PIONEER OVERLAY JOB USES FIBER-REINFORCED CONCRETE

A fiber-reinforced concrete overlay was placed over 12,600 ft of 50-year old, 8.5 in. thick concrete pavement. The overlay thickness was varied in this research project. In various places it was bonded, unbonded by a plastic sheet, and partially bonded to the old pavement. Steel fibers of different lengths (1 and 2.5 in.), various concentrations, and different fiber cross-sections (round and rectangular) were used. Fourteen days after the concrete was poured, the flexural strength was 750-1,100 pis. A 2-step procedure is described for the solution of the fiber balling or clumping problem. The use is described of a vibrating screen to break up fiber balls before introduction of fibers to the concrete mix. In another method, fibers are added gradually after all other ingredients are in the mixer (in a central mix job), or 70 percent of the water is put in the mixer first, then aggregates, fibers, cement, and finally the other 30 percent of the water. Research on fiber-reinforced concrete is reported. It is recommended that water reducers be added to (to fiber-reinforced concrete) improve workability and permit reduction of the water/cement ratio. Tests revealed that a 6-in.-thick fibrous slab developed its first and second visible crack after 350 and 700 traffic loadings while a 10-in. plain concrete slab developed such a crack after fewer than 40 loadings. Steel fibers are the most commonly used but the investigation is reported of the use of alkali-resistant glass fiber. The likely future uses of fibrous concrete are briefly discussed.

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00265204
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 11 1975 12:00AM