Influence of the microstructural properties of biocemented sand on its mechanical behavior

Abstract

Summary The mechanical efficiency of the biocementation process is directly related to the microstructural properties of the biocemented sand, such as the volume fraction of calcite, its distribution within the pore space, coordination number, contact surface area, and types of contact. In the present work, some of these microscopic properties are computed, from 3D images obtained by X‐ray tomography of biocemented sand. These properties are then used as an input in current analytical models to estimate the elastic properties (Young and shear moduli) and the strength properties (Coulomb cohesion). For the elastic properties, the analytical estimates (contact cement theory model) are compared with classical bounds, self‐consistent estimate and numerical results obtained by direct computation (FEM computation) on the same 3D images. Concerning the cohesion, an analytical model initially developed to estimate the cohesion due to suction in unsaturated soils is modified to evaluate the macroscopic cohesion of biocemented sands. Such analytical model is calibrated on experimental data obtained from triaxial tests performed on the same biocemented sand. In overall, the presented results point out the important role of some microstructural parameters, notably those related to the contact, on such effective parameters.

Micro-feature-motivated numerical analysis of the coupled bio-chemo-hydro-mechanical behaviour in MICP

“…Non-treated soil E g (MPa) 80 [47] Fully cemented soil E b (MPa) 300 Fitted Poisson's ratio m (-) 0.25 [11] Constitutive parameter (-) 1.…”

Discrete Element Modelling for biocemented sand: effect of calcite distribution at the microscopic scale

“…Generally, in granular materials, the tensile strength depends on the intrinsic strength of the cement material and its adhesion at the grain surface. According to [8], the tensile strength σ ten was calibrated in order to reflect the experimental results obtained for the biocemented samples in which the cohesion was measured by drained triaxial tests on the same bio-cemented sand. This calibration yielded to σ ten = 2.75 MPa .…”

“…It is quite clear that the mechanical efficiency of the bio-cementation process is directly related to the microstructural properties of the bio-cemented sand, such as, the volume fraction of calcite, its distribution within the pore space (localized at the contact between grains, over the grain surfaces) * e-mail: moha.abbas1996@gmail.com and the contacts properties: coordination number, contact surface area, contacts orientation, types of contact. [8] have used microscopic properties computed from 3D images obtained by X-ray tomography of bio-cemented sand as an input in current analytical models to estimate the elastic properties (Young's and shear modulus) and the strength properties (Coulomb cohesion). However, the effect of these microstructural parameters such as the contact surface distribution on the global mechanical behaviour of the soil remains hypothesized or vague and still needs some clarification using advanced modeling methods.…”

Impact of wetting and drying cycles on the mechanical behaviour of a cement-treated soil

“…In a few studies, the relationship between mechanical characteristics and the amount of cementitious products was investigated (e.g., [33,34]). For instance, Dadda et al [35] investigated the biocementation process effect on the micromechanical properties (coordination number, contact surface, and volume fraction of calcite) of biocemented Fontainebleau sand. This study managed to link the cohesion of the biocemented sand to the evolution of the cohesive surface and other micromechanical properties within the sand specimen using high resolution 3D images obtained by X-ray synchrotron microtomography.…”