Chloride analysis in concrete by LA-ICP-MS

Chloride induced corrosion is the main problem affecting the durability of reinforced concrete structures. Therefore, the ability to measure chlorides in cementitious materials is of great importance. In this paper, we propose the application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the determination of the total chloride content in concrete, highlighting the potential of the technique for overcoming two main difficulties: the time consuming depth profiling and the representativeness of the sampling procedures in concrete at the interface with steel. Portland cement concrete powder pellets were used for calibration purposes and the accuracy of the chloride determination is verified by the analysis of certified reference materials. Experimental conditions were adjusted in order to optimize the detection limit which was found to be of 0.011 wt%. Using fly ash and slag cement concretes, the influence of the matrix was assessed by comparing the results from LA-ICP-MS measurements to those obtained by potentiometric titration. The method was applied for chloride profiling along the concrete-steel interface of a specimen subjected to chloride exposure, showing good reproducibility within the calibration range