Note: Descriptions are shown in the official language in which they were submitted.
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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.
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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
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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.
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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,
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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
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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~
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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
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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~
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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.
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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.
