Optimisation of magnesium oxychloride cement properties by silica glass

Abstract

The influence of different parameters on magnesium oxychloride cement (MOC) was investigated in this study. The use of experimental design was found to be very beneficial for determining suitable experimental conditions to obtain a better composition of cement. The studied factors used to model and optimise the operating parameters were stirring speed, mixing time, mass ratio of magnesium chloride/magnesium oxide, silica glass powder (SGP) percentage and SGP particle size. The considered responses were compressive strength and setting time. The phase compositions of MOC were evaluated by x-ray diffractograms, the morphological properties were examined by means of scanning electron microscopy and phase decomposition was analysed using differential thermal analysis/thermogravimetric analysis. It was found that the use of SGP can enhance the water resistance of MOC by the formation of forsterite, which can limit the decomposition of phase 5 and prevent the formation of brucite in water.

Recent development in magnesium oxychloride cement

“…74 The compressive strength retention coefficient was improved from 0.41 to 0.75. 74 The water resistance was improved.…”

“…With the increasing incorporation of SGP from 2 to 6%, the setting time was retarded from 166 to 259 min when MgO/MgCl 2 was 1.42, and compressive strength decreased from 70.4 to 51.76 MPa, but the water resistance was improved from 0.41 to 0.75 . The improvement of the water resistance of MOC with added SGP was attributed to the formation of forsterite, which filled the pores in the cement, restrained the decomposition of phase 5, and prevented the formation of brucite in water …”

“…Because of the low alkalinity of MOC, silica glass powder (SGP) was added into MOC as a modifier. It was revealed that the optimal dosage of SGP was 6% by weight of MgO powder, and the particle size of SGP was 150–200 μm . With the increasing incorporation of SGP from 2 to 6%, the setting time was retarded from 166 to 259 min when MgO/MgCl 2 was 1.42, and compressive strength decreased from 70.4 to 51.76 MPa, but the water resistance was improved from 0.41 to 0.75 .…”

“…SGP 2-6% by weight of the MOC paste. 74 The setting time was retarded and compressive strength was decreased. 74 The compressive strength retention coefficient was improved from 0.41 to 0.75.…”

“…74 The setting time was retarded and compressive strength was decreased. 74 The compressive strength retention coefficient was improved from 0.41 to 0.75. 74 The water resistance was improved.…”