Study on pore structure characteristics of circulating fluidized bed fly ash-based lightweight foamed filler based on X-ray computed tomography

Abstract

As the main solid waste of coal-fired power plants, circulating fluidized bed fly ash (CFBFA) has a huge emission, but its resource utilization in the field of construction materials is limited due to the generation of volume-expanding substances such as caliche and gypsum during the hydration process. A lightweight foamed filler (LFF) was prepared by taking CFBFA as the main material and mixing the foam produced by mechanical foaming to obtain a LFF, which utilizes its internal porosity to alleviate the expansion. The pore structure characteristic parameters such as porosity, homogeneity, pore size distribution, fractal dimension, sphericity, etc. of LFF specimens with different foam doping amounts were investigated from the three-dimensional level using X-CT tomography and other technical means. As the foam doping increases, the phenomena of foam rupture and dissipation and merger and fusion were frequent, which led to the deterioration of the consistency of the morphology of the pores in the LFF materials, and the inhomogeneity of the pore size and the average pore size increased, but the distribution of the pore size conformed to the log-normal distribution. The parameters of the LFF such as the porosity, the homogeneity of the pore distribution, the pore size, etc., were exponentially related to the compressive strength, and relationships of the sphericity with the pore size and homogeneity were quasi-linear.