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 (MgKPO4·6H2O, MKP) is the main hydration product of the 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. 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 both 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.
Highlights
The production of widely used Portland cement consumes a lot of energy and emits a large amount of carbon dioxide, causing serious environmental pollution
The tetrahedral mesh generated by AVIZO software was imported into ABAQUS software as the X-ray Computed Tomography (X-CT) nanoindentation model of the MgKPO4·6H2O where potassium hexahydrate hexahydrate (MKP)
A MKP particle with the size of about 3 mm was tested by mercury intrusion porosimeter (MIP) and X-CT, respectively
Summary
The production of widely used Portland cement consumes a lot of energy and emits a large amount of carbon dioxide, causing serious environmental pollution. Magnesium phosphate cement (MPC) is a carbon-free cement that does not emit carbon dioxide during the production process (Walling and Provis, 2016). MPC is considered as a new Experimental-Computational Approach to MKP Nanoindentation type of environmentally friendly cement (Haque and Chen, 2019). It is believed as a cementitious material formed by acid-base chemical reaction between water, magnesium oxide, and phosphate. The main chemical reaction equation of potassium MPC is shown in Equation (1): MgO + KH2PO4 + 5H2O→MgKPO4·6H2O where potassium hexahydrate hexahydrate (MKP) is the main hydration product of the MPC (Vinokurov et al, 2018a)
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