Equipment for making asphalt paving compositions

Claim 2

A plant for the preparation of asphalt paving compositions by coating of aggregate with a liquefied asphalt composition wherein a paving composition is discharged having uniform compaction, wherein there is less aging of the asphalt composition during coating of the aggregate and wherein there is a reduced amount of air pollution discharge into the atmosphere resulting from a fines associated with the aggregate, comprising: (1) an inclined, rotatable, cylindrical shell having an upper charge end, a lower discharge end opposite the charge end and an intermediate mixing and drying zone, the upper and lower ends of the shell closed by end walls, (2) means for introducing an unconditioned aggregate having about 1% to 10% water based on the weight of the aggregate associated therewith into the charge end of the shell, (3) means for metering a liquefied asphalt composition onto to the unconditioned aggregate prior to any substantial removal of moisture from the aggregate in the mixing and drying zone, and (4) means for removing moisture from the asphalt-aggregate mixture in the mixing and drying zone as it progresses from the charge end through the mixing and drying zone to the discharge end of the shell.

Claim 3

The plant of claim 1 wherein the means for removing moisture includes (a) heating means for combusting a fuel-air mixture and producing hot combustion gases mounted in the charge end wall of the shell and (b) exhaust means having its intake communicating with the discharge end of the shell for inducing and maintaining a relatively high velocity flow of the hot combustion gases through the mixing and drying zone of the shell, the hot combustion gases removing excess moisture from the asphalt-aggregate mixture with a portion of the heat used to convert the water associated with the aggregate to steam and thereby maintain the temperature in the mixing and drying zone sufficiently low to prevent adverse hardening of the liquefied asphalt composition.

Claim 4

The plant of claim 2 including a cylindrical tube surrounding the heating means and extending into the mixing and drying zone past the point of entry of the asphalt and aggregate into the charge end of the shell to prevent direct flame contact therewith.

Claim 5

The plant of claim 2 including temperature sensing means disposed to sense the temperature of the asphalt-aggregate mixture discharged from the discharge end of the shell and control means operatively connected to the temperature sensing means and the heating means to maintain a predetermined discharge temperature of the asphalt-coated aggregate.

Claim 6

The plant of claim 2 including feed control means controlling the relative amounts of aggregate and asphalt introduced into the mixing and drying zone.

Claim 7

A plant for the preparation of asphalt paving compositions by coating of aggregate with a liquefied asphalt composition wherein a paving composition is discharged having uniform compaction, wherein there is less aging of the asphalt composition during coating of the aggregate and wherein there is a reduced amount of air pollution discharge into the atmosphere resulting from fines associated with the aggregate, comprising: (1) an inclined, rotatable, cylindrical shell having a upper charge end, a lower discharge end opposite the charge end and an intermediate mixing and drying zone, the upper and lower ends of the shell closed by end walls, (2) conveying means for introducing an unconditioned aggregate having about 1% to 10% water based on the weight of the aggregate associated therewith into the charge end of the shell, (3) weighing means for feeding a predetermined amount of the aggregate onto the conveying means, (4) metering means for metering a liquefied asphalt composition onto the unconditioned aggregate prior to any substantial heating of the aggregate in the mixing and drying zone, (5) heating means mounted in the charge end wall of the cylindrical shell for combusting a fuel-air mixture and producing hot combustion gases, (6) exhaust means having its intake communicating with the discharge end of the shell for inducing and maintaining a relatively high velocity flow of the hot combustion gases through the mixing and drying zone of the shell, the hot combustion gases removing excess moisture from the asphalt-aggregate mixture progressing through the mixing and drying zone with a portion of the heat used to convert the water associated with the aggregate to steam and thereby maintain the temperature in the mixing and drying zone sufficiently low to prevent adverse hardening of the liquefied asphalt composition.

Claim 8

A plant for the preparation of asphalt paving compositions by coating of aggregate with a liquefied asphalt composition wherein a paving composition is discharged having uniform compaction, wherein there is less aging of the asphalt composition during coating of the aggregate and wherein there is a reduced amount of air pollution discharge into the atmosphere resulting from fines associated with the aggregate, comprising: (1) an inclined, rotatable, cylindrical shell having a upper charge end, a lower discharge end opposite the charge end and an intermediate mixing and drying zone, the upper and lower ends of the shell closed by end walls, (2) conveying means for introducing an unconditioned aggregate having about 1% to 10% water based on the weight of the aggregate associated therewith into the charge end of the shell, (3) weighing means for feeding a predetermined amount of the aggregate onto the conveying means, (4) metering means for metering a liquefied asphalt composition onto the unconditioned aggregate prior to any substantial heating of the aggregate in the mixing and drying zone, (5) heating means mounted in the charge end wall of the cylindrical shell for combusting a fuel-air mixture and producing hot combustion gases, (6) exhaust means having its intake communicating with the discharge end of the shell for inducing and maintaining a relatively high velocity flow of the hot combustion gases through the mixing and drying zone of the shell, the hot combustion gases removing excess moisture from the asphalt-aggregate mixture progressing through the mixing and drying zone with a portion of the heat used to convert the water associated with the aggregate to steam and thereby maintain the temperature in the mixing and drying zone sufficiently low to prevent adverse hardening of the liquefied asphalt composition.