Calibrating the Iowa Pore Index with Mercury Intrusion Porosimetry and Petrography

The Iowa Pore Index (IPI) test is a fast, non-destructive, inexpensive, and environmentally friendly test used by several Midwestern state departments of transportation to determine the volume ratio of macropores to micropores in a coarse rock aggregate. When combined with x-ray diffraction and x-ray fluorescence, this method has been shown to be effective in predicting the performance of aggregates in portland cement concrete. The test has the potential to replace mercury porosimetry and be integrated into any petrophysical laboratory. This research aimed to understand the geological factors (depositional environment, facies, grain and pore types, texture, and paragenesis) responsible for the results of the IPI test. Samples of various geologic ages were collected around Iowa to represent different combinations of accepted and rejected porosity and clay contents. The pore index of each sample was calibrated quantitatively via helium and mercury porosimetry and qualitatively via thin section petrography. The findings show that even the most homogeneous sources have at least three different rock types. Petrographic analysis showed that limestones with a sparite matrix, peloidal grains, and a low matrix-to-allochem ratio (i.e., grainy) are better for road construction than limestones with a micrite matrix, skeletal grains, and a high matrix-to-allochem ratio (i.e., muddy). Dolostones with fine to coarse grains, crystal-supported euhedral to subhedral rhombs, and porous intercrystalline areas are more desirable than dolostones with very fine grains and a tightly interlocking crystal mosaic in anhedral form. Several linear models were developed to relate IPI to helium porosity. Limestones with a helium porosity less than ~7% and dolostones with a helium porosity greater than ~13% were found to be desirable for use in road construction. The critical range of pore-throat size was found to be between 0.02 and 0.1 µm. Coarse aggregates with modal pore throat sizes above this range were found to be desirable for use in road construction.

• Record URL:
  • http://www.intrans.iastate.edu/research/documents/research-reports/Iowa_pore_index_calibration_w_cvr.pdf
• 
• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/32887
• Supplemental Notes:
  • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
• Corporate Authors:

  Iowa State University, Ames

  Institute for Transportation
  2711 South Loop Drive, Suite 4700
  Ames, Iowa  United States  50010-8664

  Iowa Department of Transportation

  Ames, IA  United States  50010

  Midwest Transportation Center

  Iowa State University
  2711 S Loop Drive, Suite 4700
  Ames, IA  United States  50010-8664

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Hasiuk, Franciszek
  • Ridzuan, Muhammad Firdaus Ahmed
  • Taylor, Peter
• Publication Date: 2017-10

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Appendices; Figures; Maps; Photos; References; Tables;
• Pagination: 68p

Subject/Index Terms

• TRT Terms: Calibration; Coarse aggregates; Helium; Mercury; Petrography; Pore size distribution; Porosimeters; Porosity; Portland cement concrete; Rocks; X ray fluorescence
• Geographic Terms: Iowa
• Subject Areas: Construction; Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 01648593
• Record Type: Publication
• Report/Paper Numbers: InTrans Project 15-553
• Files: UTC, NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Oct 20 2017 9:53AM