A nanoscale perspective on the effects of transverse microprestress on drying creep of nanoporous solids

Robert Sinko, Zdeněk P. Bažant, Sinan Keten*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The Pickett effect describes the excess non-additive strain developed during drying of a nanoporous solid material under creep. One explanation for its origins, developed using micromechanical models, is the progressive relaxation of internally developed microprestress. However, these models have not explicitly considered the effects of this microprestress on nanoscale energy barriers that govern the relative motion and displacement between nanopore walls during deformation. Here, we evaluate the nanoscale effects of transverse microprestresses on the drying creep behaviour of a nanoscale slit pore using coarse-grained molecular dynamics. We find that the underlying energy barrier depends exponentially on the transverse microprestress, which is attributed to changes in the effective viscosity and degree of nanoconfinement of molecules in the water interlayer. Specifically, as the transverse microprestress is relaxed (i.e. its magnitude decreases), the activation energy barrier is reduced, thereby leading to an acceleration of the creep behaviour and a stronger Pickett effect. Based on our simulation results, we introduce a new microprestress-dependent energy term into our existing Arrhenius model, which describes the relative displacement of pore walls as a function of the underlying activation energy barriers.

Original languageEnglish (US)
Article number20170570
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume474
Issue number2209
DOIs
StatePublished - 2018

Funding

Data accessibility. A representative LAMMPS input file for our simulations and the entirety of our simulation output files have been made available as the electronic supplementary material. Author contributions. R.S. carried out CGMD simulation work including designing simulations and analysing simulation data, developed the analytical model and drafted the manuscript. The majority of the work was conducted at Northwestern University and prior to publication, R.S. moved to Northern Illinois University. S.K. assisted in designing the simulations and helped in drafting the manuscript. Z.P.B. conceived of the study, designed the study and helped in drafting the manuscript. All authors gave final approval of the manuscript for publication. Competing interests. We declare we have no competing interests. Funding. S.K. acknowledges funding from the Army Research Office (award no. W911NF-13-1-0241). R.S. was supported by the DoD through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program. Z.P.B. was partially supported by Army Research Office (award no. W911NF-15-1-0240). The authors acknowledge support through a supercomputing grant from Northwestern University High Performance Computing Center and the Department of Defense (DoD) HPC System. S.K. acknowledges funding from the Army Research Office (award no. W911NF-13-1-0241). R.S. was supported by the DoD through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program. Z.P.B. was partially supported by Army Research Office (award no. W911NF-15-1-0240). The authors acknowledge support through a supercomputing grant from Northwestern University High Performance Computing Center and the Department of Defense (DoD) HPC System.

Keywords

  • Concrete
  • Drying creep
  • Molecular dynamics
  • Nanoconfinement
  • Pickett effect

ASJC Scopus subject areas

  • General Engineering
  • General Physics and Astronomy
  • General Mathematics

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