title: Combinatorial molecular optimization of cement hydrates.
abstract: Despite its ubiquitous presence in the built environment, concrete's molecular-level properties are only recently being explored using experimental and simulation studies. Increasing societal concerns about concrete's environmental footprint have provided strong motivation to develop new concrete with greater specific stiffness or strength (for structures with less material). Herein, a combinatorial approach is described to optimize properties of cement hydrates. The method entails screening a computationally generated database of atomic structures of calcium-silicate-hydrate, the binding phase of concrete, against a set of three defect attributes: calcium-to-silicon ratio as compositional index and two correlation distances describing medium-range silicon-oxygen and calcium-oxygen environments. Although structural and mechanical properties correlate well with calcium-to-silicon ratio, the cross-correlation between all three defect attributes reveals an indentation modulus-to-hardness ratio extremum, analogous to identifying optimum network connectivity in glass rheology. We also comment on implications of the present findings for a novel route to optimize the nanoscale mechanical properties of cement hydrate.
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Abdolhosseini Qomi
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Krakowiak
authors.affiliation: 1] Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA [2] <MSE>2 MIT-CNRS Joint Laboratory, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bauchy
authors.affiliation: Department of Material Science and Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Stewart
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: R
authors.initials: R
authors.lastname: Shahsavari
authors.affiliation: Department of Material Science and Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: D
authors.initials: D
authors.lastname: Jagannathan
authors.affiliation: 1] Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA [2] Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Brommer
authors.affiliation: Centre Interdisciplinaire des Nanosciences de Marseille, CNRS and AIX-Marseille Université, Campus de Luminy, 13288 Marseille, Cedex 09, France.
authors.forename: A
authors.initials: A
authors.lastname: Baronnet
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Buehler
authors.affiliation: 1] Department of Material Science and Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA [2] Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: S
authors.initials: S
authors.lastname: Yip
authors.affiliation: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: F-J
authors.initials: FJ
authors.lastname: Ulm
authors.affiliation: Department of Material Science and Engineering, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Van Vliet
authors.affiliation: 1] Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA [2] <MSE>2 MIT-CNRS Joint Laboratory, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA [3] Centre Interdisciplinaire des Nanosciences de Marseille, CNRS and AIX-Marseille Université, Campus de Luminy, 13288 Marseille, Cedex 09, France.
authors.forename: R J-M
authors.initials: RJ
authors.lastname: Pellenq