Hiep Nguyen

Hiep Nguyen

Tufts University

Civil Engineering


1998

Mentor: Dr. David L. Gress, Professor of Civil Engineering

Evaluating the Early Distress of Wyoming I-80

This study investigates the cause of the early distress in the Wyoming Interstate-80 concrete pavement. The concrete pavement was recently recycled utilizing fly ash with recycled concrete aggregate (RCA) that had shown distress from alkali-silica reaction (ASR).

Since its introduction into construction technology, it has been known that, depending on its type, fly ash can have a beneficial or damaging effect on new concrete which is subject to ASR. High volume use of type F fly ash has been considered one of the efficient ways of preventing damage from ASR in new concrete. Type C fly ash however may increase the reaction. Ironically, in the reconstruction of Wyoming I-80, the ASR appeared early though type F fly ash is claimed to have been used.

In this study, several methods including petrographic microscopy, elemental scanning microscopy, ASTM 1260 rapid test, and Uranyl-UV light test were performed to evaluate distressed concrete obtained from Wyoming I-80. Laboratory testing of concrete made with RCA from I-80 included accelerated curing, expansion due to ASR, petrographic and elemental analysis. Emphasis was placed on determining the exact type of fly ash used.

Based on the findings, it is recommended that the effectiveness of fly ash type in preventing ASR in RCA should be further evaluated.

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