Haleh Azari, Ph.D. AASHTO Materials Reference Laboratory (AMRL) AASHTO Subcommittee on Materials Meeting August 2007

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1 Haleh Azari, Ph.D. AASHTO Materials Reference Laboratory (AMRL) AASHTO Subcommittee on Materials Meeting August 2007

2 AMRL Research Program Mission Meet the Research and Standards Needs of the AASHTO Member States

3 AMRL Unique Position AMRL is located at National Institute of Standards and Technology (NIST) campus Part of the Materials and Construction Research Division Unique equipment and laboratories to conduct research Access to NIST technical expertise and state-of-the-art materials testing technology

4 AMRL Role in Innovation in Paving Materials There are wealth of research done at NIST that can be: applied to solve the challenges of state DOTS used to improve the AAHSTO standards Benefits from NIST research findings can be obtained by: making the connection between NIST and pavement community having NIST participate in highway research AMRL can make this connection

5 AMRL Research Program Vision Apply NIST Innovations in Construction Materials to Improve Pavement Materials Technology

6 Research Activities Accomplished work Current research activities Future research plans Research potentials

7 Accomplished Work NCHRP 9-26 (4): Precision Estimates for Selected Volumetric Properties of HMA Using Absorptive Aggregates Interlaboratory Study (ILS) provided estimates of precision for various test methods associated with HMA mix design when absorptive aggregates are used. Aging Time Experiment determined the effects of aging time on mixtures containing absorptive aggregates and provided appropriate aging time for mixtures with absorptive aggregates.

8 Accomplished Work, Cont. NCHRP 9-26 (5): Precision Estimates for AASHTO Test Method T 269 Determined Using AMRL Proficiency Sample Data Provided precision estimates that reflect four different compaction methods included in the scope of the AMRL Proficiency Sample Program. Provided recommendations for improving the precision estimates of AASHTO T 269.

9 Current Research NCHRP 9-26 (A): Interlaboratory Studies and Data Mining to Collect Data for the Preparation of Precision Statements Develop, verify, or update precision estimates for several AASHTO test methods selected by AASHTO Highway Subcommittee on Materials (HSOM) Broad range of highway materials including soil, aggregate, asphalt binder, asphalt mixture, hydraulic cement, and hydraulic cement concrete

10 Test Methods in NCHRP 9-26 (A) AASHTO T 22, Compressive Strength of Cylindrical Specimens. AASHTO T 104, Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate. AASHTO T 105, Chemical Analysis of Hydraulic Cement. AASHTO T 186, Early Stiffening of Hydraulic Cement (Paste Method). AASHTO T 154, Time of Setting of Hydraulic Cement Paste by Gilmore Needles. AASHTO T 180, Moisture-Density Relations of Soil Using a 4.54-kg. (10-lb.) Hammer and a 457-mm (18-in.) Drop. AASHTO T 287, Asphalt Cement Content of Asphalt Concrete Mixtures by the Nuclear Method. AASHTO T 265, Laboratory Determination of Moisture Content of Soils. AASHTO T 148, Measuring the length of Drilled Concrete Cores. AASHTO T 242, Frictional Properties of Paved Surfaces Using a Full-Scale Tire. AASHTO T 283, Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage.

11 Current Research, Cont. NCHRP 20-7/ Task 243: Development of a Test Method for Optical Sizing and Roundness Determination of Glass beads Utilized in Pavement Markings Joint AMRL/NIST effort Interlaboratory study Glass beads optical measurements 15 Labs Measurements at NIST laboratories using confocal scanning laser microscopy x-ray computed microtomography

12 Future Research (1) NCHRP 04-35: Enhanced Test Method for Specific Gravity and Absorption of Coarse and Fine Aggregates AMRL/NIST/NCAT joint effort x-ray absorption x-ray computed microtomography SEM

13 Future Research (2) NCHRP D-08: Developing a Laboratory Test for Determining the Initial Retroreflectivity Level of Glass Beads in Pavement Makings (Contingent on the availability of funds) optical scattering instrumentation and laser scanning confocal microscopy will be used to study the effect of size distribution, morphology, and dispersion of glass beads on optical reflection

14 Future Research (3) Proposed supplementary research related to NCHRP 9-26(A): Hydraulic Cement Composition Analysis and Performance Prediction (will be presented in detail at the Technical Section 3a)

15 Future Research (4) Pooled fund study Measurement of Cement Paste Workability Using Asphalt DSR (will be presented in detail at the Technical Section 3a)

16 Future Research(5) Proposal for NCHRP 20-7 : Development of a Standard Test Method for Particle Size Measurement of Cement Utilized in Concrete Pavements Measure particle size distribution (PSD) using laser diffraction (LD) Determine correlation between measuring fineness by PSD using LD and values obtained with the Blaine method (T153)

17 Future Research (6) Proposal for NCHRP 20-7 : Measurement of Early-Age Deformation of Concrete No standard test method exists for measuring earlyage deformation of concrete Evaluate feasibility, repeatability and robustness of using a vertical dilatometer Collect deformation measurements on wide variety of freshly cast concrete cylinder

18 Virtual Compaction Science-based compaction models Computer simulation of aggregate packing, Accurate calculations of compaction force transmission through an aggregate packing

19 Potential Research based on Current NIST Capabilities

20 Environmental Influences

21 Laboratory Aging Controlled temperature, humidity, ultra violet radiation, and strain is used to age materials in a custom SPHERE device (Simulated Photo degradation due to High Energy Radiant Exposure)

22 Total Effective Dosage Model E o E reflected E absorbed TOTAL EFFECTIVE DOSAGE D(t) DAMAGE Dissipated E transmitted

23 Total Effective Dosage Model D total ( t ) t λ = E ( λ, t )( 1 e ) φ ( λ ) d λ dt 0 λ max min o A ( λ ) D total (t) = total effective dosage E o (λ,t) 1-e -A(λ) = spectral absorption of specimen φ(λ) λ min, λ max = spectral UV irradiance from light source = spectral quantum yield of specimen = min. and max. photolytically effective wavelengths

24 Computational Materials Science Research dominated in past by empiricism, due to complicated nature of material Key to transforming the study of random materials like concrete and asphalt?

25 Material Characterization Cement X-ray diffraction, scanning electron and optical microscopy, laser diffraction particle size distribution Aggregates particle shape via x-ray tomography, laser diffraction particle size distribution SEM Ion chromatograph Impedance spectrometer

26 X-Ray Powder Diffraction Source: Copper Target 2200 watts, Cu Kα, nm Detector direct phase analysis each phase produces a unique pattern each pattern is produced independent of the others intensity is proportional to concentration Specimen: powdered and packed providing a smooth surface raw data alite belite

27 SEM/BSE Image Ca Si Al K X-ray element maps are used to segment image into phases Complete particle characterization

28 Full 3-D shapes One slice from an X- ray microtomography, stack together to get 3-D cement or aggregate particle information Model cement + water mixture

29 L = 3.85 W = 3.17 T = 1.0 ASTM D 4791 L = length W = width T = thickness

30 Aggregate for Hot-Mix Asphalt & Concrete

31 From Composition to Concrete Concrete composition aggregate gradation and shape supplementary cementitious materials chemical admixtures cement type Fresh concrete Workability Placement Finishability

32 Rheology, Science of the Flow of Materials Slump flow Stability Filling capacity Passing ability Yield stress Plastic viscosity Quantitative but empirical parameters Materials science-based rheological parameters NIST research on concrete rheology: Measurement and simulation of the mixing, flow, and consolidation process

33 Concrete Flow measurement Confined Flow Free Flow Vibration Slump Flow Cone Vibrating Table: Ve-Be, remodeling test

34 Multi-scale approach to experimental rheology Cement paste Mortar Concrete truck and rheometer

35 Bingham model concept Yield stress ~ slump Stress Stress Plastic viscosity Shear strain rate Shear strain rate Same yield stress BUT different plastic viscosity Same plastic viscosity BUT different yield stress

36 3-D dissipative particle dynamics simulation of real-shape aggregates in simple shear flow

37 Virtual Cement and Concrete Testing Laboratory (VCCTL) Use known physics, chemistry, and materials science to develop predictive models of properties and performance Working with 10 companies and associations to develop this tool

38 Virtual Cement and Concrete Testing Laboratory Internet-based and menu driven Predict properties based on detailed microstructure simulations of wellcharacterized starting materials Based on NIST modeling effort over last 17 years

39 Simulation of a physical testing laboratory cement and aggregate databases instead of bins and hoppers material combination and concrete curing models instead of mixers and molds software interface instead of a cart to take materials and samples around the laboratory accurate models for performance prediction instead of instrumented testing machines

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45 Prospectus Is a Virtual Asphaltic Concrete Testing Laboratory (VACTL) on the path of progress? Characterize asphalt, aggregates (dust to coarse) Model for chemistry of asphalt matrix, model for packing of aggregates Models for response of AC to mechanical and chemical and thermal loads

46 Conclusion Prediction capability, based on correct characterization, will allow performance-based use of cement, concrete, asphalt, and asphalt mixture AMRL and NIST can work together to improve the economic, efficient, and durable use of hydraulic cement- and asphalt-based materials in pavement applications

47 Acknowledgements Special thanks to Dr. Ed Garboczi and Dr. Joannie Chin the Inorganic and Polymeric Materials Group leaders at NIST for providing assistant with this presentation.

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