POLYMER SHOTCRETE

The results are presented of work oriented toward the development of a polymer shotcrete type material, the development of an application technique, and the development of the necessary application equipment. The materials investigation was directed toward the development of a suitable monomer system, the determination of aggregate properties and optimum gradings, and the selection of a promotor-catalyst system for polymer shotcrete applications. Factors of particular concern were the cohesive qualities of the mix, the physical properties of the cured material and the low temperature performance of the polymerization system. The results of laboratory tests indicated that a monomer system containing 72 weight percent MIMA (methyl-methacrylate), 13 weight percent TMPTMA (Trimethylolpropane trimethacrylate), and 15 weight percent Acryloid A-11 (a moulding powder composed primarily of polymethyl methacrylate) had the proper viscousity and was suitable for use in polymer shotcrete. The MMA based system had an ambient temperature polymerization pot life of about 2 minutes in 100 gram bulk samples. When this system was mixed with graded aggregate to form a PC mix composed of 15 to 20 percent monomer by weight, the resulting concrete generally cured in about 5-10 minutes. The rapid cure was obtained by adding to the monomer system a polymerization catalyst-promoter system composed of benzoyl peroxide as catalyst and the promotoer, n,n, dimethyl-o-toluidine in concentrations of 2 percent each by total monomer weight. The gradation of aggregate used in polymer shotcrete are tabulated. It was determined that the viscosity of polymer concrete using 0.375 in. maximum size aggregate was acceptable for shooting and that extremely high ultimate compressive strengths in the 12,000 to 14,000 psi range could easily be obtained with most of the strength gain occurring in the first 10 to 15 minutes at ambient temperature. Two application techniques (in one the shotcrete equipment was modified to accommodate the 2-part monomer system and aggregate, and in the other, the application technique was altered) are described. Application equipment and tests are also described.

Media Info

  • Features: Figures; Photos; Tables;
  • Pagination: p. 418-434

Subject/Index Terms

Filing Info

  • Accession Number: 00263701
  • Record Type: Publication
  • Report/Paper Numbers: SP-45 Conf. Proc
  • Contract Numbers: H0111881
  • Files: TRIS
  • Created Date: Dec 31 1974 12:00AM