Molecular dynamics simulation of N-A-S-H geopolymer macro molecule model for prediction of its modulus of elasticity

摘要

Geopolymer as a new type of alkaline cement with low CaO is produced by the synthesis of aluminosilicate materials with an alkaline solution. The identical structure of geopolymers is still unclear, although a number of structures have been considered. N-A-S-H compound as one of these introduced structures consists of different molecule components. The latest N-A-S-H model for geopolymers includes structural aluminosilicate molecules with various motifs of charge balancing of Q(4)(4Al)Si seems to be appropriate for molecular dynamic simulations. Since the optimum ratio of Si/Al = 2 is reported by different researchers, in this paper the N-A-S-H model is modified by reconsidering this ratio for molecular dynamics simulations to obtain its modulus of elasticity. Simulation parameters were chosen based on the findings of the past literature review. In order to consider the randomness of the proposed amorphous structure of N-A-S-H several simulations were conducted to find the mean value of the modulus of elasticity. The modulus of elasticity was calculated by an existing stress-strain script in the Material Studio (R) software. The simulation results showed good agreements with the existing experimental ones. This finding proves that the proposed modified N-A-S-H model is capable of being considered for further research and investigations. (C) 2020 Elsevier Ltd. All rights reserved.