Reaction-induced fracturing in a hot pressed calcite-periclase aggregate. (January 2017)

• Record Type: Journal Article
• Authors: Kuleci, H.; Ulven, O.I.; Rybacki, E.; Wunder, B.; Abart, R.
• Is Part Of: Journal of structural geology. Volume 94(2017:Jan.)
• Page Start: 116
• Page End: 135
• Publication Date: 2017-01
• Subjects: Hot isostatically pressed calcite-periclase aggregate -- Hydration of periclase -- Swelling particles -- Reaction induced fracturing -- DEM modelling; Geology, Structural -- Periodicals; Géomorphologie structurale -- Périodiques; Geology, Structural; Periodicals; 551.805
• DOI: 10.1016/j.jsg.2016.11.009
• Languages: English
• ISSNs: 0191-8141

Abstract

Abstract: The chemo-mechanical feedbacks associated with hydration of periclase immersed in a calcite matrix were investigated experimentally. Dense calcite-periclase aggregates with <5% porosity and with a calcite to periclase ratio of 90/10 and 95/5 by volume were prepared by hot isostatic pressing. Subsequent hydration experiments were performed in a hydrothermal apparatus at temperatures of 580–610 °C and a pressure of 200 MPa for run durations of 5–60 min. The rate of the periclase to brucite transformation was primarily controlled by the access of fluid. Where fluid was present, the reaction was too fast for the associated positive volume increase of the solids of about 100% to be accommodated by creep of the calcite matrix, and fracturing was induced. The newly formed cracks greatly enhanced the access of fluid leading to a positive feedback between hydration and fracturing. Mostly the newly formed cracks follow pre-existing grain boundaries in the calcite matrix. Comparison of experimental results with numerical 2D discrete element modelling (DEM) of crack formation revealed that the geometry of the crack pattern around a reacting particle depends on the shape of the original periclase particle, on the mechanical strength of the particle-matrix interface and on the mechanical strength and arrangement of grain boundaries in the calcite matrix in the immediate vicinity of the swelling particle. Highlights: Hydration induced fracturing in periclase-calcite aggregates is investigated. Strain cannot be accommodated by creep of the calcite matrix. Resulting crack pattern is controlled by the shape of the swelling particle. The mechanical strength of the grain-boundaries/matrix influences crack pattern. The mechanical strength of contact between swelling particle/matrix affects also.