USE OF SPECIAL CEMENTS IN SHOTCRETE

The results are presented of an experimental program performed to evaluate shotcrete properties important to underground structural support systems. A series of vertical and horizontal panels containing various amounts of accelerators were shot, and specimens cut from them were tested to obtain mechanical properties. Two fast setting agents and one controlled setting cement were evaluated and both wet and dry process machines were used in the study. Two thicknesses of shotcrete (2-in. and 6-in.) were studied to determine thickness and layer effects on strength. The properties obtained include compressive, flexural and shear strengths, secant and tangent moduli, Poisson's ratio, gas permeability, and shear and tensile bond strength of shotcrete to coal, shale and sandstone. The data were analyzed using statistical techniques to show trends between shotcreting methods and the concrete mixes and additives used. A series of small scale bench experiments were performed in which several types of Standard Portland and accelerated cements were evaluated. Various liquid and dry accelerators were investigated as admixtures for the Portland cements. Details are given of the test panel fabrication and testing. Based on the result of bench tests, Type III Portland cement with Tricasol and Isocrete, and RSPC were chosen for evaluation with full size shotcrete panels. The highlights based on average values of the test results are presented. Shotcrete mixes are discussed and a table is presented of shotcrete mix design. Shotcrete properties are reviewed. The data presented here indicate that the use of reg-set cements would increase the versatility of shotcrete. However, modifications (listed) in current procedure would be required. An alternative approach would be the development of suitable additives so that the cements behave similar to Regulated Set Portland Cement in setting and strength characteristics.

Media Info

  • Features: Figures; Photos; Tables;
  • Pagination: p. 200-231

Subject/Index Terms

Filing Info

  • Accession Number: 00263693
  • Record Type: Publication
  • Report/Paper Numbers: SP-45 Conf. Proc
  • Contract Numbers: H0111881
  • Files: TRIS
  • Created Date: Dec 19 1974 12:00AM