Study on fractal characteristics of pores of NAS reinforced by MICP under the control of electric field

Abstract

Natural aeolian sand (NAS) widely distributes all around the world, whereas, NAS have inferior mechanical qualities compared with the ordinary river sand, such as poor grading and low adsorption, resulting in the restricted application in engineering construction. The aim of this work is to improve the mechanical properties of NAS with microbial induced calcite precipitation controlled by electric field (EMICP). The transverse relaxation time T2 distribution spectrum of different electrifying time (0, 1 h, 2 h, 4 h, 8 h, 16 h) was collected with nuclear magnetic resonance (NMR) technology, and the multiple fractal dimension of pore volume was calculated according to the T2 spectrum. The evolution of micro structure with power on time of the reinforced aeolian sand (RAS) was analyzed with SEM test, and the crystal morphology in different mineralization stages was obtained by optical microscope. The geometry parameters of roundness and shape index were adopted to study the pore morphology characteristics, and the relationship between geometry parameters and pore fractal dimension of the RAS were established by regression analysis method. The adsorption and permeability test were carried out, and the equation of adsorption rate and permeability were established, too. The result indicating that, the pore volume of RAS has multi fractal dimensions, which were related with adsorption and permeability properties, showing the prospect of application of RAS in engineering field.