Title: Investigation of Causes of Delayed Expansion of Concrete in Buck Hydroelectric Plant
Author(s): A. A. Levison and Lion Gardiner
Publication: Journal Proceedings
Appears on pages(s): 665-672
The concrete in Buck Hydroelectric Plant, built in 1912, qave first noticeable evidence of expansion, in 1922. Expansion continued until at date of this writing dimensions had increased by about 1/2 percent, and potential growth remained. No serious expansion was observed in another hydroelectric plant built only 3 miles away at same time with the same cement, but with different coarse aggregate. The Buck coarse aggregate was crushed phyllite (near slate) and the other crushed gneiss. Comparable expansion was ob-served in certain accelerated laboratory tests on concretes made with the Buck aggregate but with modern cements. The laboratory specimens expanded only, where a high alkali cement was used or where alkali was added to a cement. Also, up to the age of I year, specimens expanded only when stored at an accelerating temperature (I IO F in these tests). It is concluded that expansion is due to a reaction between aggregate and alkalis in cement, probably to form sodium or potassium silicate, and that test specimens stored at 70 F will expand in due time.