AASHTO T 185-2015 Standard Method of Test for Early Stiffening of Hydraulic Cement (Mortar Method).pdf

1、Standard Method of Test for Early Stiffening of Hydraulic Cement (Mortar Method) AASHTO Designation: T 185-15 ASTM Designation: C359-13 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3a T 185-1 AASHTO Standard Met

2、hod of Test for Early Stiffening of Hydraulic Cement (Mortar Method) AASHTO Designation: T 185-15 ASTM Designation: C359-13 1. SCOPE 1.1. This method covers the determination of early stiffening in hydraulic cement mortar. 1.2. The values stated in SI units are the standard. The values in parenthese

3、s are for information only. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations

4、 prior to use. 1.4. WarningFresh hydraulic-cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure. 1.5. The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables

5、and figures) shall not be considered as requirements of the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 71, Sampling and Amount of Testing of Hydraulic Cement T 129, Amount of Water Required for Normal Consistency of Hydraulic Cement Paste T 137, Air Content of Hydraulic Cement Mortar

6、 T 162, Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials C778, Standard Specification for Standard Sand C1005, Standard Specification fo

7、r Reference Masses and Devices for Determining Mass and Volume for Use in the Physical Testing of Hydraulic Cements D1193, Standard Specification for Reagent Water E2251, Standard Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids 3. TERMINOLOGY 3.1. Definitions: 2

8、016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 185-2 AASHTO 3.1.1. early stiffening, nthe early development of stiffness in the working characteristics of a hydraulic cement paste, mortar, or con

9、crete. Varieties include false set and flash set. 3.1.2. false set, nthe early development of stiffness in the working characteristics of a portland cement paste, mortar, or concrete without the evolution of much heat. This stiffness can be dispelled and plasticity regained by further mixing without

10、 addition of water. Also known as “grab set,” “premature stiffening,” “hesitation set,” and “rubber set.” 3.1.3. flash set, nthe early development of stiffness in the working characteristics of a hydraulic cement paste, mortar, or concrete, usually with the evolution of considerable heat. This stiff

11、ness cannot be dispelled nor can the plasticity be regained by further mixing without addition of water. Also known as “quick set.” 4. SUMMARY OF TEST METHOD 4.1. A mortar is prepared with the cement to be tested, using specified quantities of cement, standard sand, and an amount of water that will

12、produce a mortar with an initial penetration of 46 3 mm, using the modified Vicat apparatus. Measurements of penetration are made at stipulated intervals after the beginning of the mixing procedure. Upon completion of the first series of penetration measurements, the mortar is returned to the mixer

13、to be remixed. Following the remix procedure, an additional penetration, termed the “remix penetration,“ is determined. The report is a tabulation of the penetration measurements and the amount of mixing water used. 5. SIGNIFICANCE AND USE 5.1. The purpose of this test method is to determine the deg

14、ree to which a cement mortar develops early stiffening. It is intended for use by those interested in methods for determining the potential early stiffening of hydraulic cement. 5.2. When used for estimating the relative tendency of a cement to manifest early stiffening, a judgment may be made by co

15、mparing the behavior in the penetration series (see Sections 10.4.1 and 10.4.2) and the remix procedure (see Section 10.4.3) to differentiate a relatively less serious and less persistent tendency to early stiffening from one that is more persistent and, consequently, more serious (flash set). 5.3.

16、Severe false setting in a cement may cause difficulty from a placing and handling standpoint, but it is not likely to cause difficulties where concrete is mixed for a longer time than usual, as usually occurs in transit mixing, or when it is remixed prior to placing or transporting, in concrete pump

17、ing operations. It is most likely noticed when concrete is mixed for a short period of time in stationary mixers and transported to the forms in nonagitating equipment, as on some paving jobs, and when concrete is made in an on-site batch plant. 5.4. Cements with severe false setting usually require

18、 slightly more mixing water to produce the same consistency, which may result in slightly lower strengths and increased drying shrinkage. 5.5. Early stiffening resulting from false set is not likely to cause a cement to fail the applicable time of setting requirement. 5.6. Early stiffening resulting

19、 from flash set, depending on severity, can cause a cement to fail the applicable time of setting requirement. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 185-3 AASHTO 6. APPARATUS 6.1. Vicat

20、 ApparatusConforming to the requirements of Figure 1 in T 129, with the following modifications: 6.1.1. The 1-mm needle shall be replaced by a mass such that the total mass of the 10-mm plunger, indicator, and added mass shall be 400 0.5 g. 6.2. SpoonConforming to the requirement of T 137. 6.3. Mixe

21、r, Bowl, Paddle, and ScraperConforming to the requirements of T 162. 6.4. Glass Graduates200- or 250-mL capacity, conforming to the requirements of ASTM C1005. 6.5. Masses and Mass Determining DevicesConforming to the requirements of ASTM C1005. The devices for determining mass shall be evaluated fo

22、r precision and accuracy at a total load of 1000 g. 6.6. ThermometerASTM No. S12C or S12F, conforming to the requirements of ASTM E2251. 6.7. Flat TrowelHaving a sharpened straight-edge steel blade 100 to 150 mm (4 to 6 in.) in length. The edges, when placed on a plane surface, shall not depart from

23、 straightness by more than 1 mm. 6.8. Clock TimerHaving readability to the nearest second. 6.9. ContainersApproximately 50 by 50 by 150 mm (2 by 2 by 6 in.) inside dimensions (see Figure 1). These containers, which may be made of any suitable materials such as sheet metal or plastic, shall be rigid,

24、 watertight, and at least 50 mm (2 in.) deep. Figure 1Container for Early Stiffening Test 50 mm150 mm(6“)50 mm240 mm(9 )14“25mm (1“)(2“)(2“) 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 185-4

25、AASHTO 7. REAGENTS AND MATERIALS 7.1. Standard Sand, 2030 and GradedConforming to the requirements of ASTM C778. 7.2. Mixing WaterPotable water is satisfactory for routine tests. For all referee and cooperative tests, reagent water conforming to the requirements of ASTM D1193 for Type III or Type IV

26、 grades of reagent water shall be used. 8. SAMPLING 8.1. When the test is part of acceptance testing, sample the cement in accordance with R 71. 9. CONDITIONING 9.1. The temperature of the room, dry materials, paddle, bowl, and containers shall be maintained between 23.0 3.0C (73.4 5.4F). 9.2. The r

27、elative humidity of the mixing room shall not be less than 50 percent. 10. PROCEDURE 10.1. BatchMix at one time 600 g of cement, 300 g of graded standard sand, 300 g of 2030 standard sand, and an amount of water that produces a mortar with an initial penetration of 46 3 mm. 10.2. Mixing of MortarMix

28、 in the mechanical mixer as follows: 10.2.1. Place the sand and cement in the dry bowl, and mix the dry materials for a few seconds with the spoon. 10.2.2. Place the bowl in the mixer, set the paddle in place, and mix the dry materials for 10 s at slow speed (140 5 r/min). 10.2.3. With the mixer ope

29、rating at slow speed (140 5 r/min), add the entire quantity of mixing water within 5 s. Stop the mixer, quickly change to medium speed (285 10 r/min), and continue the mixing for 1 min, timing from the first addition of water. 10.2.4. Stop the mixer, scrape the sides of the mixing bowl with the rubb

30、er scraper, and quickly place the thermometer in the mortar. Allow it to stand undisturbed for the remainder of a 45-s interval from the time of stopping the mixer. 10.2.5. Read the temperature, remove the thermometer, start the mixer, and mix for 15 s at medium speed (285 10 r/min). If the mortar t

31、emperature is not in the range from 23 2.0C (73.4 3.6F), discard the batch and adjust the temperature of the water or sand, or both, to give the required temperature. 10.3. Filling Container: 10.3.1. Immediately after completion of the mixing, remove the bowl from the mixer, and, with a spoon, unifo

32、rmly distribute a portion of the mortar into the container until the container is heaping full. Quickly and gently place each spoonful of mortar in the container. When removing the mortar from the bowl, do not remove the material pushed up on the side of the bowl by the paddle. After the container h

33、as been filled, reassemble the mixer, cover the bowl with a lid, and retain the 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 185-5 AASHTO remaining mortar for a remix test to be performed late

34、r. To compact the mortar in the container, lift the container approximately 80 mm (3 in.) from the table with both hands and rap it twice against the surface of the table. 10.3.2. With the leading edge slightly raised, strike off the mortar with one stroke of the trowel along the length of the conta

35、iner. Then remove the excess mortar by means of a sawing motion with the straight edge of the trowel along the length of the container in a direction opposite to that used in striking off. Then smooth the surface of the mortar with a single stroke of the trowel. 10.4. Penetration Tests: 10.4.1. Afte

36、r filling the container, immediately place the 10-mm plunger of the modified Vicat apparatus in contact with the surface of the mortar at the midpoint of the container on the longitudinal center line. Set the movable indicator at zero. Release the plunger 3 min after the beginning of the wet mixing,

37、 and record, as the initial penetration, the depth in millimeters to which the plunger has settled below the surface 10 s after being released. If the plunger does not settle to a depth of 46 3 mm, discard the batch and adjust the quantity of water to produce the required consistency. 10.4.2. Immedi

38、ately withdraw and clean the plunger. In a similar manner, determine, after moving the Vicat apparatus to the desired location, the penetrations at intervals of 5, 8, and 11 min after the beginning of mixing. Do not move the filled container until these measurements are completed. Make all penetrati

39、ons along the longitudinal center line of the container. Obtain 5- and 8-min penetrations at a distance of approximately 40 mm (11/2in.) from each end of the container, respectively, and determine the 11-min penetration at a point approximately midway between the points at which the initial and 5-mi

40、n penetrations were determined. 10.4.3. At the completion of the measurement of the 11-min penetration, immediately return the mortar in the container to the bowl. Start the mixer, raise the bowl into mixing position, and remix the contents of the bowl at medium speed (285 10 r/min) for 1 min. Fill

41、a clean container as outlined in Sections 10.3.1 and 10.3.2, and determine the penetration 45 s after completion of mixing. 11. CALCULATION 11.1. Early Stiffening AmountThe change in penetration from the initial penetration to the 11-min penetration. 11.1.1. Calculate as follows: A D where: A = init

42、ial penetration, and D = penetration at 11 min. 11.1.2. Report to the nearest mm. 11.2. Average Early Stiffening RateAn average of the rate penetration change between each set of measurements. 11.2.1. Calculate as follows: 2333AB BC CD+ 2016 by the American Association of State Highway and Transport

43、ation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 185-6 AASHTO where: A = initial penetration, B = penetration at 5 min, C = penetration at 8 min, and D = penetration at 11 min. 11.2.2. Report to the nearest 0.1 mm/min. 11.3. Early Stiffening RecoveryThe perce

44、nt penetration recovery accomplished with the remix procedure. 11.3.1. Calculate as follows: 100EA where: E = penetration after remix, and A = initial penetration. (See Note 1.) Note 1Because it is possible for the remix penetration to exceed the initial penetration, this number may exceed 100 perce

45、nt. 11.3.2. Report to the nearest percent. 12. REPORT 12.1. Report the measured and calculated values as shown in Table 1: Table 1Penetration Report Mixing water _ mL Initial penetration _ mm 5-min penetration _ mm 8-min penetration _ mm 11-min penetration _ mm Remix penetration Early stiffening amo

46、unt Average early stiffening rate Early stiffening recovery _ mm _ mm _ mm/min _ percent 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 185-7 AASHTO 13. PRECISION AND BIAS 13.1. Early Stiffening

47、 Amount: 13.1.1. The single-operator standard deviation has been found to be 1.8 mm over a range from 35 to 49 mm. Therefore, results of two properly conducted tests by the same operator on the same cement are not expected to differ by more than 5 mm. (See Note 2.) Note 2These numbers represent, res

48、pectively, the (1s) and (d2s) limits as described in ASTM C670. 13.1.2. The multilaboratory standard deviation has been found to be 2.5 mm over a range from 35 to 49 mm. Therefore, results of two properly conducted tests from two different laboratories on samples of the same cement are not expected

49、to differ by more than 7 mm. (See Note 2.) 13.2. Average Early Stiffening Rate: 13.2.1. The single-operator standard deviation has been found to be 0.50 mm/min over a range from 4.0 to 8.0 mm/min. Therefore, results of two properly conducted tests by the same operator on the same cement are not expected to differ by more than 1.4 mm/min. (See Note 2.) 13.2.2. The multilaboratory standard deviation has been found to be 0.86 mm/min o