It is observed that the black cotton soil predominant with montmorillonite, quartz and microcline revealed new peaks pertaining to alunogen and bassanite
due to contamination with sulfuric acid.
Shibi, "Effect of freeze-thaw cycles on durability and strength of very soft clay soil stabilised with recycled bassanite
," Cold Region Science and Technology, vol.
Because gypsum content was relevant in the studied soils, a temperature of 50[degrees]C was used to avoid constitutional water release by the gypsum crystal following the transformation of gypsum into bassanite
or anhydrite at temperatures >50[degrees]C (Herrero et al.
The mineral part of analysed samples is composed of clays, feldspars, carbonates, analcime, natrolite, quartz and bassanite
The salicylic acid and methanol (SAM) extraction dissolves alite ([C.sub.3][S.sup.1]), belite ([C.sub.2]S), and free lime (CaO), leaving behind a residue of the tricalcium aluminate ([C.sub.3]A) and ferrite ([C.sub.4]AF) interstitial phases as well as minor phases including periclase (MgO) and alkali sulfates such as arcanite (K[bar.S]), thenardite (N[S.sub.S]), and langbeinite (K[M.sub.2] [[bar.S].sub.3]), calcium sulfates (gypsum, bassanite
, and anhydrite), and carbonates (calcite and dolomite).
4), which demonstrated that in activated E-PG specimens no bassanite
was found, while in the case of gypsum cement the peaks of unhydrated gypsum were sufficiently distinct.
The most common minerals are halite, gypsum (or its water-depleted form, the so-called bassanite
), anhydrite, primary dolomite, and sodium sulphates.
Formula Mineral amount 05-0586 CaC[0.sub.3] Calcite Major 33-0311 CaS[O.sub.4]*2[H.sub.2]0 Gypsum Major 41-0224 CaS[O.sub.4]*0.5[H.sub.2]0 Bassanite
Minor 46-1045 Si[O.sub.2] Quartz Minor ICDD, International Centre for Diffraction Data.
Compositional estimates Type I/II Mass fraction % ASTM C 150 XRD Alite 62.5 62.1 Belite 11.4 12.1 Aluminate 7.2 4.5 Ferrite 8.0 9.7 Arcanite 0.4 Periclase 2.3 Gypsum 0.7 Bassanite
3.1 Anhydrite 0.3 Dolomite 0.8 Calcite 0.5 Quartz 0.2 Table 3.
The diffraction pattern of zinc-modified bentonite also shows the presence of bassanite
2CaS[O.sub.4]-([H.sub.2]O) with intense peaks at 2[theta] = 17.2, 34.6, and 37.2[degrees] .