US1704268A - Art of making cementitious mixtures - Google Patents

Description

Patented Mar. 5, 1929.

UNITED STATES i .1,104,268 PATENT OFFICE.

WILLIAM M AYO VENABLE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T BLAW- KNOX COMPANY, A CORPORATION OFTNEW JERSEY.

ART OF MAKING CEMEINTITIOUSMIXTURES.

Application filed March 31, 1925. Serial No. 19,694.

This invention relates to improvements in the art of making ccmentitious mixtures such as concrete and the like and is particularly directed to the apportioning o f sand and water for a batch of concrete.

It is well known in the art that when perfectly dry sand of uniform quality is measured by bulk, a given bulk container, filled always to the same level, in the same manner,

will always contain the same weight of sand; also that if the container be entirely filled with water, and sand be poured into it slowly in a. uniform manner until the container 4is level full of sand and Water, the excess water overflowing, the total weight of sand and wat-er in the container will always be the same, no matter whether the sand be wet or dry before being poured into the container.

However, moist sand, lmeasured in a. container Without an excess of water, will not always pack to the same extent, and the total weight of sand so measured will be found to vary from batch to batch. As it is impracticable to obtain perfectly dry sand in the 25.large quantities used in concrete construction, and as sand must have water as well as cement and other materials mixed with it in order to make concrete, bulk measurement of the sand may be rendered more accurate by measuring the sand under water, or in a completely saturated condition.

It happens that generally it is necessary, in mixing concrete, to have a larger quantity of water in the mix than necessary to saturate the sand completely. As a consequence,

it is practicable to measure the sand in a satff urated condition, and to dump the saturated 1 sandwith the Water contained in it into the mixer, adding such amount of water as may 4o be necessary to give the desired consistency,

which amount depends upon the amount of cement used, and other factors, but is uniform as long as those factors are kept uniform. Therefore, bymeasuring the sand in a saturated condition, the variation in amount of water to be added, Which is seri-1 ous when moist sand, not uniform in vwater content is employed, i'seliminated, and an important cause forI lack of uniformity in strength of concrete-variation amount of water from batch to batch* eliminated.

These facts have hitherto been used in making mixtures, Jut the methods employed have had disadvantages Whichare not enin the' countered in the method to which this invention relates. One method is to place in the container ,more thanenough waterv to completely saturate a batch of sand, and to sift sand therein until the container is filled to an overflow level, at which the surplus Water escapes, leaving saturated sand up to that overflow level. This method has practical difficulties. In the first place, it is slow because the sand must not be shaken into the water more rapidly than the grains can be thoroughly wetted, as otherwise air is entrapped with the sinking sand. In the second place, it is difficult to gauge the amount of water and it is necessary always to Waste more water by overflow than is desirable, and with this waste water some ofthe sand always is carried off.

Furthermore an excess of sand usually accumulates on top of the saturated sand above the overflow level of the water which makes the process additionally `inaccurate.

From the foregoing it will he readily seen, that, in order torender such a process accurate, considerable care is required on the part of the operator and the time necessary toso prepare the sand with water is many times greater than that required to measure the sand and water separately, without inundation, in the usual way formerly e1n ployed. `In addition, itis pointed out that when sand is poured into standing water there, is a great deal ofsplash and slop and a considerable amount of sand is washed `over with the excess ofk water.

Thru my inventionI aim to overcome the abovedefects in a simple, ex editions and economical manner particularly as regards time. i f y I introduce suiiicient water to saturate the sand andF to lill the voids therein withoutl .putting the sand in suspension thus avoiding the necessity ofwaiting for the sand to settle Land consequently shortening the time interval between successive withdrawals for loo the batch. v Stated more specifically I propose to saturate by percolatiomso to speak, an

amount/of sand in excess ofthe amount to be withdrawn for al batch and subsequently towithdraw a predetermined'amount of the 105 so saturated sand. Hence a mixture of sand and water is made and held in reserve by adding Water t0 the relatively dry sand in such amounts as will always produce complete saturation and this without waste and l10` method, it is a fact proven by experience that the sand and vvater Will tlovv together from the receptacle intothe measuring ves-v sel Without change of the mixture so that the actual' quantity of sand and the actual quantitty ot Water in the measuring vessel at the time it is filled to the overflow level are constant; that is' to say, the method gives a uniform measure of both sand and Water, substantially invariable for a given size receptacle.

Another point otimportance is the fact that Where saturated sand is allowed tolloiv into a measuring receptacle there is no splash or'slop and hence no Waste.

Another object is the application of the liquid for saturating the sand in such a manner that a head or" substantially dry sand may be maintained above the'saturated portion, such dry sand gravit-ating to the region of saturation as sand is Withdrawn for the batch. l

i further object of the invention is the provision of means for adding sucient Water to saturate the relatively dry sand which replaces that removed for the batch.

Still another object is the provision of a novel valve peculiarly adaptable for use in connection With au apparatus as herein set forth..

Another object is the provision of a supplementary water measuring device for adding a predetermined quantityof Water to the measured saturated sand after measurement thereof.

Further advantages of a mechanical nature willpbe apparent when comparing the apparatus for carrying out the method here.- in disclosed, with other systems and appaia tus now in use.

The foregoing together With such other .objects as may hereinafter appeal', or are incident to my invention, I obtain by means of a construction which I have illustrated in preferred forni inthe accompanying drawings, wherein:

Fig. 1 is a partial longitudinal elevation4 of and sect-ion thru an apparatus utilized in carrying out my invention and Fig. 2 is a detail plan View of the delivery valve removed `from the apparatus, and showing the valve in open position in full Llines and in closed position in dotted lines.

Referring novvr to Fig. 1 it Will be seenthat the apparatus in general, comprises a bm A divided into compartments B and C, lthe commoesen partment li, in this instance being used for crushed stone and thecompartment C for sand; a measuring device D for apportioning material from the compartment B; a measuring receptacle E for receivingmaterial from the compartment C; and a receiving device F .'hich may very Well be a concrete miner.

rllie compartment C, hereinafter referred to as a delivery receptacle is divided into an upper portion 7 having an inlet for the sand to be prepared for delivery and an open bottom; and a lower portion 8 having an outlet 9 provided With a control valve 10. 'l`his lower portion 8 may bc of a conical or inverted pyramidal shape and of such dimension at the top as to receive the lower part of the upper portion 7 of corresponding shape which entends part Way into and is spaced as at 11 from the lower portion 8. In the par ticular device shown the space 11 extends around only three sides but it is to be understood that in other instances it may be desirable to have the space extend all way around as Would particularly be the case if the compartment B were omitted. Vlhe lower portion 8 of the delivery receptacle C is Water tight as is the bulk head or partition 12 which divides the bin A. v

l-laving thus described the construction of the delivery receptacle C it Will be seen that when it is filled With sand, the sand takes a natural slope between 7 and 8 asvindicated at 13 exposing surface sand to the space 11 above mentioned. As it is a purpose of this invention to have a reserve of saturated sand f always in readiness, from which, certain amounts may be Withdrawn orthe' batch, that is as long as there is dry orisubstany tially dry sand in the receptacle C, I Will now describe the manner in which this is accomplished. i

A water level 14 ismaintained above the exposedl surface sand indicated at 13, by means of a lioat valve 15 in a suitable tank 16 which communicates with the receptacle G thru the pipe connection 17 so that the level ot' Water in the receptacle and tank are kept the same. The float valve 15 controls the admission of Water thru the Water supply pipe 18 which in this instance is shown lea-ding into the lower portion of the delivery receptacle- C somewhat above the wat-er level 14, and hence regulates the water level' therein. Thus, a considerable amount of standing water is iiiaintained'bctwecii the surface sand 13 and the water level 14 for keeping the sand filled with Water and this Without putting the sand in suspension as will further appear. In this connection it is to be understood that the pipe 17 might be made large enough to carry the Water supply to the receptacle C in which case the pipe 18 would discharge into the tank 16; or that the pipe 18 might discharge at any other convenient place, even into the receptacle C at some higher 4elevation it' desired. Furthermore it is to loe observed that the space 11 may be made large enough so that the float valve could be placed directly in the space, thus eliminating the auxiliary tank 16 entirely. Certain advantages as for instance accessibility of the parts have led to the particular arrangement shown in the drawings. The operation of the device as thus far described is as follows:

Let us consider for the purpose of illustration a device of the proper size to furnish sand to be measured out for use with a oneyard concrete mixer. In that case the discharge of the valve 10 will be made approximately 4% inches in diameter and the water supply pipe 18 approximately 2 inches in diameter and it will be desired to draw off the necessary amount of sand once every minute or perhaps every one-half minute at times, depending upon Whether the sand is to be discharged directly into the mixer, or into containersifor hauling to some other point, for it is quite feasible to make this device serve more than one concrete mixer if desired. We will then assume that the delivery receptacle "C is full of sand, the Water level in the lower portion 8 thereof at the elevation 14, and the sand saturated with Water and the voids filled y with water to this velevation entirely across the receptacle C. The valve 10 is then opened and a 4% inch stream of sand and Water flows out and into the measuring receptacle E.

rThe immediate result of the flowing out of the saturated sand is that. the dry sand from the upper portion 7 ofthe receptacle C settles Llll into the lower portion 8 andthe Water level in the tank 16 lowers from the level lil to some lower level. Cf course When this occurs thereis a lowering of the water level in the space 11 between 'l' and 8 and the float valve 15 is opened, discharging water thru pipe 18 into the lower portion 8 of the receptacle. lt would then be possible to draw off sand and water from 8 until practically dry sand reaches that level. ln practice l propose to make the capacity of the portion 8 ot the receptacle et such size that it will never be likely that the quantity of sand drawn olf at one time will allow dry san-d to reach the valve 1l). lVhen. however, the valve l() is closed, water will continue to percolate or seep into the sand at 13, without putting the sand in suspension and will gradually restore the water level to the-level lll. I

Y l have 'found from actual experience that with a properly'diinensioned device :1s-above einemplified,` the amount of excess Water drawn oit with the sand Iis negligible so that the sand drawn olf at the/valve 10 carries substantially but little more Water than necessary to saturate it and to fill all the-voids, hence my device is not wasteful of water and is very accurate in the measurement thereof.

Revel-ting now to the construction of the measuring receptacle E it will be seen that it is pivotally mounted below the valve 10, and that any suitable means may be provided for holding the receptacle E in mixture receiving position. lVhen measuring out the mixture of sand and water the valve 10 is opened and the mixture is allowed to run into the measuring receptacle E until itis entirely filled, the proportion ot sand to water in the measuring receptacle E being the same as that in the premixing receptacle 8 as before pointed out. The contents may be then discharged into the mixer or other receiving device F, by tipping the measuring receptacle E.

In this connection it is pointed out that should the operator 4fail to close the valve 10 at the proper time, the mixture would over'- flow at 19, the surplus sand being carried alongl by the waterso that the mixture contained in E would not, even' under these circumstances, he excessive. Hence I am always enabled to get the same volume of the mixture in a batch without havingl to resort to other means of control.

In order to utilize the same measuring receptacle for various sized hatches ot cementitious mixtures I have shown the bottom 2l thereot' adj ustahle `to alter its volumetric capacity. Then the capacity is set to meet the particular requirements of the specications the measured amount is substantially invariable and will not change until the adjustment of the capacity is changed.

Another feature of my invention is the auxiliary water measuring device indicated as a whole by the reference letter C.

lt is sometimes desirable to supply a littleA more water to the mix than that which is contained in the mixture in the receptacle E, therefore l have provided an auxiliary Water n'ieasuring device by means of which a predeternlined amount of water may be added to each batch. The device Cr, comprises a tank Q2, having a valve controlled water inlet 23, and a valve controlled water outlet 24, in this instance leadingl to the mixer; and a weighted bucket Q5, having adjustable means 26 whereby it may he raised and lowered in the tank 22 to alter the capacity ofthe tank. A pointer E27 and scale 28 are provided to indicate the amount of water the tank will hold when filled to the overtlow 29.

In operation the valve in the inlet line 23 is opened to admit water into the tank 22 until it overflows at .29 at which time the valve is Y closed. The tank now contains a predetermined amount of waterfwhich upon opening of the valve in the outlet line 24 may be discharged into the mixer or Whatever other fhrm of device F is being employed. This of course may he done either While the container is being filled or after it has been filled as desired. .By supplying additional Water in this manner I am enabled to cleanse the interior llll parts of the mixer in a very convenient Inanner.

rll`urning back now to the particular construction of the valve 10, the general function of which has been hereinb'efore described, it will be seen that the valve comprises a body or casing 30 preferably made in two parts, an

upper and lower, the whole being secured to the receptacle C; and a rotatable valve plate or disc 3l provided with a discharge passage or opening 32.

'lhc lower part of the body y30 is provided with a seat 323 in the form of an upwardly projecting nipple, on which the valve disc 3l rests, additional support being provided by the screws 34. ris best seen in Fig. 2, the discharge opening 32 in the. disc 3l .is elongated while the opening and nipple 33 of the valve body are circular, so that when the valve is in open position as shown the disc covers the edge 34 of the nipple on one side and leaves the balance uncovered. It will be noted that by this arrangement no sticks, stones, grass or other obstructions can get between the outside of the nipple and the opening in the disc on the covered side. As the other side is not covered it is possible for obstructions to settle on that side between the nipple and disc so that in closing` the valve to the dotted line position 35 there will be no interference.

It is also to be noted that the disc will soon become entirely surrounded by sand both above and below, except at the nipple. It is for this reason made circular so that it may turn under these circumstances without having to displace any sand and thus not o nly work easily, but not be subject to packing. The opening at the pipe, however, will always relieve the pressure, and there is no necessity of providingany-means for holding the disc down against the pipe.

lVhile I have shown the sand saturating and measuring ,device in connection with av stone bin and batcher in a manner to form a unit it is to be understood I might employ the stone device as a separate unit leaving the sand device also a separate unit as may best suit lparticular conditions.

Y It is obvious that under ordinary operatingconditions there will be very little surplus water in themeasuring receptacle E, but in the event that any excess water should iind its way thereto, which would be at the tail end of delivery, it would wash over the. spout 19.

I claim 1; -In the herein described process of preparing `and measuring sand and water for celnentitious mixtures, the steps which consist in delivering sand into a suitable delivery receptacle and inpercolating to the saturation point, into the voids ofthe sand particles, in thev lower portion of such receptacle.

2. In a system for'preparingcementitious mixtures employing a suitable sand delivery receptacle to which sand is supplied and from which sand is to be periodically withdrawn, the steps which consist in preparing sand for withdrawal by percolating water into, and filling, the voids in the .sand in the receptacle as it is withdrawn therefrom, without putting said sand in suspension, and in controlling such percolation by the withdrawal of sand.

InA a system for preparing cementitious mixtures employing a suitable .sand delivery receptacle to which sand is supplied and from which sand is to be periodically withdrawn, the step which consists in preparing sand for withdrawal by percolating water into the voids in the sand in the receptacle, such water being introduced below the normal level of the sand in the receptacle.

4. ln a system for preparing cementitious mixtures employing a suitable sand delivery receptacle. to which sand is supplied and from which s and is to be periodically delivered into a measuring receptacle, the step which con sists in saturating more sand with water in the delivery receptacle than the measuring receptacle will hold.

5. The method of preparing and measuring sand and water into batches for concrete mixing, which consists in saturating a predetermined quantity of sand, in maintaining a head of dry sand on said saturated sand, in withdrawing a predetermined quantity of saturated sand, and in adding suilicient water to saturate the dry sand which replaces the withdrawn sand.

G. In the process of handling', storing and delivering sand and water for Vuse in cementitious batches, the step which consists in maintaining a predetermined part of the sand inthe sand receiving and delivery receptacle saturated.

7. In the art of making cementitious mixtures those steps which consist in storing a quantity of sand in a suitable receptacle. from the lower portion of which it may be withdrawn for the batch. and in automatically maintaining liquid substantially constantly at a given level in the lower portion of the receptacle to saturate the sand in that portion.

8. In the art of making cementitious mixtures those steps which consist in storing a quantity of sand in a. suitable receptacle, from the lower portion of which it may be withdrawn for the batch, in maintaining liquid in the lower portion of the receptacle to saturate the sand in that portion` in withdrawing a predetermined batch of the saturated sand and in adding liquid to replace that withdrawn Iand to saturate the'portion of sand from the upper part of the container which replaces that withdrawn.

9. The method, of saturating and measuring sand into batches which consists in feeding substantially dry sand from a supply bin into a hopper so that when the hopper is uring out a predetermined quantity of the saturated sand and in simultaneously flowing suflicient water into the hopper to saturate the dry sand which replaces the removed water into batches which consists in saturating a portion of a mass of sand, in withdrawbatch of saturated sand.

10. The method 'of saturating and measuring sand into batches which consists in supplying a suitable container 'withfsand, in introducing liquid to the supply of sand between the top and bottom thereof and thereby saturating the sand below the point of liquid introduction, in withdrawing a predetermined quantity ot' the saturated sand, and in controlling the introduction of the liquid so as to maintain a substantially Constant reserve ot' saturated sand.

11. The method of measuring sand and ing a predetermined quantity of sand from the saturated portion, and in adding water to the mass of sand to maintain a constant reserve of saturated sand to an amount not less than the quantity to be withdrawn at any one time.

l2. In the art of making cementitious mixtures those steps Vwhich consist in storing a quantity of sand in a suitable receptacle, from the lower portion of which it may be withdrawn for the batch, in maintaining liquid in the lower portion of the receptacle to sat-V urate the sand in that portion, in adding liquid to replace that withdrawn with the saturated sand, and in adding a predetermined quantity of liquid to the withdrawn saturated sand.

13. In the art of making cementitious mixtures those steps which consist in storing a quantity of sand in a. suitable receptacle, from the lower portion of which it may be withdrawn for the batch, in maintaining liquid in the lower portion of the receptacle t0 saturate. the sand in that portion. in withdrawing a predetermined batch of the saturated sand, in delivering said measured batch' into a receiving container, and in adding a predetermined quantity of liquid thereto.

14. In apparatus for preparing sand and water for cementitious mixtures the'combination of a Vdelivery receptacle having an inlet opening for substantially dry sand and an outlet opening for saturated sand, and means for percolating Water from below the normal sand level into'the voids of the sand particles to the point 'of saturation.

15. In apparatus for preparing sand and Water for cementitious mixtures the combination of a delivery receptacle having an inlet opening for substantially dry sand and an outlet opening for saturated sand, and means for percolating water into the voids of the sand particles, the point of admission of the water being in the lower portion ofsiich receptacle. i

16. In apparatus for making cementitious mixtures t e inclusion of means for creating a saturated mixture of sand and water without putting thesand in sus ension.

17. In apparatus for making cementitious mixtures t a saturated mixture of sand and Water Without putting the sand in suspension, and means for periodically withdrawing batches of such mixture. q 18. In apparatus for preparing sand for cementitious mixtures the combination 4of a delivery receptacle having an inlet opening Vfor substantiallydry sand and an outlet opening for saturated sand, and means for percolating water into the voids of the sand particles, together with means for maintaining a substantially constant reserve of water for percolation.

19. In apparatus for preparing sand for cementitious mixtures the combination of a delivery receptacle having inlet and outlet openings and a contracted portion between them providing a dry` sand compartment above the contracted portion and a saturated sand compartment below and means for saturating the sand'in the lower compartment.

20. In apparatus for preparing sand for cementitious mixtures the combination of a sand delivery receptacle having its upper portion extending partway into and spaced from the lower portion and means for introducing liquid to said receptacle and for automatically maintaining a substantially con-- e inclusion of means for creating4 stant level of the liquid in `the space between the upper and lower portions thereof to -saturate the sand in the lower portion of the receptacle. Q V

21. In apparatus for preparing sandior cementitious mixtures the combination of a sand delivery receptacle having its upper .portion extending partway into and spacedfrom the lower portion, the sand in said receptacle 1n its natural slope forming a botstanding Vwater in said space.

22. In combination with apparatus for handling saturating and delivering sand for use in cementitious batches, an auxiliary water measuring device comprising a. reservoir having valve'contrblled water inlet and outlet, and means for altering the volumetric content of said reservoir, said Water outlet leading the'contentsof the reservoir to the receiving medium for the batch of sand.

23. In combination with apparatus for4 tom for the space, means for introducing handling -saturating and delivering sand for use incementitious batches, an auxiliary water measuringdevice comprising a reservo1r having valve controlled Water inlet and outlet, and an adjustable non-buoyant memthe contents thereof, said water outlet leading the contents of the reservoir to the delivered batch of sand.

24:.. In apparatus tor making cementitious mixtures, the inclusion of means for creating1 AA for periodically withdrawing batches of such mixture, together with means for automatically maintaining said mixture in an amount at least as great as that withdrawn for a batch. Y

25. ln the art of making cementitious mixtures, the method which consists in introducing liquid and granular' material to a suitable container', and in initiating and carrying on a, combiningof the two from below.

26. ln the art ot making cementitious mixtures, the method which consists in introducing liquid and granularmaterial to a suitable container, and in initiating and carrying on a combining of the two from below, to the 'saturation point ot the granular material.

- 27. rlhe method ot preparing granular and liquid materials for making cement-itious mixtures, employing a mixing receptacle,

which consists in maintaining the granular material constantly above a given level in said receptacle, and in maintaining a head of liquid on the material at said given level.

28. 'In the art of making cementitious materials, the method which consists in introducing into, and storing for discharge from, a container, said and water, and in maintaining a head of sand and a head of water each above the point of its introduction to the container. l

29. The method ot combining granular and liquid material which consists in passing a substantially solid mass of the granu- .lar material downwardly through a containing means, from the lower part of which it is withdrawn as needed, and in introducing the liquid into said containing means below the point of introduction of the granular inai terial.

30. The method of combining granular and licnid material which consists in passing a stantially solid `mass of the granular material downwardly through a containing means, from the lower part of which it is withdrawn as needed, and in introducing the liquid into said containing means under a constant head, regardless of withdrawals of the material.

3l. lllhe method of proportioning granular and liquid ingredients of a mixture to be delivcred trema receptacle by batches which consists in feeding a granular materia-l to the receptacle and in maintaining in said receptacle a substantially constant level of liquid at a height below-the normal level of the granular material.

32. rll`he method ot proport-ioning granular and liquid ingredients of a mixture to be delivered trom a receptacle by batches which consists in feedinga granular material and liquid to the receptacle, in drawing ofl1 batches ot mixed material, and in maintaining in said receptacle a substantially constant level ot' liquid at a height sufiicient to maintain a predetermined supply ot completely,y

'saturated granular material.

ln' av system ot proportioning liquid material and aggregate employing a suitable recepatcle to which aggregate is supplied and from which it is to be discharged, the step which consists in preparing the aggregate for discharge by introducing liquid into the receptable at a level below the normal level of the aggregate in the receptacle.

34. In the art of measuring sand and water for a cementitious mixture, the method which consists in combining water and sand at least to the saturation pointot the latter, and in subsequently measuring them together.

35. ln the art of measuring sand and water tor a cementitious mixture, the method, em-

ploying a delivery receptacle and a measuring container, which consists in combining water with sand in said receptacle at least to the saturation point of the latter, in periodically filling said container Jfrom said receptacle, and in maintaining a constant supply ot the saturated mixture in said receptacle not less in amount than the -volume of said container.

ln testimony whereof, I` have hereunto signed my name.

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