixing'of concrete, too little attention has been paid to this fundamental necessity, largely because of the difliculty of carryingout economically any process for the adequate cleansing of materials. It is the practice to sometimes wash sand, and gravel or stonewith water before incorporating themwith cement, but this not only entails additional time, labor and expense, but it also does not remove foreign coatings inhibitive of such gluing, except those that might be readily dissolved or washed away by a simple fluxing with water.

It is also a fact that air bells adhering to the solid particles when these are wet-ted with mixing Water are productive of voids in the set concrete;and that minute lumping of very fine cement particles is common in commercial cements due to slight hydration by steam treatmentat mills, or by contact with moist air; and that these out down the elliciency ofuse of cement in all concretes as usually made.

Grouping and surface hydration-of cement particles before use particularly re ducesthe strength of concrete by preventing thorough and uniform hydration of the cement and its utilization in suflicient quantity to bring about complete coating of the inert particles by the hydrated cement, as is essential for proper results.

Unclean surfaces of inert particles; the presence of weak particles, such as mica;

I lumpsjor groupings of cement particles;

and the occlusion of air-all tend to produceconcrete that is structurally weak and ununiform, through voids, feebly united surfaces and particles which'make it a reticulated mass in plaeeof a homogeneous solid.

Commercial practice has therefore become fore, for means to overcome thesevarious deficiencies incident to usual methods; and this should be effected without reduction in output.

The. principal objects of my invention then, are to produce a novel andeflicient method of mixing cement with other ingredients (particularly in the making of concrete), and novel and efficient apparatus for carrying out the same, whereby these detrimental factors are overcome My invention consists in the process hereinafter set forth according to the preferred manner of practising the same, and in the novel features and combinations of parts hereinafter shown and, described in their preferred formsyand the inventionis more particularly set forth in the appended claims. V

Further objects .and advantages of the invention will more fully appear from the following description and the accompanying drawings illustrating the preferred form of mixing machine.

In carrying out my invention, I effect interparticle attrition sufficient to scour all particles, and compacting of the mass sufficient'to release entrained air" under the ac.- tion of centrifugal force-and higlrvelocity mass flow. This inter-particle attrition is sufficiently violent to elevate the temperature of the mass; toscour the inert particles and remove from their surfaces dirt and foreign coatingsgto scour the cementpartt cles and remove "any 'preuse surface hydra 'tions, to break off weakly attached parts, and to break down and comi nlnute' fragile,

to break upand. separate small and to thoroughly mix the cement and w'atcrso as to form a cementitious fluid ofsuperior hydration with which the inert particles are intimately contacted, while the compacting squeezes out of the mass air bells released particles i by scouring of particles, so thatin a mix ing opeiution ofbrief duration a batch of thoroughly mlxed concrete havlng uniform conslstency and improved strength is pro- 7 .duced.

' According to the preferred manner pf practising my process, as for example in the mixing of Portland cement with water, sand and stone or gravel for forming concrete, I place the ingredients in a suitable rotary container, preferably an upright bowl with curved outwardly flaring side walls, and while the ingredients are being placed therein, or after they have been placed therein, the container is rotated rapidly so as to subject the batch while confined therein, to such centrifugal force as to-produce high velocity mass flow. I have found that a peripheral velocity ofthe bowl of approximately 1500 feet per minute is suflicient to give the desired velocity and flow to the mass when apparatus of the character shown herein is utilized. Under the momentum of the mass it is caused to circulate at high velocity in a steady continuous stream along one or more predetermined paths (determined 'by theshape' of the. container and the location and shape of the massdefiecting devices) rapidly changing in direction, in such manner as to produce compacting of the mass during said circulation together with violent interparticle attrition so as rapidly to scour all particles of the mass and thoroughly mix and incorporate the same with the cement and the water in a substantially uniform mass Without undue aeration.

The preferred manner of carrying out the process will be more readily understood from the following description taken in connection with the accompanying drawings illustrating the preferred form of'machine for carrying out the process, and also forming a part of my invention, andin which- Figure 1 is a plan view of a concrete mixer embodying the preferred form of my invention;

Fig. 2 is a sectional view taken on line 2'2 of Fig. 1; j

Fig. 3'is an enlarged view of a part of theapparatus showing the contour of the inner face of the mixing blade; Figf l is a similar view with the lower end of the blade'lifted; i Fig. 5 is an enlarged detail showing the supporting. stanchion for the mixing and deflecting blades;

, Fig. 6 isa fragmentary sectional viewtaken on line .6 6 of Fig. 2 looking in the direction of the arrow 7 Fig/(is ap erspective view of the interior of a concrete mixer in operation, showing the'action of the mass therein; and Fig. 8 illustrates some comparative plotted curves} Referring to the drawings (Figsfl and 2) l is a vertical mixing bowl the depth of which is equal to about one-half of its diameter. The bowl has curved outwardly flaring walls with a slight flattening at the bottom, and 1s preferably madeup in sections. It" is shown in its present form consisting tion of the materials in the rapidly flowing mass, and the scraping of the entering edge against the sides of the bowl, it willbe rapidly worn down unless it is hardened. It is alSO important to have-it hardened so that a fairly sharp entering edge may be maintained to cleanly and smoothly divert the mass from the sides of the bowl.

The inner or mass-engaging face 457 of the blade is preferably concaved along its length as well as across its width, and the blade is so located and positioned against the side of the bowl that the blade forms an acute angle with the side of the bowl to the rear of the enteringedge, the inner face of the blade being inclined forwardly and inwardly against the direction of, flow of themass, so that the blade somewhat overhangs its entering edge which is inclined upwardly and against the direction of flow of the mass, the'top of the entering edge terminating approximately at the rim of the bowl. The

concaving ofthe inner face of the blade starts somewhat gradually at the upper extremity of the entering edge and increases its curvature toward the center, from'which position the curvature is gradually lessened toward the trailing or discharge end of the blade, The object is to provide a deflecting blade which will engage the high-speed mass as'it flows upwardly along the sides of thebowl' and turn it therefrom. and divert and direct it toward the center of the bowl in as smooth, solid and-steady a stream as possible so as to reduce to a minimum any splashing oraeration of the mass. 7

V The mixing blade is provided with an upturned flange or cowling 49 extending along its'upper edge to facilitate the smooth flow of the material and avoid. splashing. It willalso be seen by this arrangement and construction of the blades that the action of the mass against ,th e blades, tends to. hold them firmly against the'side'wall of the bowl. W w

Mixing blades as herein shown; and d escribed have proven very, eflicient because the blade first engages the most rapid flow.-

ing portion ofthemass, namely, thatfa'djacent the rim of the bowl, and takes this top portion of, the mass and divert and turns it over first, thereafter: progressively engaging the mass toward thelower portion of the side of the bowl, and the top or more rapidly flowing portion of the mass is, by reason of the shape of the inner surface of the blade, directed along the longer path of flow, toward the centerof the bowl,

than the portions of the mass lower down. Thus not only is the top and morerapidly flowing portion engaged and turned over first, but the mass is so 'gulded; that while its directio-nis rapidly and abruptly'changed i by these mixing blades, it'is accomplished in such manner as tocause the mass to be compacted against the face of the blade and made to flow in a steady smooth stream to avoid aeration.

The contour of the vbowl is'such as toper mit the material to flow outwardlyand upwardly toward the rim'of thebowl under the action of centrifugal'force, at the same time securing the desired compacting of the material by pressureagainst the sides of the bowl. -The upwardly curving bowl permitsthe mass 'to flow joutwardlyin a smooth stream, but itsinclination is such as to give sufficient resistance to th out ward flow of the material to cause it to be compacted by pressure against the side Walls as it flows, so as to increase the interparticle attrition and; squeeze out or liberate entralned alr; wh1lethe action of the mlxing blades on the mass 1s such" as to contlnue this compacting of the mass and interparticle attrition therein. 1 I

Theiparticularpaths taken by the mass will be determined by the shape and'locaof the bowl. y Y

In Fig. 7 isfshown a perspective view of the interior of a concrete mixer illustrating the manner in which the mass is caused to flow for mixing concrete according to 'my invention. The particular. machine, more or less diagrammatically shown in this view, contains three mixing blades instead of'four. Referringto Fig. 7,-the operation is as follows The ingredientsof the concrete are emptied into the bowl, which is then rotated at relatively-high speedsuch as to-produce a peripheralvelocity preferably of approximately 1500 feet per minute. As the bowl is speeded up, the mass is impelled under the action of centrifugal force outwardly. and upwardly along the inclined curved sides of mass in the bowl may be traced as follows: Commencing, forexample, at; point .50, the

rapidly flowing mass, sweeps upwardly and outwardly in a spiral path toward the rim of t of the onwardly sweeping mass and diverts itfrom the side of the bowl along the inner face of the deflecting bladein suchmanner as to turnthe mass back on itself and toward thecentraliportion of the bowl. All of that the bowl in a spiral path. The flow ofithe portion of the mass. which has beenimpelled upwardly onthe side of thebowl' in front of the blade 52. and tothe height of-the blade,

is thus deflected, away from the side and to the central portion of the bowl, as shown at 53; This deflected portionof the mass is im polled inwardly in a smooth steady stream, and the contour of the blade, as'heretofor'e described, is such tliatthe'VBlOCitY oftlie deflected portion ofthe mass is reduced as little as possibleby the deflecting action.

The deflected mass is 'concaved in crosssection; as'in'dicated by the shaded portion at impelled upwardly and outwardly on the side of the bowl at 54, is in like manner caught by blade 55 and'defiected to the central portion of the bowl as shown at'56; and likewise with thelolad'e 57. Most of that portion of the m'assdefiected by blade 52, for example, does not again'reach the upper portion of the bowl in time to be caught and defie'c'te'd'by the next succeeding blade 55, but reaches it "in time to becaught and deflected by the second succeeding blade, namely, 57'. In other words, the flow of por tioii's 'of'the mass is suchas to engage every other blade. There are thus in'this instance three distinct paths or cycles over or through which the mass flows in very swift smoothly flowingst'reams', during which the mass is turned, coinmingled, and'compacted as and for the purposes heretofore described. The interparticle attrition has been found to be so extensive asto actually increase the temperature of the mass app'rorimately 10 F. in two minutes of mixing time.

The raising of thetemperature'of the massis a highly 'desirablefeature, $11108 it increases the reaction of the f'cementwith the water, thus effecting a'inor e rapid and complete transformation of the powdered cement into liquid form 'andincreasing its coi'icentration and usefulness.

By utilizingthedescribed process and the preferred 1 formof nii'xing apparatus as shown and describedher'ein, largebatches of concrete may be rapidly and thoroughly mixed. A'eharge'of ingredients sufficient to fill the bowl'to about two-thirdsof its ca-' pacity'can be thoroughly and commin' ied in about 20 seconds. 1

In Fig." 8 two sets of plotted curves-are shown illustrating the comparative strengths of set mortars and concretes as miXed'by hand and as mixed by my; process. The

ordinate" of"-tliese" curves is in compressive strength per square inch, while the abcissa is in age in days. The curve: 62 ,is one illustrating the compressive strength ofa 152 3 concrete carefullyf: mixed in the; laboratory by hand for twenty minutes while curve 61 is a concrete inade of thefs'anieproportions' and ingredientsmixed accordingto my inventionfor two minutes; and curve 60111115- uniformly v trates'f the co pressive; strength. of a: 1 t 2 mortar carefully ini ved'in thelaboratoryby hand for twenty minutes, and curve L59 illus mares "amortariof the saline" pro onions nd ingredients n \ed fortwo ni tesla' ccord ing'tofi'ny"invention; twenty ifiinute han n ik'ji f n cceptable staiida assess ents R bp fly mixed y hand Qqf f t s hlb umejs su erior tof'coiicret mixed with may chines for the time interval new used in coiiii'nercial operations. 4

comparing curves 6 1; aiid'62i it will be seen, that concrete ninety days oldiriade by a 1 careful" hand mixing shows a compressive s't'ren'gtlrof less than IGOQpo'unds pe'iasqii r'e inch, while concrete 'of the smj ro a titns and ingredients made according to my irive i'tion' and "of the l same age, k shows a coin. pressi've strength o f approiiimately" 2900' pounds per square 'ineh. comparing cui*ves60faiicl 5Q itwill be seenthata "mos, tar made by hand mixing and fifty d a'ys old; shows a compressive strength of a little'over QGOO'poun'ds per square inch; While a"mdrtar of the same ingredients janclfproportions made" according to my v invention shows a tar, after being allowed'to' stand'for afew months; vastly improved in' strength when mixed according ,to my invention, "but that I it shows a decided increasedstrength while newly set or fairly green. Thisy of course has'its advantages in permittingmore rapid building operations in inanyinsta ncesl cording to the preferred manner of emying out the same, and have illustrated aria described preferred "formis'j of machines enibodying' 'tlie'sa'me; itwill be obvious to those skilled in 'the' art, after understanding my inx'fentioii, that various alterations; -modifica tions 'an'd substitutions may be madewithout departing from the spirit and cepter the invei'itions'aiid I aim in i v to cover all'such modifications. V Having thus de'scribed my invention; what I claim as new nd desired to secure by Let-' ters Patentfis 1. The' method niciiringf cement"and I paeted" during their fc'entrifugal flow, arid. diverting the rapidly moving} mass while lVh ile I I "have described my invention? ac} the appended claims still compacting it; and cai'ising it to "flow into position where it is "again ino vediandl compacted under the influence of the testerugal force, and continuing'the cycle until water in batches with or without other in- 'gredients',ywhich comprlses subjecting the batch while confined in a container, to such centrifugal forceas to produce high velocity mass flow of thebatchQand under centrifugal'force and momejntum causing the mass to I circulate rapidly in a continuous stream such. circulation? interp article attrition suff along one or more predetern' ined paths rapidly 'changingjin' direction, and in such manner as to cause the particles of any particular portion' of the mass' to be compacted together'during and at the end of its centrifugalfiow,thereby effecting themixing distribution and with compacting and v10- lentinterparticle' attrition under the influ ence of centrifugal force.

'3. The nethed of mixing cement and -water in 'batches withor without other ingredients, which comprises subjecting the batch while 'confinedin a container, to cen-. trifugal force andhigh velocity movement, causing the particles to be compacted under theaction of centrifugal force, and at the. end of said action on any particular portion of the mass diverting itwhile continuingthe compacting of the particles of said portion, and causing it to flow athigh velocity into position where it is again brought under the action of centrifugal force, and continuing the cycle causing the mass to circulate in one or more steady streams until it is mixed.

4:. The method of mixing cement and water in batches with or without other 111- gredients, which comprises subjecting the batch while con'fined in a container to such centrifugal force as to produce high velocity mass' flow of the batch therein, and under tlie momentuinof the mass causing it to circulate in such manner'as to produce interparticle attrition sufficient to. substantially raise thetemperature of the mass in a brief time interval and withoutsubstantial aeration thereof;

5. The method of mixing cement and water in batches with or without other in gredients,- which comprises subjecting the batchwhile confined in a container to such centrifugal force as to produce high velocity produce compacting of the mass and vduring ficient' to tlieroughlyscour adherent coatings 7 6O e I temperature oftheniass andr to incorporatev thejpa'rticl'es 1n a mass of highly uniformlfro theparticles, substantially to raise the composition and consistency in a brief mix ng per od.

In a machine for niixing cement with I I upon by centrifugal force;

other ingredients, the combination of an up right rotatable container with side walls, adapted to receive the ingredients to be mixed and rotatable at such speed as to subj ect the ingredients to the action of centrifuR gal force and cause them tobe moved at high overhanging said edge so asto engage the" rapidly moving mass at theisidesofthe container andcause it to be turned therefrom and projected into another position in the container where it may again be acted upon by centrifugal'force. o

7 7. In a machine for mixing sides of the container so as to engage the moving mass at the sides of the container, engaging the upper portion of the mass first, and havmg a eoncaved mass engaging face,

V cement with other ingredients, the combination of an upwhereby the rapidly moving mass is diverted from the side of the container, turned over and projected into another position'in' the container where it may be again vacted 8. In amachine for mixing cement with other ingredients, the combination of an upright rotatable bowl with upwardly and outwardly sloping side walls adapted to recelve the mass of ingredientsto be mixed and rotatable at such speed as to subject the lngredientsto'the action of centrifugal force and cause them to bemovedat high velocity, and one or more stationary massdeflecting devices positioned adjacent the side of the bowl and having a mass-entering I edge portion inclined upwardly and against massfiow, and causing it to circulate at high 7 velocity in a steady continuous flow along, one or more predetermined paths rapidly o changing'in direction in such-manner as to 'ing face being broad andEconca Ved curving v over and inclining-inwardly toward the. 'cen-- tral portionof the bowl so as' to cause the.

material; e01 turned over in, asmoothlv flowing stream from the side of the bowl j and directed inwardly of the bowl and de livered' adjacent the central portion thereof in a continuous and rapid stream.

9. In a machine for mlxmg cementiwith other ingredienm, the combination of an upright rotatable container with sloping side walls, adapted to receive the ingredients to be mixed and rotatable at such speed as to subject the ingredients to the action of centrifugal force and cause them to be moved at high velocity, and one or more stationary mass-deflecting devices positioned adjacent the side of the container and freely sup ported so as to be moved by gravity against the sides of the container and be self-seating against the same and having a mass-engaging face positioned to engage the rapidly flowing mass under pressure and divert the mass from the side of the container into another position in the container where the mass may again be acted upon by centrifugal force.

10. In a machine for mixing cement with other ingredients, the combination of an upright rotatable container with sloping side walls, adapted to receive the ingredients to be mixed and rotatable at such speed as to subject the ingredients to the action of centrifugal force and cause them to be moved at high velocity, and one or more stationary massdeflecting devices positioned adjacent the side of the container and having a massengaging face for engaging the rapidly flowing mass and diverting the same from the side of the container into another position therein where the mass may again be acted upon by centrifugal force, said deflecting device being pivotally supported about an inclined axis so as to gravitate downwardly against the side of the container in position where it is pressed against the side by engagement of its face with the rapidly flowing mass.

11. In a machine for mixing cement with other ingredients, the combination of an upright rotatable container with sloping side walls, adapted to receive the ingredients to be mixed and rotatable at such speed as to subject the ingredients to the action of centrifugal force and cause them to be moved at high velocity, and a long and relatively narrow discharge blade having one end adjacent the side of the container and having its longitudinal axis extending in a radial direction toward the center of the container and with its mass-deflecting face inclined backwardly from its entering edge in the direction of flow of the mass to form an acute angle with the vertical.

12. In a machine for mixing cement with other ingredients, the combination of an upright rotatable container with sloping side walls, adapted to receive the ingredients to be mixed and rotatable at such speed as to subject the ingredients to the action of centrifugal force and cause them to be moved at high velocity, one or more stationary mass-deflecting devices positioned adjacent the side of the container for engaging the mass adjacent the side of the container to divert it into another position in the container where it may again be subjected to centrifugal force, means for lifting said deflecting device from its mass-engaging position, and a discharge blade located behind said massdeflecting device in position to engage the flowing mass and discharge it over the side of the container when said mass-deflecting device is lifted, but being normally shielded from the flowing mass by said mass-deflecting devices during the mixing operation.

18. In a machine for mixing cement with other ingredients, the combination of an upright rotatable bowl having sloping sides, adapted to receive the ingredients to be mixed and rotatable at such speed as to cause the mass of ingredients to be impelled by centrifugal force outwardly, upwardly and along the walls of the bowl with high velocity mass flow, and a long and relatively narrow discharge blade having one end adjacent the side of the bowl and having its longitudinal axis extending substantially radially toward the center of the bowl with its mass deflecting face. inclined backwardly from its entering edge in the direction of flow of the mass to form an acute angle with the vertical, and having its inner end curved upwardly and opposite the direction of mass flow.

14. In a machine for mixing cement with other ingredients, the combination of an upright rotatable bowl adapted to receive the ingredients to be mixed, and one or more stationary mass-deflecting devices posi tioned adjacent the sides of the bowl and having an entering edge adapted to engage the side of the bowl and turn the mass therefrom during the mixing operation, the upper portion of said bowl where engaged by the entering edge of said deflecting device being made of replaceable sections detachably secured to the bottom portion of the bowl and fitted one to the other along lines inclined to the engaging entering edge of said deflecting device, so as to provide smoother engagement between the said entering edge and the joints of said removable sections during the rotation of the bowl.

In testimony whereof, I have signed my name to this specification.

NATHAN C. JOHNSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C.

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