000263064 001__ 263064
000263064 005__ 20190213112551.0
000263064 0247_ $$2doi$$a10.1007/s11440-019-00764-3
000263064 037__ $$aARTICLE
000263064 245__ $$aCell-free soil bio-cementation with strength, dilatancy and fabric characterization
000263064 260__ $$c2019
000263064 269__ $$a2019
000263064 336__ $$aJournal Articles
000263064 520__ $$aA multi-disciplinary approach is adopted in the present work towards investigating bio-cemented geo-materials which extends from sample preparation, to microstructural inspection and mechanical behaviour characterization. We suggest a new way to induce “cell-free” soil bio-cementation along with a comprehensive description of bio-improved mechanical and microstructural properties. We utilize the soil bacterium Sporosarcina Pasteurii in freeze-dried, powder -instead of vegetative-, state and determine overall reaction rates of “cell-free” Microbial-Induced Calcite (CaCO3) Precipitation (MICP). We further investigate strength and stiffness parameters of three base geo-materials which are subjected to MICP under identical external bio- treatment conditions. Different trends in the mechanical response under unconfined and drained triaxial compression are obtained for fine-, medium- and coarse-grained sands for similar range of final CaCO3 contents. Pre- and post-yield dilatancy-stress relationships are obtained revealing the contribution of dilatancy in the achievement of peak strength. Medium-grained sand yields higher dilatancy rates and increased peak strength with respect to fine-grained sand. Further, insight into the bio-cemented material’s fabric is provided through scanning electron microscopy, time-lapse video microscopy and X-ray micro-computed tomography with subsequent 3D reconstruction of the solid matrix. A qualitative description of the observed precipitation behaviours is coupled with quantified microscopic data referring to the number, sizes, orientations and purity of CaCO3 crystals. Results reveal that MICP adapts differently to the adopted base materials. Crystalline particles are found to grow bigger in the medium-grained base material and yield more homogenous spatial distributions. Finally, a new workflow is suggested to ultimately determine the crucial contact surface between calcite bonds and soil grains through image processing and 3D volume reconstruction.
000263064 536__ $$aFNS$$c200021_140246
000263064 6531_ $$amaterial fabric, strength, micro tomography, 3D image processing, microbial-induced calcite precipitation
000263064 700__ $$0248054$$aTerzis, Dimitrios
000263064 700__ $$0240226$$aLaloui, Lyesse
000263064 773__ $$tActa Geotechnica
000263064 8560_ $$fdimitrios.terzis@epfl.ch
000263064 909C0 $$zPasquier, Simon$$xU10264$$pLMS$$mlyesse.laloui@epfl.ch$$0252080
000263064 909CO $$ooai:infoscience.epfl.ch:263064$$pENAC$$particle
000263064 960__ $$adimitrios.terzis@epfl.ch
000263064 961__ $$apierre.devaud@epfl.ch
000263064 973__ $$aEPFL$$sACCEPTED$$rREVIEWED
000263064 980__ $$aARTICLE
000263064 981__ $$aoverwrite