US2078289A - Cement flooring construction method and apparatus - Google Patents

Description

ANMB 3W 1937 F. P. sLoAN 2,078,289

CEMENT FLOORING CONSTRUCTION METHOD AND APPARATS Filed Jan. 11, 19:53

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\W` Kmwfrl c ATTORNEYS Patented Apr. 27,l 1937 UNIT-Eo s'TATss PATENT :ol-FICE 3EMENT FLOORING CONSTRUCTION METHOD AND APPARATUS 13 Claims.

` 'Ihis invention is a-novel cement flooring constructionmethod and apparatus, and relates to' the construction ofvarious kinds of cement ilooring whether for interior 4uses or outside paving purposes. Forillustration the features of the present invention are' herein particularly described in 'their application-to the production of a topping or inishig layer of cement laid upon a rough concrete base. or arch; although certain features'of the invention are of utility in the laying of cement iiocring upon other kinds of concrete-or analogous of supporting base and wherein smoothingv or analogous surfacing steps are performed in the operations of ilnishing the 15 ooring; and the apparatus features hereof are susceptible of an extended range of vutility 'as will be further explained.

The general object of the present invention is to afford an improved method of procedure in the construction of cement ooring, and improved apparatus therefor, so yas to enable the production of a ,flooring of superior quality and durability. A particular obiect is to aiford a system of cement flooring production having great flexibility and complete control in. practical use, so that thegbest reactions' Amay readily be assured notwithstanding varying conditions and incidents met with in practical work; the invention in certain situationseifecting a substantial conservation of labor andsaving of expense. A special 'object is to afford correction or equalization of ithe degreeofwetness over the area of a door i-n cases where'there are preexisting or accidental .dierences f wetness at various parts of the floor Vfor one reason or another, so thatv in lthe 'final Vresult areas of -undue wetness will be absent and the ill effects avoided of delays, shrinkage and other objections caused thereby.

A furth'erobjectfisgto, provide an apparatus or 40 machine by which. Vin the process of finishing a flooring, thestep of `heating or otherwise smoothing the'surface and a supplemental wetting thereof,l selectively or uniformly, may be performed in coordination and substan tially simultaneously or 15in the same operation or stage, thus permitting intelligent andsatisi'actory regulation of the final degree 4and distribution` .of wetness during the step of carrying out the4 main or semi-iinal surface smoothing or noatingn'operation.

l Other biects'or advantages will'be explained 'in the following description of an illustrative embcdiment of the invention ci'l will be appreciated by those conversant with'the subject. To the attainment of such objects, the invention consists in the novel method and apparatus and the novel features of procedure, treatment, operation, construction and detail herein illustrated or described.

In the accompanying drawing Figures 1, 2, 3 and 4 are vertical sections in diagram showing 5 certain selected progressive steps or stages in the production of a finishing cement layer or flooring, in accordance with this invention.

Fig. 5 is a diagram like Fig. 3 but on a smaller scale and showing the invention applied to different practical conditions.

Fig. 6 is a, top plan view of the lower or disk portion of the machine of Fig. 7, taken partly in section on the horizontal plane 6-6 of Fig. '1.

Fig. 'I is an elevation of a oor treating or smoothing apparatus or floating machine constituting part of this invention,` and adapted to perform in one operation the oating and wetting steps ofthe method hereof, as well as other like operations.

For convenience the "power operated machine or apparatus will be first described, referring to Figs. Gand 7. The floating or surfacing part thereof may be of any usual type, such as the well known Kelley electric oating machine, comprising a circular disk I0 slightly convex under'- neath and adapted to rest* and rotate upon the flooring or surface to be treated. The disk is attached to a body Il which is secured to the vertical shaft I2 of a driving motor I3,the housing or frame of which has a cover I4 and an upslanting guiding rod I5. The rod has a cross bar or handle It carrying an electric switch I1 connected by cable I8 to the motor and cable I8 to a power source.

`:The present invention comprises a combined surfacing or iloating and wetting apparatus, and the conventional floating machine is herein moditied by being provided in any suitable manner with awater containing vessel 25, conveniently 'shown as of bucket shape and mounted directly `on top of the motor, thus occupying but little space and providing a11.11316 Yhead for l,the down- 'flow of water. The vessel is shown as having a cover 26 centrally apertured to receive the stem y 21 of a gage float 28, the gage thus visually 1ndicating the depth of water in the vessel. The bucket and cover are shown held rmly but removably on top of the motor by a number of hook-spring devices 29, for example four of them, each comprising `a strong tension spring with a hook overlying the top of the vessel and another hook engaging under the flange of the motor cover. The vessel may readily be illled through the central opening of its cover; and it may read- 55 of the vessel.

ily be removed to allow ordinary uses of the oating machine. v

For the purpose of drawing water from the lower part of the vessel there is shown a. perforated horizontal pipe 30 extending through from side to side and rigidly secured tothe sides .delivery is important and a spring closed valve 32 is shown provided in the pipe 3l and having a long valve handle connected by a exible connection as a cord or cords 33 with the crossbar t5 or other accessible point at the handle of the machine. The valve is shown closed by its spring, and it may be opened more or less by merely deecting the upper end of the cord, manually, in any direction to afford a high or slow rate of delivery of liquid or waterupon the instrument or disk l0 or flooring. The wetted disk being.. rotary discharges centrlfugally, as indicated, around part of its periphery, thus wetting the ooring for example at the left or right hand side of the machine, depending on direction of rotation, as the latter is shifted about, under full control and guidance of the operator.

I'he apparatus or machine thus`- described is not made the subject of claim herein, but is referred to and claimed in copending application Serial No. 41,371, filed September 20, 1935.

Referring next to the method features, these are best described by outlining a substantially complete flooring method including many usual steps as well as the characterizing features of this invention. The construction will be assumed to start with a rough concrete base A as indicated in Fig. 1, although as already explained certain novel features are o f utility irrespective of the character of the base. Fig. 1 being a diagram, for clearness the conventional cross hatching of concrete material is conned to the right vend of the drawing, the left end being purely diagrammatic, and the same with other figures. The rough concrete, with its surface depressions is assumed to have beenthoroughly cleaned, and according to the best practise, as shown at B, it'is either thoroughly wetted or preferably overlaid'with a coating of grout, consisting of a cement and water, or cement, water and sand, brushed `onto the surface; and the applied water tends to gather in small bodies or pools in the several depressions of the surface as shown.

It is sometimes necessary to apply a cement finish topping to a rough concrete oor area which has been saturated for some time and which has surplus water lying in the depressions of its surface. As a practical matter it is impossible to bring all parts of the surface of such a oor to the same degree of wetness and the variations in wetness as embodied in the little pools resting in the surface depressions present a. decided problem to the workmen endeavoring .to lay a vcement finish topping that will be substantially uniformly wet over its whole area.

' The ingredients for the topping or nishing layer of the oor are to be premixed, for-example in a conventional rotary mixing machine, and the mix may be of various proportions comprising sand with stone (broken or gravel) and 'Ihe exterior end of pipe 80 isv the requisite amount of cement, for example sand 1 part, stone 1% parts and cement '1 part by weight. With these, in the mixer, is included only a deficiency of water, such as may in some cases even be scarcely adequate, or substantially inadequate for complete hydration. Thus where it is usual to add from 8 gallons of water down to as low as 41/2 gallons, for each 94 pound sack of cement, (in wet and damp mixes) for the present invention the added water should be well below 3 gallons and preferably not over 2 gallons per sack, which I term ultra dry. The result of these requirements is that a mix is provided which is relatively very dry, and, for the purposes hereofso exceedingly dry or lacking in moisture that when spread the water collected in the usual depressions of the base will be wholly absorbed in the lower stratum of the nishing layer, and not penetrate high or to the top thereof, unless in cases of extreme wetness of the base, as will be specially considered below. The mixing step is not shown on the drawing. In referring to sand this term is intended to include any fine aggregate adapted to the purposes, while stone includes gravel or any-other coarse\ aggregate. If the stone content of the aggregate be reduced to zero the concrete mix is reduced to a mortar of sand and cement which may frequently be used herefor. In any case it is usual that the aggregate runsbetween 1 and 4 or 5 times the weight of cement in a topping mix; while the topping layer may run fromyg inch to 2 inches thick more or less.

From the excessively dry mix thus described the topping of the oor is spread over the base and compacted; and these operations, may include the usual steps of distributing, tamping, levelling and rolling, and perhaps even the starting of the smoothing, floating or other surfacing operation. Fig. 2 shows this stage of the method. The water B in the depressions of the base A has penetrated upwardly as at b into the tpping C, it being noted that, due to the excessive or ultra-dryness of the mix the penetration is restricted, and preferably does not reach or pass the center or mid level of the topping. With an ordinarily wet mix, lacking the awsorptive capacity of the specified mix, the places of wetness of the base frequently encountered could readily penetrate clear to the top and thus result in excessive surface wet areas and inequalities. 'Ihe difllculties of excessive and unequal wetness of the topping surface are so well recognized that a practise now lprevails of deliberately employing an excessively wet mix and thereafter carrying out a cumbersome and expensivel absorptive drying step, consisting o f spreading over the wet topping a drying material, acting like a blotter, and thereafter removing it, before the finishing operation. The present method therefore iscontrary to the established practise, excess dryness replacing wetness thereby avoiding the drying step referred to, and avoiding other objections, including the undue shrinkage accompanying a toowet topping mix.

Next, having spread and compactedfthe topping'layer as shown in Fig. 2, its surface is herein treated to asmoothing or floating step, and in the same operation or stage ls supplementally wetted or sprinkled to a suitable restricted extent, which it is found may readily be judged by skilled mason oaters during the smoothing oppower driven floating machine, such as already described, having a weight for example between 150 and 200 pounds and a rotary speed of'say 150 to 200 R. P. M. 'I'he smoothing action and the distribution of Waterover the surface are performed in coordination or cooperatively, and in this sense simultaneously, both in the same stage or time period, which is preferred over effecting the supplemental wetting substantially either before or after the surface smoothing operation. i 4

Fig. 3 shows this stage of the method, the top stratum c of the topping C having been wetted and floated, the wetting being in judged restricted quantities so as to give the optimum final degree of wetness of the topping layer. Fig. 3 is intended to indicate the condition immediately produced by the water distribution. The moisture is shown confined to the upper stratum of the layer, but is in process of penetrating downwardly. This action in a sense is complemental of the upward penetration b from the base, and when completed the entire body of the layer is frequently substantially uniformly moist, as indicated in Fig. 4, to a degree in excess of that of the original mix, but substantially not in exce'ss of what is best for eilicient surfacingA and setting. As stated it is found that the conditions and-the wetting requirements can be substantially judged by a skilled operator of a floatingmachine, by sense of touch and sight, the feel of the smoothing machine moving upon the floor telling him by experience the degree of wetness or dryness and the needs as to further wetting.

The described principle of delayed completion of the wetting of the topping and effecting it at the oor after the compacting is contrary to the settled practice of introducing the full quantity of water in the mix, and it assures that while the topping layer will contain adequate moisture above, below and throughout for proper hydration and setting, yet there will be no over- `wet spot or area, a very important consideration.V The delayed wetting of this invention may in' many cases be effected by substantially uniform distribution, as indicated in Fig. 3; but /as will be described in connection with Fig. 5, it is sometimes necessary to apply the supplemental water selectively, as where there are substantial variations in the wetness or the dryness of the layer as caused by underneath or other conditions. When the desired wetness has been attained at any given area portion it is preferred that the smoothing operation be continued thereover to complete the purpose of smoothing and floating. Fig. 5 illustrates a variation of Figs. 2 and 3, namely wherein the base is of such character, with an extreme waterl holding contour or contours, like basins, that the penetrating moisture b resulting therefrom may at certain areas or spots reach to the top surface of the finisher layer, as at b', causing large wet spots prior to the floating stage, although the layer generally may be too dry for smoothing. This produces a differential surface condition, with some spots considerably more moist than others, from several inches to several yards in extent, although not necessarily too wet at these spots for proper surfacing and setting purposes. Or, irregularities in surface wetness may be due to other causes, for example, to the use of a mix which is not uniform in character, duel to incomplete mixing, or due to non-uniform evaporation.

These conditions of varying degrees of dryness at various portions of the surface are taken care of by this invention by an equalizing operation, performed at the flooring, the inequalities being corrected by a plying restricted supplemental water selective y at the floor, for example at c, c Fig.y 5, skipping or working around the wetter portions b 'of the topping, and thus finally affording a substantially uniform degree of wetness such as is best for efficient surfacing and setting. While in Fig. 5 the areas b' and c are shown slightly separated it will be understood that a certain lateral spreading of moisture will occur, both by absorption and by the action of the floating machine, thus aiding the equalization of the n'al wetness at the surface and through the topping layer. In general, and in both forms of method de-. scribed, the underneath wetting or moisture penetration, and the top surface wetting and penetration,l in the described abnormally dry topping layer, are coordinated in the sense that the absorbed moisture penetrations at top and bottom are mutually complementary, each entering the dry layer from its own side without substantial interference from the other, and the topping-as a whole thereby taking the most advantageous degree of wetness for the purposes of the setting and hardening reactions, and the surfacing treatments. Frequently a very slight sprinkling of water adjacent the machine smoothing operation, just enough to Awet the top surface and permit effective smoothing, will afford the best results. 4

Following the described steps the ooring may be subjected to the following usual steps requiring no especial illustration, namely; further machine iloating as may be judged requisite; followed by hand floating, trowelling or the equivalent, except in cases where this is unnecessary, as sometimes for sidewalks; and nally the subsequent curing in any suitable manner after the setting.

Practical economies in labor and expense, and

saving in time, are permitted by the use of the principles of this invention. Because the topping is rendered uniformly wet, for example, and oated or surfaced at the stage of progress when floating is easiest, no time is lost waiting for wet spots to lose their excess water by Aevaporation or absorption. The extent of ooring oated per machine-hour is substantially increased because the topping is never too dry to be floated quickly and effectively. And subsequent hand trowelling is facilitated by the uniformity of wetness attained.

In one aspect the essence of the method or system of the present invention is that the control of the total water content of the topping layer is left to the mason who operates the iloater or smoothing machine and who is best able, by sight and touch to determine the needs of the floor, or of different areas of the flooring, at the time of floating; as distinguished from the usual practice of adding to each mixer batch the full amount of water which will be required for the oating, hours later, of that area of the floor subjected to the greatest absorption and evaporation and the longest delay between placing and smoothing. Stated another way, only a deciency of water is supplied at the time of the gnix, the balance orcomplement of moisture belng delayed until after the ultra-dry mix has been spread and compacted and the floating ops eration is to be performed. The application of the complemental or delayed water except at the same stage with the floating is impractical because the water quickly sinks from the surface taking with it the cement and finer particles of the aggregate which should be kept at the surface to provide the desired smoothness of nish.y 'Ihe invention has the additional advantage of eliminating the danger of premature setting, especially on warm dry days, which is highly probable with a sufficiently wet mix, especially where large areas are spread and compacted in advance of the floating step. The term oating is used in a general sense; while smoothing occurs, the restriction of added water prevents any but shallow penetration, and `the rearrangement of aggregates is proportionally shallow. The product is thereby improved by reduction of its total water over that required if water is included at the mixer adequate for the smoothing because then the entire depth of topping is made unduly wet to ensure surface wetness.

The excellent results obtained in practice by this invention may be explainable as follows. In the stage including mixing, transporting and spreading these operations are facilitated by the ultra-dry, frlable consistency of the mix. For the densifying stage the lubrication is less than optimum, but this is more than offset by the immediate adaptability to receive compacting blows and pressures and transmit them down tothe lowest stratum and base. The dryness of this invention avoids transporting and spreading difiiculties from stickiness, as well as the displacement of aggregates occurring in a spread wet mix. It is not necessary to add water for the densifying, and

the .prewetness of the base provides what is needed for bonding, the compacting pressure' afl fording the intimate contact.

Only after such densifying is added the slight water requisite for the smoothing operation, in which the pressure causes also acertain further densication.

The water-cement ratio of this invention (gallons per bag) is ail'ected by the following cony siderations. Experiments on different classes of mix, for'example one relatively rich in cement, as 1 cement, 1 sand, 1% stone, referred to asa 1--1-lfil mix, and one relatively. lean, as a 1 2-4 mix, reveal that to obtain the desired degree of dryness the total'amount` of water,

that is, including the surface water in the ag- A gregate, should be determined not only from the amount o f cement but also from the amount of aggregate. The fact that the best proportion of water t0. aggregate varies according to the surface area of the aggregate indicates that some water must be providedl to wet the aggregate in addition to that provided to `wet the cement. Approximate proportions of water herein found desirable are: Per bag of cement, usually 94 lbs., water 2 gallons;` per cubic foot of sand, say` 100 lbs., water V2 gallon; per cubic foot stone, say 110 lbs., water'1/4 gallon. 4Applying these vproportions to the rich mix 1-1l'% gives water, for cement 2 gallons, for sand 0.5 gallon, for stone 0.44 gallon, total-2.94 gallons, namely, under 3 'gallons total water per bag of cement. For the lean mix 1-24, for cement 2 gallons, for sand 1 gallon, for stone 1 gallon, total 4 gallons, this not being generally suitable for toppings. The proportions assigned to the ne and coarse aggregates (sand and stone) have a basis in fact as is shown by the amount of moisture generally held by these aggregates in their natural state. Reliable tables give the water held by sand as varying between V4 and 3/4 gallons per cu. ft. and that held by gravel or crushed stone ,as V4 gallon per cu. ft. In the practise of this invention the actual amount of water held by the aggregates used is frequently rslt determined by test and allowed /for in measuring the quantity of Water added at or -in the mixer. The water content is herein predetermined not for securing a given strength, but, as above indicated, to afford a certain high degree of dryness for the purposes of this invention; however the product is of high strength. In any case the water content of the mix may be reduced somewhat below the maxima designated, but preferably is substantial in amount; and in some cases the natural wetness in the aggregate may provide sufficient water for the purposes of the invention, in view ofthe subsequent addition at the smoothing stage of the supplemental Water required for the smoothing;

Referring further to the combined surfacing and wetting machine of Figs. 6-and 7, this is well adapted to carrying out themethods hereinabove described. It dispenses with fthe need of two operators, one for the surfacing or smoothing, and one for the wetting, thus saving labor, but more importantly, placing in -thecontrol and responsibility of a single operator both the surfacing or smoothing operation and the cooperative completion of thewetting of the topping layer. A single water ycarrier may by observation of the gages 21 take care of the refilling 'of the water vessels of the surfacing machines of a large number of masons.

Considered as a combined surfacing and wetting machine the present invention is of value for additional purposes. Thus the .portion of the water which is withheld at the time of mixing may subsequently be used as a means of spreading over the flooring various'agents, such as hardeners, or coloring materials for the cement. For the purpose of going over a floor to correct accidental conditions where areas of too great dryness appear, the machine may be used for the purpose of distributing selectively a grout sufiiciently wet to be handled by the machine, thus improving the conditions at the corrected areas and permitting simultaneous refloating thereof. On cold days the apparatus may distribute hot water to accelerate the setting action. j; An illustrative cement flooring method and apparatus having been described, and many matters of procedure, treatment, operation, constructions and details being subject to modification Within the lscope ofthe invention, it' is not in tended to limit the patent to such mattersv except to the extent set forth in the appended claims.

What is claimed isz f 1. In the art of constructing cement ooring having a concrete base with a wear-resisting topping layer, the method which comprises the steps of (l) preparingthe topping "mix of ily-- draulic or Portland cement and aggregate in suitable proportions, and Water, but restricting the water to a deficient proportiont substantially below that proportion practically necessary for the subsequent smoothing step, -(2) spreading such toppingm'ix upon the preformed concrete base to the required thickness of layer and promptly', Without delay for stiiening of mix, applying to the layer heavy compacting pressure thus densifying it and securing optimum bonding contact of its lower stratum-with the base, but leaving its upper stratum yet insumciently wet for the smoothing step, (3) and promptly then smoothing to a suitable finish the densifled topping layer by surface rubbing action and in the same stage therewith distributing supplemental water upon its surface in restricted quantity sufllcient to produce in its top stratum the degree of wetness and lubrication practically necessary for such smoothing; whereby said series of steps may be performed in prompt sequence, without need of delay for stiffening by evaporation or partial setting, and the topping is efciently bonded to the base, is of high densityand optimum structure. of suitable finish and free of excess wetness.

2. Themethod as in claim 1 and wherein the total water included in the mix is substantial and (a) is ample for the step of densificatlon and bonding to the base, but (b) insuilicient to cause rise of water to the surface or flotation of fines, and (c) substantially inadequate for the lubrication necessary for the step of smoothing the top surface involving rearrangement of particles.

3. The method as in claim 1 and wherein the base is wettedbefore spreading the topping layer, and the layer takes up in its lower stratum moisture from the base assisting lubrication and the rearrangement under pressure of the particles adjacent the under surface of contact as necessary for eiiicient bonding of topping to base, and subsequently the top surface is subject to the recited smoothing action while the restricted supplemental water is applied accompanying such smoothing, both under control of the mason.

4. The method as in claim 1 and wherein the mix contains aggregate between 1 and 4 'times the weight of cement and the total water in the mix is substantial but restricted to substantially below 3 gallons per 94 lbs. cement inclusive of surface water carriedby the aggregate.

5. In the art of constructing cement flooring having a concrete base with a wear-resisting topping layer, the method which comprisesv the steps of 1) preparing the topping mix of hydraulic or Portland cement and aggregate and water, but restricting the water content and resulting wetness to a proportion definitely below that practically necessary for the subsequent smoothing Step, (2) spreading such topping mix upon the preformed and clean concrete base to the required thickness and in bonding contact with the.base; but leaving the top st ratum yet insufficiently wet for the smoothing step, and (3) promptly, without awaiting stiffening of mix, then smoothing to a suitable finish the topping layer by heavy surface smoothing action and at the same time distributing upon the surface being smoothed supplemental water inrestricted quantity suhicient to produce in its top stratum the degree of wetness and lubrication practically necessary for such smoothing; whereby said series of steps may be performed in prompt sequence,

without need of delay for stiifening by evaporation or partial setting,` and the topping is eiliciently bonded to the base, is of good density and optimum structure, of good finish, and free of excess wetness.

6. The method as in claim and wherein the total water in the mix is substantial but not over' 2 gallons per 94 lbs. cement plus about 1/2 gallon per cubic foot of ne aggregate and V4 gallon per cubic foot of coarse aggregate. y

7. The method as in claim 5 and wherein the lmix contains aggregate between 1 and 4 times the weight of cement, and the total water is substantial but not over 2% gallons per 94L lbs.

cement. Y

8. The method as in claim 5 and wherein the mix contains aggregate between 1 and 4 times the weight of cement, andthe added water therein is not over 2 gallons per 94 lbs. cement.

9. The method as in claim 5 and wherein, to equalize non-uniform degree of wetness of topping layer preceding the smoothing step, due for example to irregular pre-wetness of theunderlying base, the supplemental water is `applied selectively during the smoothing st ep under mason control in a manner substantially to correct non-uniformity and avoid unduly wet areas.

10. In the art of constructing cement flooring having a concrete base with a finishing layer or topping, as 2 inches or less in thickness, the method which comprises the steps of (l) preparing the topping mix of hydraulic or Portland cement, aggregate between about 1 and 4 times the weight of cement, and water, but restricting the water to such a decient proportion or dryness and resulting lack of. lubrication of mix that it may be spread and promptly d ensiiied by heavy compacting pressure without impairment of the surface or segregation of aggregates, namely substantially under 3 gallons total water per 94 pounds of cement, (2) spreading such ultra dry topping mix upon the preformed and wetted base to the required thickness and promptly, without awaiting partial stiffening, densifying it by heavy compacting pressure, permitted by its aforesaid dryness and non-pliability, thus securing optimum bonding contact with the base and avoiding flotation of fine particles to the surface, the topping layer takingupl water from the base into its lower portion, (3) and thereafter suitably finishing the top surface of the densiiied topping layer; whereby said steps may be performed in prompt sequence, and the topping is eiciently bonded to the base, is of high density and optimum structure and free of excess wetness.

ll. In the art of constructing cement flooring the method of applying to a concrete base a wearresisting topping by the series of steps of first,

preparing the topping mix of hydraulic or Portland cement, with aggregate and water, second, spreading such mix upon the preformed and moist concrete base to the required thickness of layer, third, compactingsuch spread layer, and fourth, smoothing or floating the top surface by heavy. rubbing action, followed by trowelling when required; and characterized as follows: (a) producing the mix with its water content restricted to such small proportion as to constitute an'ultradry mix, sufficiently friable for spreading and too deficient in moisture to allow practical smoothing or floating, (b) then, after spreading, compacting ,A the layer by applying pressure sufficiently heavy eectively to densify the ultra-dry material and bond it with the moist base, (c) and then, smoothing or floating the ultra-dry topping surface to tion practically necessary for eflicient smoothing or floating; whereby said series of steps may be performed in prompt sequence, without need of delay for stiffening of mix, and the topping is efiiciently bonded to the base, is substantially of optimum structure and free of injurious shrinkage from excess wetness.

12. The method as in claim 11 and wherein the mix is prepared, spread and compacted in a condition with the water content appreciable but substantially below 3 gallons total water per 94 pounds cement.

y13. In the art of constructing cement flooring the method of applying to a rough concrete base a wear-resisting topping between about 1,4 inch and 2 inches thick by the steps of rst, preping the topping mix of Portland cement, with aggregate and water, the-aggregate between one and four times the cement by weight, seccnd, spread- A ing such mix upon the preformed wet concrete base to the required thickness of layer, third, compacting such spread layer, and fourth, smoothing or floating the top surface by heavy rubbing action, followed by trowelling when required; and

10 characterized as follows: (a) producing the mix with its water content restricted to such small proportion as tc constitute an ultra-dry mix, sumciently friable for spreading and too dry to allow practical smoothing or oating,j(b) them' l5 promptly alter spr, compacting layer ing or floating the topping surface to a :sultallrlel ilnish, and in the same stage therewith distributing selectively upon the surface :supplemental water in restricted quantity suiilclent to produce atthe too-dry places the degree of surface wetness and lubrication practically necessary for emcient smoot or iloating.

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