ASTM C1749-2017a Standard Guide for Measurement of the Rheological Properties of Hydraulic Cementious Paste Using a Rotational Rheometer《用旋转流变仪测量水硬性水泥凝膏流变特性的标准指南》.pdf

《ASTM C1749-2017a Standard Guide for Measurement of the Rheological Properties of Hydraulic Cementious Paste Using a Rotational Rheometer《用旋转流变仪测量水硬性水泥凝膏流变特性的标准指南》.pdf》由会员分享，可在线阅读，更多相关《ASTM C1749-2017a Standard Guide for Measurement of the Rheological Properties of Hydraulic Cementious Paste Using a Rotational Rheometer《用旋转流变仪测量水硬性水泥凝膏流变特性的标准指南》.pdf（5页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: C1749 17C1749 17aStandard Guide forMeasurement of the Rheological Properties of HydraulicCementious Paste Using a Rotational Rheometer1This standard is issued under the fixed designation C1749; the number immediately following the designation indicates the year oforiginal adoption or, i

2、n the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide covers description of several methods to measure the rheological prope

3、rties of fresh hydraulic cement paste. Allmethods are designed to determine the yield stress and plastic viscosity of the material using commercially available instrumentsand the Bingham model. Knowledge of these properties gives useful information on performance of cement pastes in concrete.1.2 The

4、 values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This guide offers an organized collection of information or a series of options and does not recommend a specific courseof action. This document cannot replace education or expe

5、rience and should be used in conjunction with professional judgment.Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replacethe standard of care by which the adequacy of a given professional service must be judged, nor should th

6、is document be appliedwithout consideration of a projects many unique aspects. The word “Standard” in the title of this document means only that thedocument has been approved through the ASTM consensus process.1.4 This standard does not purport to address all of the safety concerns, if any, associat

7、ed with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on s

8、tandardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C305 Practice for Mechanical Mixing of Hydra

9、ulic Cement Pastes and Mortars of Plastic ConsistencyC511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of HydraulicCements and ConcretesC1005 Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Phys

10、ical Testing ofHydraulic CementsC1738 Practice for High-Shear Mixing of Hydraulic Cement PastesE2975 Test Method for Calibration or Calibration Verification of Concentric Cylinder Rotational Viscometers2.2 Other Standards:API Recommended Practice 10B Testing Well Cements, American Petroleum Institut

11、e, Washington, DC (1997)ISO 10426-2 (2003) Petroleum and Natural Gas IndustriesCements and Materials for Well CementingPart 2: Testing ofWell CementsSection 5.23. Terminology3.1 DefinitionsFor definitions of terms used in this test method, refer to Terminology C125 and C219.3.2 Definitions of Terms

12、Specific to This Standard:3,41 This guide is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.22 on Workability.Current edition approved March 15, 2017May 1, 2017. Published March 2015May 2017. Originally approved in 2012. Last previous edit

13、ion approved in 20122017 asC1005 12.C1749 17. DOI: 10.1520/C1749-17.10.1520/C1749-17A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary

14、page on the ASTM website.3 H.A. Barnes, J.F. Hutton and K. Walters, An Introduction to Rheology, Elsevier (1989).4 Hackley V.A., Ferraris C.F., “The Use of Nomenclature in Dispersion Science and Technology” NIST Recommended Practice Guide, SP 960-3, 2001.This document is not an ASTM standard and is

15、intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the c

16、urrent versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.1 apparent viscosity, nt

17、he shear stress divided by rate of shear, in units of Pa.s.3.2.2 plastic viscosity, nin the plastic (Bingham) model, the slope of the shear stress shear rate curve, in units of Pa.s.3.2.3 thixotropy, na decrease of the apparent viscosity under constant shear stress or shear rate followed by a gradua

18、l recoverywhen the stress or shear rate is removed.3.2.4 yield stress, nthe stress corresponding to the transition from elastic to plastic deformation, in units of Pa; it is alsoreferred to as the stress needed to initiate flow. It would be calculated using the Bingham model in this guide.3.2.5 Bing

19、ham model, na rheological model for materials with non-zero yield stress and a linear relationship between shearrate and shear stress, following the equation: = B + pl; where B Yield stress in Pa, Shear rate in 1/s, Shear stress in Pa,and pl Plastic viscosity in Pa.s.4. Significance and Use4.1 Rheol

20、ogical properties determined using this guide include plastic viscosity and yield stress as defined by the Binghammodel and apparent viscosity.4.2 Rheological properties provide information about the workability of cement hydraulic cementitious paste. As an example,the yield stress and plastic visco

21、sity indicate the behavior of a specific cement paste composition.As another example, the apparentviscosity indicates what energy is required to move the suspension at a given strain rate. This test may be used to measureflowability of a cement paste or the influence of a specific material or combin

22、ation of materials on flowability.4.3 Rheological properties may be sensitive to the procedure being used. This guide describes procedures that are expected toprovide reproducible results.5. Summary of Guide5.1 This guide provides procedures for the determination of rheological properties of fresh c

23、ement paste using a rotationalrheometer with geometries, such as parallel plate, narrow-gap and wide gap concentric cylinders.6. Interferences6.1 Rheological properties may be sensitive to the procedure, so a comparison of properties obtained using different proceduresis not recommended, unless rela

24、tive viscosity (ratio between the plastic viscosity of a materials and the plastic viscosity of areference material, both measured using the same rheometer) is considered.6.2 Rheological properties may be sensitive to the shear history of the sample, so comparison of properties using differentmixing

25、 procedures is not recommended.6.3 Paste mixtures (water and cement particles) that are very fluid may yield erroneous data using this procedure due to settlingof particles. Such settling is especially likely in shear thinning and thixotropic mixtures.6.4 Larger cement particles or aggregations of c

26、ement particles may block flow in a narrow-gap rheometer and thereby increasethe shear stress. The gap between the shearing surfaces needs to be selected with consideration of the particle size of the materialto be tested. Depending on the gap size, it may be necessary to remove larger particles by

27、sieving or otherwise prevent segregation.6.5 Incorporation of air in the paste during mixing reduces viscosity and increases flow.6.6 The time of testing after initial contact of cement with water influences the results.7. Apparatus7.1 General Description:7.1.1 The apparatus shall be a rotational rh

28、eometer in which the sample is confined between two surfaces (called the shearingsurfaces), one of which is rotating at a constant rotational speed, and the other being stationary. The apparatus shall measureboth the rotational speed and the torque required to maintain that speed.7.1.2 The rheometer

29、 geometry shall provide a simple shearing flow (laminar, without turbulence). Allowable geometries andtheir equations for computing stress and strain rate from the measured values of rotational speed and torque are described in 7.4.7.2 The rotational rheometer shall be capable of measuring shear str

30、ess at strain rates in the range from 0.1 s-1 to 600 s-1. Therange of shear rates will be selected by the operator depending on the geometry used. At least five measurements need to berecorded.NOTE 1Most experiments found in the literature do not use the full range of shear rates prescribed here. Fo

31、r example, most parallel platemeasurements are done between 0.1 s-1 to 50 s-1. The selection of the shear rate range might take into account the exact geometry of the rheometer.7.3 Regularly check the calibration and zeroing of the apparatus, as discussed in 7.9.7.4 Rheometer Geometry:7.4.1 The rheo

32、meter geometries described in this section provide simple shearing flow, essential for reliable computation ofstress and strain rates. The equation for computation of stress and strain rates is given for each geometry.C1749 17a2NOTE 2The following assumptions were made to develop the equations that

33、appear in this section: (1) the fluid is homogeneous, (2) slip at the wallis negligible, and (3) the flow regime is laminar.7.4.2 Selection of the geometry of the rheometer. Three geometries are described here: narrow-gap concentric cylinders,wide-gap concentric cylinders, and parallel plates. The s

34、election of the geometry should be based on the type of rotationalrheometer available. One criterion to select between the narrow-gap and the wide-gap should be based on the maximum size ofthe particles in the cement tested.7.4.2.1 Narrow-Gap Concentric CylinderWith this type of rheometer, the sampl

35、e is confined between two concentriccylinders of radii R1 and R2 (R2R1), one of which, the rotor, is rotating at a constant rotational speed and the other is stationary.The rotation of the rotor in the presence of the sample produces a torque that is measured at the wall of the inner cylinder. Thecy

36、linder radii should be selected such that the shear stress is uniform across the gap. This condition is assumed to be satisfied if:SR1R2D.50.92 (1)where R1 is the radius of the inner rotating cylinder (m) and R2 is the radius of the outer stationary cylinder (m).5To prevent slip (development of a li

37、quid layer at the wall of the rotating cylinder that produces an anomalously low stress), thesurface of cylinders may be serrated or at least rendered rough by attaching a sand paper, sand blasting, or other methods thatroughen the surface such as serration.The nominal shear rate and stress are calc

38、ulated at the inner cylinder wall by the following expression: 5 R231R22R1(2)where is strain rate (s-1) and 1 is rotational speed at the inner cylinder (r/s). The nominal shear stress is calculated at theinner cylinder wall by the following expression:5 2R12L (3)where is shear stress (Pa), is torque

39、 (Nm), L is cylinder length (m), and R1 is the inner radius (m). These equations assumethat the slurry is homogeneous, the shear stress is uniform in the gap, the flow regime in the gap is laminar, and slip at the wallis negligible.7.4.2.2 Wide-Gap Concentric CylinderThis type of rheometer is simila

40、r to the narrow-gap concentric cylinder described in7.4.2 except that there is no limit on the gap value and the gap is larger. Computation of strain rate and stress is simplified if itis assumed that the material follows a power-law model. In that case, the nominal shear rate, , is calculated at th

41、e inner cylinderwall by the following expression: 5 231n12b2/n! (4)where is strain rate (s-1), 1 is the rotational speed at the inner cylinder (rad/s), b is the ratio of the inner to the outer radius,and n is the power-law exponent. A procedure for determining the value of n is presented elsewhere.3

42、 Nominal shear stress, , iscalculated at the inner cylinder wall by the following expression:5 2R12L (5)where is shear stress (Pa), is torque per unit length (Nm), L is cylinder length (m), and R1 and R2 are inner and outer cylinderradii (m).Some concentric cylinder rheometers use an extreme wide ga

43、p such that the radius of the outer cylinder approaches infinity and(1-b2/n) approaches unity. This type of rheometer normally operates only at moderately low shear rates, typically 0.1 s-1 to 10 s-1.For a material following a power-law model, the nominal shear rate is calculated at the inner cylind

44、er wall by the followingexpression: 5231n (6)where is strain rate (s-1), 1 is the rotational speed of the inner cylinder (rad/s), and n is the power-law exponent. Nominalshear stress, , is calculated at the inner cylinder wall by the following expression:5 2R12L (7)where is shear stress (Pa), is tor

45、que (N.m), L is cylinder length (m), and R1 is inner cylinder radius (m).5 DIN 53019-1:2008, ViscometryMeasurement of viscosities and flow curves by means of rotational viscometersPart 1: Principles and measuring geometry.C1749 17a37.4.2.3 Parallel PlateIn this type of rheometer the sample is held b

46、etween two parallel horizontal plates, each equal andcircular cross section. The plates may be serrated to avoid slippage. When one of the plates is rotating and the other is stationary,the shear rate varies from zero at the center to a maximum at the rim, and the value at the rim is: 5R 31h (8)wher

47、e is strain rate (s-1), R is the plate radius (m), 1 is the rotational speed (rad/s), and h is the gap between the two plates(m). Viscosity is given by:5 3h2R41S11 1dln3dln1D (9)where is viscosity (Pa.s) and is the torque (N.m).7.5 GapThe gap between the shearing surfaces of the rheometer should be

48、wide enough that the sample is homogeneousthroughout or be of the same magnitude of the distance between aggregates in concrete (typically 0.4 mm). If the gap is too narrowrelative to the size of particles in the cement paste (less than 10 times the maximum particles size), the torque will be very h

49、ighor even the plate will lock and not rotate.7.6 SlippageSlippage can occur if the shearing surfaces are smooth, due to the formation of layer of water near the surface.If slippage occurs, the torque measured is smaller than it should be. It could be even zero. Therefore, some precaution should betaken to avoid slippage by serration of the shearing surfaces. It can be done either by gluing a sand paper, or by sand blasting thesurfaces or by serration of the surface with groov