Mg-Xonotlite and its coexisting phases

Effect of magnesium on calcium silicate hydrate (C-S-H)

“…with repeating building blocks consisting of two pairing silicate tetrahedra attached to the calcium oxide layer and a bridging position, which can be occupied by a bridging silicate tetrahedra or be empty, depending on the C-S-H composition. Thus, silicate in C-S-H, investigated by 29 Si MAS NMR, is either bound to one silicate neighbor (Q 1 ) at high Ca/Si or to two neighbors, Q 2 at low Ca/Si ratio. In contrast, M-S-H gels have a layered silicate structure [13,15,16,27,28], similar as in clay minerals, and silicate is bound to two or three neighbors (Q 2 and Q 3 ).…”

“…It has been suggested that magnesium could be incorporated in calcium silicate hydrate [29][30][31], although no clear experimental evidence was presented. Very limited Mg-Ca exchange could have occurred at the surface of tobermorite (natural mineral with a structure, stoichiometry and density similar to a low Ca/Si C-S-H) [32,33] while for natural samples of tobermorite rather the presence of tobermorite with M-S-H and calcite in small veins have been observed [34].…”

“…The concentrations of Mg, Ca, Na, Si, Cl, in undiluted solutions or in solutions diluted by factors 10, 100 and 1000 were quantified using a Dionex DP serie ICS-3000 ionic Thermogravimetric analyses (TGA) were done on ground powder (~ 20-30 mg) using a heating rate of 20 °C/min from 30 to 980 °C with a Mettler Toledo TGA/SDTA 8513 instrument. The amount of Mg(OH) 2 (brucite) was quantified from the water weight loss around 400-420 °C using the tangential method [37] and calculated according to the Equation (1): 29 Si resonances were analysed using the Q n classification, where a Si tetrahedron is connected to n Si tetrahedra with n varying from 0 to 4.…”

Preparation of ultra-light xonotlite thermal insulation material using carbide slag

“…The physical performance of material was mensurated using GB/T 10699-1998 methods. The thermal conductivity and stability at different temperature of materials were tested using the JR-2 thermal conductivity tester (DRX-I-JR2, 0.01-10 W·(m·K) - Ǻ ) that the product was identified as pure xonotlite phase [15] , the result shows that xonotlite could be prepared by using carbide slag.…”

“…It could find typical xonotlite of "chestnut bur shape" [16] in Fig.3(a) and the size of these particles are about [15][16][17][18][19][20][21][22][23][24][25] μ m in diameter. The xonotlite crystal of "chestnut bur shape" stays in nemaline or needle shape shown in Fig.3(b).…”