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:
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.
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. Thus, tools and methodologies are needed to assess an existing structure’s current state or level of performance. NIST will develop tools and methodologies to assess the performance of materials used in an existing structure and predict its remaining service life.
These two thrusts will enable prediction of service life of infrastructure. It will allow development of tools for engineers, inspectors, and owners to make decisions on materials based on an accurate projection of the time and exposure dependent conditions 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.
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.
Once the strategic plan is completed, all resources are to be directed towards the resilience measurement science challenges identified in the strategic plan. The goal is to ensure development of tools for the industry to address two main thrusts: Material Selection and Material Assessment.
The projects objectives are listed here as per the two thrusts:
- 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.
- 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.
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.