1、Standard Method of Test for Air Content of Hydraulic Cement Mortar AASHTO Designation: T 137-12 (2016)1Release: Group 1 (April 2016) ASTM Designation: C185-08 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3a T 13
2、7-1 AASHTO Standard Method of Test for Air Content of Hydraulic Cement Mortar AASHTO Designation: T 137-12 (2016)1Release: Group 1 (April 2016) ASTM Designation: C185-08 1. SCOPE 1.1. This test method covers the determination of the air content of hydraulic cement mortar under the conditions hereina
3、fter specified. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. Values in SI shall be obtained by measurement in SI units or by appropriate conversion, using the Rules for Conversion and Rounding in IEEE/ASTM SI10, of measurements made in other units. 1.4. This standard d
4、oes 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 prior to use. WarningFresh hydraulic cementitio
5、us mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 85, Portland Cement M 152M/M 152, Flow Table for Use in Tests of Hydraulic Cement M 240M/M 240, Blended Hydraulic Cement R 71, Sampling and Amount of Test
6、ing of Hydraulic Cement T 106M/T 106, Compressive Strength of Hydraulic Cement Mortar (Using 50-mm or 2-in. Cube Specimens) T 162, Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency 2.2. ASTM Standards: C91/C91M, Standard Specification for Masonry Cement C778, Standard S
7、pecification for Standard Sand C1005, Standard Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Physical Testing of Hydraulic Cements E438, Standard Specification for Glasses in Laboratory Apparatus E694, Standard Specification for Laboratory Glass Volume
8、tric Apparatus 2.3. IEEE/ASTM Standard: SI10, American National Standard for Metric Practice 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 137-2 AASHTO 3. SUMMARY OF TEST METHOD 3.1. Prepare a
9、mortar with standard sand and the cement to be tested using a water content sufficient to give a required flow. Compact the mortar into a measure of known volume and determine mass. Calculate the air content from the measured density of the mortar, the known densities of the constituents, and the mi
10、xture proportions. 4. SIGNIFICANCE AND USE 4.1. The purpose of this test method is to determine whether the hydraulic cement under test meets the air-entraining or nonair-entraining requirements of the applicable hydraulic cement specification for which the test is being made. The air content of con
11、crete is influenced by many factors other than the potential of the cement for air entrainment. 5. APPARATUS 5.1. Flow Table, Flow Mold, and CaliperConforming to the requirements of M 152M/M 152. 5.2. MeasureA cylindrical measure having an inside diameter of 76 2 mm and a depth (approximately 88 mm)
12、 adjusted by standardization with water to contain 400 1 mL at 23.0 2.0C (see Note 1). For the purposes of this test, the capacity of the measure in milliliters is the mass of the water content of the measure, in grams, divided by 0.9976, no correction in mass being made for the buoyant effect of ai
13、r. The measure shall have a uniform wall thickness. The thickness of the wall and bottom shall not be less than 2.9 mm. The total mass of the empty measure shall not be more than 900 g. The measure shall be made of a metal not attacked by the cement mortar. Note 1The 400-mL measure can be calibrated
14、 readily by filling with distilled water at 23.0 2.0C to a point where the meniscus extends appreciably above the top of the measure, placing a clean piece of plate glass on the top of the measure, and allowing the excess water to be squeezed out. The absence of air bubbles as seen through the glass
15、 ensures the measure is completely full. Care shall be taken that the excess water is wiped from the sides of the container before determining the mass. 5.3. Mixer, Bowl, and PaddleConforming to the apparatus section of T 162. 5.4. StraightedgeA steel straightedge not less than 200 mm long and not l
16、ess than 1.5 mm or more than 3.5 mm in thickness. 5.5. Standard Masses and BalancesConforming to the requirements of ASTM C1005. The balance device shall be evaluated for precision and accuracy at a total load of 2 kg. 5.6. Glass GraduatesGlass graduates of 250-mL capacity, conforming to the require
17、ments of ASTM E438 and ASTM E694. 5.7. TamperIn accordance with T 106M/T 106. The tamping face of the tamper shall be flat and at right angles to the length of the tamper. 5.8. Tapping StickA piece of hard wood having a diameter of approximately 16 mm and a length of approximately 152 mm. 5.9. Spoon
18、A metal restaurant-type serving spoon not less than 230 mm in length and with a bowl approximately 100 mm in length. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 137-3 AASHTO 6. TEMPERATURE AN
19、D HUMIDITY 6.1. Maintain the temperature of the room and dry materials at 23.0 4.0C. 6.2. Condition the mixing water and the measure, if it is being calibrated at 23.0 2.0C. 6.3. The relative humidity of the laboratory shall not be less than 50 percent. 7. STANDARD SAND 7.1. Use sand conforming to t
20、he requirements of ASTM C778 for 2030 sand. 8. SAMPLING 8.1. Sample the cement in accordance with R 71 (see Note 2). Note 2Polyvinyl chloride (PVC) sample containers, upon occasion, have been found to affect the air-entraining potential of a cement sample. The same problem might be experienced with
21、containers made from other plastics. 9. PROCEDURE 9.1. BatchProportion the standard mortar using 350 g of cement to 1400 g of 2030 standard sand and sufficient water to give a flow of 87.5 7.5 percent when determined in accordance with Section 9.3. Note 3T 137 refers to hydraulic cements that comply
22、 under M 85 and M 240M/M 240. Masonry cements, mortar cements, and plastic (stucco) cements require different sand, mass, and flow. Refer to the applicable specification. 9.2. Mixing of MortarMix the mortar in accordance with T 162. 9.3. Flow DeterminationCarefully wipe dry the flow table top and pl
23、ace the flow mold at the center of it. Using the spoon, place a layer of mortar about 25 mm in thickness in the mold and tamp 20 times with the tamper. The tamping pressure shall be just sufficient to ensure uniform filling of the mold. Over fill the mold approximately 20 mm with mortar and tamp as
24、specified for the first layer. Then cut off the mortar to a plane surface, flush with the top of the mold, by drawing the straightedge with a sawing motion across the top of the mold. Wipe the flow table top clean and dry, being especially careful to remove any water from around the edge of the mold
25、. Lift the mold away from the mortar 60 s after completing the mixing operation. Immediately drop the table ten times in accordance with M 152. The flow is the resulting increase in average diameter of the mortar mass, as determined with the calipers, measured on at least four diameters at approxima
26、tely equispaced intervals and expressed as a percentage of the original diameter. Make trial mortars with varying percentages of water until the specified flow is obtained. Make each trial with fresh mortar. 9.4. Mass per 400 mL of MortarWhen the quantity of mixing water has been found that produces
27、 a flow of 87.5 7.5 percent, immediately determine the mass per 400 mL of mortar, using the mortar remaining in the mixing bowl after the flow has been determined. In the determination of the mass per 400 mL, do not use the portion of the mortar used in the flow determination. Using the spoon, place
28、 the mortar gently into the 400-mL measure in three equal layers, tamping each layer 20 times with the tamper around the inner surface of the measure. The position of the tamper shall be that the broad side of the tamper is parallel to the radius and is perpendicular to the inner surface of the meas
29、ure. Each layer is tamped in on complete revolution (rotation) with only 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 137-4 AASHTO sufficient pressure to adequately fill the measure and elimin
30、ate voids within the mortar. After the measure has been filled and tamped in the above-prescribed manner, tap the sides of the measure lightly with the side of the tapping stick, one each at five different points at approximately equal spacing around the outside of the measure, to preclude entrapmen
31、t of extraneous air (see Note 4). No obvious space shall be left between the mortar and the inner surface of the measure as a result of the tamping operation. Then cut the mortar off to a plane surface, flush with the top of the measure, by drawing the straightedge with a sawing motion across the to
32、p of the measure, making two passes over the entire surface, the second pass being made at right angles to the first. If, in the striking-off operation, loose sand grains cause the straightedge to ride above the top surface of the measure, these grains shall be removed and the operation repeated. Co
33、mplete the entire operation of filling and striking off the measure within 90 s. Wipe off all mortar and water adhering to the outside of the measure. Determine the mass of the measure and its contents. Subtract the mass of the container, and record the mass of the mortar in grams. Note 4This operat
34、ion may be facilitated by placing the measure on a steady flat-surfaced support of lesser diameter than the measure while filling and wiping. 10. CALCULATION 10.1. Calculate the air content of the mortar from the following formula (see Note 5), which is based on batch proportions given in Section 9.
35、1, taking the specific gravity of portland cement as 3.15 and of 2030 standard sand as 2.65. When the hydraulic cement is other than portland, the appropriate value for its specific gravity shall be substituted for the value of 3.15 and the formula rederived accordingly: air content, volume, percent
36、 100 (182.7 )/(2000 4 )WP P= + (1) where: W = mass of 400 mL of mortar, g; and P = percentage of mixing water, based on mass of cement used. Note 5This formula can be derived as follows: air content, volume, percent 1001 ( )acW /W= (2) where: Wa= actual mass per unit of volume as determined by this
37、test method; = W/400 g/mL, where W is the mass in grams of the specified 400 mL of mortar (see Section 9.4); Wc= theoretical mass per unit of volume, calculated on an air-free basis as follows and using the values for quantities of materials and specific gravities as given in Sections 9.1 and 10.1:
38、350 1400 350 0.01350 1400 350 0.013.15 2.65 1PP+ + =+(5 0.01 )(1.827 0.01 )PP+=+P = percentage of mixing water, based on mass of cement. Substituting for Waand Wc, we have: Air Content, Volume, Percent: 1.827 0.01100 1400 5 0.01WPP+= + 2016 by the American Association of State Highway and Transporta
39、tion Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 137-5 AASHTO (1.827 0.01 )1004 (5 0.01 )WPP+= +(182.7 )100 2.5(5000 10 )PWP+= +(182.7 )100(2000 4 )PWP+= +10.2. Make only one determination of air content on a batch. (See Note 6.) Note 6Difficulty has occasiona
40、lly been experienced with this test by some persons. These difficulties usually have taken the form of values for air content that are abnormally high and that may be greater than the specified maxima in specifications for hydraulic cement. The air-entraining potential of the sand may be reduced by
41、washing in the laboratory with potable water by decantation until a clear, colorless supernatant liquid is obtained. In case of dispute, such freshly washed sand shall be used. 11. REPORT 11.1. When this test method is used for specific action in compliance testing, the value for air content shall b
42、e reported to the nearest 1 percent. 12. PRECISION AND BIAS 12.1. The single operator, within-laboratory, standard deviation has been found to be 0.56 percent air content throughout the range of 8 to 19 percent air. Therefore, results of two properly conducted tests by the same operator on similar b
43、atches should not differ by more than 1.6 percent air. 12.2. The multilaboratory standard deviation has been found to be 1.0 percent air content throughout the range from 8 to 19 percent air. Therefore, results of two different laboratories on similar batches should not differ from each other by mor
44、e than 2.8 percent air. 13. KEYWORDS 13.1. Air content; hydraulic cement; mortar. 1Reapproved with no technical changes; minor editorial revisions have been made at the discretion of the authors responsible for standards on hydraulic cement and lime (technical section 3a). 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
