Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) puts forward many merits in material characterization like spatially resolved measurements of elemental distribution on macroscopic samples, or multi-element analyses with a low detection limit in a short time. Although its many advantages, LA-ICP-MS is not immensely employed in the field of building materials. In this study, we applied LA-ICP-MS as a method for examining the composition of the Interfacial Transition Zone (ITZ) in concrete. The ITZ describes the contact zone between aggregate and hardened cement paste. This zone typically shows significantly higher porosity and contains more calcium hydroxide than bulk hardened cement paste. Consequently, the ITZ affects the mechanical properties and the durability of concrete considerably [1].
The aim of this study is to develop an optimal strategy to evaluate the LA-ICP-MS results of a heterogeneous material like concrete for a quantitative interpretation, in an attempt to have a deeper look at the ITZ composition in concrete structures. For our research, we prepared special prisms (4 x 4 x 16 cm) consisting of cement paste with various water/cement ratios (w/c = 0.3; 0.4; 0.5) and randomly distributed cubic aggregates (0.5 x 0.5 x 0.5 mm; calcite, dolomite or granite). To determine the positions of the cubes, we conducted CT measurements. This enabled us to cut the prisms in the middle of every dice with a precision saw, achieving adequate surface quality to carry out LA line scans from the aggregate through the ITZ into the bulk cement paste.
With the obtained results, we will investigate the variation in composition between disturbed (ITZ) and non-disturbed (bulk) hardened cement paste. A crucial step in LA-ICP-MS measurements is the calibration strategy, especially in our case of materials with different ablation behavior [2]. The currently most adequate calibration strategy for our results is an external calibration with internal standardization over the sum of all oxides and water to 100%. Furthermore, we plan to develop a calibration strategy with various Reference Materials to optimize the quantitative determination of elements when the laser ablates diverse material phases.
Literature:
[1] The Interfacial Transition Zone (ITZ) Between Cement Paste and Aggregate in Concrete, K.L. Scrivener, A. K. Crumbie, P. Laugesen, Interface Science 12 (2004), 411-421
[2] LA-ICP-MS on hardened cement paste: laser-material interaction, signal formation and optimization of laser fluence, M. Decker, J. Siegel, H. Hilbig, D. Heinz, Materials and Structures (2021) 54:144; https://doi.org/10.1617/s11527-021-01736-4
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Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) puts forward many merits in material characterization like spatially resolved measurements of elemental distribution on macroscopic samples, or multi-element analyses with a low detection limit in a short time. Although its many advantages, LA-ICP-MS is not immensely employed in the field of building materials. In this study, we applied LA-ICP-MS as a method for examining the composition of the Interfacial Transition Zone (I...
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