Abstract:
Apparatus and method for processing asphalt material to be recycled by introducing used asphalt material from the field in relatively large pieces, as received from the field, into one end of a cage-like array of tubular breaker members while simultaneously heating the tubular breaker members from the other end of the cage-like array and rotating the cage-like array about a tilted central axis of rotation to tumble the material within the cage-like array and reduce the size of the pieces of material to a desired aggregate size within a mass of material moving toward the other end of the cage-like array, the tubular breaker members being spaced apart circumferentially such that only the desired aggregate-sized pieces in the mass of material pass radially out of the cage-like array for delivery and reuse.
Abstract:
A drum mixer asphalt plant is provided with a rotatable cylinder having an internal passageway where the aggregates and asphalt are mixed to produce an asphaltic composition. In a first zone within the mixer, aggregates are heated and dried by heat radiation and the stream of hot gases produced by a burner flame. In a second zone within the mixer, liquid asphalt is mixed with the aggregates. An exhaust tube is disposed within the passageway and extends from the output end of the drum mixer into the first zone to remove the hot gases to prevent degradation of the asphalt. Thus, the second zone wherein the liquid asphalt is mixed with the aggregate is isolated from the hot gases used for heating and drying. Recycle asphalt material may be added in both the first and second zones of the mixer drum.
Abstract:
A drum mixer asphalt plant is provided with a rotatable cylinder 10 in which virgin aggregate, recycle material and liquid asphalt are mixed to produce an asphaltic composition and the hot gas stream for heating and drying the materials flow in countercurrent relation. In a first zone within the cylinder 10, aggregates are heated and dried by heat radiation and a hot gas stream generated at a burner head 46 of a combustion assembly 40. In a second zone within the drum cylinder 10 isolated from the burner flame and hot gas stream by the combustion assembly 40, liquid asphalt is sprayed from an injection tube 76 to mix with aggregate materials. A recycle feed assembly 60 delivers recycle asphalt material to the second zone also for mixing with the aggregate and liquid asphalt.
Abstract:
A method and apparatus for recycling asphalt shingles in an asphalt plant which heats and dries aggregate and mixes the heated and dried aggregate with liquid asphalt to form an asphalt paving composition. The shingles are comminuted to particles of a size which can be easily flowed and metered, and the shingle particles are introduced into the asphalt plant such that they are heated to melt the asphalt in the shingle particles. The aggregate, heated shingle particles, and liquid asphalt are thoroughly mixed to form an asphalt paving composition.
Abstract:
Fragmented old asphaltic concrete or the like is recycled into new hot-mix by temporarily separating larger pieces from the smaller fragments, generating heat internally within the large pieces with penetrating microwave energy, separately heating the smaller fragments by exposure to hot gas, and then recombining and remixing the separately heated components. The old concrete can be heated very rapidly, highly uniformly and economically while avoiding asphalt degradation and pollution problems that can be caused by exposure to extreme high temperature and while avoiding the relatively high costs of heating the entire volume with microwave energy. Sorting, heating and mixing apparatus (11, 11a) embodying the invention may be made transportable to a site at or near a repaving operation or may be travelable along a roadbed to pick up old concrete and deposit new hot-mix or may be integrated into a fixed hot-mix plant (73, 73a, 73b) to enable, among other modes of operation, production of hot-mix wholly from old reclaimed concrete or production of hot-mix from both old and new materials in any desired proportions.
Abstract:
An improved process for recycling asphaltic concrete comprises introducing asphaltic concrete particles at one end of an elongated rotating drum while supplying flame and hot gases of combustion to the drum at the opposite end, and introducing virgin aggregate into the drum intermediate the two ends. The asphaltic concrete is heated as it travels along a portion of the length of the drum and is recovered just prior to reaching the position along the drum length at which the aggregate is introduced. The aggregate is heated as it travels toward the end of the drum at which the flame and hot gases are introduced. Heated aggregate may be returned to the drum for further heating, and may be directed to the opposite drum end and mixed with the asphaltic concrete in a section of the drum.
Abstract:
A drum mixer for recycling old asphalt pavement features a stationary shroud enveloping a series of circumferentially spaced feed ports medially of the drum. The old pavement is introduced tangentially into the shroud and then into a series of "hoppers" within the shroud formed about the feed ports and revolving with the drum. The old pavement falls through the feed ports onto the exterior of a conical inner drum and is directed to the downstream end of the latter by flighting thereon where it joins virgin aggregate emerging from the interior of the inner drum.
Abstract:
An elongated drum for mixing asphalt materials has a rear inlet end, a front outlet end and a side wall concentric to a substantially horizontal axis about which the drum rotates. For feeding salvaged asphalt material into the drum, the side wall has circumferentially spaced ports in a zone intermediate said ends. As ports move upwardly in their orbits, material falls toward them from the bottom outlet of a hopper above the drum and is guided into them by chutes, one for each port, that are fixed to the side wall and project out from it. Also, fixed to the side wall is an inwardly projecting spout for each port whereby material entering the port is deflected forwardly to fall to the bottom of the drum in front of the ported zone. Material moving forward from the rear of the drum is deflected around the ports by the spout walls. An annular trough-like shroud encircles the drum at said zone, embracing the chutes as they move orbitally and preventing incursion of external ambient air into the ports. A hole in the shroud, in line with the upper outlet, is either blocked by salvaged material in the hopper or is closed by a gate for use with all-virgin materials.
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:
The device includes in a rotary cylindrical drum (1) a zone for transfer and heating (11) where the inner surface of the drum (1) is fitted with sections of blades (17) wound in a spiral across the drum (1). These blades (17) arranged projecting with respect to the inner surface of the drum (1), by their edges remote from the drum support baffleplates (18) in a longitudinal direction. The drum (1) likewise exhibits an isolation and drying zone (12) where the inner surface of the drum (1) is fitted with lifter devices (20-21) having a high retention capacity for lifting materials (25) up to the upper portion of the drum (1) and the formation by falling back of these materials (25) of a continuous screen isolating the flame (5) of the burner (4) from the next zone of the drum (1).