Experimental evidence of reaction-induced fracturing during olivine carbonation
by Wenlu Zhu, a visiting Associate Professor from the University of Maryland.
Mineral carbonation, a process that binds CO2 in the form of carbonates by silicate weathering, is widespread on the Earth’s surface. However, it is unclear how the fluid-rock reaction proceeds to completion in spite of an increasing solid volume. We conducted a mineral carbonation experiment in which a sintered olivine aggregate reacted with a sodium bicarbonate solution at reservoir conditions. Time-resolved synchrotron X-ray microtomographic images show cracks in polygonal patterns arising in the surface layers and propagating into the interior of the olivine aggregate. The nanotomography data reveal that the incipient cracks intersect at right angles. Based on these findings, we infer that stretching due to non-uniform volume expansion generates polygonal cracking of the surfaces.