US3625487A

US3625487A - Placing of concrete

Info

Publication number: US3625487A
Application number: US866860A
Authority: US
Inventors: Harry Spragg
Original assignee: MARKHAM AND CO Ltd
Current assignee: MARKHAM AND CO Ltd
Priority date: 1968-11-13
Filing date: 1969-10-16
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: DE1952415A1; BE741496A; FR2023171A1; GB1233272A; CA931558A; NL6916972A; ZA697187B

Abstract

Apparatus for placing concrete comprises a duct to guide the concrete from a mixing station to a placing station, a pump to provide a continuous flow of air in the duct in the direction towards the placing station, a rotor at the mixing station to feed a dry concrete mix into the duct at a predetermined rate, and a ring of nozzles around the duct adjacent the placing station to inject water into the duct at a predetermined rate, the rates being set to provide a predetermined wet concrete mix.

Description

United States Patent Harry Spragg Chesterfield, England Oct. 16, 1969 Dec. 7, 1971 Markham & Company Limited Chesterfield, England Nov. 13, 1968 Great Britain Inventor Appl. No. Filed Patented Assignee Priority PLACING 0F CONCRETE 4 Claims, 14 Drawing Figs.

US. Cl 259/ 153, 259/165, 259/168 Int. Cl 1328c 7/04 Field of Search. 25 /147, 148, 149, 151, 153, 164, 168, 145,146, 165

[56] References Cited UNITED STATES PATENTS 1,731,953 10/1929 Thomson 259/147 2,161,553 6/1939 Westberg 259/151 2,577,664 l2/l951 Pro 259/151 2,637,539 5/1953 Crom 259/147 3,006,615 10/1961 Mason 259/168 Primary Examiner-Robert W. Jenkins Attorney-Watson, Cole, Grindle & Watson ABSTRACT: Apparatus for placing concrete comprises a duct to guide the concrete from a mixing station to a placing station, a pump to provide a continuous flow of air in the duct in the direction towards the placing station, a rotor at the mixing station to feed a dry concrete mix into the duct at a predetermined rate, and a ring of nozzles around the duct adjacent the placing station to inject water into the duct at a predetermined rate, the rates being set to provide a predetermined wet concrete mix.

PATENTED DEC H97! SHEET 2 OF 8 Ill;- r

PATENTED BED mm 3 5254 7 sum 7 or 8 \u ll /62 PLACING F CONCRETE The invention relates to the placing of concrete, for example, in moulds or a framework.

In the past concrete has been placed by first preparing a concrete mix, and then pumping the wet mix along a pipe to the desired location. In many cases the concrete at the location has to be vibrated to achieve compaction. The method has a disadvantage that in order to be able to pump the mix the mix has to have a far greater water content than is consistent with the ideal mix for good properties in the placed concrete. In addition pumping imposes strict limitations on the type of mix which can be used.

A further proposal has been to pass a dry mix of cement and ballast along a pipe in a fluidized stream with air and to inject water into the stream at the end of the pipe nearer to where the concrete is to be placed. This technique has the disadvantage that a highly skilled operator is required, as in the well-known gunniting process, because the water has to be injected by means of a valve controlled by the operator. Even with a skilled operator the method has only been used for applications where the strength and appearance of the concrete have not been very important. It is an object of the invention to provide an improved method of placing concrete.

The invention provides apparatus for placing concrete comprising a duct to guide the concrete from a mixing station to a placing station, means to provide a continuous flow of air in the duct in the direction towards the placing station, means at the mixing station to feed a'dry concrete mix into the duct at a predetermined rate, and means adjacent the placing station to inject water into the duct at a predetermined rate, the rates being set' to provide a predetermined wet concrete mix. Preferably the water injection means and the dry mix feed means are arranged to be driven from the same power source so that any rate alteration by either means is automatically compensated.

It is further preferred that the water injection means and the mix feed means are relatively adjustable so that the proportion of water to mix can be adjusted.

A specific example of apparatus for placing concrete according to the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a part side elevation and vertical section through the pneumatic placing machine, partly in section on the line 1-1 in FIG. 2;

FIG. 2 is a part section on the line 2-2 of FIG. 1;

FIG. 3 is the plan view of the arrangement shown in FIG. 1;

FIG. 4 is an end view of the water injection flange;

FIG. 5 is a section on the line 5-5 in FIG. 4;

FIG. 6 is an end view of the water injection ring which fits within the flange;

FIG. 7 is a side view of the ring;

FIG. 8 is an enlarged section on the line 8-8 in FIG. 6;

FIG. 9 is a side view of the water injection pump;

FIG. 10 is a section on the line 10-13 in FIG. 9;

FIG. 11 is a section on the line l1ll in FIG. 10; and

FIGS. 12a, 12b and 120 are diagrams showing how the stroke of the pump is adjusted.

The placing apparatus shown in FIGS 1 to 3 comprises a hollow platform 10 on which is mounted a compressed air motor or electric motor 11 which drives the feeding mechanism through a suitable gearbox 12, and coupling 25. As best seen from FIG. 2 the feeding mechanism comprises two casing parts 13 which are adjustable towards one another between top and

bottom plates

14 and 15 in known manner by screwjacks 16 mounted on suitable supports 17. A suitable hopper or funnel 45 is secured to the upper plate 14.

End members 18 have attached to them closure plates 19 in which are mounted bearing holders 20. Bearing members 21 and 22 in said holders respectively support a journal portion 23 of a shaft 24 driven from the gearbox I2 and one end 26 of a hollow rotor 27 which is keyed to another part of the shaft 24.

As best seen in FIG. 2 the rotor is provided with a number of circumferentially spaced pockets 28 the bottoms of which are curved in the direction of the axis of rotation as best seen in FIG. I.

As best seen in FIG. 2 the two casing parts 13 are arranged to provide between them spaces 32 and 33 at the top and bottom of the apparatus respectively.

The base 10 is formed with a compressed-air inlet pipe 39 which directs high-velocity air through one end of each pocket as it sweeps past so as to force any material in the pocket into a delivery conduit 40 which extends through the base and is provided with a flange 41 for connection to a delivery pipe which delivers the material to the required destination. The inlet pipe 39 is similarly provided with a flange 42 for connection with a conduit leading to a source of compressed air.

The delivery pipe connected to the flange 41 extends to the location where the concrete is to be placed and adjacent the end of the pipe at the location there is a water injection flange which is shown in FIGS. 4 to 8.

The flange comprises an outer flange member 50 which is of annular fonn and is provided with holes 51 for attachment to the delivery pipe. There is a channel. 52 around the inner periphery of the member and there is a drilling 53 connected to the channel and for connection to a water pump.

A water injection ring fits within the member 50 and consists of two

rings

54 and 55 which are joined together with a lap joint as shown in FIG. 8. The two rings are separated at the inner face of the joint to provide a channel 56.

There are a number of spaced holes 57 for connection to the channel 52 in the outer member 50 so that water entering the channel 52 passes to the channel 56.

The driving mechanism for the water pump which supplies water to the injection ring is shown in FIGS. 9 to 12 and comprises a casing 60 which houses the working mechanism. The output is by way of a crosshead 61 mounted in guides 62 and the crosshead drives the piston of a reciprocating pump which is not shown. The stroke of the crosshead can be varied between full stroke and travel by a system of linkages controlled by the positioning of the pivot position of an intermediate link.

Attached to the crosshead by a pin 59 is a connecting rod 64. This connecting rod is provided with a hinge pin 65 to which is secured a connecting link 66 which is given a reciprocating motion substantially at right angles to the axis.

The reciprocating motion of the link 66 is obtained by means of a crank driven from a pulley 67. The pulley 67 is driven from the gearbox 12 so that the pump motion is positively connected to the motor of the rotor 27.

The hinge pin 65 is secured to a pair of links 68 which are hinged at precisely the same center distance as the connecting rod 64, by means of binge pins 69, which are carried in a cradle or frame 70 which can be swung about axis pins 71. The center distance between

pins

69 and 71 is precisely the same as that between

pins

69 and 65, and also the connecting rod center distance.

When the center line of pin 69 is coincidental with the pin 59 on the crosshead, no movement of the crosshead will take place.

If however, the swing pin 69 is swung out of line with the crosshead pin 59, then a reciprocating motion will be imparted to the crosshead as indicated in FIGS. 12a, 12b and 120 of the drawing.

There is therefore an infinitely variable arrangement to control the stroke of crosshead 61.

The relative positions of the

pins

59 and 69 are altered by rotating the cradle 70 using an am 72 keyed to an axle 73 which forms one bearing for the cradle. The arm 72 slides over a scale 74 and is held in any selected position by means of a bolt 75 with a head 76 which is received in a slid 77 pivotally attached to the casing 60. The bolt can be tightened by a ring nut 78 to lock the arm in position.

In use of the apparatus a dry concrete mix with a predetermined cement to ballast ratio is placed in the hopper 45, and

air is fed to the pipe 39. if the pipe has a diameter of 6 inches the air feed rate should be about 2,000 cubic feet per minute.

The rotor 27 is set in motion and is timed to release the dry mix at a predetermined measured rate.

The dry mix is swept in the airstream from the lower pocket of the rotor through the delivery pipe to the water injection flange where it meets a curtain of water which it picks up. The wet mixture then passes out to the desired concrete location.

As the water pump is connected to the drive mechanism for the rotor the amount of water required to provide the best mix can be calculated and injected into the mix by varying the stroke of the pump.

The wet concrete emerging from the apparatus has sufficient velocity to enable high compaction to be achieved even at distances of the order of 20 feet from the end of the delivery pipe. The concrete can also be forced into moulds such as are used for moulding precast concrete members and because of the high compaction achieved no vibration in the mould is necessary.

I claim:

1. Apparatus for placing concrete comprising a duct to guide the concrete from a mixing station to a placing station, means to provide a continuous flow of air in the duct in the direction towards the placing station, means at the mixing station to feed a dry concrete mix into the duct at a chosen rate, and means adjacent the placing station to inject water into the duct at a chosen rate, the water injection means and the dry mix feed means being arranged to be driven from the same power source so that any rate alteration by either means is automatically compensated, and being relatively adjustable during operation of the apparatus so that the proportion of water to mix can be adjusted to provide a chosen wet concrete mix.

2. Apparatus as claimed in claim 1 in which the water injection means comprise a pump of which the stroke is adjustable to alter the proportion of water to mix.

3. Apparatus as claimed in claim 1 in which there is means to adjust the speed of the drive from the power source to the feed means and the injection means to vary the rate at which concrete is fed to the placing station without varying the ratio of water to mix.

4. Apparatus as claimed in claim 1 having a duct to a concrete mix from a mixing station to a placing station, an air pump to provide a continuous flow of air in the duct in the direction from the mixing station towards the placing station, at the mixing station a rotor having a plurality of identical pockets one of which is open to the duct and another of which is open to a supply of mix, means to rotate the rotor at a chosen speed to release successive equal quantities of mix into the duct at a chosen rate, adjacent the placing station a ring of inlet nozzles around the duct, a variable displacement pump to pump water through the nozzles into the duct at a chosen rate, common drive means and a gearbox for the rotor and the water pump, and means connecting the gearbox to the rotor and to the water pump.