1、Designation: C1749 12C1749 17Standard 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, in
2、 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 Scope*1.1 This guide covers description of several methods to measure the rheological
3、properties 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.
4、2 The 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
5、 experience 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 shou
6、ld this 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, ass
7、ociated 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.2. Referenced Documents2.1 ASTM Standards:2C305 Practice for Mechanical Mixing of Hydraulic Cement Pas
8、tes 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 Physical Testing of
9、Hydraulic CementsC1738 Practice for High-Shear Mixing of Hydraulic Cement Pastes2.2 Other Standards:API Recommended Practice 10B Testing Well Cements, American Petroleum Institute, Washington, DC (1997)ISO 10426-2 (2003) Petroleum and Natural Gas IndustriesCements and Materials for Well CementingPar
10、t 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 Specific to This Standard:3,43.2.1 apparent viscosity, nthe shear stress divided by rate of shear, in units of Pa.s.3.2.2
11、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 gradual recoverywhen the stress or shear rate is removed.1 This guide i
12、s under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.22 on Workability.Current edition approved Feb. 1, 2012March 15, 2017. Published March 2012March 2015. Originally approved in 2012. Last previous edition approved in 2012 asC1005 12. DOI: 10
13、.1520/C1749-17.2 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 page on the ASTM website.3 H.A. Barnes, J.F. Hutton and K. Walters, An
14、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 intended only to provide the user of an ASTM standard an indication of
15、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 current versionof the standard as published by ASTM is to be considered
16、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 States13.2.4 yield stress, nthe stress corresponding to the transition from elastic to plastic deformation
17、, 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 Bingham model, na rheological model for materials with non-zero yield stress and a linear relationship between shearrate and shear stress, following the e
18、quation: = 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 Rheological properties determined using this guide include plastic viscosity and yield stress as defined by the Binghammodel and apparent viscosity.4.2 Rhe
19、ological properties provide information about the workability of cement paste. As an example, the yield stress andplastic viscosity indicate the behavior of a specific cement paste composition.As another example, the apparent viscosity indicateswhat energy is required to move the suspension at a giv
20、en strain rate. This test may be used to measure flowability of a cementpaste or the influence of a specific material or combination of materials on flowability.4.3 Rheological properties may be sensitive to the procedure being used. This guide describes procedures that are expected toprovide reprod
21、ucible results.5. Summary of Guide5.1 This guide provides procedures for the determination of rheological properties of fresh cement paste using a rotationalrheometer with geometries, such as parallel plate, narrow-gap and wide gap concentric cylinders.6. Interferences6.1 Rheological properties may
22、be sensitive to the procedure, so a comparison of properties obtained using different proceduresis not recommended, unless relative 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.
23、2 Rheological properties may be sensitive to the shear history of the sample, so comparison of properties using differentmixing 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.
24、 Such settling is especially likely in shear thinning and thixotropic mixtures.6.4 Larger cement particles or aggregations of cement 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
25、of the particle size of the materialto be tested. Depending on the gap size, it may be necessary to remove larger particles by 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 conta
26、ct of cement with water influences the results.7. Apparatus7.1 General Description:7.1.1 The apparatus shall be a rotational rheometer 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 stat
27、ionary. The apparatus shall measureboth the rotational speed and the torque required to maintain that speed.7.1.2 The rheometer geometry shall provide a simple shearing flow (laminar, without turbulence). Allowable geometries andtheir equations for computing stress and strain rate from the measured
28、values of rotational speed and torque are described in section7.4.7.2 The rotational rheometer shall be capable of measuring shear stress 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 measu
29、rements need to berecorded.NOTE 1Most experiments found in the literature do not use the full range of shear rates prescribed here. For 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
30、 rheometer.7.3 Regularly check the calibration and zeroing of the apparatus, as discussed in section 7.9.7.4 Rheometer Geometry:7.4.1 The rheometer geometries described in this section provide simple shearing flow, essential for reliable computation ofstress and strain rates. The equation for comput
31、ation of stress and strain rates is given for each geometry.NOTE 2The following assumptions were made to develop the equations that appear in this section: (1) the fluid is homogeneous, (2) slip at the wallis negligible, and (3) the flow regime is laminar.C1749 1727.4.2 Selection of the geometry of
32、the rheometer. Three geometries are described here: narrow-gap concentric cylinders,wide-gap concentric cylinders, and parallel plates. The selection 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 b
33、e based on the maximum size ofthe particles in the cement tested.7.4.2.1 Narrow-Gap Concentric CylinderWith this type of rheometer, the sample 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 isst
34、ationary. The rotation of the rotor in the presence of the sample produces a torque that is measured at the wall of the innercylinder. The cylinder radii should be selected such that the shear stress is uniform across the gap. This condition is assumed tobe satisfied if:SR1R2D.50.92 (1)where R1 is t
35、he radius of the inner rotating cylinder (m) and R2 is the radius of the outer stationary cylinder (m).5To prevent slip (development of a liquid 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
36、attaching a sand paper, sand blasting, or other methods thatroughen the surface such as serration.The nominal shear rate and stress are calculated 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). T
37、he nominal shear stress is calculated at theinner cylinder wall by the following expression:5 2R12L (3)where is shear stress (Pa), is torque (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, t
38、he 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 similar to the narrow-gap concentric cylinder described insection 7.4.2 except that there is no limit on the gap value and the gap is larger. Computation of strain ra
39、te and stress is simplifiedif it is assumed that the material follows a power-law model. In that case, the nominal shear rate, , is calculated at the innercylinder wall 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),
40、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 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 l
41、ength (Nm), L is cylinder length (m), and R1 and R2 are inner and outer cylinderradii (m).Some concentric cylinder rheometers use an extreme wide gap such that the radius of the outer cylinder approaches infinity and(1-b2/n) approaches unity. This type of rheometer normally operates only at moderate
42、ly 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 cylinder 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
43、 exponent. Nominalshear stress, , is calculated at the inner cylinder wall by the following expression:5 2R12L (7)where is shear stress (Pa), is torque (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 mea
44、ns of rotational viscometersPart 1: Principles and measuring geometry.C1749 1737.4.2.3 Parallel PlateIn this type of rheometer the sample is held between two parallel horizontal plates, each equal andcircular cross section. The plates may be serrated to avoid slippage. When one of the plates is rota
45、ting 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)where 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
46、 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 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 th
47、e 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 highor 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
48、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 serrati
49、on of the surface with grooves or a pattern.7.7 EvaporationPrevent evaporation of water from the paste by covering the paste with a vapor barrier or a water-saturatedmaterial.7.8 Temperature ControlControl the temperature to the nearest 2C. The temperature may be selected to reflect thetemperature at which the cement paste would be used in the field.7.9 VerificationPeriodically follow the procedures suggested by the manufacturer to assure the repeatability of themeasur
