Concrete Capillary Porosity as It Relates to Durability of Pavements Built with Alkali-Silica-Reactive Aggregates

Abstract

Several concrete pavements have been constructed in southwestern Minnesota using aggregates that recently have tested as being potentially deleteriously alkali-silica reactive. Standard ASTM test procedures were used. Most of these pavements fail to meet their design life. However, the rate of deterioration varies. Six pavement sites varying in age and performance were selected for comparison. Alkali-silica gel is present in all six pavements, even in the 36-year-old pavement still in good condition. Similar aggregate types were used for all six pavements. The coarse aggregate was a low-grade metamorphic quartzite, and the fine aggregate was a glacial sand obtained from various local sources. The relative capillary porosity of the concrete paste was examined using fluorescent dye epoxy impregnated with thin-section samples from each pavement site. Preliminary results suggest that the capillary porosity is linked to the durability of the concrete pavement. The best-performing concretes had a homogeneous capillary porosity that was moderate to low, and the poorer-performing concretes had paste with a capillary porosity that varied from high to low.

Get full access to this article

View all access options for this article.

References

Ojakangas

R. W.

, and Weber

R. E.

. Petrography and Paleocurrents of the Lower Proterozoic Sioux Quartzite, Minnesota, and South Dakota. In Shorter Contributions to Geology of the Sioux Quartzite (Early Proterozoic) Southwestern Minnesota, Report 32, Minnesota Geological Survey, 1984, pp. 1–15.

Whiting

N. M.

, and Peterson

K. W.

. An Ongoing Pathological Study of the Concrete Pavements in Minnesota. Proc., 20th International Conference on Cement Microscopy, Duncanville, Tex., 1998, pp. 84–102.

McConnell

, Mielenz

R. C.

, Holland

W. Y.

, and Greene

K. T.

. Petrology of Concrete Affected by Cement-Aggregate Reaction. In Application of Geology to Engineering Practice, Berkey Volume, Geological Society of America, New York, 1950, pp. 225–250.

Jakobsen

U. H.

Understanding the Features Observed in Concrete Using Various Fluorescence Impregnation Techniques. Proc., 19th International Conference on Cement Microscopy, Duncanville, Tex., 1998, pp. 281–301.

Jakobsen

U. H.

, Johansen

, and Thaulow

. Optical Microscopy—A Primary Tool in Concrete Examination. Proc., 20th International Conference on Cement Microscopy, Duncanville, Tex., 1997, pp. 275–294.

Walker

N. H.

, and Marshall

B. F.

. Methods and Equipment Used in Preparing and Examining Fluorescent Ultrathin Sections of Portland Cement Concrete. Cement, Concrete and Aggregates, Vol. 1, No. 1, 1979, pp. 3–9.

Jepsen

B. B.

, and Christensen

. Petrographic Examination of Hardened Concrete. Bulletin of the International Association of Engineering Geology, No. 39, 1989, pp. 99–103.

Andersen

K. T.

, and Thaulow

. The Study of Alkali-Silica Reactions in Concrete by the Use of Fluorescent Thin-Sections. In Petrography Applied to Concrete and Concrete Aggregates, ASTM, STP 1061, pp. 71–89.

Neville

A. M.

Properties of Concrete, Fourth and Final Edition. John Wiley & Sons, Inc., New York, 1997.