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Title:

Relating Iowa Pore Index to Concrete Aggregate Pore Structure

Accession Number:

01661493

Record Type:

Component

Abstract:

Iowa Department of Transportation has developed Iowa Pore Index test to determine the D-cracking susceptibility of carbonate limestone aggregate. The method measures the amount of water entering aggregate under a 35 psi pressure for 1 minute, expressed as Primary Pore Index (PPI) and then 14 minutes, expressed as Secondary Pore Index (SPI). PPI is generally associated with the amount of macro-pores, while SPI (i.e., Iowa Pore Index) represents the amount of micro-pores in the tested aggregate, the latter of which has a more significant effect on aggregate freezing-thawing durability. In this study, the relationship between IPI and aggregate pore structure was studied in order to further the understanding of IPI as a direct aggregate durability test. A total of 27 samples from 15 different sources were studied; 12 sources included gravel deposits with varying percentages of carbonate particles, and the rest was composed of 100% carbonate particles from limestone quarries. The aggregates were tested for 24-hour water absorption and Iowa Pore Index; the pore size distributions were also determined using mercury intrusion porosimetry. The test results from water absorption, IPI and mercury intrusion porosimetry showed that the carbonate aggregates had higher porosity than the non-carbonate aggregates. The predominant pore size range was 0.1 – 1.0 micron for the carbonate aggregates and >100 micron for the non-carbonate aggregates. The results suggested that it is very likely that during the first minute of the pore index test, water also penetrates into some micro-pores, thus, Iowa Pore Index may not accurately represent the total amount of micro-pores.

Supplemental Notes:

This paper was sponsored by TRB committee AFP70 Standing Committee on Aggregates.

Report/Paper Numbers:

18-03293

Language:

English

Authors:

Bektas, Fatih
Wang, Kejin

Pagination:

6p

Publication Date:

2018

Conference:

Transportation Research Board 97th Annual Meeting

Location: Washington DC, United States
Date: 2018-1-7 to 2018-1-11
Sponsors: Transportation Research Board

Media Type:

Digital/other

Features:

Figures; References; Tables

Identifier Terms:

Iowa Pore Index

Subject Areas:

Highways; Materials; Pavements

Source Data:

Transportation Research Board Annual Meeting 2018 Paper #18-03293

Files:

TRIS, TRB, ATRI

Created Date:

Jan 8 2018 10:48AM