Though fiberglass reinforced plastic (FRP), aluminum, wood, and steel are stronger materials for hull fabrication, ferro-cement has the competitive advantage for boat-building in certain situations where labor costs are low, construction facilities are minimal, low first cost is important, and high weight is acceptable. Fire and abrasion resistance, ease of maintenance, and adaptability to complex shapes are additional positive features. Ferro-cement's impact resistance is inferior to that of FRP hull materials, however, since its impermeability at the damage site is impaired to a greater extent than with FRP composites. This study aimed at improving the impermeability of ferro-cement, and hence its impact resistance, to increase its suitability as a hull material. The established theories and findings on ferro-cement impact resistance are reviewed, and the mechanisms of impact failure, both in general and for materials used in the study, are examined. Several configurations of ferro-cement modified with laminations of FRP and sheet rubber, as well as unmodified ferro-cement, were tested for impact strength and leakage. All configurations were chosen to retain most or all of the advantages of ferro-cement. Results indicated that combinations of FRP and ferro-cement with FRP on the impact side are superior to other configurations tested, and represent a 500% improvement over unlaminated ferro-cement, whether impact resistance derives from a low modulus of elasticity or high tensile strength. However, the bonding of FRP laminations to the ferro-cement failed in 7 of 8 cases before reaching the impact failure condition; further study is recommended to correct this. Rubber laminations appear more feasible for increasing ferro-cement's impact resistance than FRP: debonding was minimal in testing, and a 270% improvement over basic ferro-cement was realized. Such improvements, both with rubber sheet and with FRP, are possible while maintaining ferro-cement's advantages of ease of fabrication, low cost, and low maintenance.

  • Corporate Authors:

    Massachusetts Institute of Technology

    Sea Grant Program, 77 Massachusetts Avenue
    Cambridge, MA  United States  02139
  • Authors:
    • Snyder, P G
    • Mandell, J F
    • McGarry, F J
  • Publication Date: 1974-3

Subject/Index Terms

Filing Info

  • Accession Number: 00057541
  • Record Type: Publication
  • Source Agency: Massachusetts Institute of Technology
  • Report/Paper Numbers: MITSG 74-18
  • Files: TRIS
  • Created Date: Aug 28 1974 12:00AM