Background Art In general, there are three kinds of asphalt mixtures: hot-mix asphalt mixture that is manufactured by being heated up; cutback asphalt mixture, manufactured with petroleum being used as a solvent; and cold-mix asphalt emulsion mixture, manufactured with water based asphalt emulsion without heat.

The hot-mix asphalt mixture requires a great deal of heat in the manufacturing procedures. Particularly, due to a dramatic increase in the volume of traffic that surpasses the capacity of a road, the oxidation deterioration action of asphalt components during the manufacturing process may form cracks by cementing and deteriorating the asphalt mixture. Cutback asphalt can be manufactured at a normal temperature without heating procedure but it must use expensive petroleum as a solvent. Other European countries and U. S. A are regulating the use of it because its high oil content exhausts oil into streams and soil during the curing after construction and pollutes the environment.

As a solution to the above problem, suggested is an

apparatus for manufacturing cold-mix asphalt emulsion mixture which can'manufacture a product with granularity appropriate for road pavement materials in cold state where the aggregates and asphalt are not heated, that is, at a ambient temperature. With no need to be heated, the mixture obtained from this apparatus can save energy. Moreover, it is environment-friendly and it can take recycled asphalt pavement (RAP) as resources and use it continuously.

In addition,. when the cold-mix asphalt mixture is manufactured, the oxidation deterioration action that directly contributes to the deterioration of asphalt does not occur, and the air is not polluted because the problem of hot-mix asphalt mixture that it emits much carbon dioxide is solved. The cold asphalt mixture is very economical because it's free from the effect of temperature and it can be kept after production, while a hot asphalt mixture should be used in time or, stored in a special silo for 2-3 days and its remainder after the use has to be disused.

Conventionally, as an apparatus for manufacturing the cold asphalt mixture with this positive property, a continuous type plant has been used..

Referring to Fig.. 1, the continuous type apparatus is for manufacturing cold-mix asphalt emulsion mixture by putting aggregates with different granularities into each of the separately set-up three hoppers 101,102, 103, inputting them to the mixer 105 while mixing and providing them to the tilting conveyer 104 continuously, and putting water and bituminous emulsion asphalt into the mixer 105. It can control granularity very well and improve quality. With a wheel on it, this apparatus can be moved easily. However, the continuous type apparatus for manufacturing cold-mix asphalt emulsion mixture has a bridge effect that hinder easy ladle-out caused by adhesive RAP or virgin aggregates containing moisture stuck to the incline plane, while the RAP (recycled asphalt pavement) is taken out of the inversed-trapezoid-shaped hopper.

In other words, the recycled aggregates, which are waste aggregates made of crushed or selected RAP, has adhesiveness to each other by the atmospheric temperature and gravity because they have a great deal of small particles and asphalt components. Also, the properties of waste aggregates getting lumped together and solid in a hopper stops the supply of the aggregates and hinder normal production, as only those in the lower end part of the hopper are put out leaving the sticky waste aggregates accumulated on the incline plane.

In addition, it's difficult to mix aggregates in a mixer with a fixed amount of asphalt emulsion, because large size aggregates, medium size aggregates and fine aggregates inputted in the respective three-hoppers are conveyed while being provided to the conveyer and mixed continuously.

In particular, with short mixing time, a continuous type plant can hardly coat aggregates of large particles with asphalt emulsion, so it may be used for a low volume road but cannot be used for high volume road, for instance, for the surface of a road. pavement.

Disclosure of Invention It is, therefore, an object of the present invention to provide an apparatus for manufacturing a batch type double mixed cold asphalt. mixture and method therefor.

In accordance with one aspect of the present invention, there is provided an apparatus-for manufacturing a batch type double mixed cold asphalt mixture, the apparatus comprising: a plurality of hoppers for inputting aggregates with different granularity in order of coarse aggregates to fine aggregates; a conveyer unit. placed under the plurality of hoppers, for conveying the aggregates therefrom; a mixing unit placed at the vertical end of the conveyer unit, for mixing an asphalt emulsion injected from outside into the conveyed and dropped coarse aggregates on a first time and

then mixing the fine aggregates with the primary mixture of the coarse aggregates and asphalt emulsion on a second time, and discharging the mixture ; and an asphalt emulsion supply unit for providing a predetermined amount of asphalt emulsion into the mixing unit, wherein the plurality of hoppers arrayed in order from one for coarse aggregates to one for fine aggregates and the aggregates are provided onto the conveyer unit in a batch type.

In accordance with one aspect of the present invention, there is provided a method for manufacturing a batch type double mixed cold asphalt mixture, the method comprising the steps of: a) separating aggregates with different granularity into coarse aggregates and fine aggregates and putting them into-a a'plurality of hoppers, respectively; b) conveying the aggregates let out of the respective hoppers in a batch type to a mixer in order of coarse aggregates to fine aggregates; C) inputting in the mixer the coarse aggregates and such additives as an asphalt emulsion in a predetermined ratio and mixing the aggregates and the asphalt emulsion together ; d) inputting the fine aggregates into the first mixture of the coarse aggregates and asphalt emulsion, and mixing them on a second time; and e) discharging the asphalt mixture mixed in the mixer.

Brief Description of Drawings The above and other objects and features, of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: Fig. 1 represents a schematic view of a conventional continuous type apparatus for manufacturing cold-mix bituminous emulsion asphalt; Fig. 2 is a schematic view illustrating the process for manufacturing a batch type double mixed cold asphalt mixture in accordance with an embodiment of the present invention ;

Figs. 3A and 3B show a front-view and a plane figure of an apparatus for manufacturing a batch type double mixed cold asphalt mixture in accordance with an embodiment of the present invention ; and Figs. 4A and 4B are a plane figure and a side view depicting the configuration of a hopper in accordance with an embodiment of the present invention.

Best Mode for Carrying Out the Invention Other. objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter. With reference to the accompanying drawings, an embodiment of the present invention is described below.

An apparatus for manufacturing a batch type double mixed cold asphalt mixture and method. therefore are embodied to produce a stable cold-mix asphalt emulsion mixture by putting virgin aggregates and fine recycled aggregates obtained by crushing reclaimed asphalt pavement (RAP), together in a mixer in a batch type and mixing them with such an additive as an asphalt emulsion. As illustrated in Figs. 2 and 3, this embodiment'is equipped with a plurality of hoppers 2 for holding aggregates with large particles <BR> <BR> (i. e. , coarse aggregates) and aggregates with small particles (i. e., fine aggregates) that have different granularities to each other ;, a scale hopper 2 placed on the perpendicular lower. part of the hoppers 1, for measuring the aggregates coming therefrom in a predetermined weight and discharging them ; a belt conveyer 3 provided in the lower part of the scale hopper 2, for transferring the aggregates from the scale hopper 2, thus the aggregates being provided and conveyed in order of coarse aggregates to fine aggregates from the hoppers 1 onto the belt conveyer 3 in a batch type.

The present embodiment shows an example where four hoppers 1 are arranged on a straight line, and in the lower part of each, two or more outlets 1A are formed. Each hopper 1 is inputted with one among coarse aggregates of 13mm, 20mm, 25mm and 40mm or fine aggregates including screenings of 6mm size agreeably to the condition on granularity required by the regular industrial standard or a specification.

Also, the fine aggregates. inputted to the hopper 1 are inputted in one or two hoppers among the four and in the other hoppers, virgin aggregates such as pebbles or crushed aggregates that belong. to coarse aggregates are inputted.

Here, the fine aggregates are sands or, screenings or, obtained by crushing lumps of reclaimed asphalt pavement from road excavation works.

Referring to Figs. 4A'and 4., the hoppers 1 of the present embodiment comprises a hopper body 31 provided with a plurality of outlets'in the lower part; a switching door 32 for opening and shutting the outlets of the hopper body 31; a driving cylinder 33 placed at a. predetermined position on the external incline plane of the hopper body 31, one end of which is fixed on the switching door 32, for opening and shutting the switching door by its expansion and contraction movement.

In addition, the hopper for fine aggregates further comprises an oscillator 4 for separating the aggregates attached to an incline plane of the hopper 1.

The oscillator 4 includes a spring 36 for buffering placed on the external surface of the hopper 1; a motor for providing the buffering force to the spring 36; an oscillation plate. 38 placed on the internal surface of the hopper 1, for moving up and down by the buffering force of the spring 36 and hitting the incline plane of the hopper 1 ; and a rubber plate 39 provided between the oscillation plate 38 and the incline plane, for increasing the efficiency of oscillation.

This embodiment represents an example of adding an

oscillator as a means for getting rid of the aggregates attached to the incline plane of the hopper 1. However, this invention is not limited to it but scrapers for scraping them off the incline plane can possibly be added thereto, and the detailed description on this will be omitted since it is shared knowledge that can be embodied by those skilled in the art easily.

The vertical end of the belt conveyer 3 includes a mixer 5 for mixing the conveyed and dropped aggregates with an additive or an asphalt emulsion consisting of water, asphalt and a emulsifying agent and discharging them; an asphalt emulsion supply device 6 for providing a predetermined amount of asphalt emulsion into the mixer 5; and an additive supply device 7 equipped in the upper part of the mixer 5, for providing additives, for increasing the adhesiveness of the aggregates mixed with asphalt emulsion inside, each time at a predetermined amount.

The asphalt emulsion supply device 6 includes an emulsifier tank 11; a supply pump 12 for providing asphalt emulsion into the asphalt emulsion tank 11; an electric heating line 14 for heating up asphalt emulsion provided through the supply pump. 12; a three-way valve 14 placed at a predetermined position on the electric heating line 14, for converting the flow path of asphalt emulsion towards the asphalt emulsion tank 11 when suspending the production of cold-mix asphalt emulsion mixture temporarily; an emulsifierasphalt emulsion scale bin 15 for measuring asphalt emulsion provided through the three-way valve 14 to be inputted into the. mixer 5 in a uniform amount; a surge tank 16 for containing asphalt emulsion discharged from the asphalt emulsion scale bin 15 and jetting it out into the mixer 5 by the flux fluctuation from the shaking of asphalt emulsion inside; a spray pump 17; a flux control valve 18 for controlling the amount of asphalt emulsion to be sprayed and flowed in the mixer through the spray pump 17; and a compressed air spray device 19 for spraying the emulsifying

agent provided through the flux control valve 18 with compressed air. Here, the flux control valve 18 is formed with a three-way valve for converting the flow path of asphalt emulsion-towards the surge tank 16 when the production of cold-mix asphalt emulsion mixture is suspended.

Also, the additive supply device 7 includes a silo 21 with additive inside; a discharge subsidiary device 22 set up on the outlet of the lower part of the silo 21, for letting out the additive smoothly; a rotary feeder 23 for supplying the additive let out by the discharge subsidiary device 22; an additive.. scale bin 24 for measuring the additive provided by, the movement of the rotary feeder 22; and a discharge valve 25 for providing the additive measured at the additive scale bin 24 to the mixer 5. Meanwhile, it is still possible to add a powder supply device 8 and a liquid supply device 9 for. providing pigments, transparent or not, to the mixer 5 in order to manufacture cold-mix asphalt emulsion mixture using RAP as recycled aggregates.

The powder supply device 8 includes a powder storage 41 for storing powdered pigment; a powder scale bin 42 for measuring the amount let out of the powder storage 41; and a discharge door 43 opened or closed so as to add the powder measured at the powder scale bin 42 to. the aggregates conveyed by the belt conveyer 3.

The liquid supply device 9 is provided with a liquid tank 51 for storing liquid such as liquid additives; a liquid supply pump 52 for providing the liquid in the liquid tank 51 to the mixer ; a liquid storage 53 for storing the liquid provided by the liquid pump; a liquid scale bin 54 for measuring the amount of the liquid let out of the liquid storage 53; and a discharge valve 55 opened and closed for providing the liquid measured in the liquid scale bin 54.

The input amount of powder or liquid provided by the powder supply device B and the liquid supply device 9 is commonly determined to occupy more or less 1 per cent of the whole asphalt emulsion mixture.

The procedures of the present invention of the above configuration will be described with reference to Fig. 2.

First of all, aggregates with different granularity are inputted to the four hoppers 1 according to the required granularity. At this moment, one or two among the four hoppers are inputted with fine aggregates including screenings and in the remaining hopper, coarse aggregates including medium size aggregates are inputted. In case the fine aggregates are RAP, they are inputted to a crushing device, crushed. into granularity appropriate for the production of cold-mix asphalt emulsion mixture and inputted in the hopper 1.

The virgin, aggregates and the fine aggregates inputted in the hopper 1 are. measured in the scale hopper 2 established in the perpendicular lower part of the hopper, provided onto the conveyer 3 in a batch type and conveyed.

When the aggregates. are let out of the hopper 1, the RAP and virgin aggregates stuck to the incline plane are scraped off and dropped into the outlet by giving oscillation force on the incline plane of the hopper 1 with the movement of the oscillator 4 set up to prevent the bridge effect.

When the aggregates let out of the respective hoppers 1 in a batch type are inputted to the mixer 5 through the conveyer 3, asphalt emulsion and additives are measured out in a predetermined amount at the asphalt emulsion supply device 6 and the additive supply device 7, inputted in the mixer 5 and the surface. of the aggregates are coated with asphalt emulsion, thus the particles of the aggregates get stuck to each other by the adhesive component of asphalt emulsion and the additive.

The asphalt mixture manufactured through the mixing procedures is loaded on a truck through the outlet formed on the mixer 5.

The present embodiment arranges the hoppers 1 to have the mixture of the aggregates and asphalt emulsion coated

double in the mixer 5. That is, the hopper 1 containing coarse aggregates is placed in front so as for the coarse aggregate with a predetermined granularity to be provided onto the conveyer 3 first, followed by the hoppers 1 holding aggregates with smaller granularities as it goes back.

With this arrangement of hoppers 1, the coarse aggregates are put into the mixer 5 first and mixed with an appropriate amount of the emulsifying agent on a primary round. Then fine aggregates are inputted into the first mixture of coarse aggregates and asphalt emulsion in the mixer 5, and they are mixed on a second time adding the remaining asphalt emulsion therein. This way, the coating efficiency of the coarse aggregates is improved and the fine aggregates forms mastic, producing stable cold asphalt mixture.

As described above, the present invention coats the whole aggregate mixture with the marginal amount of asphalt emulsion efficiently.. and manufactures stable cold asphalt mixture by providing fine aggregates made of RAP and coarse aggregates to a conveyer in a batch type and putting them in the mixer 5 in order of. coarse aggregates to fine aggregates.

That is, this invention addresses the problem of a continuous type plant that aggregates with large particles are not coated with. an asphalt emulsion evenly by putting and mixing the fine aggregates in the primary mixture of coarse aggregates and asphalt emulsion on a second time, after having coarse aggregates and emulsifying agent inputted therein get mixed first and coating the asphalt emulsion on the coarse aggregates evenly. Therefore, the asphalt mixture manufactured in the method of the present invention has an advantage of high quality enough to be used for high volume roads with a little amount of asphalt emulsion, i. e. , the least amount of an asphalt emulsion that can bring the optimum effect.

Also, when the aggregates in the hoppers are put out, the aggregates stuck on the incline plane of the hopper can

be easily taken off'with'oscillation force, thus improving the productivity and the machine operation rate because the aggregates supply doesn't-halt.

While the present'invention has been described with respect to certain preferred-embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.