THE COMPRESSIVE STRENGTH DEVELOPMENT OF A MAGNESIUM OXYCHLORIDE CEMENT COMPRISING A COMPOSITE ADDITIVE IN BRINE

Abstract

In this paper, the performance of a magnesium oxychloride cement (MOC) in a brine environment after the addition of an anti-corrosion admixture (Q101) was investigated. The compressive strength, compressive strength retention, crystal composition and microstructure were analysed in detail. The results show that the compressive strength of the MOC with the Q101 admixture maintains a high compressive strength of more than 100 MPa in air, and decreases slightly in the raw brine and the ageing brine, but the decreases are not significant with the compressive strength of 80 MPa. This demonstrates the excellent salt brine resistance in brine environment of the MOC. One reason is that the high content of Mg2+ and Cl- in brine suppress the dissolution rate of main hydration product in the MOC. The other is the addition of an anti-corrosion additive that improves the salt brine resistance by about 30%. However, the compressive strength and strength retention of the MOC after the raw brine immersion are higher than the ageing brine immersion. The reason may be that the salts fill the surface and the pores in the samples that prevented water erosion to some extent. Meanwhile, the MOC pastes have the biggest compressive strength retention when the Q101 was up to 10% over the long run. As a result, the optimum dosage of Q101 is 10% in this experiment.

Keywords

• magnesium oxychloride cement
• anti-corrosion additive q101
• compressive strength development
• compressive strength retention
• optimum dosage
• brine environment