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 to high microfine content of silica fume and light specific gravity. It is only possible to produce workable mixes in use of suitable superplasticizers. Use of polymer-based superplasticizer is more effective than inorganic superplasticizer to reduce water to cementitious materials ratio to 0.40. The optimal binder composition for strength and workability is found to contain 60% magnesium oxide and 40% silica fume (Mg/Si molar ratio equals 2.25) at which the proportions are not fully dependent on stoichiometry for formation of magnesium silicate hydrate gel but in line with high packing density mixtures to reduce …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
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 to high microfine content of silica fume and light specific gravity. It is only possible to produce workable mixes in use of suitable superplasticizers. Use of polymer-based superplasticizer is more effective than inorganic superplasticizer to reduce water to cementitious materials ratio to 0.40. The optimal binder composition for strength and workability is found to contain 60% magnesium oxide and 40% silica fume (Mg/Si molar ratio equals 2.25) at which the proportions are not fully dependent on stoichiometry for formation of magnesium silicate hydrate gel but in line with high packing density mixtures to reduce …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