Evidence of the production and dissolution of carbonate phases in bentonite formations

Cementation of Sands Due to Microbiologically-Induced Carbonate Precipitation

“…The unconˆned compressive strength of theˆne sand layers was estimated from the gradient of penetration using the relationship in Eq. (12).…”

“…The needle was penetrated into the sand specimens after microbiologically cemented, and the penetration resistance (kPa) and penetration distance (mm) were measured. From the results, the unconˆned compressive strength of the sands was estimated using the correlation between unconˆned compressive strength and so called``penetration gradient (N/mm)'' which can be determined penetration and penetration resistance of the needle, by log (qu)＝0.978x＋2.599 (12) where x is the logarithm of``the penetration gradient'', when the logarithm of qu is the unconˆned compressive strength. The relationship is presented as a calibration of the penetrometer.…”

“…Larger amounts of Mg possibly contribute to the formation of dolomite or magnesite, because of the high Mg/Ca ratio. Dolomite (CaMg(CO3)2) and magnesite (MgCO3) can resist against acid more than calcite (Fukue et al, 2010).…”

Effective Use of Plant-Derived Urease in the Field of Geoenvironmental/ Geotechnical Engineering

“…Larger amount of Mg contribute to form dolomite (CaMg (CO 3 ) 2 ) or magenesite (MgCO 3 ). Both of them can resist against acid more than calcite [90]. The resistance against acetic acid is stronger for the cementation with Mg/Ca ratio of 0.5 than calcite without magnesium, and UCS value estimate as 3.2 MPa for Mg/Ca ratio of 0.5 and 1 MPa for calcite without magnesium [91].…”

“…Ureolytically-driven calcium carbonate precipitation is a basis for a promising in-situ remediation of contaminants. Co-precipitation in calcium carbonate is one attractive in-situ remediation strategy for divalent radionuclide and trace metal ions, such as 60 Co, 137 Cs, and 90 Sr. The reactions involved in this process are as follows [117].…”