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Recycling Spent Asphaltic Concrete.

McBee-WC; Sullivan-TA
U S Pat 4 239 547 1980 Dec; :
Spent asphalt concrete paving materials are recycled effectively and economically by heating at 120 deg-150 deg c and mixing with sulfur long enough to ensure thorough blending and sulfur reaction with the binder. Thus, spent materials containing 4.5 Wt pct asphalt and the remainder limestone aggregate were crushed to <1-in particles, heated 25 min at 150 deg c and mixed 2 min with s 1.25, Asphalt 1.0, and s 12.5 Or with a light aromatic hydrocarbon oil 0.50 and asphalt 1.25 Wt pct. The additives improved marshall flow, percent of voids, and resilience modulus. Chem. Abstr. 94:108,287D (see also chem. Abstr. 92:63,604V) spent asphalt pavement is recycled by crushing, heating to 120 deg-150 deg c, mixing with 20-50 wt pct s or s and asphalt (ed.: Evidently based on asphalt content of recycled pavement), and reheating to 120 deg- 150 deg c sufficiently long for thorough mixing. Thus, spent runway pavement consisting of 4.5 pct asphalt and 95.5 pct limestone aggregate was crushed, heated 25 min to 150 deg c, mixed with (1) 1.25 S, (2) 1.25 S and 1.0 Asphalt, (3) 0.50 Paxole 1009 softening agent and 1.25 Asphalt wt pct, or (4) no additives, heated at 150 deg c for 2 min, and compacted at 125 deg-140 deg c by 75 blows on each side with a 10-lb compacting hammer. Compositions 1, 2, 3, and 4 had stability 9,330, 4,125, 4,640, and 9,260 lb; voids 4.4, 2.6, 2.3, and 6.7 pct; resilience modulus 3.27, 3.59, 2.27, and 4.85 X 106 psi; viscosity 1,100, 1,135, 880, and 7,800 cp at 135 deg c; and softening point 144, 146, 123, and 180 deg f, respectively.
Publication Date
Document Type
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
P 26-80
NIOSH Division
Source Name
U.S. Pat. 4,239,547; Dec. 16, 1980; Chem. Abstr. 92:63,604V