ENERGY ABSORBING HIGHWAY BARRIER MATERIAL INVESTIGATIONS

This report describes three investigations of materials and components used or intended for use in highway energy absorbing barriers. Part I: Preliminary Development of a Vermiculite Concrete Crash Cushion. The primary objective to develop a crash cushion using vermiculite concrete in bulk form was not accomplished due mainly to difficulties in attaining a reliable mix design with a consistent compressive strength range. Vermiculite concrete compressive strengths were sensitive to aggregate gradation, moisture content, mixing procedures, sampling techniques, and testing procedures. Attempts to develop a vermiculite concrete mix design that could be steam cured were also unsuccessful. A safety-shaped block of low strength lightly reinforced vermiculite concrete, however, supported the mass of a 4900 lb. (2222 kg) passenger car driven onto the sloping face at speeds of about 5 mph (2.2 m/s). Discussion of a barrier concept employing precast modular units and the designs of two full size barrier modules absorbing about 42 and 32 foot-kips (56.9 and 43.4 kJ) of energy during static compression tests are also reported. Part II: Evaluation of Vermiculite Concrete Helicells. Vermiculite concrete cells used as the energy absorbing elements of crash cushions were exposed to various temperature and humidity conditions, and then were subjected to static and drop weight compressive strength tests. It was concluded the cells had effective moisture proof coverings. Temperatures varying from 0 deg to 150 deg F (255 to 339K) did not affect the strength of the cells. Curves of deflection vs energy consumed were similar for both static and drop weight compression tests. There was a wide range in weights of individual cells. Part III: Strength Investigations of Sand-Filled Plastic Crash Cushion Barrels. Failures in the field prompted the study of the frangible polyethylene material used in sand filled barrel type crash cushions. Test specimens were exposed to weathering, accelerated ultraviolet light conditions, and temperatures of 30 deg to 120 deg F (272 to 322K), and then subjected to tensile strength tests. Only high temperatues significantly lowered the strength. Despite several later improvements in the barrel design, a small number of failures have occurred in the field. The reasons for these failures are unclear. /Author/

  • Supplemental Notes:
    • Conducted in cooperation with DOT, Federal Highway Administration.
  • Corporate Authors:

    California Department of Transportation

    Transportation Laboratory
    5900 Folsom Boulevard
    Sacramento, CA  USA  95819
  • Authors:
    • Stoughton, R L
    • Parks, D M
    • STOKER, J R
    • Nordlin, E F
  • Publication Date: 1977-6

Media Info

  • Features: Figures; Tables;
  • Pagination: 129 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00168392
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: FHWA-CA-TL6405-77-17, FCP 41F1032
  • Contract Numbers: D-4-69 HP&R
  • Files: TRIS, STATEDOT
  • Created Date: Feb 16 1978 12:00AM