Strength And Workability Of Magnesium Silicate Hydrate Binder System

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Experimental Study of Strength and Workability of Magnesium Silicate Hydrate Binder System
H.M. Tran, A. Scott
Abstract—The novel binder system of magnesium silicate hydrate has the advantage of low-CO2 production and potential use for structures and nuclear waste immobilisation. This paper discusses the experimental study to optimize proportions of cement paste and mortar for compressive strength and workability using magnesium silicate hydrate system. Binary systems containing magnesium oxide and amorphous silica (silica fume) were studied in which amount of each constituent accounted for 40-60% by mass of the binder. It is found that magnesium silicate hydrate binder system requires very high water demand compared to Portland cement due
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The low Mg/Si molar ratio system contained the highest silica fume content (Mg/Si = 1.0 corresponding to MgO/SiO2 = 40/60 wt.% by mass), represented chemical stoichiometry to facilitate formation of M-S-H gel [7, 8]. On the other hand, due to the large difference of particle sizes between MgO and SF, the high Mg/Si molar ratio combination (Mg/Si = 2.25 corresponding to MgO/SiO2 = 60/40 wt.% by mass) was assumed to improve packing density of the binder despite decreasing formation of M-S-H gel. In such cases of high MgO content, the hydration products might contain residual brucite (Mg(OH)2) and therefore both brucite and M-S-H gel exist in the …show more content…
Fresh M-S-H paste/mortar mixtures were prepared and placed in the standard cone (50 mm in height, 70 mm internal top diameter, 100 mm internal base diameter) in two layers; each 25 mm layer was tamped 20 times with the tamper. Excess paste/mortar was removed from the top of the cone and the mold was lifted up slowly away from the paste/mortar in 1 minute after completing the mixing operation. The table was immediately jolted 25 times in 15 seconds and flow value was measured by the increased base diameter of the mixture spreading on the

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