International Workshop on Innovation in Low-carbon Cement & Concrete Technology
Abstract
Magnesium phosphate cement (MPC) is a promising material applied for rapid patch
repairing in civil engineering and waste immobilisation in nuclear industry. However, the
rheological properties of this new binder material which highly affects its engineering application,
is to be explored. The current work aims at investigating the rheological properties of MPC along
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with determining the optimum conditions to obtain MPC materials with desirable rheological
performances. The Response Surface Methodology (RSM) accompanied by Central Composite
Design (CCD) were adopted to establish mathematical model describing the rheological
characteristics of MPC in terms of yield stress (Pa) and plastic viscosity (Pa.s), as a function of
three independent variables namely W/S ratio, M/P ratio and Borax dosage. The analysis of
variance (ANOVA) was also conducted to assess the significance and adequacy of the regression
models attained. The results showed that the M/P ratio and Borax dosage could affect significantly
the yield stress of MPC, while W/S ratio was the significant coefficient influencing the plastic
viscosity. The numerical optimised values of the W/S ratio, M/P ratio and Borax dosage were 0.25,
8.97 and 0.17 respectively, and a MPC paste with desirable rheological characteristics (yield stress
of 0.40 Pa and plastic viscosity of 0.93 Pa.s) can be obtained. Further experiments will be carried
out to verify the predicted optimum conditions and study the interactions between the factors in
relation to the responses