CA1173429A - System mixing preproportioned sealed-container- transported concrete ingredients - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

This describes a method and an apparatus for supplying freshly made concrete. Containers having two compartments are used, one compartment for aggregate and a companion compartment for cement. The container compartments are loaded from the top and are amptied simultaneously or one after another through apertures at the bottom of each compartment opened and closed by manually or power operated gates. The top of the compartments is closed by covers which protect against humidity infiltration or humidity loss. The contents are discharged through the respective aperture onto a receiving conveyor which carries the contents into an adjacent mixer where they are mixed together with the specified amount of water and specified additives which are measured out and introduced by appropriate apparatus mounted on or near the mixer to make the eventual viscous concrete.

Description

~'7~9 FIELD OF INVENTION

The pre~ent invention rslat~s to a method and mean~ for supplying fre~hly-mede concrRt~.

Concrute is generally supplied to a delivery sitD from a concrRte batching pl~nt locatsd of~ the site, usually at the suppliQr's place o~ busine~s. Thers, the rsquired ingredisnts are weighed out and mixed, then loaded into a concr0te mixer truck ~or del~very to ths custom~r.
Tha ingredients are crushed stone and¦or gravel, aand, cement, watsr and certain additives.
Immediately upon entsrlng in contact, ths c~m~nt and the water start e chemical reaction, ths ultimate rs~ult o~ which i8 the hydration of tha concret0, lt~ "~etting" or "hardening~.
aecau~e of this r~action, and to avo~d ~egregation e~ the ingredients during tren~port, ths concrete i~ agitated ln a revolving mixer drum mounted on the truck, until di~charged at the ~ob siteO A concrete truck is therafor~ a very costly p$ecs o~
equipment.
Also because of the a~orementionsd reaction, this 80 called ready-mix concrete is the mo~t psrishable cargo carriad in any quantity in modern urban traP~ic. ~ood~tu~s, ice, ~10WBr8 etCO
all last in good condition for mors than 90 minutes, which i8 the g~nerally accepted time limit for condemning a load o~ concrete.
A~ tha averag0 str~ngth and quality of concrete kRep~ going up, 80 doss ths stringency o~ rul~s by which the o~ner'~ engineers try to protect that quality. What in bygone days was tolerated ~or the wsaker mixe~ cannot be permitted ~or today~s highsr otrength concrsteg. ThR ~snsitivity of ~uture concretes to ths requir3ment~
u~tablishsd for quality concrete can be predicted to incrsase not least in what concerns delivery time, alrsady count~d in minutes.

3~

-2-Meanwhilo ths conditions in which ready-mix concrnte is del1vered are becoming progressively worsa. Traffic d0n~ity ~hcreases, the numb~r of gtop signs and traffic lights constantly grows, routes on which truck traffic is allowed ars prograssivoly mora restricted, limitations ars legislated reducing ~shicls loads, etc. ~one of thase tandencies work in the concreta supplisrs'favour;
On top o~ the above mentionad problems, the ready-mix concrete businsss in most areas su~fers from a seasonal faast-and-famln~
pattern. Whil~ August to October the industry is hard pressed to find anough delivary capacity to satisFy tha market, it has its yords full of idle equipment ~rom ~anuary to ~arch, due to the seasonal nature of its clients' businass, in turn imposed by ths climate~
Another wsel<ly cycle superimposes itself on this annual cycls.
~ost construction sites so organize their work that placing of concrete is done on Thursdays and Fridays. This is 50 bacauss thus the hydration process can taka placa over th~ w~akand, on idle time.
~hen the crews raturn on Monday morning, stripping of forms can be undertaken without any loss of working tima, the setting Df tha con-creta having occurrad on Saturday and Sunday. Tharafore, avan in the ~0 busy season~ ready-mix suppliers find themsslvas saddled uith idle equipment and underutilized batch plants on Mondays, tuesdays and Wednesdays, while the next two days see heavy overtime costs incurrad.
The industry thus finds itself in a situation9 where a chaap product (valua just ovar l¢/lb), is transportad in very expensivs and complicated aquipment in conditions which rendar it rather precarious to mset delivery timas imposed by tha extrame perishability of the product. Tha large investment in equipment is in full USB only two days a weak under 3 or 4 months of the year and must thus bs amortized over a fsw annual hours only. Obviously, soma place along the road this industry either took a wrong turn, or mora likely~ failed to mak~
a turn it should have.
U.S. Patent Numbsr 31Bû686, of 1965~ has propossd rsndering the concrste product non-perishable by not adding water to it until the time of its use at the tsrmiral sita. In this Patsnt~ a trailer truck

-3-transports the aggrsgate in one compsrtment and cement in a~othor compartmHnt to the delivery sit~, ~hore ths lngradlant~ are discharg~d onto a convsyor which ~seds the dry materi~l to a concrete mixer where water i~ added. However, in this PAt2nt~ thc dry aggregate i~ sxposed to the elements and to humidlty in~iltratlon or evaporation during tran~port 80 that there are no means to ascertain the degres of its humidity when arriving at the con~truction aite and there~ore it is imppssible to calculate ths exact amount o~ water to be ~dded in the concrete mixer for qbtaining the speoified hydration and lD strength of the concrete~ Furthermore th~ patsnt requiras that the cement compartment havs ite diecharge opening situated above that of the aggregat~ compartment, th~reby restricting the flow of the aggregate.
O~JECTS OF THE INVENTION
It i8 tha ~eneral object of the prssent invsntion to rendar the concrste materials bsing delivered non-pbrishable by providing a method and means of delivery of cement ano other companion concrste ingredients to 8 delivery site Without the required water addsd snd mixing these ingrsdisnts at such site with the precis~ly ~pecified quantity of water and additivss roquired to obtain concrete o~ optimum specifiad quality and charactsrlstic~.
Anothsr ob~ect of the present invention is to provide equipment of simpler and less axpensive canstruction fo~ the transportation of concrete ingredients and for delivering the ~ame to a mixer at the indicated destin~tion. Still anothsr obj0ctive9 through renderLng the load non-parishabls ~nd tran~portable at a convsn~ent time without regard to perishability, in les~ sxpsn~ive equipment than that used in conventlonal methods, is to reduce ths coet of concrete delivery.
A further objective i8 to improvs the quality o~ th~ concrete by delivering it to the eite of placing 8~ fre8h a8 poB8ible~
Still a further ob~ectivs is to rendar the aupply o~ concrete flexible enough to3ccDmmOdata changaa $n the placing schedule9 occasiDned by ~sather, accidents or any other reason.

-4-z~ ~
SU~IIlARY OF THE INVENTION
The method of th~ invention consists of individually weighing required amounts of aggragQte in its existing state of humidity and a proportionatH amount of` csment at the batching plant~ msasuring tha humidity content o~ the aggregate at said plant, loading the aggregate into one compartmant and tha camant into another compartment of a container, tran~porting ths containar to th~ daliuury site, discharging tha ingredients from the respective compartmsnts into a-conorete mixer at the deliuery aite and adding the speoified quantity of water and additives to said ingredient3 in the mixer3 mixing the ingrsdients and discharging the fresh concreta into concrete placament means~ and protecting the ingredisnts against humidity infiltration or evaporation from the time the humidity measuremant has been effected at the batching plant to the time the ingredients haue been loaded into the mixer so that the exact amount o~ water and additives may be added to the mix in said mixer~
Preferably the ~0ans of transportation is a trailer truck built to comprise one or more individual container~. Each container has two compartment~ each providsd with a dicharge aperture st the bottom.
All the discharge apertures are in longitudinal alignment parallel to the trail~r centerline. Appropriata gata mean ara prouided to close and open the two compartments of aach container and clo~ure means or hatches cover the tops o~ the compartments to protect the contents against pracipitation and al~o to prevent humidity ~vapDra-tion during transport and storage~
A moblle platform i3 also provided~ this plat~orm baing pr~fe-rably equipped with ground engaging shsels which are retractable to allow the platform to be lower~d onto tha ground. The platform pro~
vides two tracks for guid~d positioning tha trailar onto the plat~orm and is provided with a centrally lDcated weatherproJf conveyor means to racei~a the matsrial discharged from the compartments and dischargH
the same into a mixer at the dalivery site,

-5~

~'7~Z,~

In tha annexsd drawings: ~ j Figure 1 is a sid~ elevation o~ the trailsr truck ~ur trans-porting the dry ingrsdients ~rom the batching plant to th~ delivsry site:
Figure 2 is a cros~-s~ction taken alang lin0 2~2 o~ Flgure l;
Figure 3 i~ a plan section takon along lins 3-3 D~ Figure l;
Figure 4 is a sids alsvation ot` a positioning platfDrm shown in ~levated position r~ady to be tow~d by a hauling vohiel~;
Figurs 5 i8 a side slevation o~ the platform in lowsrsd groun~-engaging position rQady to recsive the truck trail~r o~ Figure l;
Figure 6 is a partial ~ide elevation of ths ramps in operativo position and partially cut away to show the tow-bar;
Figure 7 is a sida elsvation of the plat~orm and o~ the truck trailer in dischsrging positinn ovsr the aame and al90 ahowing the elavating convsyor means, togethsr with the coner~te mixer truck shown in dotted line; and Figure 8 is a rear end view o~ the arrangement of Flgure 7 In the drawings, like referenc~ charaeters indicate likQ
slements throughout.

The truck trailar T used ~or the transpDrt of the dry conerete ingredients is shown in Figures 1,2,3 and 70 lt comorisss an elongated frame 1 carried by ground-engagin9 t re wheels 2. Ths number and spacing of the axles are arrangsd to comply with rDad regulations as to road loading. The front end of ths frams 1 is adaptsd to be hitched to a truck tractor 3 by way of a so called fifth wheel apparatus. Th~ trailer frame 1 carries one or more containers each divided into two compartmants 4 and 5 and mounted on fram~ 1. Compartments 4 ars designed to contain ths sand and the gravel or othsr aggregate in their natural stats ~hile CD~-partmsnts 5 are adapted to eontain cement in a quantity required to produce the quality of conerets required by the consumsr. Compartm0nts 5 arB Df SmallQr SiZB than compartments 4. Eaeh compartment 4 i9

-6-3~ 9 open at ths top for ths loading of ths ssme and ha3 a ~unnel s~aped lowsr portion tsrminatad by a dischargs apsrture 7 and each cement compartment ha~ a top lDading op~ning normally clossd by a seallng hatch 9. The lowsr portiun of thH cemsnt compartmant 5 may be wider than ths top to ~acilitata loading th~l aggregate compartm0nt and ia also of ~unnel shapa and has a dischalge aperture lO. All the dischsrgs apsrturss 7 and lO ars longitudinally aligned and disposed parallel to the centre lina o~ the trailer To Compartments 4 have their top loading opening prouided with a closure means to protsct th0 contents against humidity infiltration or loss. In the embodiment shown? ths closure ia a cover 11 consisting of two mutually-hingsd panals 12 and 13. Panel 12 is conneoted to an operating means~ for instancs a power cylindsr 14 Por opening the same. In the open position~ pansl 13 folds against the opan panel 12 as shown in dotted lina in Figurs 2.
Ths dischargs aperturas 7 and lO of two associated compartments 4 and 5 o~ Dn~ group may be provided with a common gate cl~sure~
generally indicatsd at 15. A flange 16 surrounds the two apertures

7 and lO. A closure plats 17, of ths same 8iZ~ a flange 16~ is slidably supportad against the underside o~ ~langa 16 by spaced straps lB secured to the longitudinal sdges o~ flangs 16. An opsrating msansg for instance a power cylindsr 19 is connacted at ons snd to ths closurs plats 17 at 2O7 and at ths othsr end to bracket 21 secured flange 16~ In the clossd position of the plate 17~ the two apsrturss ars sQalsd C1DSe and ths closurs plats 17 rsgistsrs with flangs 16~ as shown in Figurs 3~ Upon operation of ths powsr cylinder 19~ ths plate 17 is movad to the position shown in dotted line in Figure 3, whereby its opaning 22 comes in rsgister with apsrturs 7 of tha aggregata compartmant 4 and the frea sdga of tha plats 17 uncouers aparture lO of the cement ~ompartment 5.
~igures 4 and 6 show.ths portable plat~orm P to be used in association with ths truck trailer T ~or the con~eying o~ tha dry concrste componsnts to ths csment mixsr at tha construction ite~

~ . . .

''3 This platform consists of a ganerally rsctangular rigid frame ~S
- ~orming two laterally-spaced longitudinally-extsnding parallel tracks 26 for receiving the wheels 2 oF the trailnr T. These tr~cks are interconnected by cro-~s beam~ 27~ which support a convcyor system> in the form of a conventional convayor 28~ which i8 dispossd along the centerlins of the platform~ Conveyor 28 is enclosed by a casing 6 which haa top loading opening~ adapted to registsr with the dischargs apsrturss 7 and lO Df tha compartmsnts 4 and 5 when trailer T is prop~rly positionsd on platform PO Convsyor 2a has an upwardly inclined conveyor portion 29 at its rear end~ also totally enclosed by casing 6 and which provides a discharge 30 at a lsvel for loading ths matsrial into a regular concrsta mixer indicated in dotted line at 310 The conveyor portion 29 is prafsrably foldable over the main conveyor portion 28 when not in useO As an alternative~
a separate elevating conveyor may ba used instsad of convey~r portion 29.
The platform P is provided at~its front end with two ramps 32 of triangular shape which are pivoted at 33 to ths front end of th0 platforrn so as to be foldable over the platform as shown in figure 4 when the latter is not in use. Theso ramps ar~ in alignmsnt with the respectiue tracks 26.
A tow bar 34 is secured to the front end of the plat~orm P
and is provided with a hitching eye 35 to engage a hook of a towing vehicle. Tow bar 34 is disposed between the two ramps 32.
A rstractabla and adjustable supporting 1B9 36 is mountsd on the tow bar to raise and lower the front end o~ the platform.
Arms 37 are pivoted at 38 to ths rear end of sach track 26.
A ground-engaging whesl 39 is rotatably carried by tha frse end of each arm 37. Powsr cylinders 40 serve to lower and raiss the wheels 39, so that the platform may be raised, as shown on figure 4~ for transport on a road and lowured into ground-engaging position, as shown in Figure 5~ for receiuing the truck trailer ~, as shown in Figure ~ The whesls 39 ars in alignmsnt with the respective tracks 26 of the trailer and serue as a positioning bumper for the rsar ~l~'7~342~3 whssls of ths truck trsiler T, so that ths discharge aperturey of khe compartments 4 and 5 will ba respectively aligned with tho top openings in the casing 6 of th~ convsyor 2~, so that the mat~rial Prom th~
compartmsnts 4 and 5 will properly discharge onto said conv0yor 2~.
Furthermore, the truck trailer is laterally positioned on the platPorm P by lateral guide rails 41 extsnding along the inner longitudinal side of tha rsspsctius tracks 26, as shuwn in Figurs 8.
At the batching plant~ the humidity content o~ the aggregate~
normally sand and stone to be dslivered by the truck trailer T to the delivsry site~ is first measured and rscorded. The top clos~re 11 is open and all the compartments 4 ars loaded with the required amount of aggregats. The hatchss 9 are open and ths cement compartmants 5 are each loaded with the rsquired amount of cement~ as speci~ied by th~ customer. The hatches 9 are closed and also the closures 11 and the trailer T is movsd by road by means of $he tractor 3 to the dslivery site, in ths neighbourhood o~ which construction takes place~
The loaded trailer T can be left standing at any convenient place~
Por instanc~ along a street curb, its legs 42 supporting the same.
The tractor 3 is therefors free to move an smpty trailer T back to the batching plant for reloading~
Previously, the platPorm P had been hauled by a suitable tractor to the dslivary site where the concrete is to be delivered.
In practice, platPorm P will be low~red at a position ad~acent whers Goncrets placement means ars installsd. PlatPorm P is lowsred into ground-engaging position, as shown in Figurs 5, with its ramps 32 pivoted to rest on the grnund. The conveyor portion 29 is raised intu its operative position~ as ~hown in Fiture 7~ and the mixer truck 31 is backed up to recaive ths material discharged from the conveyor portion 29~
3U Another tractor~ similar to tractor 3~ and which is made available at ths terminal site, is hitched to the loadsd trailer T

and back~ up this trailsr ovsr ths platPorm P, using the ramps 32.
The trailer is mDvsd back until it abut~ the platform wheels 39~

734~9 which act as a positioning bumper for the trailer. In this po~ition~
the trailer legs 42 are lowered to engage the piatform snd maa!ntain the trailer leval. Tha tractor can then be unhitched.
Operation of the conveyors 28 and 29 i~ stsrted and the closure gats 15 of one container is open to di~charge the contents of said container, namely its two compartments 4 and 5 simultaneously or consecutively onto the conveyor 28, 29, which disc~rges th0 material into the mixer 31. Each container as designed for one batch suited for tha capacity o~ the mixer. In the mixer; the specified amount o~ water and additiues are added and~ ~fter mixing for a specified time, the concrete is ready to be poured into placement means~ such as buckets, adapted to be hoisted by a crane.
The trailer shown has three containers and is therefore capable of supplying three batches for the concrete mix~r. Once tha trailer T is emp~y, it ls removed from the platform by the site tractor and placsd at a suitable parking place ready to be hauled back to the batching plant. Another fully loa~ed tractor can ba immediately positioned onto ths platform for its unloading~
It should be noted that the cement and aggregate ara fully prDtected against humidity infiltration and lnss~s from tha tima the conrrats ingredients are loaded into the truck trailer at tha batching plant to the time these ingradients are discharged into the mixer 31 at the delivery site. Therefore, since weight and humidity measuraments o~ the sand and aggregate had been taksn at the batching plant~ ths correct amount of ~ater can be added into the mixer~
Since the cement and aggregats are contained in trailer T
without water sdded, the trailer T can be left loaded at the deliuery site for any amount of time and~ therefore9 the system 3~ provides highly flexible loading and unloading sequences. Yet ~reshly-mixed concrets is always available at the deliuery site and at the required time.

, ~-~7342"3t Tlle plat~orm P and th~ waiting trailars T can bs positijned~
for instancs, along a str0et curb should the co~struction sitb be in a city, and the trailers T on adjacent streets ready to be moved by the "jockeying" tractor on and o~ the platPorm P.
Trailers T can be used ~or the transport of sand and grav01 from th~ sand and gravel pits to the batching plant.
Although ths method and systsm have been de~cribed in conjunction with tha concrete industry, it should be noted that the same method and system could be ufled for other applications where it is desirsble or imperative to mix at the last momont two or more separate ingrodients which are designed to chemically react with one ~nother.
Also, although the containers with their two compartm~nts have been shown as being moùnted on a truck trail~r~ it is obvious that other means of transportation could bfl provided for such containers.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of supplying concrete ingredients to a delivery site, comprising the steps of separately weighing appropriate amounts of aggregate and cement at a batching plant removed from the delivery site; measuring the humidity content of the aggregate at said plant and loading the aggregate into one compartment and the cement into another compartment of a two-compartment mobile container mounted on a truck with the two compartments disposed longitudinally of the truck;
moving the latter to the delivery site; placing the truck onto a positioning elongated platform placed at the delivery site with the two compartments disposed longitudinally of the platform, simultaneously and completely discharging the ingredients from the bottom of both compartments onto a common conveyor carried by the platform located under said compartments in longitudinal alignment with said common conveyor and movable longitudinally of the truck; conveying the discharged ingredients via an elevator means into a concrete mixer positioned in longitudinal alignment with the platform and truck;
adding a specified quantity of water in the concrete mixer; mixing the ingredients and discharging the fresh concrete into concrete placement means; and protecting the aggregate and the cement against humidity infiltration or loss from the time the humidity measurement has been effected at the batching plant to the time the aggregate and the cement have been loaded into the concrete mixer at the delivery site.

2. A method as defined in claim 1, wherein said truck includes a tractor and a detachable trailer and said container is mounted on said trailer which is adapted to be placed on said positioning platform.

3. In combination, a truck trailer for the transportation of concrete ingredients from a batching plant to a concrete mixer, said trailer including an elongated frame, mounted on road wheels, at least one container carried by said frame, said container having two compartments open at the top and each having a funnel-shaped lower portion with a discharge opening, the discharge openings being longitudinally aligned parallel to the centerline of said truck trailer and disposed between the truck trailer wheels, gate means for both said openings and movable between a closed position sealing said openings, and an open position, opening both said openings, and closure means for the top of said compartments to prevent humidity infiltration or losses in the ingredients of said compartments, and a mobile platform for receiving said truck trailer at a delivery site, said platform including an-elongated frame adapted to rest on the ground and defining a pair of lateral transversely-spaced longitudinally-extending tracks for receiving the wheels of the truck trailer, a longitudinally-extending concrete ingredients conveying means disposed longitudinally of said platform in vertical register with the discharge openings of said compartments when said truck trailer is positioned on said platform; said conveying means including an elevating conveyor portion located at the rear end of said platform and having an upper discharge end at a level to dis-charge the ingredients into a concrete mixer positioned in longi-tudinal alignment with the platform at said one end; and ramp means at the front end of said platform to permit said truck trailer to embark onto said platform.

4. The combination defined in claim 3, wherein said closure means include a hatch cover for the cement-containing compartment and a cover for covering both said compartments, as well as said hatch cover.

5. The combination as defined in claim 4, wherein said cover is made of two longitudinal panels hinged to each other and foldable one against the other.

6. The combination as defined in claim 3, wherein said ramp is pivoted to the forward end of said platform and is movable between a ground-engaging position extending forwardly of said platform and a stored position folded backwardly over said platform, a towing arm secured to and extending forwardly from the front end of said platform for hitching the platform to a towing truck, ground-engaging wheels carried by the rear end of said platform, and power means to raise and lower the platform with respect to said wheels, whereby said platform, when raised, can be towed by a truck on a road.

7. The combination as defined in claim 6, wherein said conveying means is disposed along the longitudinal centerline of said platform and includes a conveyor enclosed in a casing, said casing having spaced load-receiving apertures adapted to register with the discharge openings of said container compartments.

8. The combination as defined in claim 7, wherein said ground-engaging wheels are aligned with the rear end of said tracks and protrude upwardly from said tracks when said platform rests on the ground to act as positioning bumpers for the rear wheels of said truck trailer, thereby compelling the positioning of the container discharge openings immediately over the conveyor load-receiving apertures.

9. The combination as defined in claim 8, further including lateral guides extending alongside the respective tracks for laterally guiding the wheels of the truck trailer.