Probing pH Levels in Civil Engineering Materials

Optical spectroscopy is a viable approach for subsurface monitoring of pH levels in civil engineering materials. In this work, we describe a method by which optical fibers may be implemented as probes for the in situ measurement of pH levels. This paper describes the development of a nanoporous polymeric matrix, which hosts pH-sensitive chromoionophores. Details of how this pH indicator is strongly attached to the polymer chains through hydrogen bonds are described. Experiments are conducted in the laboratory in aqueous media for monitoring pH levels in highly alkaline and moderately acidic regions. Some detail on indicator immobilization, and signal reversibility are also reported.