Abstract: A counter-flow asphalt plant with a separately controlled and operated dryer 50 and mixer 52 in which virgin aggregate, recycle material and liquid asphalt are mixed to produce an asphaltic composition. The dryer 50 is rotated by a variable dryer drive 58 about a central longitudinal dryer axis disposed at a dryer angle of declination. Within the dryer 50, aggregates are dried and heated by heat radiation and a hot gas stream generated at a burner head 112 of a combustion assembly 106 positioned inside the downstream end of the dryer 50. The downstream end of the dryer 50 is inserted within the first end of the mixer 52 for delivery of the heated aggregate. The mixer 52 is carried on a tiltable frame 54 and is rotated by a variable mixer drive 88 about a central longitudinal mixer axis disposed at a mixer angle of declination.

Abstract: A method of and device for improving the quality of fresh concrete and preventing adhesion and hardening of the mixed fresh concrete in a rotary mixer drum of a concrete mixer truck or a stationary mixer drum of a concrete mixer plant which involves delivering selectively and continuously either cold or warm air into the mixed fresh concrete in the rotary or stationary concrete mixer drum in order to delay the hardening time of the mixed fresh concrete, and to avoid adhesion and hardening of the mixed fresh concrete on a plurality of blades and an inner periphery of the mixer drum.

Abstract: The described process utilizes the ash from a trash-to-steam plant and a cementitous binder along with the hot output of an earth purification process and a strictly defined quantity of water in calculated amounts to produce an aggregate which satisfies leach and strength tests and qualifies for use in road building and as a landfill cover.

Abstract: A cooling apparatus for used foundry sand provided with a homogenizing and conveying apparatus in a constant vacuum with controlled water inflow and a suction point for the water vapor, the water evaporating due to the reduced pressure draws the heat of evaporation from the sand, the apparatus having a condenser in which the vapor condenses into water which is cooled and re-used, and coupled locks provided on the inlet and outlet of the conveying apparatus, through which the sand enters and leaves the reduced pressure area.

Abstract: Salvaged foundry sand is reclaimed by introducing salvaged sand into a vacuum kneading tank, adding water and binder to the salvaged sand and kneading the salvaged sand under vacuum. A target strength value of the reclaimed sand is set and the amount of water and binder to be added to the salvaged sand on the basis of the temperature of the salvaged sand before kneading in the vacuum kneading tank so that reclaimed sand of the target strength value is obtained.

Abstract: The counterflow drum mixer includes an elevated virgin aggregate inlet end and an opposite asphaltic product discharge end. A burner lies intermediate the ends and defines a combustion volume. Shield flights surround the combustion volume defining an annular chamber with the drum wall. Recycle material is supplied to the annular chamber at the upstream end of the combustion volume for heating by convection and conduction in the annular chamber. The virgin aggregate material flows through a drying zone, into the combustion volume and between the shield flights into the annular chamber for contact with and conductive heating of the recycle material. Radiant heat transfer from the combustion volume along radii of the drum to the annular chamber is prevented.

Abstract: A drum mixer is provided with a rotatable cylinder in which aggregates, reclaimed asphalt pavement and liquid asphalt are mixed to produce an asphaltic composition. The drum cylinder includes a first region, in which virgin aggregate is heated and dried by heat radiation and the stream of hot gases produced by a burner flame flowing in countercurrent flow to the aggregate itself to establish a highly beneficial heat transfer relationship. A second region doubles as combustion and mixing zones. In the mixing zone the reclaimed asphalt pavement and liquid asphalt is added and mixed with the aggregates. The combustion zone is formed along the center of the mixing zone by an elongated combustion assembly disposed along the central axis thereof. The combustion assembly and chamber extend from the discharge end of the drum through the mixing zone to the heating and drying zone to segregate the hot gases from the asphalt, thereby preventing degradation of the final product.

Abstract: A method of cooling white cement clinker sintered in a rotary kiln includes the following steps: introducing the white cement clinker from the rotary kiln into a first cooling stage; comminuting the white cement clinker in the first cooling stage; quenching the white cement clinker with a coolant in the first cooling stage in a short dwell period in an oxygen-poor environment to a mean temperature of approximately between 650.degree. C. and 750.degree. C.; introducing the white cement clinker from the first cooling stage into a second cooling stage; mixing and simultaneously conveying the white cement clinker in the second cooling stage in an oxygen-poor environment for a period of at least 15 seconds for obtaining a homogeneous mixture of particles of the white cement clinker and for further cooling the white cement clinker to a temperature of approximately between 550.degree. C. and 650.degree. C.

Abstract: A combination continuous/batch asphalt plant includes mechanisms and controls which permit it to be hot-stopped when operating in the continuous mode.

Abstract: A rotary drum dryer has devices for cooling shielding flights located in the combustion zone of the drum. The devices comprise cooling flights which rotate with the drum to scoop up relatively small amounts of virgin aggregate from aggregate accumulated in the lower portion of the drum and to shower this aggregate over the outer radial surface of the shielding flights upon further rotation of the drum, thereby cooling the shielding flights without substantially decreasing the mean temperature of the aggregate. Cooling efficiency is enhanced by the continuous cascading of fresh aggregate over the shielding flights from the cooling flights through a substantial portion of the drum's rotation. The cooling flights and shielding flights preferably cooperate to limit or even prevent the showering of materials into the burner flame and thus inhibit burner flame quenching and accompanying emissions.

Abstract: A designated amount of recycled asphalt product (RAP) is fed to the pugmill of a batch asphalt plant during the production of hot mix asphalt (HMA) at a controlled rate so as not to overload the pugmill scavenging system. The designated amount of RAP is metered in a RAP weigh hopper, stored temporarily in a RAP holding hopper, and is then fed from the RAP holding hopper to the pugmill at a controlled rate. The feed of RAP to the pugmill, though electronically initiated, is preferably manually or automatically adjustable so as to avoid overloading the pugmill scavenging system while at the same time assuring adequate mixing of the RAP with the virgin aggregate and liquid asphalt. The scavenging system directs vapors removed from the pugmill to the dryer and preferably includes electronically operated dampers connecting the combustion air inlet of the dryer to the pugmill only during the mixing operation and otherwise connecting the combustion air inlet to the ambient atmosphere.

Abstract: A method of incorporating used automobile tire scrap into asphalt uses a step of saturating rubber particles with an aromatic oil. The rubber particle containing oil does not absorb additional oils from the asphalt binder materials and the integrity of the asphalt mix is not compromised.

Abstract: An apparatus and method for heating and drying stone aggregate used in the production of asphalt, which also remediates and disposes of contaminated soil. Aggregate is introduced into a drum chamber of a fixed sleeve rotary drum mixer for heating. The aggregate is discharged into an annular chamber and mixed with contaminated soil that has been processed to be suitable for use in asphalt. As the soil is heated, the contaminants are vaporized and drawn into the drum chamber where they are oxidized by high temperature. Secondary aggregate in the form of recycled asphalt pavement (RAP) and/or virgin aggregate are also added to the annular chamber and mixed with the aggregate and soil to form asphalt and to cool the aggregate/soil mixture.

Abstract: A process using an improved apparatus for mixing and cooling molding sand.

Abstract: A process for the production of hot mix asphalt (HMA) by the treatment of virgin material alone or adding reclaimed or recycled asphalt pavement (RAP) (up to 100% of the HMA). The HMA is first heated in either a parallel or a counter flow rotating drum which is supplied with hot combustion gases generated by a remote low NO.sub.x burner. The process is controlled by a micro-processor which controls RAP temperature, mixture gradation, emissions and production rate as a function of measured drum conditions such as temperature at the drum inlet, drum speed, drum slope, drum RPM, output hydrocarbons, drum gas outlet temperature, and amount of aggregate added.

Abstract: Method and apparatus for producing mixtures containing bitumen, in which the material to be treated is conveyed by the force of gravity through a slit-type space between two vertically arranged heated surfaces.

Abstract: Dispersions of hydrophobic substance e.s. resin emulsions, usually having a relatively low average particle size can be continuously and speedily prepared by feed a hydrophobic substance in the liquid state into at least two static mixers, arranged in a series. The resin is introduced at a temperature above 50 degrees C. but below its degradation temperature of hydrophobic substance and water under pressure is introduced into the first mixer. The mixture of resin and water is passed to another mixer maintained at a temperature lower than that prevailing in the first mixer and below the boiling point of water. Optionally aqueous solution of surfactant under pressure instead of water is introduced into the first mixer and optionally aqueous surfactant is introduced into the second mixer.

Abstract: An asphalt production system utilizing a pair of rotatable drums for producing an asphaltic composition is provided. The asphaltic composition is produced by separately heating a volume of virgin aggregate material in a countercurrent drum dryer and heating a volume of recycle material in a parallel flow drum mixer. The hot virgin aggregate material is mixed with the heated recycle material at an intermediate location within the parallel flow drum mixer. A ducting system is provided for interconnecting the ends of the drums such that the hot exhaust gases from one drum are circulated into the other drum thus producing a common flow of exhaust gases between the drums.

Abstract: An apparatus is disclosed which is capable of efficiently decontaminating soil, and which has several common components with a conventional asphalt production plant. This feature permits a conventional asphalt plant to be retrofitted by the addition of a relatively small number of additional components, so as to permit the apparatus to selectively produce asphalt, or to decontaminate soil. When operated in the configuration for decontainating soil, the soil is initially heated to a temperature above the vaporization temperature but below the autoignition temperature of the contaminants, so as to volatilize the contaminants. The volatilized contaminants are then delivered to an incinerator, wherein the volatilized contaminants are heated to a temperature sufficient to be converted to non-toxic products, such as carbon dioxide and water.

Abstract: The apparatus for making cooled concrete of this invention produces cooled fresh concrete by cooling the aggregate (or gravel). The aggregate is cooled by immersion in a cooling water bath accommodated in a cooling water tank. The cooling water in the tank is cooled by a heat exchanger, which in turn is cooled by a forced cooling device. The aggregate is immersed into the cooling water bath by a supply and ejection apparatus, which also removes the cooled aggregate from the cooling water bath. The cooled aggregate is supplied to a cement mixer where it is mixed to become cooled fresh concrete.

Abstract: Method for manufacturing concrete by mixing concrete materials including a cement, aggregate, admixture and at least one of water and ice. The aggregate is moved prior the mixing and a low-temperature liquid is sprayed on the aggregate for cooling while the aggregate is being moved.

Abstract: A continuous process aggregate drying and mixing plant for producing a hot asphaltic material, such as is used for paving highways or the like, includes a combination of a drum drier and a pugmill. Both the drum drier and the pugmill are supported by a common trailer frame. The pugmill is coextensively mounted at the discharge end of the drum drier towards the rear of the frame. The drum drier discharges dried and heated virgin aggregate material through a feed and transfer chute directly into a first, pre-mix region of the pugmill. The feed and transfer chute also provides for the addition of recycled pavement to the heated and dried aggregate and for the side discharge of such heated and dried aggregate. A second region of the pugmill within which liquid asphalt is added to the mixed aggregate is substantially separated from the first, pre-mix region. The space above the second region of the pugmill is substantially enclosed and coupled directly to a secondary air supply of a burner for the drum drier.

Abstract: A method and apparatus for producing asphaltic mix for roadway use is disclosed, and which comprises a primary plant which is designed to be located remote from the point of use, and a separate satellite plant which is designed to be located relatively close to the point of use. The primary plant heats and dries the stone aggregate, segregates the aggregate by size, and mixes the aggregate with a small amount of liquid asphalt so as to suppress the dust. The resulting pre-mixed product of the primary plant is then transported by truck to the satellite plant, where it is stored and then mixed with a further quantity of liquid asphalt to render the mix suitable for roadway use. The primary plant performs the functions which require substantial equipment and space, and which have the more significant environmental impact, whereas the satellite plant may be relatively small and inexpensive, and its operation makes no significant environmental impact.

Abstract: A burner (13) and a conveyor (6) for aggregates (7) into the drum (2) penetrate into the drum at opposite ends (2a, 2b). Circulation of the gases inside the drum occurs in direction opposite to circulation of the aggregates. The burner has an elongated body (12) arranged in the axial direction of the drum. The drum comprises, from the inlet end (2a) to the outlet end (2b), a drying zone (21), a flame zone (22), a zone for introducing recycled mixes (23') and a heating and mixing zone (23). The device may be associated with a mixer (42) of the conventional type in which the bituminous products (11) leaving the drum (2) are mixed with liquid bitumen and worked. The invention enables coated products for road surfaces to be prepared without the production of bitumen vapor.

Abstract: This invention relates to an improved aggregate drying apparatus and method where the dried aggregate is particularly useful for making hot mix asphalt. In accordance with the system, heat typically lost in exhaust gases and moisture evaporated in a heater is recovered to dry and preheat the aggregate. The invention also relates to novel components used in the system, including an improved aggregate dryer and an improved mass flow apparatus for use in an aggregate dryer or otherwise in aggregate feed bins.

Abstract: A drum mixer having a internal combustion gas cylinder extending substantially the length of the drum mixer is provided. Hot combustion gases are generated by a flame within the cylinder. The combustion gases within the cylinder flow in a countercurrent direction the to the flow of material within the drum mixer. The combustion gases exit the cylinder generally at the receiving end of the drum mixer and are directed towards the discharge end thereof in a parallel relation to the flow of material. The horizontal position of the flame within the drum is adjustable and a valve for mixing the gases within the drum adjacent the discharge end thereof with the flame is also provided.

Abstract: A method according to the invention involves continuously moving a mix within a closed vessel having loading and discharge pipes at the ends thereof. The mix is subjected to oscillations during movement by means of a source of oscillations. A gate is provided in the vessel upstream the discharge pipe for contolling the cross-sectional area of the flow path of the vessel and for defining a sealed zone in the vessel with the mix being processed. During movement, the mix is heated to 100.degree. C. and above by passing electric current therein by means of an electrode installed in the vessel. Vapor is thus formed which penetrates the whole body of the mix so as to carry out uniform and rapid heating of all components of the mix.

Abstract: A method as well as an apparatus for processing asphalt mixtures is provided in which broken-up used asphalt is employed and new material is added, utilizing a plurality of burner-heated drum devices, with the used asphalt component and the new material for the asphalt mixture to be processed or produced being processed, i.e. heated in particular, in respectively differently configured drum devices. The used asphalt component is heated separately in a drum mixer operated with parallel flow and the new material component is heated in a drying drum operated with counterflow. After leaving their respective drum devices, the components are conducted into at least one further connected mixer and are further treated there with fresh bitumen and possibly with filler material being added in the mixer. Furthermore, the exhaust gases of the drum mixer are introduced directly into the drying drum and are further heated there, thus combusting the CH.sub.x and CO component contained therein.

Abstract: This invention provides a hot-mix asphalt recycling processes for reconstituting and upgrading old road materials. In usual hot-mix plants the asphaltic material is heated by a naked flame. Residual bitument in the asphalt is exposed to the naked flame from the burner, which can seriously damage the bitument and render it largely worthless. In order to reduce wastage, the invention provides for heating of aggregate in a heating zone, and supplying of the heated aggregate, usually cold reclaimed asphalt, and suitable binder material to a substantially flame-free mixing zone. By mixing these constituents in that zone, it is possible to produce a usable hot asphalt pavement mix with reduced asphalt wastage.

Abstract: A regenerative heating and melting device is disclosed for treating asphalt concrete rubble for the recovery of an asphalt coated aggregate suitable for reuse. The apparatus includes a vertical cylindrical casing, an inlet for hot gas and an outlet for exhaust gas, conveyor means for conveying the rubble to the top of the casing and means for recovering the regenerated paving material from the casing. The internal space of the cylindrical casing is divided into a plurality of tier sections by partition plates. Each of the plates has an opening means to communicate with the adjacent lower tier section. A rotary shaft is provided in the cylindrical casing, the axis of which coincides with the axis of the cylindrical casing and extending through the tier sections and partition plates.

Abstract: An improved recycling apparatus for particulate asphaltic concrete comprises a rotatable drum in which the particulate composition is gradually heated between an input end and an output end having a retractable chute extending into a port at the output end for recovering composition of a selected temperature. The chute contains a temperature sensing device, and the apparatus preferably includes a drive means for inserting or retracting the chute, and thermostat means for selecting a product temperature whereby the drive means causes the chute to be extended into the drum to recover the composition of a selected temperature. In another embodiment, the drum includes first, second, and third lifters each extending along different respective lengths of the drum interior to achieve different exposure of the particulate composition to the heating gases in the drum in the respective different drum sections to achieve improved heating and mixing efficiency.

Abstract: A system and method for rapid beneficiation of bentonite clay is disclosed. Beneficiation of the bentonite clay occurs through oxidation of structural ferrous iron. For rapid beneficiation, bentonite clay, preferably ground, is subjected to moist air while the clay is being agitated, preferably by tumbling within a rotating drum, to provide rapid exchange of moisture and oxygen in the air with the bentonite clay aggregates to thereby increase the speed of oxidation of ferrous iron in the bentonite clay. Drying of the thus treated bentonite clay may be then achieved by agitating the clay, again preferably by tumbling within a rotating drum, in the presence of dry air.

Abstract: A batch method of producing asphalt-aggregate composition having a temperature of at least about 200.degree. F. and at least about 20% used asphaltic concrete comprises heating solid particles of the used material in a first drum to a temperature of at least about 150.degree. F., separately heating virgin aggregate in a second drum to a temperature of less than about 400.degree. F., and mixing the two materials, preferably with the addition of hot liquid or paving grade asphalt. In a second embodiment, unheated used asphaltic concrete is mixed with heated used asphaltic concrete and heated virgin aggregate.

Abstract: A process for making asphalt concrete comprises mixing starting materials including aggregate and binder material and optionally, other additives, to a final temperature of about 60.degree. C. to about 150.degree. C. in an indirectly heated mixing chamber which is sealed. The moisture content of the asphalt concrete mixture is controlled as a function of the moisture content of the starting materials. Apparatus for performing the process in a continuous or batch operation is also set forth.

Abstract: Method and apparatus for the preparation, more particularly for the cooling nd mixing of moulding sand. The method includes the steps of cooling used sand, cleaning the sand where appropriate, and mixing and homogenizing the sand by the addition of water accompanied by intensive agitation, and partly covering the particle surface of the sand with a binding agent under vacuum.

Abstract: This specification discloses method and apparatus for treating surface layers of the earth to obtain stabilization, build strength and permeability characteristics; characterized by slaking quicklime (CaO) in a mixing tank to form an elevated temperature, hydrated lime [Ca(OH).sub.2 ] slurry and working the resulting elevated temperature lime slurry into the surface of the earth at the local where the stabilization of the soil is to be achieved. This achieves a cost reduction, has greater reliability in obtaining materials, achieves better results, saves energy and extends the soil-stabilization season into cold weather previously considered prohibitive. Also disclosed are the details of preferred embodiments for admixing the unslaked lime.

Abstract: An improved apparatus for recycling asphaltic concrete comprises a rotatable drum having a first port at one end open to atmosphere, a burner adjacent the first end, a second port at a second end of the drum with means for closing the second port, means for recovering the composition from the second port and whereby the closure means and composition recovery means at the second port cooperate to maintain the second port closed except to the extent necessary to recover composition.

Abstract: A method of hot mix recycling of old asphaltic concrete paving heats the old pavement, after it has been removed and sized, to a temperature below its firing point and heats fresh aggregate to a greater temperature before combining the two and adding new asphalt. The method is embodied in a drum-mixer type of apparatus modified by inserting a smaller drum in the upstream portion of the large drum. The burner fires into the smaller drum into which the fresh aggregate only is introduced while the old mix (plus additional fresh aggregate in certain cases) is introduced into the annular space between the two drums, the fresh aggregate and the old mix being thereafter combined in the large drum, new asphalt added and the mix further heated.

Abstract: A bituminous mixture of aggregate and a bituminous binder, especially for road construction or repair is prepared by mixing a batch of still moist aggregate with the bituminous binder in a pressurized mixing container. The gauge pressure in the mixing container is maintained at or just above the saturation pressure of the water adhering to the surfaces of the aggregate, at the desired mixing temperature. Upon completion of the mixing the pressure in the mixing container is reduced to below one bar whereby moisture is removed from the mixture. The present mixing apparatus is rotatable about a hollow axle through which a supply of heating gas is maintained during the mixing. During the removal of the mixture from the mixing container the heating gas may be circulated through the next batch of aggregate being prepared.

Abstract: A process for rejuvenating and recycling used asphalt and a machine including a pugmill mixing chamber for mixing crushed asphalt supplied thereto and for mixing water, calcium oxide and asphalt oil therewith is disclosed. The water and calcium oxide mixture react and chemically combine to form a calcium hydroxide filler material to thus fill the voids and gaps in the rejuvenated asphalt that would otherwise exist. The reaction, being exothermic, increases the temperature of the resultant asphalt based mixture to a level suitable for spreading of the rejuvenated material on a prepared surface. The asphalt oil is preferably preheated using a heat exchanger coil connected to a diesel engine radiator, which coil is immersed in an asphalt oil storage tank carried on the machine so that the viscosity of the oil may be reduced to a reasonable value suitable for pumping to the mixing chamber and spraying on the materials contained therein.

Abstract: An improved apparatus for recycling asphaltic concrete includes an inclined chute for introducing composition into an open port into which a burner also feeds hot gases of combustion. The apparatus provides for improved continuous processing by feeding composition containing relatively large particle sizes into the open port and recovering heated composition adjacent the opposite drum end.

Abstract: An apparatus for heating and mixing an asphalt-aggregate composition comprises a drum rotatable about an axis, having a mixing and heating chamber with a restricted port at one end into which a flame and hot gases of combustion are directed and through which exhaust gases simultaneously pass to atmosphere, and a heating means comprising a burner nozzle for directing flame and the hot gases of combustion into the chamber at the restricted port. The nozzle is adjusted relative to the port whereby the volatiles from the asphalt are ignited and burned within the mixing chamber prior to being vented to the atmosphere from the restricted port. Composition may also be introduced and/or removed from the chamber through the restricted port.

Abstract: In a process for recycling asphalt and aggregate containing composition, the improvement comprises separating the composition into a plurality of portions having different particle sizes, ranging from coarse to fine, introducing the particle portions into different mixing and heating drums, one of the drums being for the coarse particle portion, and one or more additional drums for smaller particle portions, and heating the particles in the respective drums with hot gases of combustion at temperatures below that which will burn the asphalt particles in each of the respective drums.

Abstract: In an apparatus for heating and mixing asphalt-aggregate composition in a rotating cylindrical drum by contact with a plurality of elongated heating tubes extending along the drum interior, the improvement comprises introducing coarse particles of the composition at a relatively cool end or area in the drum and introducing smaller sized composition particles in a relatively warmer area of the drum.

Abstract: A process and an apparatus for cooling and handling sand in which hot used sand is delivered to a mixer and mixed with cooler sand. The mixed sand is discharged from the mixer for circulation on conveyor means for further cooling and the cooled sand is separated into a first fraction for discharge to successive milling and moulding stages and a second fraction for return to the mixer to effect sand mixing with the hot used sand. Water may be added to the mixed sand in the mixer to adjust the moisture content and to increase cooling.

Abstract: In an apparatus for heating and mixing asphalt-aggregate composition in which composition particles are exposed directly to hot gases of combustion, a plurality of lifters are secured around the drum interior surface adjacent the input end of the apparatus where flame and hot gases of combustion are supplied, opposite the output end, and a space is provided between the lifter surface and the interior drum surface, whereby coarse composition particles are alternately lifted and dropped by the lifters as the drum rotates, and any fine composition particles pass along the space between the lifter and drum interior surfaces. In another embodiment, a barrier plate is provided across the hollow drum interior, and having peripheral edge spaced apart from the drum interior surface, and behind which plate fine composition particles are introduced.

Abstract: A method of treating bituminous paving mixtures to reduce the amount of aggregate fines discharged into the atmosphere. Aggregate is fed into a charging end of an inclined drum mixer and is heated by a low-velocity gas stream to form steam from the moisture contained by the aggregate within a steam zone. Liquified asphalt is supplied to the aggregate in an asphalt injection zone as it moves downstream in the drum from the steam zone and coats the aggregate as it is tumbled and moved along the drum in a coating zone toward a discharge end. In the gas stream, the ratio of airflow into the drum mixer is accurately controlled with respect to the rate of fuel flow to a burner located at the charging end of the mixer, to consume during burner combustion all oxygen supplied by the airflow to produce a heated gas stream, thereby eliminating free oxygen from the interior of the drum mixer.

Abstract: Recycled asphalt-aggregate compositions prepared by adding a suitable amount of make-up asphalt to pieces of the used composition and heating the mixture in a rotating cylindrical drum by tumbling the composition over heated pipes as it is gradually directed towards an output end of the drum, the improvement comprising adding an amount of petroleum hydrocarbon to achieve a laid down asphalt penetration of between 25 and 300 dmn at 77.degree. F. A further embodiment of the improved process comprises venting a mixture of hydrocarbon gases and moisture vaporized from the hot composition mixture at the output end of the apparatus, condensing the moisture and removing it and returning the hydrocarbon gases to a combustion chamber for providing heat to the apparatus tubes.

Abstract: A process for making asphalt concrete comprises mixing starting materials including aggregate and binder material and optionally, other additives, to a final temperature of about 60.degree. C. to about 150.degree. C. in an indirectly heated mixing chamber which is sealed. The moisture content of the asphalt concrete mixture is controlled as a function of the moisture content of the starting materials. Apparatus for performing the process in a continuous or batch operation is also set forth.