A REPORT ON THE CONSTRUCTION AND INITIAL MONITORING OF AN EXPERIMENT LAID ON YALDWYN ROAD, BOKSBURG, IN MAY/JUNE 1974 TO EVALUATE VARIOUS TAR AND BITUMEN BINDERS IN HOTMIX

This report describes the construction of a hotmix surfacings experiment of which the main object is to study the performance of mixes made with unmodified coke-oven tar, PVC modified coke-oven tar, Lurgi tar, "cracked" bitumen and normal production bitumen. Details of the construction, sampling and measuring procedures are given. Initial results, after on year's service, are recorded. Generally the performance of the mixes is satisfactory with the exception of mixes made using unmodified coke-oven tar. These densified and became very fatty due to the low viscosity of the tar and the lack of filler material. The shortage in filler was common to all the mixes which initially were all low in stability. Nevertheless initial results are encouraging in that they show that in mixes with low voids (2-3 per cent after one year) the hardening of the tar can be kept low. The change in viscosity of the tar after one year is much less than would have occurred if the tars had been used in a single surface treatment. These results and mix stiffness measurements augur well for the resistance to cracking and ravelling of the mixes in service. Results of initial measurement of the structural condition of the road and skid resistance of the surfacings are also given. Measurements of the pollution of the atmosphere by volatile hydrocarbons show that the concentration of volatiles is higher than benz-a-pyrene determined previously in tarring operations. Benz-a-pyrene has been associated with the carcinogenic properties of tar whereas the main constituents of the volatiles (naphthalene and phenols and cresols) are believed to be responsible for the irritation to the eyes and respiratory system. /Author/

• Corporate Authors:

  National Institute for Transport & Rd Res S Af

  P.O. Box 395
  Pretoria 0001, Transvaal,   South Africa 
• Authors:
  • Jamieson, I J
• Publication Date: 1976-3

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 64 p.

Subject/Index Terms

• TRT Terms: Bitumen; Coke; Fillers (Materials); Fracture mechanics; Hot mix asphalt; Hydrocarbons; Skid resistance; Stiffness; Surface treating; Tar; Viscosity
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00165492
• Record Type: Publication
• Report/Paper Numbers: RB12/76
• Files: TRIS
• Created Date: Dec 27 1977 12:00AM