InterPore2025

A scaling law for reaction-induced fracturing during mineral carbonation and hydration

22 May 2025, 12:05

15m

Oral Presentation (MS25) Advances in Carbon Mineralization: Unveiling Multiscale Geo-processes and Coupled Mechanisms MS25

Speaker

Masaoki Uno (Tohoku University)

Description

Mineral carbonation and hydration involve a large solid volume increase of tens of percent and may result in clogging of pores in the rocks and inhibit further reaction. On the other hand, natural observation of carbonated or hydrated peridotite and serpentinite suggests that the volume increase of the reactions can fracture rocks, enhance fluid flow, and promote further reactions [1,2]. Such reaction-induced fracturing has been considered as a key process promoting subsurface mineral carbonation, however, up to now, the majority of laboratory carbonation experiments result in pore clogging and have not reproduced macroscopic fracturing.

Here we show a clear experimental example of macroscopic reaction-induced fracturing caused by carbonation of brucite-rich serpentinite. During the reaction with CO2-saturated water, the brucite selectively dissolves from the sample surface, with minor magnesite precipitation on the surface and no fracturing. In contrast, the reaction with NaHCO3 solution shows that brucite selectively dissolves at the reaction fronts, and magnesite precipitates within the pre-existing micro-cracks, causing macroscopic fracturing of the sample, which promotes further carbonation in the sample interior. These contrasting mechanical responses during carbonation in our experiments, as well as differences in the previous laboratory experiments and field-scale carbonation, would be explained by the competition between the rates of carbonate precipitation and rates of solute transport, and may provide clues for the acceleration of anthropogenic mineral carbonation.