The Relationship of Ferroan Dolomite Aggregate to Rapid Concrete Deterioration, HR-266, 1987

Some of Iowa's 13,200 miles of portland cement concrete (pcc) pavement have remained structurally sound for over 50 years while others have suffered premature deterioration. Research has shown that the type of coarse aggregate used in the pcc is the major cause of this premature deterioration. Some coarse aggregates for concrete exhibit a nonuniform performance history. They contribute to premature deterioration on heavily salted primary roadways while providing long maintenance-free life on unsalted secondary pavements. This inconsistency supports the premise that there are at least two mechanisms that contribute to the deterioration. Previous research has shown that one of these mechanisms is a bad pore system. The other is apparently a chemical reaction. The objective of this research is to develop simple rapid test methods to predict the durability of carbonate aggregate in pcc pavement. X-ray diffraction analyses of aggregate samples have been conducted on various beds from numerous quarries producing diffraction plots for more than 200 samples of dolomitic or dolomite aggregates. The crystalline structures of these dolomitic aggregates show maximum-intensity dolomite/ankerite peaks ranging from a d-spacing of 2.884 angstroms for good aggregates to a d-spacing of 2.914 angstroms for nondurable aggregates. If coarse aggregates with known bad pore systems are removed from this summary, the d-spacing values of the remaining aggregates correlate very well with expected service life. This may indicate that the iron substitution for magnesium in the dolomite crystal is associated with the instability of the ferroan dolomite aggregates in pcc pavement.

Boone County, Township 83 North Range 28 West

Des Moines River Plat Maps.

Boone County, Township 84 North Range 28 West

Des Moines River Plat Maps.

Boone County, Township 85 North Range 28 West

Des Moines River Plat Maps.

Webster County, Township 86 North Range 28 West

Des Moines River Plat Maps.

Webster County, Township 87 North Range 28 West

Des Moines River Plat Maps.

Webster County, Township 88 North Range 28 West

Des Moines River Plat Maps.

Webster County, Township 89 North Range 28 West

Des Moines River Plat Maps.

Webster County, Township 90 North Range 28 West

Des Moines River Plat Maps.

Humbolt County, Township 92 North Range 28 West

Des Moines River Plat Maps.

Friday Facts, July 28, 2015, Vol. 258

Bureau of Nutrition and Health Promotion part of the Iowa Department of Public Health produces of weekly newsletter about the Iowa WIC Program for the State of Iowa citizen.

Report on a review of selected general and application controls over the Iowa State University of Science and Technology Kuali Financial System for the period April 30, 2014 through May 28, 2014

Report on a review of selected general and application controls over the Iowa State University of Science and Technology Kuali Financial System for the period April 30, 2014 through May 28, 2014

Friday Facts, August 28, 2015, Vol. 263

Bureau of Nutrition and Health Promotion part of the Iowa Department of Public Health produces of weekly newsletter about the Iowa WIC Program for the State of Iowa citizen.