X-ray Computed Tomography for Characterization of Expanded Polystyrene (EPS) Foam

Abstract

Expanded polystyrene (EPS) foam is widely used in building and construction applications for thermal and acoustic insulation. This material is nearly transparent for X-rays, making it difficult to characterize its pore structure in 3D with X-ray tomography. Because of this difficulty, the pore network is often not investigated and is, thus, poorly known. Since this network controls different physical properties, such as the sound absorption, it is crucial to understand its overall structure. In this manuscript, we show how to reveal the pore network of EPS foams through the combination of high resolution X-ray tomography (micro-CT) and saturation techniques. The foams were saturated with CsCl-brine, which acts as a contrasting agent in X-ray micro-CT imaging. This allowed us to separate the beads, making up the foam, from the pore network. Based on the 3D micro-CT results, we were able to assess a representative elementary volume for the polystyrene, which allows for calculating the acoustical parameters from the Johnson–Champoux–Allard (JCA) model, the pore and bead size distribution. The 3D data was also used as input to simulate sound absorption curves. The parametric study showed that an increase in the bead size influenced the sound absorption of the material. We showed that, by doubling the diameter of beads, the absorption coefficient was doubled in certain ranges of frequency.

IRT and GPR Techniques for Moisture Detection and Characterisation in Buildings

“…Next, the combination of Figure 27 and Figure 28 b allows corroborating that the visible deterioration (detachment) on the external surface of Wall_2 matches with the interpretations achieved: The joints with the most visible detachment on the outside surface of Wall_2 (blue dashed line rectangles in Figure 28 b) correspond to the ‘Upper Origin’ and ‘Lower Origin’ from the interior (Wall_2) with a slight difference in height (around 25 cm), being the joints above the interior detachment. Thus, the entry of water from the exterior to the interior can be deduced, which is in agreement with the porosity of the materials composing the wall, as seen in Figure 11 c (from exterior to interior): ceramic bricks (porosity 33%), EPS (porosity 15%), and double-hollow bricks (porosity 45%) [ 71 , 72 ]. By analysing the distribution of the degree of visible deterioration on the external surface of Wall_2, it is possible to confirm the circulation of water downwards by gravity and to the right (seen from the interior).…”

“…The joints with the most visible detachment on the outside surface of Wall_2 (blue dashed line rectangles in Figure 28 b) correspond to the ‘Upper Origin’ and ‘Lower Origin’ from the interior (Wall_2) with a slight difference in height (around 25 cm), being the joints above the interior detachment. Thus, the entry of water from the exterior to the interior can be deduced, which is in agreement with the porosity of the materials composing the wall, as seen in Figure 11 c (from exterior to interior): ceramic bricks (porosity 33%), EPS (porosity 15%), and double-hollow bricks (porosity 45%) [ 71 , 72 ].…”

Review of Microfluidic Devices and Imaging Techniques for Fluid Flow Study in Porous Geomaterials

“…Therefore, it has a very wide range of applications, including medical science, biology, earth science, material science and many other areas [ 209 , 210 , 211 ]. Characterization of pore shape and structure [ 12 , 212 , 213 , 214 ], saturation distribution [ 200 , 215 , 216 , 217 , 218 , 219 ], fluid flow mechanisms, soil deformation [ 220 ], and reactive transport [ 221 ] have been some of the main applications of X-ray CT in geological and hydrological studies.…”

Innovations in laboratory‐based dynamic micro‐CT to accelerate in situ research

“…The investigation of foams is widespread in the literature and are used for various applications ranging from building and construction (Banhart, 2003; Al‐Homoud, 2005; Salimon et al ., 2005; Zhang et al ., 2015) over packaging (Zhang & Ashby, 1994; Wang et al ., 2010) to food and beverages (Rouimi et al ., 2005; Narsimhan & Xiang, 2018). For the latter application, one important topic is the foaming of liquids and the stability of the foam over time.…”

“…During the experiment, scans of 5 min were taken by rotating the source and detector around the set-up. Another complex in situ setup was built inside the EMCT for the study of expanded polystyrene (EPS) foam (Meftah et al, 2019). The fluid flow set up was used to saturate the container with contrast agent.…”