Landmark Series: Cracking of Concrete in the Tuscaloosa Lock

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Title: Landmark Series: Cracking of Concrete in the Tuscaloosa Lock

Author(s): Bryant Mather

Publication: Concrete International

Volume: 26

Issue: 9

Appears on pages(s): 66-81

Keywords:

Date: 9/1/2004

Abstract:
At first glance, the paper before you simply recounts a routine investigation into the first major occurrence of concrete distress due to alkali silica reactivity (ASR) in a U.S. Army Corps of Engineers structure. Read on. There is much more to it . As an early tribute to the many contributions to our understanding of concrete and concrete materials made over 5 decades by the Mathers, Bryant and Kay, this report would be noteworthy enough. It is stamped with Bryant's trade-mark of good English usage and logical progression from facts to findings. It is a monument to painstaking petrographic work by Kay, which is at the heart of the study and included identifying over 5000 individual coarse aggregate particles intercepted on sawed surfaces of cores. Together with the nature of deposits found in cracks or voids, this led to chalcedonic chert in reaction with cement alkalies being fingered as the culprit for the observed expansive concrete distress in the Tuscaloosa Lock. ASR had first been identified by Stanton in California in the late 1930s. A sizeable body of knowledge about it had been developed by the time (1947-9) of the lock investigation that was one of the first to implicate concrete Outside of the Western part of the U.S. and to confirm chalcedonic chert, an aggregate in widespread use, as reactive. More importantly, while petrographic analysis had been used over the previous decade to help both the U.S. Bureau of Reclamation and the Corps of Engineers select aggregates, the Tuscaloosa Lock study marked the coming-of-age of petrography as a diagnostic tool of choice for investigating many types of distress in in-service concrete. The significance of the Tuscaloosa Lock study rests to this day on its demonstration of the power of petrography and the investigative template Bryant and Kay Mather helped devise and bring into general practice.