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Engineered Materials for Resilient Infrastructure Program

Summary

Infrastructure is essential for commerce.  Planners and stakeholders want to develop infrastructure that is resilient to both chronic (e.g., material degradation) and episodic (e.g., earthquake) hazards. Accuracy in service life prediction remains elusive, particularly when episodic events are experienced in an aging structure that might no longer have the designed properties. This Program will develop and deploy measurement science to promote resilient infrastructure with a focus on materials properties by

  1. developing tools and methodologies for selecting materials to achieve desired performance given exposure to chronic and episodic hazards; and 
  2. developing methods to assess the current performance of existing infrastructure.  

This project would enable stakeholders to better manage US infrastructure assets through improved assessment of existing infrastructure and science-informed selection of materials for more resilient infrastructure.

Description

Objective - To develop and deploy measurement science to reliably assess the current and future performance of engineered materials in support of resilient infrastructure given exposure to chronic (e.g., materials degradation) and episodic (e.g., earthquakes) hazards.

What is the technical idea? 
To ensure that materials perform as needed for the expected service life of infrastructure, knowledge and prediction of the service life of the materials are necessary. Today, the selection of materials for new construction and the estimate of the remaining service life of materials already in place is left to the engineer and the inspector, respectively.  The technical idea is to enable solutions to these two needs that would ensure a resilient infrastructure: 

Materials Selection: 
To maintain resilience, it is necessary to build or repair infrastructure with the appropriate materials to achieve the desired level of performance for the anticipated hazards for the planned service life. Thus, tools are needed to ensure that the selection of materials is done using science-based predictive methodologies that forecast the performance of materials under actual operating conditions both in new construction and in repair. NIST will develop tools and methodologies to predict the performance of materials, starting with concrete and polymeric materials, needed for new construction and for repair.

Materials Assessment: 
To have a resilient community, it is necessary that the infrastructure is operational at all times. Operational infrastructure implies that all the parts of a structure (from roads to schools, hospitals, power/energy generation & distribution, communication) operates as designed. Due to chronic or acute hazards, the materials of construction are likely compromised. NIST will develop tools and methodologies to assess the performance of materials used in an existing structure and predict their remaining service life. An additional goal is that the material assessment will also assist with shortening the time towards achieving a functional recovery.

These two thrusts will enable prediction of service life of infrastructure based on the materials. It will allow development of tools for engineers, inspectors, and owners to make decisions on the materials used based on an accurate projection of the time and exposure of the structure.

If the information is known for each material in a structure, the next stage would be to determine the status of the entire structure by combining all the material service curves for the structure and working directly with the NIST Engineering Laboratory Resilience Programs to conduct validation studies. It could be assumed that the structure would fail (no longer functional) if the most critical component fails or is sufficiently deteriorated. This information could then be integrated with other programs in the resilience goal to ensure that models have the materials parameters needed to inform a community for planning resilience.

By knowing how materials age, observed laboratory material damage could be related to material damage in the field allowing for methods to predict future damage. There still is a knowledge gap between estimating material damage and estimating structural performance. This program will work to develop a future project to evaluate structural materials to chronic and acute hazards and to help support a collaboration with the Structural Performance under Multi-Hazards program.

What is the research plan? 
Traditionally, this program has limited its research to two materials, concrete and polymers.  To better address the resilience of structures, this program will develop a strategic plan that identifies the most important measurement science challenges for achieving resilient buildings and infrastructure by material selection and assessment for all infrastructure materials, such as concrete, steel, wood, ceramics, and polymers, as it applies to the leading chronic and episodic hazards.  It will also pursue activities that would enhance the capabilities for research on any material, including those listed below in five projects.  

Outputs from the projects will go into a materials database, comparable to the MML Materials Data Curation System framework, and will consist of materials properties as a function of a variety of environmental stressors or other variables so that stakeholders can use the data to develop predictive models for their products. NIST will collaborate closely with the industry to ensure that any tools developed will be quickly adopted as standards.

Once the strategic plan is completed, all resources are to be directed towards the resilience measurement science challenges identified in the strategic plan.  

In FY18 and FY19, the projects objectives listed here as per the two thrusts were:

Material Selection:

  • Direct Assessment of Concrete-Making Materials for Standards and Specification: To develop and promote new standard test methods and specifications for cement and concrete materials based upon a comprehensive assessment of mineralogical, chemical and textural properties.
  • Hydration Reactions in Microstructures: Generate and publish reaction rate data and enhanced computer modeling tools to better understand and predict the rates of microstructure development and phase interactions in portland cement concrete binders.
  • Accelerated Weathering and Service Life Prediction of Engineered Polymer Materials: Develop indoor accelerated and outdoor weathering property-performance database, traceable measurements, validated statistical models for service life prediction models of engineered polymer materials for resilient infrastructure.

Material Assessment:

  • Additive Manufacturing with Cement-based Materials: Develop measurement science tools (metrologies, standards, and guidance documents) for quantitatively evaluating the critical material properties and ensuring the desired field performance of cement-based additive manufacturing.
  • NIST Accelerated Weathering Laboratory-Metrology and Technology Transfer: To maintain, improve and expand capabilities at the NIST Accelerated Weathering Laboratory (AWL) to conduct safe, accurate and traceable aging experiments and to transfer the SPHERE technology to industrial stakeholders. Commercialize a NIST-traceable weathering device and develop complementary standard test methods to improve accuracy of accelerated aging for our stakeholders.

For FY20, the projects were reorganized due to several changes for the groups in the EMRI program. First, the Inorganic and Polymeric Materials Groups merged to become the Infrastructure Materials Group. The new Group’s objective is to conduct research to develop a fundamental understanding of the properties and the degradation mechanisms required for predicting performance throughout the service life of conventional and innovative materials, components, and systems composing US buildings and infrastructure systems exposed in their intended or accelerated loading environments. The group merger should aid collaborations and leverage common goals by reducing silos and group-oriented optimization and provide opportunities for all staff to apply their expertise to the important problems that will make the new group successful. Second, there was a wave of staff retirements and one staff departure for a university position for a total group loss of 4 senior researchers. Finally, there were also changes in leadership for both the group and for the projects. The Hydration Reactions project has been cancelled due to Bullard’s departure. The NIST Accelerated Weathering Laboratory-Metrology and Technology Transfer project was re-focused to achieve the operation and validation of the 6-Port SPHERE device. The SPHERE Data Validation task is in the Materials selection thrust and the 6-Port SPHERE Operation and SPHERE Engagement tasks are in the Materials Assessment thrust. A new Group Leader was hired from outside of NIST and will work to develop a new “whole” group culture, and takeover the Program strategic plan to develop an infrastructure materials area.

For FY21, all projects from the prior year will continue with the same level of funding. One change will occur in the NIST Accelerated Weathering Laboratory-Metrology and Technology Transfer for the SPHERE Engagement task, which will conclude after Q1. This change will allow for further cross-pollinating of staff expertise and apply their skills in new ways to current projects. The Program will also plan a workshop with stakeholders to validate the strategic plan identifying the most important measurement science challenges for achieving resilient buildings and infrastructure such as concrete, steel, wood, ceramics, and polymers) it applies to the leading chronic and episodic hazards.

Major Accomplishments

Progress on Program Strategic Plan: In FY18 and FY19, Watson and Ferraris compiled a review of literature, codes, and standards related to materials for resilient infrastructure. Infrastructure categories were defined as building envelope (polymer/composites, ceramic/glass, gypsum products, bituminous materials); structural materials (concrete, brick/structural clay, wood/timber, and structural steel); water and communications (polymer/composites, concrete, and metal); transportation (concrete, asphalt, metal), and energy (polymer/composites, concrete and metal). Interviews were also held with industry and experts in the construction field and SDOs associations. Interview topics included polymer composites, wood/timber, concrete, and structural steel. A detailed outline of a roadmap document was completed. With staff and leader changes to the groups in the EMRI program, the new Group Leader will take over Program strategic plan and develop an infrastructure materials area starting in FY20.

FY18: For Materials Selection: A subset of CCRL cements was identified and procured for characterization and sulfate resistance testing by ASTM C1012 and the NIST small neat cement paste bar methods. A continuous stirred reactor for cementitious material reactivity measurement was constructed and tested. A quantitative model for polymeric infrastructure materials that relates the UV degradation from outdoor exposure to laboratory exposure data taken from the NIST 2m SPHERE weathering device was validated. This seminal tool will demonstrate the applicability of using laboratory exposure data to predict the corresponding UV degradation of the same polymeric material in an any outdoor exposure, for industrially relevant performance properties. For Materials Assessment: Rheology studies correlated printability and rheological measurements for bench scale concrete 3D printing. Operation of a new commercial 0.5 m industrial-scale sphere system was attained for benchmarking and validation against the NIST 2m SPHERE to ensure that measurements are consistent and traceable.

FY19: For Materials Selection: A database was created with data on materials mineralogy, physical characteristics, and proficiency test data from CCRL. Chemical degradation (crystallinity and molecular weight) for PE and PET was tracked to understand underlying mechanical property trends for SPHERE aging compared to outdoor weathering. For Materials Assessment: A pilot-size mortar 3D printer was installed in bldg. 206. A guidance document for converting an off-the-shelf desktop fused filament fabrication additive manufacturing device (3D printer) to a device that can print cement paste objects by extrusion was published. This capability, to construct a cementitious printer, would provide industry with a means of engineering the required flow properties for the paste component of full-scale 3D printed concrete structures by printing standardized test artifacts. The NIST Journal of Research paper describes hardware, software, programming modifications, and steps to calibrate modified device. Spectral radiometry was used to compare differences in exposure conditions on 6-Port device compared to the 2m SPHERE.

FY20: For Materials Selection: A proficiency test program for XRD analysis of commercial Portland cements was coordinated with ASTM and proficiency test scores, precision, and relative bias for each participating lab were calculated. A metadata set of chemical and mechanical properties was compiled for PET and a polyester system to sunset the results from last year’s polymer weathering project. A “real” polymer system with additives was identified, PE with UV absorber, and procured from the manufacturer to test the NIST SPHERE accelerated weathering protocol. For Materials Assessment: The mortar 3-D printer in building 206 was commissioned and Discrete Element Method (DEM) simulations were completed to monitor and optimize flow through the nozzle and the mixing nozzle. Information was compiled from NIST stakeholders, customers, other interested parties about the issues surrounding the broader adoption of the NIST SPHERE based SLP approach, which will result in an internal NIST report. A standard operating procedure was developed to accurately measure the irradiance for accelerated weathering devices, including the NIST 6-port SPHERE. The standard operating procedure includes specifications for radiometer hardware and software for irradiance measurements; calibration requirements and calibration frequency; and specifications to characterize long-term irradiance levels and uncertainty for weathering devices. an infrastructure materials area.

For FY21, all projects from the prior year will continue with the same level of funding. One change will occur in the NIST Accelerated Weathering Laboratory-Metrology and Technology Transfer for the SPHERE Engagement task, which will conclude after Q1. This change will allow for further cross-pollinating of staff expertise and apply their skills in new ways to current projects. The Program will also plan a workshop with stakeholders to validate the strategic plan identifying the most important measurement science challenges for achieving resilient buildings and infrastructure such as concrete, steel, wood, ceramics, and polymers) it applies to the leading chronic and episodic hazards.


Created December 1, 2017, Updated January 7, 2021