USE OF AGING TESTS TO DETERMINE THE EFFICACY OF HYDRATED LIME ADDITIONS TO ASPHALT IN RETARDING ITS OXIDATIVE HARDENING (WITH DISCUSSION)

The occurrence of premature cracking of asphaltic concrete surfacings in South Africa is currently causing great concern to road authorities, and much effort is being devoted to finding preventive and remedial measures. The addition of hydrated lime to asphalt has been considered as a preventive measure. As a first step, a laboratory study was initiated, to be followed by field trials; this paper reports on the laboratory study. In this study 60/70 and 80/100 penetration grade asphalts, most commonly used in the surfacings exhibiting premature cracking, were modified with 6% and 12% of hydrated road lime. Laboratory aging was effected by the weatherometer and the extended rolling thin-film oven test. The residues from the latter aging test were further subjected to either the pressure oxidation bomb or to a modified thin-film oven test. Oxidative hardening was determined by viscosity measurements, infrared spectra and quantitative measurement of the high molecular weight constituents (HMWC) of the samples. It was determined that the addition of hydrated lime to asphalts retards the increase in oxidation products and HMWC, resulting in less hardening as measured by change in viscosity after aging tests. The addition of 12% hydrated lime has a greater effect in retarding the formation of oxidation products and HMWC than the addition of 6% of hydrated lime. However, owing to the detrimental effect of the lime particles on viscosity, the overall effect on the reduction of age-hardening as measured by aging indices after laboratory aging tests is similar for the two hydrated lime contents.

• Corporate Authors:

  Association of Asphalt Paving Technologists (AAPT)

  400 Selby Avenue, Suite I
  St Paul, MN  United States  55102
• Authors:
  • Edler, A C
  • Hattingh, M M
  • Servas, V P
  • Marais, C P
• Conference:
  • Association of Asphalt Paving Technologists Proc
• Publication Date: 1985

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 118-139
• Serial:
  • Volume: 54

Subject/Index Terms

• TRT Terms: Aging (Materials); Asphalt concrete; Asphalt hardening; Asphalt pavements; Calcium hydroxide; Laboratory tests; Oxidation; Pavement cracking; Viscosity
• Geographic Terms: South Africa
• Subject Areas: Design; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces; I31: Bituminous Binders and Materials;

Filing Info

• Accession Number: 00739614
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 1 1997 12:00AM