Simulation of Prepackaged Grout Bleed under Field Conditions

This report contains a summary of the research performed in the area of reproducing and determining the cause of soft grout, which has been found in several PT (Post-Tensioned) tubes around the state of Florida. A modified version of the Euronorm inclined tube test named modified inclined tube test (MITT) was developed and used to conduct the majority of the testing.This research was divided into three primary phases. The first was to develop the Modified Inclined Tube Test and determine the tendency of prepackaged grout for producing soft grout under laboratory and field test conditions. None of the commercially available prepackaged PT grout tested with MITT produced bleed or soft grout when the grout was mixed and injected in accordance with manufacturer’s recommendations and tested well before the expiration date printed on the bag. A number of variations on MITT were introduced that would simulate more closely the variations that occur in field conditions. Additional mix water and residual water in the tube produced soft grout consistently in one of the PT grouts. Supplemental tests of fresh grout properties, such as flow cone, unit weight, wet density, pressure bleed, sedimentation, and bleed readings on inclined tubes, did not provide indications that soft grout would be formed during MITT. The second phase of testing focused on the effect of low-reactivity fillers on the production of soft grout in plain grout formulations of portland cement, ground calcium carbonate, and high-range water-reducing admixture (HRWR). Mixtures with 45% and 35% additional filler material consistently generated more soft grout than mixtures with 0% additional filler for any given water-to-solids ratio (w/s). The third and final phase of testing focused on the shelf life of bagged PT grout. Potential modes of degradation included pre-hydration of the portland cement and deterioration of the admixtures over time. Three exposure conditions were developed that provided a broad spectrum conditioning; these conditions were named Laboratory, Field, and Extreme. PT grouts were exposed to these conditions and then tested with MITT for soft grout. Companion particle size analysis (PSA) tests were conducted to determine correlation between the production of soft grout and changes in particle size due to prehydration. Prolonged storage times increased the susceptibility of prepackaged PT grouts to the formation of soft grout, even in favorable environments.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 150p

Subject/Index Terms

Filing Info

  • Accession Number: 01529033
  • Record Type: Publication
  • Report/Paper Numbers: BDK75 977-59
  • Files: NTL, TRIS, ATRI, STATEDOT
  • Created Date: Jun 9 2014 2:20PM