1、Standard Method of Test for Autoclave Expansion of Hydraulic Cement AASHTO Designation: T 107M/T 107-18 Technical Section: 3a, Hydraulic Cement and Lime Release: Group 1 (April) ASTM Designation: C151/C151M-16 American Association of State Highway and Transportation Officials 444 North Capitol Stree
2、t N.W., Suite 249 Washington, D.C. 20001 TS-3a T 107M/T 107-1 AASHTO Standard Method of Test for Autoclave Expansion of Hydraulic Cement AASHTO Designation: T 107M/T 107-18 Technical Section: 3a, Hydraulic Cement and Lime Release: Group 1 (April) ASTM Designation: C151/C151M-16 1. SCOPE 1.1. This te
3、st method covers determination of the autoclave expansion of hardened hydraulic cement paste when exposed to the autoclave conditions in this method. 1.2. The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be e
4、xact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibili
5、ty of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precaution statements, see the section on Safety Precautions. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 201, Mixing Rooms,
6、Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes R 70, Use of Apparatus for the Determination of Length Change of Hardened Cement Paste, Mortar, and Concrete T 129, Amount of Water Required for Normal Consistency of Hydraulic Cement Paste T
7、162, Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency 2.2. ASTM Standards: C856, Standard Practice for Petrographic Examination of Hardened Concrete C1005, Standard Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Physical T
8、esting of Hydraulic Cements C1157/C1157M, Standard Performance Specification for Hydraulic Cement 3. SIGNIFICANCE AND USE 3.1. The autoclave expansion test provides an index of potential delayed expansion caused by the hydration of CaO or MgO or both, when present in hydraulic cement.1 2018 by the A
9、merican Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3a T 107M/T 107-2 AASHTO 4. INTERFERENCES 4.1. Pozzolans containing fine-grained quartz have been reported to cause excessive expansion under autoclave test conditi
10、ons due to alkalisilica reaction that will not occur under normal service conditions.2When excessive expansion of paste containing pozzolans occurs, it is recommended that the specimens be examined (see ASTM C856) for evidence of alkalisilica reaction (see Note 1). Note 1If the excessive expansion h
11、as r esulted from alkalisilica reaction under autoclave conditions, the pozzolan can be evaluated for alkali reactivity using the procedure described in ASTM C1157/C1157M. 5. APPARATUS 5.1. Weighing Devices and WeightsFor determining the mass of materials conforming to the requirements of ASTM C1005
12、. 5.2. Glass Graduates200- or 250-mL capacity, and conforming to the requirements of R 70. 5.3. MoldsConforming to the requirements of R 70 for test specimens used in the determination of length change of cement paste. 5.4. Flat TrowelConforming to the requirements of T 129. 5.5. AutoclaveConsisting
13、 of a high-pressure s team vessel provided with a thermometer well. The autoclave shall be equipped with automatic controls and either a rupture disk with a bursting pressure of 2.4 MPa 350 psi 5 percent or a safety valve that actuates at this pressure. In addition, the autoclave shall be equipped w
14、ith a vent valve to allow the escape of air during the early part of the heating period and to release any steam pressure remaining at the end of the cooling period. The pressure gauge shall have a nominal capacity of 4.0 MPa 600 psi, a dial with a nominal diameter of 115 mm 41/2in., and shall be gr
15、aduated from 0 to 4.0 MPa 0 to 600 psi with scale divisions not exceeding 0.03 MPa 5 psi. The error in the gauge shall not exceed 0.02 MPa 3 psi at the operating pressure of 2 MPa 295 psi. The capacity of the heating unit shall be such that with maximum load (water plus specimens) the pressure of th
16、e saturated steam in the autoclave may be raised to a gauge pressure of 2 MPa 295 psi in 45 to 75 min from the time the heat is turned on. The automatic control shall be capable of maintaining the gauge pressure of 2 0.07 MPa 295 10 psi for at least 3 h. A gauge pressure of 2 0.07 MPa 295 10 psi cor
17、responds to a temperature of 216 2C 420 3F. The autoclave shall be designed to permit the gauge pressure to drop from 2 MPa 295 psi to less than 0.07 MPa 10 psi in 1.5 h after the heat supply has been shut off. 5.5.1. Rupture DiskThe rupture disk shall be made of a material having a tensile strength
18、 that is relatively insensitive to temperature in the range 20 to 216C 68 to 420F and that is electrochemically compatible with the pipe leading to it and to its holder. 5.6. Length ComparatorThe comparator used for measuring length change of specimens shall conform to the requirements of R 70. 6. T
19、EMPERATURE AND HUMIDITY 6.1. Molding RoomMaintain the temperature of the molding room, dry materials, and mixing water, and the relative humidity of the molding room within the limits of R 70. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplic
20、ation is a violation of applicable law.TS-3a T 107M/T 107-3 AASHTO 6.2. Moist Storage FacilitiesMaintain the temperature and hum idity of the moist storage facilities to the requirements of M 201. 7. SAFETY PRECAUTIONS 7.1. The pressure gauge should have a maximum capacity of 4.0 MPa 600 psi. A gaug
21、e with too small or too large a capacity may be a hazard because for pressure above the specified maximum working pressure, with a smaller capacity gauge, the pressure may be off scale, and with a larger capacity gauge, the arc of movement may be too small to invite attention. The operator shall be
22、sure the gauge hand has not passed the maximum graduation on the scale. 7.2. Test the pressure gauge for proper operation. Always use a thermometer together with the pressure gauge, so as to provide a means of detecting any failure of the pressure gauge to operate properly and to indicate any unusua
23、l condition. 7.3. Maintain the automatic control in proper working order at all times. 7.4. Set the safety valve to relieve the pressure at about 6 to 10 percent above the maximum of 2.1 MPa 305 psi specified in this test method, that is, at about 2.3 MPa 330 psi. Unless the manufacturer has given s
24、pecific instructions as to maintenance of the safety valve, test the valve twice each year. Test with a gauge testing device or by adjusting the automatic controls to allow the autoclave to reach a pressure of about 2.3 MPa 330 psi, at which pressure the safety valve will either open or be adjusted
25、to open. Direct the safety valve discharge away from the operator. (See Note 2.) Note 2Unexpected combinations of conditions may occur. For example, in one case the automatic control had failed; the safety valve had become stuck; and the gauge hand, which at first glance appeared to be at about zero
26、, had passed the maximum graduation and had come to stop on the wrong side of the pin. This condition of the gauge was finally detected and the pressure, then of an unknown magnitude, was released before failure could occur in the apparatus. 7.5. Wear heavy leather work gloves to prevent burning of
27、the hands when removing the top of the autoclave at the end of the test. Direct the vent valve away from the operator. When removing the autoclave lid, tilt it so that any steam escaping from beneath the lid may be discharged away from the operator. Care shall be taken to avoid scalding by any liqui
28、d that may have been used in the autoclave well. 7.6. The operator shall be made aware that for many autoclave pressure gages the return of the gauge hand to the initial rest or starting point does not necessarily indicate zero pressure within the autoclave. There may then still remain an appreciabl
29、e dangerous pressure.Procedures in Section 11.2 shall be followed. 8. NUMBER OF TEST SPECIMENS 8.1. Make at least one test specimen. 9. PREPARATION OF SPECIMEN MOLDS 9.1. Prepare the specimen molds in accordance with the requirements of R 70, except that molds need not be sealed. 2018 by the America
30、n Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3a T 107M/T 107-4 AASHTO 10. PREPARATION OF TEST SPECIMENS 10.1. Mixing Cement PastePrepare the standard batch consisting of 650 g of cement and s ufficient water to give
31、 a paste of normal consistency in accordance with the procedure described in T 129. Mix this batch in accordance with the procedure described in T 162. Both a time of setting specimen and an autoclave bar may be made from the same batch. If the paste to be used for time of setting is the paste sampl
32、e already used to determine normal consistency, the autoclave bar may be prepared immediately from the remainder of the batch. 10.2. Molding SpecimensImmediately following preparation of the time of setting speci men or completion of mixing, mold the test specimen in two approximately equal layers,
33、each layer being compacted with the thumbs or forefingers by pressing the paste into the corners, around the gauge studs, and along the surface of the mold until a homogeneous specimen is obtained. Compact the top layer, cut off the paste flush with the top of the mold with a thin-edged trowel, and
34、smooth the surface with a few strokes of the flat trowel. During the operations of mixing and molding, protect the hands with rubber gloves. 10.3. Storage of Test SpecimensAfter filling the mold , place it in the moist closet or moist room. Store the specimens in the molds in the moist enclosure for
35、 at least 20 h; if removed from the molds before 24 h, they shall be kept in the moist closet or moist room until time of test. 11. PROCEDURE 11.1. At 24 h 30 min after molding, remove the specimens from the moist atmosphere, immediately obtain a length comparator reading for each specimen, and plac
36、e in the autoclave at room temperature in a rack so that all sides of the specimen will be exposed to saturated steam. The autoclave shall contain enough water, at an initial temperature of 20 to 28C 68 to 82F, to maintain an atmosphere of saturated steam vapor during the entire test. Ordinarily 7 t
37、o 10 percent of the volume of the autoclave should be occupied by the water. 11.2. To permit air to escape from the autoclave during the early portion of the heating period, leave the vent valve open until steam begins to escape. (Warning See Section 7 on Safety Precautions.) Close the valve and rai
38、se the temperature of the autoclave at a rate that will bring the gauge pressure of the steam to 2 MPa 295 psi in 45 to 75 min from the time the heat is turned on. Maintain 2 0.07 MPa 295 10 psi pressure for 3 h. At the end of the 3-h period, shut off the heat supply and cool the autoclave at such a
39、 rate that the pressure will be less than 0.07 MPa 10 psi at the end of the 1.5-h period, and slowly release any remaining pressure by partially opening the vent valve until atmospheric pressure is attained. Then open the autoclave and place the test specimen in water at a temperature above 90C 194F
40、. Cool the water surrounding the bars at a uniform rate by adding cold water so that the temperature of the water will be lowered to 23C 74F in 15 min. Maintain the water surrounding the specimens at 23C 74F for an additional 15 min. Then, remove one specimen at a time from the water; blot the pins,
41、 but not the specimen; and obtain a length comparator reading for each specimen. 12. CALCULATION 12.1. Calculate the change in length of the test specimen by subtracting the length comparator reading before autoclaving from that after autoclaving, and report as percent of the effective gauge length
42、to the nearest 0.01 percent. Report the percentage of increase in length as the autoclave expansion. Indicate a decrease in length by a minus sign prefixed to the percent value. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a viol
43、ation of applicable law.TS-3a T 107M/T 107-5 AASHTO 13. PRECISION AND BIAS 13.1. PrecisionThe single-operator (within-laboratory) standard deviation has been found to be 0.024 percent throughout the range of 0.11 percent to 0.94 percent expansions. Therefore, results of two properly conducted tests
44、by the same operator for expansions of similar batches should not differ from each other by more than 0.07 percent expansion. The multilaboratory (between-laboratory) standard deviation has been found to be 0.030 percent throughout the range of 0.11 percent to 0.94 percent expansions. Therefore, res
45、ults of two properly conducted tests from two different laboratories for expansions of similar batches should not differ from each other by more than 0.09 percent expansion. 13.2. BiasBecause there is no accepted ref erence material suitable for determining bias, bias has not been determined. 14. KE
46、YWORDS 14.1. Autoclave; autoclave expansion; expansion; hydraulic cement; soundness. 1Gonnerman, H. F., W. Lerch, and T. M. Whitside. “Investigations of the Hydration Expansion Characteristics of Portland Cements,” Portland Cement Association Research Department Bulletin, Vol. 45, 1953, pp. 1168. 2W
47、ang, H., “Autoclave Soundness Test Mischaracterizes Cement-Fly Ash Blends by Introducing Alkali-Quartz Reaction,” Cement, Concrete and Aggregates, Vol. 24, No. 2, 2002, pp. 6872. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
