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Publication numberUS2595631 A
Publication typeGrant
Publication dateMay 6, 1952
Filing dateJul 2, 1951
Priority dateJul 1, 1950
Publication numberUS 2595631 A, US 2595631A, US-A-2595631, US2595631 A, US2595631A
InventorsEmil Bertsch
Original AssigneeVolkart Geb
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for cooling concrete mixture components
US 2595631 A
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Description  (OCR text may contain errors)

y 1952 E. BERTSCH 2,595,631

METHOD AND APPARATUS FOR COOLING CONCRETE MIXTURE COMPONENTS Filed July 2, 1951 2 SHEETS-SHEET 1 rhel s.

METHOD AND APPARATUS FOR COOLING CONCRETE MIXTURE COMPONENTS Filed Ju ly z, 1951 E. BERTSCH May 6, 1952 2 SHEETSSHEET 2 ums Patented May 6, 1952 METHOD AND APPARATUS FOR COOLING CONCRETE MIXTURE COMPONENTS Emil Bertsch, Bombay, India, assignor to Gebr.

Volkart, Winterthur, Switzerland Application July 2, 1951, Serial No. 234,857 In Switzerland July 1, 1950 21 Claims.

In the construction of concrete dams in which large amounts of concrete must be cast at a rapid rate, the removal of the heat developed by the setting of the concrete presents a major problem.

It has been tried to solve this problem by providing within the dam an elaborate pipe system through which refrigerating brine is circulated while the concrete is poured and thereafter water is circulated to remove the heat developed while the concrete is setting. Such cooling systems and the refrigerating plant they require are of course very costly and their operation is liable to disturbance. On the other hand, it also has been tried to cool oil the concrete during its preparation before pouring it, by adding crushed ice to its components before mixing them, while reducing by a corresponding amount the quantity of water added to the mixture. By this method, it has been possible to cool the concrete leaving the mixer to about 75 deg. F. but this is not sufficient.

It has also been tried to cool the coarse components of the concrete, i. e. the stones, by means of cold air, but this again requires a large refrigerating plant. Cooling of the concrete in the finished dam, i. e. removal of the heat developed in the setting process and in the hardening process which continues for years, which heat is generally known as chemical heat, has there fore been abandoned on account of the extraordinarily high cost involved, and the problem as herein considered is reduced to the problem of cooling the mixture components before or during the mixing process. However, to cool sufiiciently the mixture, e. g. by means of ice, during the mixing process, it would be necessary to add one pound of ice to a mixture comprising, for in"- stance, 6 lbs. of stones, 3 lbs. of sand, 1 lb. of cement and lb. of water. This would render the concrete too liquid.

Thus, there remains only one way of solving the problem, and this is to cool considerably the components of the concrete mixture, namely, the stones, the sand, the cement and the water. The stones and the water are comparatively easy to cool, but cooling of the cement and of the sand is rather difficult.

One object of the present invention is to provide an improved method of cooling the cement and the other solid components of the mixture.

A further object of the invention is to provide an apparatus by which the aforesaid method may be carried into effect.

In order that the said invention may bemore clearly understood and readily carried into efiect,

two embodiments thereof will now be described more fully by way of example, with reference to the accompanying drawings, in which Fig. 1 represents, in plan view, a concrete mixing plant comprising means for cooling the components to be mixed.

Fig. 2 represents, also in plan view, an alternative arrangement of a concrete mixing plant.

In Fig. 1, the concrete mixing plant is starshaped in layout, although it is obviously possible to give it any other appropriate layout without departing from the scope of the invention. The reference number II] indicates a conventional concrete mixer having a vertically ar ranged cylindrical receiver tank Illa for the components to be mixed, and a stirring gear having three vanes I0b jointly driven by an electric motor A for stirring the mixture in the receiver Illa. Radially of the mixer, three insulated tunnels I, 2 and 3 are arranged for feeding stones, cement and sand, respectively, into the receiver tank Illa. Stones are supplied to tunnel I through a chute Ia provided at its outer end. This chute delivers the stones to an endlessconveyor belt lb supported in tunnel I on two rollers Id and le. These are journalled in the side walls of tunnel I. Roller Ie has a shaft extension carrying a bevel gear Ic driven from an electric motor acting through a reduction gear, to provide slow movement of the conveyor belt Ib towards the concrete mixer I0. Although the primary bevel gear, the reduction gear and the electric motor are not shown in the drawing in order to improve its clearness, their arrangement is similar to that of parts 29, 2h and 2k which will be referred to below. The stones carried by belt Ib over roller Ie are dropped onto a short chute I j which directs them into the receiver tank Illa of the concrete mixer Ill.

In a similar way, powdered cement is supplied to tunnel 2 through a chute 2a at its outer end, and falls on a conveyor belt 2b running over rollers 2d and 2e journalled in the side walls of the tunnel 2. Roller 2e is slowly driven in a similar way as roller Ie in tunnel I, by means of a bevel gear 20 provided on a shaft extension of roller 2e. Bevel gear 20 is in driving engagement with a primary bevel gear 2g mounted on the output shaft of a reduction gear 2h itself driven by an electric motor 270. From the conveyor belt 2b, the cement is dropped into the receiver tank Illa of the mixer, through a chute 2 f.

The third tunnel 3 is provided for feeding sand into the receiver. It also comprises a slowly moving conveyor belt 317, which is loaded with sand through a chute 3a and which is supported on a pair of rollers 3d and 3e, the latter of which is driven from an electric motor through a reduction gear and primary bevel gear (not shown but similarly arranged and constructed as parts 2g, 2h and 2k) by means of bevel gear 30 mounted on a shaft extension of roller 36. Outlet chute 3f directs the sand from conveyor belt 31) into the receiver llla of the mixer.

It will be noted that the concrete mixer l may be operated continuously, as the three conveyor belts lb, 21) and 3b ensure continuous feeding of the receiver Illa with stones, cement and sand, respectively, provided that they are continuously supplied with such materials through the chutes la, 2a and 3a. This can easily be achieved by arranging stockage bunkers above these chutes, into which they would deliver their contents by gravity through suitable controllable outlets.

The mixing plant is connected to a water supply pipe 4 fed from any suitable source. This pipe is carried through a cooler 5 in which the water is cooled by means of refrigerated brine coming in from a refrigerating plant (not shown) through a pipe 5a and returning to the said plant through another pipe 5b. Preferably, the internal arrangement of cooler 5 is such that the Water and the brine circulate therein in counter-current in order to promote the heat exchange and the efiiciency of the water cooling.

From the cooler 5, water pipe 4 continues to a sprayer 4a arranged in tunnel I so as to spray the cooled water on the stones passing under the sprayer la on the conveyor belt lb. Due to the water spray, the air contained in tunnel l is moisted and cooled. Part of this cooled air is drawn off through a pipe 7 by a pump P1, which delivers it through a pipe 'la into tunnel 3, where it passes in counter-current over the sand carried by conveyor belt 3b, thus cooling this sand before it reaches the receiver tank ll'la of the mixer.

Another part of the cooled air passing through tunnel l is drawn off through a pipe 8 by means of another pump P2. This delivers the air through deliver pipe 8a to a drying apparatus generally indicated at T, from which it proceeds in dried but cold condition, through a further pipe 81), into tunnel 2 for cooling the cement by passing over it in counter-current.

A water pipe 6 branches off from pipe 4 between the cooler 5 and the sprayer 4a and leads into the receiver tank llla of the concrete mixer IR. A cock or other flow control device 6a is provided in pipe 6 for controlling the delivery of water through the latter. Pipe 6 serves for supplying cooled water to the concrete mixture which is produced in the receiver tank lily. of mixer l8 and stirred by the vanes lflb while these are rotated by motor A.

In the embodiment described above, it will be seen that the cooling air supplied through pipe la to tunnel 3 escapes into the open atmosphere through chute 3a, and the cooling air supplied through pipe Ba to tunnel 2 similarly escapes through chute 2a. In order to prevent the cement from being carried away by this air, a preferable Variant, however, consists in providing means for preventing the escape of air through chute M, e. g. a direct and outwardly closed connection trunk between chute 2a and a stockage bunker which is maintained conveniently filled with cement so as to prevent the passage of air therethrough, while providing separate air outlets from tunnel 2 with filters arranged therein for retaining any cement which the air may be carrying.

The alternative arrangement shown in Fig. 2 comprises substantially the same elements as that of Fig. l and these elements are indicated by the same reference numbers and letters.

However, an air cooler 11) is connected in pipe la between pump P1 and tunnel 3 to provide additional cooling for the cooling air delivered to tunnel 3. This air cooler lb is supplied with refrigerated water through a pipe 'lc branching from pipe 4 between the water cooler 5 and the sprayer 4a. After passing through the air cooler lb, the water is discharged through a pipe 'ld which, if desired, may carry the Water back to the source which feeds pipe 4.

A further air cooler is provided in the connection of pipe 8a, with the drying apparatus T adjacent to the latter. This air cooler 80 may considerably assist the drying apparatus '1 in its operation, in that its cooling effect promotes the condensation and precipitation of moisture carried by the air which arrives through pipe 8a, whereby subsequent drying of the said air is facilitated. Also, if a material decrease of the air temperature is obtained in the cooler 80, this will allow for some rise of the air temperature While the air is being dried in the apparatus T, without the temperature of the air supplied to tunnel 2 through pipe 8b becoming too high for its purpose of cooling the cement. Therefore, it is preferable to employ refrigerated brine as a coolant in the air cooler 80. This brine is supplied to the latter through a pipe 8d branching from the brine supply pipe 5a and is carried back from the cooler Sc through a pipe Be connected to the brine return pipe 5b.

The arrangement shown in Fig. 2 further differs from that of Fig. 1 in that the escape of air from tunnel 3 through chute 3a is prevented by connecting chute 3a directly to the bottom of a stockage bunker 3m which is maintained filled with sand so as to prevent any substantial escape of air from chute 3a through the said sand.

A further pipe 1c is provided connecting the outer end of tunnel 3 with the inner end of tunnel 2 so that such air as has served for cooling the sand in tunnel 3 will thereafter proceed through pipe 16 to tunnel 2 and there join the air supplied through pipe 8b. Pipe le is carried through another air cooler 11 to which refrigerated water is supplied through a pipe lg branching from pipe 'lc. After passing through the air cooler 11, the water is discharged through a pipe 111, which, if desired, may also carry the water back to the source which feeds pipe 4.

Fig. 2 also shows a cement bunker 2m whose bottof'n is directly connected to chute 2a so as to prevent the cooling air from escaping from tunnel 2 as long as bunker 2m is sufficiently filled with cement.

Further, a return pipe 8; connects the outer end of tunnel 2 with the innermost end of tunnel I. This return pipe 81 serves for carrying back to tunnel I both the air which has been fed by pump P1 through pipe la and air cooler 1b to tunnel 3, and from the latter through pipe la and cooler If to tunnel 2, and the air which has been fed by pump P2 through pipe 8a, cooler 80, drying apparatus T, and pipe 81). With this arrangement the sprayer 4a should be placed so to deliver its water spray between the delivery end of return pipe 8) and'the entries to pipes l and 8, so that'the air carried back'through pipe 8] cannot enter pipes 1 and 8 before having been cooled by the said water spray. This arrangement provides for continued recirculation by pumps P1 and P2 of the same cooling air through tunnels 2 and 3 and for its regeneration by the spray arranged at 4a in tunnel I. To make up for any leakage which may occur in tunnels 2 and 3, access of fresh air from the atmosphere is possible through chute la through which stones are fed to the conveyor belt lb.

It will be understood that many alternative arrangements could be provided without departing from the scope of the invention. Thus, air coolers and/or air drying devices could be provided in other pipe conduits. Also, cooling of either or both of the pumps P1 and P2 could be provided for; the cooling medium for the pumps and/or the air coolers could be water supplied through pipes branching from pipe 4 ahead of sprayer 4a, or brine preferably supplied from and returning to the same refrigerating plant as that circulating through pipes 5a and 5b which connect to water cooler 5.

What I claim is:

1. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water when in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, and delivering said cooled air from said first tunnel through said second and third tunnels for cooling said cement and sand.

2. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, delivering part of said cooled air from said first tunnel through said second tunnel for cooling the cement therein, and delivering another part of said cooled air through said third tunnel for cooling the sand therein.

3. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water and delivering at least part of said cooled air from said first tunnel to either of said second and third tunnels and therefrom to the other of said second and third tunnels for cooling the cement and sand therein.

4. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said 6 mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, and delivering at least part of said cooled air from said first tunnel through said third tunnnel for cooling the sand therein and therefrom through said second tunnel for cooling the cement therein.

5. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer,v drawing air through said first tunnel whereby it is cooled by said sprayed cold water, and delivering at least part of said cooled air from said first tunnel through said third tunnel for cooling the sand therein, cooling the air which has passed through said third tunnel and directing it through said second tunnel for cooling the cement therein.

6. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through asecond insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooledby said sprayed cold water, and delivering at least part of said cooled air from said first tunnel to either of said second and third tunnels and therefrom to the other of said second and third tunnels for cooling the cement and sand therein, and returning it to said first tunnel.

'7. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying; cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooledby said sprayed cold water, drying part of said cooled air and delivering it to said second tunnel for cooling the cement therein.

8. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, cooling further part of said cooled air, drying it, and delivering it to said second tunnel for cooling the cement therein.

9. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water when in said tunnel,

conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, delivering said cooled air from said first tunnel through said second-and third tunnels for cooling said cement and sand and returning it to said first tunnel.

10. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement throughasecond insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby itis cooled by said sprayed cold water, cooling further part of said cooled air and delivering it to said third tunnel for cooling the sand therein.

11. Methodofr cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, delivering at least part of said cooled air from said. first tunnel to the end of said second tunnel adjacent to said mixer and causing it to flow through said second tunnel towards the opposite end of the latter, for cooling the cement therein.

12; Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooledby said sprayed cold water, delivering at least part of said cooled air from said first tunnel to the end or said third tunnel adjacent to said mixer and causing it to fiow through said third tunnel towards the opposite end of the latter, for cooling the sand therein.

13. Method of cooling the components to be used in a mixer for preparing concrete, comprising the combination of conveying stones through a first insulated tunnel towards said mixer and spraying said stones with cold water in said tunnel, conveying cement through a second insulated tunnel towards said mixer, conveying sand through a third insulated tunnel towards said mixer, drawing air through said first tunnel whereby it is cooled by said sprayed cold water, delivering at least part of said cooled air from said first tunnel through said second tunnel for cooling the cement therein, and filtering said air substantially at its oulet from said second tunnel, in order to recover any cement suspended therein.

14. Method as claimed in claim 1, in which the said combination of steps is carried out simultaneously and continuously.

15. Apparatus for cooling the components of concrete preparatory to their delivery to a mixer, comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the delivery of cement, a third insulated tunnel for the delivery of sand, first; second and third conveying means in said first, second and third tunnel respectively, means for adducting and spraying water in said first tunnel, and pumping means connected to said first, second and third tunnels for drawing air through said first tunnel and delivering it through said second and third tunnels.

16. Apparatus for cooling the components of concrete preparatory to their delivery to a mixer, comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the de-' livery of cement, a third insulated tunnel for the delivery of sand, first, second and third conveying means in said first, second and third tunnel respectively, a water supply conduit, a water cooler connected to said supply conduit, means for circulating a coolant throughsaid water cooler, a water sprayer locatedin said first tunnel and connected to said water cooler, and pumping means connected to said first, second and third tunnels for drawing air through said first tunnel and delivering it throughsaid second and third tunnel.

17. Apparatus for cooling the components of concrete preparatory to their delivery to amixer, comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the delivery of cement, a third insulated tunnel for the delivery of sand, first, second and third conveying means in said first, second and third tunnel respectively, means for adducting and spraying water in said first tunnel, a first air pump having its inlet connected to said first tunnel and its outlet connected to said second tunnel, and a second air pump having its inlet connected to said first tunnel and its outlet connected to said third tunnel.

18. Apparatus for cooling the components of concrete preparatory to their delivery to a mixer,

comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the delivery of cement, a, third insulated tunnel for the delivery of sand, first, second and third conveying means in said first, second and third tunnel respectively, means for adducting and spraying water in said first tunnel, a first air pump having its inlet connected to said first tunnel, an air drying device having its inlet connected to the outlet of said pump and its outlet connected to said second tunnel, and a second air pump having its inlet connected to said first tunnel and its outlet connected to said third tunnel. 19. Apparatus for cooling the components of concrete preparatory to their delivery to a mixer, comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the delivery of cement, a third insulated tunnel for the delivery of sand, first, second and third conveying means in said first, second and third tunnel respectively, means. for adducting and spraying water in said first tunnel, one air pump having its inlet connected to said first tunnel and its outlet connected to one end of said third tunnel, a conduit connected to the opposite end of said third tunnel and to one end of said second tunnel, another air pump having its inlet connected to said first tunnel and its outlet connected to the said end of said second tunnel, and a return conduit connected to the opposite end of said second tunnel and to said first tunnel.

20. Apparatus for cooling the components of concrete preparatory to their delivery to a mixer, comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the delivery of cement, a third insulated tunnel for the delivery of sand, first, second and third conveying means in said first, second and third tunnel respectively, means for adducting and spraying water in said first tunnel, one air pump having its inlet connected to said first tunnel and its outlet connected to one end of said third tunnel, an air cooler having its inlet connected to the opposite end of said third tunnel and its outlet connected to one end of said second tunnel, means for circulating coolant through said air cooler, another air pump having its inlet connected to said first tunnel and its outlet connected to the said end of said second tunnel.

21. Apparatus for cooling the components of concrete preparatory to their delivery to a mixer, comprising a first insulated tunnel for the delivery of stones, a second insulated tunnel for the delivery of cement, a third insulated tunnel for the delivery of sand, first, second and third conveying means in said first, second and third tunnel respectively, means for adducting and spraying water in said first tunnel, a first air pump having its inlet connected to said first tunnel, an air cooler having its air inlet connected to the outlet of said first pump, means for circulating coolant through said air cooler, an air drying device having its inlet connected to the air outlet of said air cooler and its outlet connected to said second tunnel, and a second air pump having its inlet connected to said first tunnel and its outlet connected to said third tunnel.

EMIL BERTSCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,480,727 Greyson Aug. 30, 1949 2,491,194 McShea Dec. 13, 1949 2,533,852 Tietig Dec. 12, 1950 2,585,739 Christian Feb. 12, 1952

Patent Citations
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US2491194 *Jan 19, 1948Dec 13, 1949Royal M McsheaProcess for altering the temperature of aggregates
US2533852 *Aug 6, 1945Dec 12, 1950Chester TietigProcess and apparatus for preparing concrete
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2758445 *Nov 30, 1951Aug 14, 1956Conveyor Company IncDevice for cooling and dewatering sand and aggregate
US3108448 *Jan 7, 1960Oct 29, 1963James T ReynoldsMethod of cooling cement mixes for concrete
US5100239 *Jun 29, 1990Mar 31, 1992Shimizu Construction Co., Ltd.Method of manufacturing concrete
US5152605 *Jan 22, 1991Oct 6, 1992Ushio Co., Ltd.Apparatus for making cooled concrete
US5388771 *Aug 9, 1993Feb 14, 1995Tsau; Josef H.Replacing binder liquid with ground frozen binder liquid to granulate powders in mechanical mixing granulator results improved homogeneity, and reduced processing time
US5388772 *Nov 30, 1993Feb 14, 1995Tsau; Josef H.Method to homogeneously mix liquids with powders
US5427448 *Jun 23, 1994Jun 27, 1995Hydromix, Inc.Method for mixing concrete using a cementitious material/liquid premixer
US5582351 *Oct 7, 1994Dec 10, 1996Tsau; JosefMixing powdered aspartame with binder comprising maltodextrin, dextrose, sugar, starch; drying, sieving
US5718508 *Oct 29, 1996Feb 17, 1998Haltec CorporationSelf-cleaning mixer for cement slurry
US8066422 *Mar 27, 2006Nov 29, 2011Kajima CorporationMaterial moisture content adjustment method
DE202010010804U1 *Jul 29, 2010Nov 2, 2011Lintec Gmbh & Co. KgMobile Vorrichtung zur Betonherstellung mit Kühlung von Schüttgut
WO2012013684A1 *Jul 26, 2011Feb 2, 2012Lintec Gmbh & Co. KgMobile apparatus and method for producing concrete with cooling of bulk material
Classifications
U.S. Classification366/7, 62/331, 134/25.1, 62/64, 34/429, 62/374, 62/380
International ClassificationB28C7/00
Cooperative ClassificationB28C7/0038
European ClassificationB28C7/00A2C