GB141769A - Improvements in bituminous concrete pavements and processes for making the same - Google Patents

Abstract

141,769. Henderson, G. A. Nov. 21, 1918. Macadamized roads; cauldrons.-A bituminous composition prepared by the process set forth below and consisting of bitumen, dust, and fine aggregate such as stone or wood particles, is laid on a scarified macadam road or is moulded into paving- blocks. The mixing is effected in the apparatus shown in the Figure, such apparatus being hauled by a motor-driven bitumen-heating tank. The loosened road aggregate is heated in situ by oil burners d<1> and again scarified by centre tines b. Dust is removed by suction through flues f<2> which penetrate a bitumen-heating tank k and converge to the rear end of a drum l. The tank is heated by the waste heat from the burners. A suction fan C<1> ejects the burner gases and steam from the drum to the atmosphere, and the dust from the flues f<2> passes to a chamber f<3> where it is mixed with a predetermined quantity of other dust supplied from a hopper f<4>; the dust mixture then passes through the bitumen drum l, where it is intimately mixed with the bitumen sprayed by blades l<1>. The bitumen is further circulated by a pump o through pipes n, n<2> to the reverse side of the tank, and a portion of the bitumen is supplied by a hand' valve n<3> to a weighing-bucket n<4> mounted on a weigh beam n<5>, whence it is discharged into a pug mixer L. At the same time there is also discharged into the pug mixer from a weighing-bucket w<2> a quantity of clean, small stone or wood chips which have been partially dried so that they contain from 10 to 15 per cent of residual moisture: this smaller aggregate is led from a hopper w. Two sets of pug mixers and weighing-buckets are provided and act alternately to maintain a continuous supply to the drum l. The contents of the drum are forced by the blades l<1> through a gate valve l<4>, and are deposited either on the road or into moulds to be formed into blocks as described in Specification 8341/12, [Class 34 (ii), Drying systems &c.]. Bitumen is sprayed on the dustless road by nozzles g<1>, the surface is turned by tines a<8>, and then receives the contents from the drum. The road is finally rolled while still hot. The new materials may also be laid on a compact base or foundation in one or more layers, the base and each layer being painted with bitumen to ensure a bond. Power is taken from the rear axle S<2> to drive the shaft m and valves f<5>, l<4>.