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Check, Acceptance, and Variability of Virtual Measures. Dale P. Bentz (dale.bentz@nist.gov) National Establishment of Gauges and Innovation Global Congress on the Science of Concrete July 10, 2007. Foundation.
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Confirmation, Validation, and Variability of Virtual Standards Dale P. Bentz (dale.bentz@nist.gov) National Institute of Standards and Technology International Congress on the Chemistry of Cement July 10, 2007

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Background Abundance of Computer Models for Predicting Performance of Cement-Based Materials HIPERPAV, FEMMASSE, DuCoM, Life-365, CIKS, VCCTL Such models could shape the reason for the advancement of virtual guidelines Just as with the improvement of a physical test technique, virtual test strategies must be confirmed and approved , and their fluctuation considered

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Outline Some definitions Verification Validation Calibration Variability Example of a virtual test strategy for warmth of hydration Conventionally measured by ASTM C186 Summary and Prospectus

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Verification "The way toward establishing that a model execution precisely speaks to the engineer\'s theoretical depiction of the model and the answer for the model" from http://www.grc.nasa.gov/WWW/wind/substantial/instructional exercise/glossary.html Answers the question "Would we say we are building the model right?" Are our conditions remedy? Do we have the right (best) values for all parameters? Is our PC code without bug?

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Validation "The way toward deciding how much a model is a precise portrayal of this present reality from the point of view of the expected clients of the model " from http://www.grc.nasa.gov/WWW/wind/legitimate/instructional exercise/glossary.html Answers the question "Would we say we are building the correct model?" Are our forecasts exact and helpful for our target group? Does the model add to new specialized bits of knowledge and developments?

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Calibration "The way toward modifying numerical or physical demonstrating parameters in the computational model with the end goal of enhancing concurrence with trial information" from http://www.grc.nasa.gov/WWW/wind/substantial/instructional exercise/glossary.html

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Variability Assessment of the adjustment in model forecasts when at least one information parameters are changed in a controlled way For a reproduction, could be the arbitrary number seed Could be an information parameter describing the framework being displayed Phase portions and additionally stage edges (surface divisions) Phase connection capacities Particle estimate dispersion (PSD) Activation energies

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A Physical Testing Analogy Compressive quality of superior cement (HPC) Verification – Are we assembling the test technique right? Topping materials, strain rates, combination Carino et al. references in gathering paper Validation – Are we constructing the correct test strategy? Is compressive quality the best measure to describe the execution of HPC? Early-age splitting, toughness and transport measures might be more fitting Goodspeed, Vanikar, and Cook, Concrete International, 1996.

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Virtual Test Method Example Virtual Heat of Hydration Test ASTM C186 is the main current physical test strategy for warmth of hydration inside ASTM Few research centers have the essential hardware Results just accessible in the wake of holding up 7 d or 28 d Cumbersome-corrosive disintegration of tests, and so forth w/c =0.4, fixed hydration at 23 °C Virtual test technique depends on CEMHYD3D v3.0 demonstrate (openly accessible by means of Internet download at ftp://ftp.nist.gov/bar/bfrl/bentz/CEMHYD3D/version30 ) Validation performed utilizing an arrangement of 5 CCRL bonds Two variations: Complete PSD, SEM/X-beam picture portrayal PSD and X-beam diffraction (XRD) volumetric stage investigation just

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Enthalpy of Hydration of Cement Phases A For C 3 A hydration, qualities are for change to C 3 AH 6 , ettringite, and monosulfate (Afm) stage, separately. B For C 4 AF hydration, qualities are for change to C 3 AH 6 and ettringite, individually.

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Virtual Test Method Procedure 1) get a physical example of the bond of intrigue and portray it as for PSD and volumetric stage arrangement in light of SEM/X-beam picture examination or X-beam diffraction (norms for the PSD and stage portrayal strategies are as of now being sought after in the ASTM C01.25 and ASTM C01.23 subcommittees, separately), 2) set up a w/c =0.4 (23 ° C) concrete glue example and measure its concoction shrinkage as indicated by the ASTM C 1608 test technique, amid at any rate the initial 8 h of hydration; utilize the deliberate reaction to adjust the energy calculate, β , that interfaces display hydration cycles to time in the CEMHYD3D v3.0 PC show, for this virtual bond hydration ( w/c =0.4, immersed hydration at 23 ° C) , 3) utilizing the same aligned energy figure, lead a virtual warmth of hydration analysis ( w/c =0.4, fixed hydration at 23 ° C) with CEMHYD3D v3.0 to get the 7 d and 28 d (and other) warmth of hydration qualities for correlation with the tentatively measured qualities from the ASTM C 186 test strategy, 4) alternatively, direct virtual (semi)adiabatic hydrations, and so forth to evaluate the (semi)adiabatic temperature ascent of solid blends of intrigue delivered with this bond

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C 3 S=red, C 2 S=blue, C 3 A=green, C 4 AF=orange, gypsum=olive, CaO=yellow, K 2 SO 4 =white

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Measurement of Chemical Shrinkage Chemical shrinkage surveys the imbibition of outer water into a hydrating bond glue because of the way that the hydration items possess less volume than the reactants Standardized in 2005 as ASTM C1608 by subcommittee C01.31 Burrows has supported that the 12-h synthetic shrinkage be not exactly or equivalent to 0.0105 mL/g bond for a break safe concrete (Burrows, et al., Three Simple Tests for Selecting Low-Crack Cement, Cement and Concrete Composites, 26 (5), 509-519, 2004.) 311 380 m 2/kg

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CCRL Cement Compositions Volume parts

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Chemical Shrinkage Results CCRL Cement 141, w/c =0.4, soaked, 20 °C

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Heat of Hydration Results CCRL Cement 141, w/c =0.4, fixed, 23 °C

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Heat of Hydration Results

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Variability – Random Number Seed CCRL concrete 152

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Summary and Prospectus Virtual testing has moved the accentuation from a later age physical estimation to a point by point beginning material portrayal and a going with early-age (8 h) compound shrinkage estimation Results exhibit the possibility of a virtual warmth of hydration test technique to foresee 7 d and 28 d warms of hydration (really the total warmth of hydration versus time bend) Cement portrayal can be founded on nitty gritty SEM/X-beam picture examination or on more generally accessible XRD volume divisions, alongside a deliberate PSD (obviously) Methodology now being considered by ASTM C01.26

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