Basic Research Program Multiscale Modeling of the Structure of Materials for Adaptive Protection 28 April 2009 Dr. Mei Chandler Geotechnical and Structures Laboratory Example

Multi-scale Modeling of Structure of Materials for Adaptive Protections Purpose: To study material responses and failure mechanisms of calcium silicate hydrate phases under quasi-static and dynamic loads at submicron and nano scales. To study the effects of nanoparticle packing, pore solutions and nanopores on the fracture of C-S-H under quasi-static and impact loads. Results:  Dynamic responses of C-S-H phases  Effects of nanoparticle packing, nanoparticle interforces, properties of C-S-H gel on dynamic responses of C-S-H phases  Effects of nanopore solutions on the material response of C-S- H phases  Effects of nanopores and nanocracks on dynamic responses of C-S-H phases  Constitutive relations of C-S-H phases with strain rate effects. Payoff:  Develop concrete with superior properties against impact and penetration  Establish a modeling methodology for C-S-H phases and other hydrated phases.  Obtain constitutive laws of C-S-H phases to be used in microscale and mesoscale simulation. Those constitutive laws are difficult to determine experimentally.  Provide a foundation in modeling nano-engineered concrete material Very-High-Strength-Concrete C-S-H nanostructure Nanoindenation Status: Basic 6.1 Milestones Study interpartical forces Setup DEM models DEM simulations and compare to the existing experimental data In-house experiments and model validation Parametric studies Army 6.1 total $250,000 $_750K Total Army Program

What is the Problem? Calcium Silicate Hydrate phases take up to 60% in volume in cement paste and is the glue that holds together all of the components in cement. Yet, the material responses and underlying failure mechanisms of this material under quasi-static and dynamic loads are lacking. The latest research shows that the nanostructure of this material is made up of nanoparticles and behaves in a nano-granual manner. This provides an opportunity for us to model this material at the submicron scales by using the Discrete Element Method. What are the barriers to solving the problem?  Morphology of C-S-H nanoparticles is not well established  Experiments results are limited Collaboration across ERDC, commercial firms and/or academia: Dr. Beverly DiPaolo (GSL) – Co-PI, Experimental testing, materials investigation Dr. John Peters (GSL) – Co-PI, consultation on DEM methods Dr. Jabari Lee (ITL) _Consultation on Monte Carlo Modeling Dr. Daniele Pelesonne (ESSI)_ MARs Dr. Hamlin Jennings (Northwestern) What is innovative about this work? In this work, we will model C-S-H phases at the nanoscale and submicron scales, taking into account the experimentally- observed C-S-H nanostructures, and taking into account the physical and chemical forces between C-S-H nanoparticles. This work has not been done at this time. What is your publication plan? Proposed refereed journal articles – 1. Discrete element modeling of nanomechanics of C-S-H 2. On the fracture of calcium silicate hydrate under dynamic loads 3. Constitutive laws of calcium silicate hydrate at the microscale How will you overcome these barriers?  DEM models will be used to study C-S-H at the nanoparticle level  We will coordinate with other 6.1 projects and design suitable experiments to validate the models What are the results of this research and what is its value?  Obtain knowledge of underlying failure mechanisms of C-S-H under quasi-static and dynamic loading  Develop robust constitutive equations to be used in microscale and mesoscale simulations.  Provide insight in nano-engineering concrete material  Provide a foundation in modeling nano-engineered concrete material. Multi-scale Modeling of Structure of Materials for Adaptive Protections

Accomplishments/Status (1 - 4 Slides) Identify major accomplishments through the month prior to the IPR for this work unit. The accomplishments should reflect significant and meaningful scientific contributions or technological achievements, rather than just indicating milestones met. Include accomplishments for all years the work unit has been funded. Provide expected accomplishments through the end of the current FY. Illustrate findings through graphics, tables, charts, photography, equations, etc. Verbally describe significance of findings. Show off your great stuff!

Describe what actual technology products will be handed off during tech transfer. A technical report is NOT considered to be a product. It is the vehicle by which the technology is transferred. Products

Describe patent disclosures, patents, etc. What other work packages in 6.2/6.3 projects will receive the benefits of this basic research? Technology Transfer

Prepare as a separate attachment a list of all publications planned and published for the duration of the project using the spreadsheet template provided. Publications

Provide name, organization, and subject area of technical collaborations Collaborations

Issues Issues of major interest are those issues that may cause failure of the work unit to meet the objectives. Typically, issues are of one or two types: –Limited Resources = Personnel + facilities + equipment + funds –Scientific/Technical (e.g., results do not support the hypothesis).