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Project N.3

Title:

Microstructural

 

modelling of AAM paste

 

Objectives

The main aim of ESR3 is to simulate microstructures (in-house numerical tool GeoMic3D) of the geopolymer paste. In the microstructure simulation, at certain liquid to powder ratio the initial particles’ packing is built up by taking into account the particle size distribution and the real particle shape. The mineralogical information of each particle is assigned. The dissolution kinetics of precursor elements will be modelled. The mineralogy of reaction products in time will be quantified through thermodynamic modelling. Following aspects have to be considered in the simulation process:

1) Initial microstructure: at certain liquid to powder ratio the initial microstructure is built up based on random packing of precursors where the particle size distribution and the real particle shape are taken as input. The mineralogical information of each particles is assigned. All information for initial packing of the microstructure can be obtained from ESRs1,4,5,7,8.
2) The dissolution kinetics: modelling the dissolution kinetics of different elements (mainly Si, Al, Ca and Fe) from precursors (mainly amorphous phases) will depend on the alkaline condition in the solution, temperature of the ambient solution.
3) The mineralogy of reaction products: The mineralogy of reaction products in the varying chemical environments as a function of time will be quantified through thermodynamic modelling.
4) Rate of reaction and allocation of reaction products: in this part the gelation mechanism is elucidated and the distribution of reaction products is quantitatively described. Based on the ion concentration in the pore solution and mineralogy of reaction products, the Lattice Boltzmann method will be utilized to simulate the coupling process of chemical reaction and ion transport. The nucleation and precipitation of reaction phases is determined based on heterogeneous and homogeneous nucleation. The growth of nucleus is simulated based on the rate of reaction obtained from experiments.
5) In the end, a time-dependent microstructure of alkali activated paste will be built up. The experimental results performed in ESRs1,4,5,7,8 will be used to validate the dissolution kinetics, reaction kinetics, the mineralogy of reaction products, and the phase distribution in the microstructure.

 

Expected Results

It is expected to produce a framework for modelling the geopolymerization reaction process and microstructural formation of alkali activated paste. The output of the framework will be pore solution chemistry, the volume fraction of reaction products and the capillary pore structure of alkali activated paste.

Last Updated: Friday, 14 December 2018 23:27