US2254463A - Means for constructing and reconstructing road surfaces - Google Patents

Description

p 1941. 1. M. WELLS ETAL 2,254,453

MEANS FOR CONSTRUCTING AND RECONSTRUCTING ROAD -SURFACES Filed June 13, 1939 2 Sheets-Sheet l Z5 l-llllllllll-ll||||||||Ig UUU UUUUUUUUUUUUUUUUUUUUUUW Z /WJ Sept. 2, 1941.

|. M. WELLS ET AL MEANS FOR CONSTRUCTING AND REGONSTRUCTING ROAD SURFACES Filed Ju ne 15, 1939 2 Sheets-Sheet 2 m m m xmw w W N .\M.

Patented Sept. 2, 1941 UNlTEDi'lSTAl-E'S PATENT oFrics MEANS roacons'mootrmc AND'RECQ'N .STRUCTING ROAD summons 7 hard. Wells, Oakland, and Howard A. Olds, San

Francisco, Calif;, assignors to Spears-Wells Ma'- chinery Company,-Inc., Oakland, Calif., a corporation ofCalifornia I Application June 13, 1939, Scrial'No. 278,846

-10 Claims.

' This invention relates to a new type of road surface and to the method and apparatus necessary for producing a non-skid surface on asphal tic roads. j v H When thermo-plastic materials, such as asphalt and other bituminous materialsare used in road construction, aggregate, such as crushed rock, is mixed with the plastic material while it is in a semi-liquid to liquid condition due to; the application of heat, and while the mixture is in a heated condition it is spread over a base or subgrade, levelled and rolled.- V i In some cases the surface of such construction is apt to be porous and may permit water to seep through and thus eventually destroy the base or subgrade. possibility, a mixture containing an excess of plastic is spread, levelled and rolled over the first layer to form a seal againstwaterseepage, and this superposed layer upon cooling provides a comparatively smoothfiand in some cases even a skiddy surface, which is obviously quite familiar to the average automobile driver. This 'skiddy condition is particularly pronounced "after the road has been in use for some time and especially a so when slightly wetted following a dry spell of weather. Thus it is clearly evident that asurface which is too rich in bitumens presents this dangerous problem. 1

Several methods of reconditioning such surfaces are in current use, including dissing; cold planing, and heater planing. The principal disadvantage in these methods lies in the fact that surface material is removed and wasted and the underlying cause has not necessarily been eliminated Another method involves the application For the purpose of overcoming this pedited by the heat of the suns rays and by.traffic passing over the road, particularly heavy vehicles such as trucks, the wheelsof which react through the resiliency of the plastic to force the rigid aggregate particles down through the mass, and the result is a skiddy surface and rapid formation of ruts, corrugations and chuck holes. Thus the surfacelife of a new road is frequently of comparatively short duration as related'to the element of safety. Thus the newly-completed road may be in excellent condition, level and non-skid, butwithin a comparatively short period of timeall of the desirable advantages disappear. The lower layer or substructure hasimprovedhas formed into a compacted mass of aggregate with just suflicient plastic incorporated to fill the interstices and bind the aggregate together, which, if it extended to the surface,

would prove to be an ideal structure, and this invention is directed toward accomplishment of such a result.

In a used road of the character just described we have an excess of plastic'material or binder in the upper strata or superstructure,-and which is' directly associated with the'compacted and aggregate-binder balanced lower strata or substructure; therefore, if the upper plastic-rich of new mix, including aggregate and binder,

which obviously aggravates the condition, since more bitumen is added to the road surface which is already over-rich in bitumen. This invention is adapted to overcome all of the above-mentioned disadvantages and to provide a road surface of substantial permanency and with a non-skid surface. I In addition to the skiddy surface produced through the sealing layer as previously outlined, this same condition develops in initially non-skid surfaces through use of the road, in which the aggregate, through capillary action of the.plastie and through gravitational influence 'Of the aggregate, gradually works down through the plastic to form an interfitting, compacted mass on the subgrade or base, leaving at thesurface a layer of practically pure plastic. W Y

This settlement of aggregate is materially exstrata are provided with additional aggregate without the addition ofjany plastic orflbinder, 'a non-skid surface results, and'the surface Will retain its non-skid characteristics and remain free of ruts andcorrug'ations for a considerable length of time, and this procedure is the essence of this invention. j The objects and advantages of this invention therefore are as follows:

First; to recondition plastic-type road surfaces by heating the surface to a'condition of semi-fluidity and applying additional aggregate only, to the fluid mass.

Second; to provide anew type of road superstructure consisting of additional aggregate imbeddedn'in an aggregate-lean,1preelaid, plastic road surface, with the aggregate displacing plastic to a point where the total plastic functions only as a binder and fillerbe'tween the particles of aggregate. 4 V

Third; to carry out the above-=outlined process by heating the surface or superstructure preferably to a depth equal to the depth of theaggregate-lean mass, and to apply additional age gregate in either its natural state or cleaned and dried, and either cold or heat'ed,.and either before, during, or following the heating of the road surface; 'to mix the aggregate with the semisurface.

in the confines of the heater; road-mix means for mixing the distributed aggregate with the surface plastic; and a roller for imbedding the aggregate in the plastic.

In the following description, additional aggregate refers to any solid material which is.

suitable for use as a body material in connection with thermo-plastics used in road construction. The term plastic 'or thermo-plastic refers to any type of plastic material which is softenable by heat and suitable for road construction of the asphalt type. Semi-liquid'refers to any condition of the plastic ranging from tacky to liquid. a

In describing the invention, reference will be made-tojthe accompanying drawings, in which:

Fig.1 is a, diagrammatic v'iewillustrating the application of the process in which the aggregate. is distributed following heating 7 of the road Fig, 2; is a ;v iew similar to Fig. 1 except that the,aggregate is distributed in advance of the roadsurface heating operation. a

:Fig. 3 is a top plan view of a road-mixer suitable for use with this process,

Fig. A isa rear elevation of Fig. 3.

.Fig. 5 is a. side elevation of apparatus suit ablevfpr, carrying out this process and isshown partlyiinsection. 1

Fig.6 isa top plan view of Fig. 5'; 7 V The usual plastic or bituminous type of road. is, builtupwith a subgradeof clay, rock or gravel, upon which is sometimesplaced a base or foundation ofconcrete. Uponjthis subgrade or upon the base is laid asubstructure consisting usually of a coarse aggregate mixed with a suitable binder,- such as bituminous material of the as;

practically pure binder or plastic remaining in the superstructure.

It is this plastic-rich superstructure upon which this new process is conducted, and the process and apparatus is adaptable to new road buildingas'well asto the reconstruction of old roads, *and in this connection will be explained asapplied to old roads.

Referring to Figs. 1 and 2, it) indicates the 'usual subgrade upon which the substructure I i is formed. The original superstructure was laid on this substructure but has deteriorated due to the causes previously mentioned, into a lower layer i2 which is composed of a densely-compactedmass of aggregate, and an aggregate-lean upper layer I 3.

1 v In carrying out this process, a supply of additional aggregate 14, together with means for distributingthe aggregate, and heating means l5 for heating the road surface, is provided. The distributing means is adapted to distribute the additional aggregate in predetermined relation to the heating means l5, such as in advance of the heating means as indicated at i6, Fig. 2, or following the heating means as indicated at l7, Fig. 1, depending'upon the characteristics of the plastic and upon climatic conditions. Under specific or unusual conditions it may be neces sary to distribute the aggregate within the limits phalt type. 'Thismixtu're is often provided in the form of a plant-mix delivered in a heated condition, while-in some other types of construction the dryagg'regates, such. as coarse crushed rock, is distributed overthe subgrade'or base,

of the heater, such as through the chute l8.

Heating of the road surface must be carefully conducted and controlled inaccordance with the characteristics, such as the flash point of the material which forms the road surface. Overheating Will deteriorate or ruin the plastic. Similar care must be exercised in the selection ofthe aggregates as to strength, size, volume .and moisture, and treatment, such as cleaning,

heating and-drying, to insure maximum degree of "binding action or afiinity between the aggregateand the plastic material. These elements andvariables are conveniently and commercially controllable; j

When the additional aggregate is distributed in advanceof the heating means, the aggregate becomes highly heated and to a degree blankets the road surface, and therefore will prove efi'icacious with some types of plastics, especially thermolabile plastics or those having a low flash point, while if the aggregate isdistributed with in the confines of the heating means, as from the chute l8, the heat is applied directly to the a road surface for on'lya portion of the. total heatfollowing which the heated binder in a liquid condition is distributed over the laid rock. Fol: lowing this last step, a mixture of finer aggregate andbinder, suitably heated, is applied to form the superstructure, which is then leveledf and rolled. g

. Such structures,. and particularly the superstructures' are comparatively rich in'binder and therefore exhibitsurface aggregate only when thes tructureis new. The structure has inherent resilienc'y'when cold and becomes plastic at slightly elevated temperatures, particularly under the influence of the heatbf 'the rays of thesun, andmay evenreach a certain degree of tackinessla t summer temperatures' For. these reasons, the aggregate which is initially exhibited atjthesurface is gradually inundated through capillary action, gravity, and the pressure oftraflic' the aggregate gradually settling downto ing time and blanketed by the aggregates durmg the balance of the heating period. This procedure is preferable for more thermostable plast1cs and for those having a higher flashpoint,

while application of aggregate following complete I heating ofthe road surface is preferable for plastics having a high flashpoint and for those havmg a'suitable degree of thermostability.

In some'instances, dryingor heating of the aggregate previous to distribution may. prove advantageous and may be conducted either through separateheating means ,(not shown) or through heat derived from the road surface heating means .,as' indicated by the close relation of the distributors and chutes to .the road surface heating means. .7

- The aggregate is distributed accordingto requirements and may be permitted to settle through itsown weight into plastic which is in a thelsubstructure and being gradually compacted into a comparatively solid mass of aggregate with suitably fluid condition, but is preferably rolled into the surface promptly; or the aggregate mixed 'in situ with" the semi-fluid'material; as

effective-binder and to fill all voids.

by means of a-road-mixer 20, following which a roller 2| or other suitable means having suitable inertia-forcesthe aggregate 2 2 into'the semi-fluid mass l9,- converting the superstructure into -a correctly-balanced structure as indicated at-23, with the additional aggregate projecting'slightly up through the plastic and with the semi-fluid plastic material-sufficient in quantity relative to the-quantity of additional aggregate to form an Thus the-aggregate imbeds into the surface, which surface through rolling or other compressive treatment is level and nonskid, and may be considered as a comparatively permanent structure, since excess-of plastic can be fully compensated by this process, leaving no further room for settlement of aggregate, and under such complete compensation capillary action cannot take place to-a sufficient degree to recreate the original skiddy surface: I r I In Fig. 3 is illustrateda roadmixer which is suitablefor=carrying outthe mixing step of this process, and; has the general characteristicsof a spike-tooth harrow, and-consistsofa'frame 24' provided with a multiplicity of teeth or spikes An apparatus suitable for carrying outthe complete process is illustrated-in Figs. '5 and 6, and'is shown complete with traction means and roller, and consists of a tractor 26 provided with a fifth-wheel 21 upon which the front end 28 of the reconstruction machine is'mounted and suppofted i n ."i h V 1 V The machine consists of a frame 29 carrying a road-surface heater 30 inWhichis mounted a plurality of'burner's 3| which ar supplied with fuel through a'suitable feed line 32 from asupply tank 33; The flames 34.from the burners are indicated as :directed down onto the road surface forlconverting the top material of the road into a semi-fluid mass. However,-the heating of the road "is not limited to this specific method of heating or to the specific structure shown.

A hopper 36 is mounted on the machine for "carrying L an additional supply of aggregates,

which may be distributed by any suitable means, as by ascrew conveyor 31 which is fed through the passage 38 formed in the bottom of the hopper. The screw conveyor is operable in either directionto feed at will through either the forward chute 39 or rear chute 40, or', by withdraw- ;ing 'a slide 4| which is provided as a closure for the intermediate chute 42 and operating the conveyor for follow distribution, the aggregate will discharge through'the intermediate chute'for the step system of heating, in which the road is heated directly in the first portion of the heating cycle and followed by further heating through a blanket of aggregate and simultaneously heating the aggregate distributed; Thus the point of distribution is selectable at will in view of the reversing mechanism 43 associated'with the driving means 44 for the conveyor.

Removably and adjustably mounted rearwardly of the road-surface heating means is a road mixer which may be 'of the form illustrated in Figs. 3 'and, or,'as shown in Figs. 5 and 6, may

41 and .handwheels 48 for three-point support v and adjustment.

-Mounted in follow relation to the mixer isa roller .49 which is removably and supportingly .att'achedto the rear end of the frame 29 asindicated at 50. Suitable weighting means 5| is provided to provide the necessary inertia to force the aggregate 22 into the heated plastic surface, and when desired, down to the original aggregate which is bedded on the substructure.

In some -ca'ses,'- the'machine may prove 'unwieldy, or'for other reasons it' may be desirable to use a separate roller instead of a directly associated roller. In such cases, removal'of the roller would leave the rear end of the machine without support.

For this reason a set of Wheels 52 is mounted aheadof the heating means and thus, due to their leadingposition, the rubber tires 53 are not exposed tothe heat from the heating means or to the heat from the heated road surface.

These wheels must be made non-supporting with reference to the machine when the roller is attached, in whichcase the wheels may either be removed or may be converted into a nonsupporting condition. This non-supporting condition is arranged bymounting the wheels on a separate frame 54 which has its rear end pivotally attached to the frame 29 at 55, and its forward end normally free, under which conditions the wheels will merely track along Withthe machinebut will offer no support, and the machine will thus be transported and supported solely by the tractor 26 and roller 49.

When the roller is to be released or detached from the machine, the screws 56 are adjusted down by means of handwheels 51 to transfer support of the machine to the wheels 52 with theirassociated tires 53.

When the machine is supported 52, the overhanging weight will tend to tip the rear end of the machine down, therefore an-overbalancing weight is provided at the forward'end, and is indicated'as consisting of a heavy casting 56"which is internally hollow as indicated at '33 to form the storage reservoir for fuel for the burners Thusfno support other than that of the set-of wheels is required, andthelentire operating portion of the machine is clear and free of interfering elements. 5

' The aggregate may be heated and dried by associ'ating the hopper 36 and" conveyor housing 59 with the road surface heating means, or a separateiheater (not shown) may be provided for the purpose; l

Suitable water distribution is provided, as shown at 6B for wetting the surface of the roller to prevent sticking, and for supplying moisture to any portion of the road surface or materials in conformity with requirements.

The road mixer functions as combined mixing and. leveling means, particularly that form illustrated in Figs. 1, 2, 5 and 6 in which the mixing 7 blades 46 are mounted in suitable relation to each other both spacedly and angularly to carry out both' functions, and the adjustment provided by the screws 4! permit the forward and rearward; ends of the mixer to be relatively adjusted to. provide for mixing of the material followed by leveling of the mixed material. Thus the machine is adaptable to varying materials and conditions, and can be used for merelygheating the road surfaceand distributing aggregates in. predetermined relation to the path of travel of: the heater or to, the area being Thisiprocess can becarried out by means other by the wheels of a road and rendering the material thereoiinto' a semi-fluid mass and supported by. said vehicle; and aggregate distributing means comprising a distributing drum mounted in-a plane above said heating means :and extending longitudinally thereof and having'outlets at the front, middle and rear and supported by said vehicle for distributing aggregate over said surface along the path of said heating means and selectable at will as to the point of distribution for distribution in advance of, within the confines of, or following said heating means, to compensate for variations in the physical characteristics of said aggregates and for atmospheric conditions. i

2. A structure as definedin claim l-in which mixingmeans is mounted in follow relation to said heating means and distributing means for mixing the distributed aggregate with the semifiuid mass, and in which-a roller-is detachably mountedin follow relation to said mixing means material and for smoothing the road surface and forms a support for the rear en'dof said vehicle when attached, and an auxiliary wheeled support for supporting said rear end whensaid roller is detached. 3. A'road superstructure conditioning machine comprising tractive means ,andavehicular support; 'a heater for heatingthe'surface, of a road 7 and carried by said support; aggregate storage and feeding means supported in a plane above said heater andin feeding relation theretoand v having aplurality of outlets for feedingaggre gate 'onto' said road surface to various'close locations'related to said heater for association with the road surface'operated upon bysaid heater, and supported by said-vehicular support, and ineluding means for heating and drying said aggregate previous to' distribution thereof onto" the road surface, said aggregate feeding means-having selective control means for selective feeding of aggregates in advanceof, within the confines of, or following said heatingmeans for the most suitable. conditioning of the aggregates previous to elnbedment. a d 4. A road superstructure conditioning machine comprising; tractive meansand avehicular support; a 'heater for heating the surface of the road and carried by said support; aggregate storage and associated distributing'means carried by said support in distributing relation to said'heater and having outlets for distributing aggregate to various locations relative to said heaten'onto the surface of the road, and including means for heating and drying "said' aggregate previous to distribution thereof onto the road surface, and

also including mixing .means in terposed between said feeding means andlsaidicompressive means for. mixing the aggregates withflthe heated road surface material, said distributing means includ ing selective control'means for distributingzthe the surface of a road; aggregate storage and aggregate feeding means for feeding, aggregate onto said road surface for association with the, surface operated upon by said heating means; coma roller detachably connected to said machine for forcing the aggregateinto the heated surface 3 and coincidently formingsupporting and transporting means for the rear. end of the machine; and a wheeled supportfor supporting said rear end when said rolleris disconnected. 1

6. A road conditioning machine comprising: tractive means; a frame; an intermediate wheeled support for said frame and means for making said wheeled support non-supporting at will; overbalancing means for overcoming the weight ofthe rear end of themachine when the machine is supported byjsaidwheeled'support; a roller detachably connected to the rear end of said machine and forming. a support'therefore when connected; a heater carried by said frame for heating the surface of a=road; a hope per, andaggregate distributing means associated therewith for. distributing aggregates from any one of a plurality of points'at will; means for heating said aggregates; and a road, mixer carried by said frame in follow relation to said heater and in' advance of said roller.

7. In a road building machine; including vehicularsupporting means and a road surface heater; a reversible conveyor screw and driving means therefor, and aggregate storage means mounted inrfeeding relation to said; road surface heater and carried by said' vehicular supporting means and having end and intermediate dis- 7 charge passages leading to a pluralityof points relative to said road surface heater and includingmanual control means therefor'for selectively distributing aggregates from said passages to any one of-several points includingyin ad- 7 vance of, within the confines ofQand following.

saidheating means, and comprising a gate for the intermediate passage, with theend passages controlled by said screw, whereby the degree of heatingof said aggregates following distribution 'fis controllable at will to suit thercharacteristics of the aggregate'andiatmospheric conditions.

8. A road; reconditioning machine comprising; a vehicular support and a road surface heater carried by said support; aggregate storagemeans and a manually-controllable reversible conveyor screwand driving means thereforcarried by said support in distributing relation 'to said heater and having intermediate and end discharge passages and chutes communicating therewith a manually-controllable gate forthe intermediate passage, the end passages being-controlled by the direction-'of-rotationofflthe conveyor screw directing aggregates through=said chutes for distribution on the road 'surface'selectively to 'a plurality of points relative to said heater,- and aggregates from any one of several locations rela-- tive'to said heating means.:- a

comprising t'ractive means; a heater "fonheating including points within,'"inadvance of, ai1d following said =l'ie'ater for. controlling the heat applied to the aggregate by the heater following depositon the road surface.

said aggregatestorage means andconveyor screw mediate passage, with the other passages controllable through the direction of operation of said feed screw, and chutes communicating with said passages and leading to various points including in advance of, within, and following said heater for distribution of the aggregate on the road surface in predetermined relations to said heater in accordance with the practical heat requirements of the aggregate following distribution.

IRA M. WELLS. HOWARD A. OLDS.

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