FI82963B - Concrete road and method of making the same - Google Patents

Abstract

The invention relates to a concrete road and a method of making the same. The road is produced by using what is known as a dry concrete mass which at the moment of laying has a flexibility of roughly 36 Vb° or more rigid than this, that is to say contains at most 90 l/m3 water. The dry concrete mass laid as the surfacing contains a stone material which is so coarse that its grain size is at least 32 mm.

Description

1 82963

Concrete road and method of its preparation. - Betongväg ochörfarande för dess framställning.

The invention relates to a concrete road, the pavement of which is made of so-called dry concrete mass having a flexibility of about 36 Vb ° or more at the time of application, i.e. containing not more than 90 l / m 2 of water. The invention also relates to a method for producing such a concrete road.

The ground concrete used in the works has traditionally been produced in temporary concrete stations built in connection with aggregate depots. This has caused difficulty in getting a flexible and quick start to stabilization work. The water-cement ratio in the concrete thus produced has also been unfavorable, which, on the other hand, has meant that the amount of cement must have been disproportionately high in order to achieve the desired strength of the concrete.

Compared to the use of ground concrete, the dry concrete method, in which water is not actually added to the concrete at all, has been found in the study to be about 22-25% cheaper precisely due to the water-cement ratio. The mass to be applied is then 36 Vb ° or more rigid, i.e. it contains a maximum of 90 l / m 2 of water.

In road works, concrete usually has to be produced in moving quantities in several thousand cubic meters, so that the smaller amount of cement required in the dry concrete method compared to ground concrete is a very large part of the entire casting operation as a cost factor.

In the past, the dry concrete method has been used mainly for the manufacture of pipes, manhole rings and aisle slabs. The use of the dry concrete method for road construction has been proposed by the applicant in his patent applications FI-844463 and FI-863650, which also show a machine suitable for the application of dry concrete.

2 82963 With this method and machine previously proposed by the applicant, a dry concrete road can be made by feeding aggregate and cement separately and in relation to each other from the bottom to an open landing silo, where the aggregate and cement are mixed into dry concrete mass continuously counted through the open bottom of your landing.

Swedish Patent Publication No. 24005 discloses a method for producing a road surfacing compound in which aggregate, cement and water are mixed in stages using in a first step a aggregate having a smaller grain size and in a subsequent step a aggregate having a larger grain size. Thus, the grain size is always increased. According to the publication, if desired, using an additional dose of water, the grain size can always be 30 mm or more. Thus, in connection with the use of coarser aggregate, reference is also made to the addition of water. The present invention, on the other hand, is a dry concrete coating which is already so rigid at the time of application that the calculated mass supports the casting machine.

Although Swedish Patent Publication No. 24005 refers to the possibility of using a grain size of more than 30 mm in concrete paving aggregate, this is referred to only as an extreme possibility resulting from the use of stepwise increasing aggregate roughness to improve the mass filling in different mixing steps.

The object of the invention is to further develop the dry concrete mass forming the road pavement so that the load-bearing properties of the mass when applying the pavement are improved, while the water / cement ratio can be changed in a more advantageous direction so that the same strength is achieved with smaller amounts of cement.

To achieve this purpose, a concrete road according to the invention is characterized in that the concrete mass forming the pavement contains such a coarse aggregate that the maximum grain size of 3,8963 contained therein is 32 mm or more.

Correspondingly, the method of manufacturing a concrete road is characterized in that a dry concrete mass using such a coarse aggregate is used as the road surface, with a maximum grain size of 32 mm or more, and that the application is carried out on a machine moving on the cast mass layer.

In other words, the aggregate is selected such that it contains at least a fraction corresponding to said maximum grain size, the other fractions being present in the relative quantitative ratio which is in each case characteristic of the aggregate mass used. The quantitative ratios of the fractions vary somewhat both in natural aggregates and in aggregate masses made by crushing.

When a very coarse aggregate mass is used according to the invention, the following essential advantages are achieved: 1) When calculating the dry concrete mass, the load-bearing capacity of the coating is sufficient so that the mass calculator can run directly on top of the calculated mass. For less coarse masses, the progression of the calculator over the calculated mass is uneven; the machine may sometimes even stop and dig into place.

2) The relative proportion of aggregate increases, whereby the same strength is achieved with smaller amounts of cement, and 3) the wear resistance of the concrete road increases.

The structure of the machine used for the production of dry concrete roads according to the invention will be described in more detail with reference to the accompanying drawing, in which

Figure 1 shows the machine seen from the side and partly open-sectioned.

Figure 2 shows an embodiment of a dredging device 4 82963 for finishing the surface of a dry concrete road according to the invention.

The machine for the production, spreading and compaction of, for example, dry concrete shown in Fig. 1 comprises a frame marked with reference number 1, the front end of which is supported by track wheels 2 and the rear part by a roller drum 3 and a vibratory roller 16. The roller wheels 2, roller drum 5, 23.

By means of said piston-cylinder devices 4, 5, 23 the height and position of the body 1 relative to the ground can be adjusted and / or the body kept in the desired level by controlling the operation of the piston-cylinder devices 4, 5, 23 with a spirit level device 24 and a height scale 25.

At the front end of the machine there is a silo 6 for rock to be unloaded from the truck driving ahead. At the rear of the silo 6 there is a landing silo 8, the lower end of which has a transverse landing opening 9. The bottom of the aggregate silo 6 is formed by a belt conveyor: 10, which feeds the aggregate 7 into the landing silo 8.

At the top of the machine, above the landing silo 8, there is a cement tank 11, which is filled with cement fed from a tank car running on the side of the machine through a pipe 26. The lower part of the cement tank 11 has a dosing screw 27 and a closing flap 28, which adjust the amount of binder 12 to be fed to the downcomer 8.

In order to carry out the casting continuously in a so-called strip casting from a moving vehicle, an up-down-adjustable dam hatch 19 is provided for adjusting the mass flow of aggregate fed to the downcomer 8, whereby the mass flow can be controlled both by the damper 19 and by changing the speed of the belt conveyor 10. The amount of aggregate 7 entering the landing silo 8 is monitored by means of a mechanical device 29 measuring the thickness of the aggregate layer on the belt conveyor 10, which device is connected to an electronic measuring device 30. In addition, weighing sensors 32 are provided at the end of the belt conveyor 10 for measuring the amount of aggregate.

In the production of concrete meeting very high strength requirements, a laser measuring device 31 is used instead of a mechanical measuring device 29.

The mass flow measuring means 29, 31, 32 of the aggregate 7 control the operation of the dosing screw 27 and the shut-off flap 28 of the cement 12 so that the binder 12 fed to the downcomer 8 is in the desired ratio to the aggregate 7 to be fed.

The present invention uses such a coarse aggregate that the maximum grain size it contains is 32 mm or more. The aggregate contains a maximum of 90 l / m 2 of water, which is the amount of water required for cement setting.

The continuously fed moist aggregate 7 and cement 12 enter the mixer 18 in the settling silo 8, whereby the aggregate 7 and the cement 12 are mixed in the settling silo 8 while the mixed dry concrete mass 14 is applied through the open bottom 9 of the silo 8. Between the discharge opening 9 and the mixer 18 there is a post-mixing member 13 which is rotatable about the horizontal axis of the machine.

The layer thickness of the casting mass 14 coming from the downcomer 9 of the downcomer 8 is determined by the adjustable spreading blade 15 moving with the body 1. Behind the spreading blade 15 there is a compacting roller 16 compacting the casting mass and then a static roller

The machine has two drive motors operating independently of each other (not shown), one of which is arranged to drive devices operating synchronously with the speed of movement of the machine and the other of devices substantially independent of the speed of movement. The former motor provides power for e.g. machine movements, movement of the door 19 and movements of the conveyor belt 10 and the dosing screw 27, the latter motor in turn adjusts the height of the body 1, compaction by means of a vibratory roller 16, operation of the drawbar 17 and operation of the mixer 18.

In the embodiment of Fig. 2, a roller drum 20 is arranged between the roller drum 3 and the towing device 17 in communication with the tempering liquid tank 19. The rubber-coated roller drum 20 is moistened with the tempering fluid 21 by means of a filter 33, whereby excessive wetting of

The tempering fluid reservoir 19, the roller drum 20 for dispensing the tempering fluid, and the drag device 17 are formed as a single unit to be raised and lowered relative to the machine body 1.

The traction device 17 has two or more traction planks 22 performing a synchronous frictional movement with each other, whereby the compression pressure of the traction planks 22 against the casting surface can be adjusted by means of hydraulic piston-cylinder devices 36.

The invention has been described above with reference to only one preferred embodiment thereof. However, this is in no way intended to limit the invention to this example only, but many modifications are possible within the scope of the inventive idea defined by the following claims. Thus, the coating layer may be cast as one solid slab or two slabs, the lower cement content of which may be lower than that of the upper tread.

Claims (2)

7 82963 1. A concrete road with a pavement made of so-called dry concrete mass having a flexibility of about 36 Vb ° or more at the time of application, i.e. containing not more than 90 l / m 2 of water, characterized in that the concrete mass forming the pavement has such a coarse aggregate that it has a maximum grain size of 32 mm or more. A method for producing a concrete road according to claim 1, wherein a dry concrete mass having a flexibility of about 36 Vb ° or more at the time of application, i.e. containing up to 90 l / m3f of water, is applied to the road surface, characterized in that dry concrete mass is applied as the road surface. that its maximum grain size is 32 mm or more, and that the application is carried out from a machine which moves on top of the cast mass layer and at the same time compacts the cast mass. Patentkray 8 82963