Evaluation, presentation and Repair of Microbial Acid-Produced Attack of Concrete





CHAPTER 1: INTRODUCTION

RESEARCH BACKGROUND The Texas Department of Transportation (TxDOT) has approximately 50,000 bridges in

its inventory. The deterioration of concrete under bridge structures, most of which is reinforced, has been a critical issue affecting the service condition of these bridges. In additional to wellknown concrete durability problems associated with alkali-silica reactions (ASR), sulfate attack, delayed ettringite formation (DEF), carbonation, and freeze-thaw damage, another surface deterioration phenomenon, microbial induced deterioration (MID) has recently been identified on concrete of Texas bridges and generated strong concern at the Texas Department of Transportation (TxDOT). Figure 1 shows examples of typical TxDOT bridge columns with suspected MID issues.





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