Porosity estimation and pore structure characterization of foamed cement paste using non-specialized image digital processing

In foamed concrete, porosity is essential because it is strongly related to other properties such as density, permeability, and strength. Porosity measurement (usually expressed as a percentage of total volume) is obtained in a laboratory using experimental water vacuum saturation and MIP methods. However, pore structure -including size, distribution, shape, and connection- is also needed to understand foamed concrete performance. Pore structure characterization is estimated through specialized digital image analysis. Micro CT, scanning electron microscopy or X-ray tomography images are frequently used to obtain pore structure on cellular concrete. However, these images are highly specialized and require equipment that is not easy to find and very expensive. Also, image processing is complex, and it includes some specialized software. This paper presents a pore structure characterization and porosity estimation using non-specialized digital images on foamed cement paste made with alternative agents. The procedure for acquiring images uses only a camera without any specialized equipment. The proposed methodology isolates the pores in the image and measures shape features such as pore diameter, eccentricity, and solidity. Acquiring and processing the images is simpler, faster, and cheaper than other specialized analyses. Results show that the volumetric porosity estimation was entirely accurate, with an estimation deviation of less than 10%. Also, the pore structure parameters such as pore size and distribution of foamed pastes can be quantified accurately.