REBOUND IN DRY-MIX SHOTCRETE: INFLUENCE OF TYPE OF MINERAL ADMIXTURE

Shotcrete is fast becoming a material of choice for repair and rehabilitation, slope stabilization, and temporary support in mines and in tunneling. The high rebound in dry-mix shotcrete has severe implications both on its long-term durability and mechanical performance in service. The use of mineral admixtures is often recommended as a way of reducing rebound, but the exact influence of the admixture dosage rate, shape, and mean size of their particles on the rebound is not clearly understood. In this study, four mineral admixtures--silica fume, fly ash, high-reactivity metakaolin, and carbon black--were investigated in plain and reinforced dry-mix shotcrete for rebound and other properties. These admixtures represent particle sizes ranging from 0.05 micrometers to 10 micrometers, and particle shapes ranging from spherical to platelike. Results indicate that while fly ash is not as effective, both silica fume and carbon black substantially reduce the rebound. The performance of high-reactivity metakaolin lies somewhere in between. Overall, it appears that the mean particle size of the admixture influences the rebound far more than the shape of its particles.

Language

  • English

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Filing Info

  • Accession Number: 00792300
  • Record Type: Publication
  • Contract Numbers: 95-C-001
  • Files: TRIS
  • Created Date: May 9 2000 12:00AM