Time Effect of Alkali-Aggregate Reaction on Performance of Concrete

This paper presents a continuation of the findings of a long-time study of the performance of cements varying in their chemical and physical characteristics. Most of the cements were provided by the Portland Cement Association, and others were obtained form a local manufacturer. The study was initiated in 1940 by the Portland Cement Association in collaboration with the U.S. Bureau of Reclamation. The 28 cement types studied varied in chemical and physical characteristics and were used in the construction of the parapet wall located at Green Mountain Dam. Each of the 28 cements was used in 3 or 4 of the 104 panels of the parapet wall. The Green Mountain Dam is located on the Blue River, a tributary of the Colorado River, 21 km southeast of Kremmling, Colo. The dam itself is an earth-fill structure, 94 m high, with a crest length of 350 m. Some of the cements used were high-alkali cements, and the aggregates contained reactive silica. This paper investigates the development of alkali-aggregate reaction during the past 53 years on the parapet wall and its impact on strength and durability of concrete. Specifically, the results of a visual inspection and compressive strength are presented as a function of the amount of equivalent alkalis present in these different cements for the years 1943, 1946, and 1997.