Milli X-ray fluorescence X-ray spectrum imaging for measuring potassium ion intrusion into concrete samples

Of particular interest when studying the effects of deicing solutions on concrete is the depth of penetration of ions from deicing salts. To determine the limits of positive ion infiltration, a method based on milli X-ray fluorescence (mXRF) has been developed. This method combines traditional energy dispersive spectrometry (EDS) with stage movement X-ray mapping to analyze comparatively large areas of concrete. The result is the ability to determine the depth of ion infiltration over a distance of tens of millimeters. The technique also requires minimal preparation of the sample, and due to the nature of the X-ray beam, concrete samples do not have to be coated to reduce charging. This paper describes in detail the method of mXRF with X-ray spectrum imaging (XSI) for concrete applications and shows two examples where potassium ion infiltration was measured with mXRF-XSI as part of broader studies in pavement durability.