Experimental-Computational Approach to Investigate Nanoindentation of Magnesium Potassium Phosphate Hexahydrate (MKP) With X-CT Technique and Finite Element Analysis

Abstract

The magnesium phosphate cement (MPC) is a carbon-free cementitious material, widely used in solidification of nuclear waste, heavy metals, and repair and reinforcement. The magnesium potassium phosphate hexahydrate (MgKPO 4 ·6H 2 O, MKP) is the main hydration product of MPC, seriously affecting the mechanical properties of the MPC. Therefore, this paper presented an experimental-computational approach to investigate the mechanical properties of the MKP through nanoindentation with X-ray Computed Tomography (X-CT) technique and finite element analysis. Firstly, the micro-mechanical properties and structural distribution characteristics of the MKP were tested based on the nanoindentation and the X-CT technique, respectively. Then, the 3D structure grid model of the MKP was obtained based on X-CT data, imported into the ABAQUS software for the finite element simulation. Besides, considering the effect of porosity and pore distribution on the damage, the modified MKP constitutive relation was proposed and input into the X-CT nanoindentation model and the RAP nanoindentation model, respectively. It was found that those two models can effectively describe the mechanical and deformation characteristics of the MKP, which verified the correctness of the modified constitutive relationship of MKP. Finally, the influence of pore distribution on the nanoindentation results was predicted based on the RAP nanoindentation model.

Influence of crack width on the stiffness recovery and self-healing of reactive magnesia-based binders under CO2-H2O conditioning

“…As a part of the search for alternative materials with lower CO2 emissions, reactive magnesia cement (RMC) is being investigated due to its ability to gain strength via carbonation and the lower temperatures (700-1000 °C) used during its production in comparison with PC [19][20][21]. In addition to RMC systems, other magnesia-based formulations that have been investigated and used in a number of construction applications include magnesium oxychloride cements [22][23][24], magnesium phosphate cements [25][26][27][28][29][30][31] and magnesium oxysulfate cements [32,33].…”