AASHTO T 356-2015 Standard Method of Test for Determining Air Content of Hardened Portland Cement Concrete by High-Pressure Air Meter.pdf
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1、Standard Method of Test for Determining Air Content of Hardened Portland Cement Concrete by High-Pressure Air Meter AASHTO Designation: T 356-151American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 356-1 AASHTO Sta
2、ndard Method of Test for Determining Air Content of Hardened Portland Cement Concrete by High-Pressure Air Meter AASHTO Designation: T 356-1511. SCOPE 1.1. This test method covers laboratory determination of the air content of hardened portland cement concrete with the use of the high-pressure air m
3、eter. This determination is made from the observation of change in linear piston movement with a specimen in the test chamber from that of the linear piston movement with no specimen in the test chamber. This change is due to a replacement of specific volume of compressible air by a specific volume
4、of incompressible water. 1.2. This procedure may involve hazardous materials, operations, and equipment. This procedure does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to consult and establish appropriate safety a
5、nd health practices and determine the applicability of regulatory limitation prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: T 121M/T 121, Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete T 152, Air Content of Freshly Mixed Concrete by the Pressure Method 3. TERMI
6、NOLOGY 3.1. Definitions: 3.1.1. linear piston movement (LPM)the travel of the hydraulic piston with a specimen in the test chamber. 3.1.2. initial value (INIT)the stabilized travel of the hydraulic piston with no specimen in the test chamber. 3.1.3. saturated surface-dry (SSD)the saturated surface-d
7、ry mass (weight) of the specimen. 4. SIGNIFICANCE AND USE 4.1. This test method covers determination of the air content of hardened concrete exclusive of any air that may be inside voids within aggregate particles. Therefore, determination of an aggregate correction factor, in accordance with the ap
8、plicable requirements of T 152, is required. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 356-2 AASHTO 5. APPARATUS 5.1. High-Pressure Air Meter (see Figure 1): 5.1.1. Hydraulic Pump and Hydra
9、ulic CylinderA specially designed unit combining a hydraulic pump and a hydraulic cylinder employed to supply the 34 470 kPa (5000 psi) load required to force water into a concrete specimen in the test chamber. The unit is supplied hydraulic pressure, which is converted to water pressure by movement
10、 of the hydraulic piston. 5.1.2. Test Chamber (Figures 2, 3, and 4)A specially designed stainless steel seamless tube secured with a stainless steel plate at the bottom and a stainless steel lid at the top. This chamber is designed to contain water under pressure. 5.1.3. The SystemThe cylinder, of k
11、nown volume, is attached to the test chamber, of known volume, that is completely filled with deionized water. This is done in order to enable load from the hydraulic pump to be applied to the test chamber. The system is equipped with a dial gauge accurate to 0.0254 mm (0.001 in.), in order to measu
12、re the movement of the hydraulic piston. Volume displacement is determined by the measured movement of the hydraulic piston. Note: Not to scale Figure 1High-Pressure Air Meter (Plan View) 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication
13、is a violation of applicable law.TS-3c T 356-3 AASHTO Note: Not to scale. Figure 2Test Chamber 280 mmWing Nutand BarGraduatedCylinder40 mm15 mm 15 mm25 mm25 mm255 mm305 mm40 mm480 mm525 mm 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication
14、 is a violation of applicable law.TS-3c T 356-4 AASHTO Note: Not to scale. Figure 3Test Chamber (Front View) 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 356-5 AASHTO Note: Not to scale Figure
15、 4Test Chamber Lid 6. SAMPLING 6.1. Obtain a sound concrete sample free of steel reinforcement. The sample must be of suitable size to fit into the test chamber. The diameter of the stainless steel lid is 173 mm (6.8 in.) and the depth of the seamless tube is 480 mm (18.9 in.). 7. PREPARATION OF THE
16、 TEST SPECIMENS 7.1. Oven DryingOven-dry the specimens for 72 h at 138 to 149C (280 to 300F). 7.2. SaturationAfter the specimens have been oven dried, saturate in 21 6C (70 10F) water for a period of 40 to 48 h. 7.3. Unit Mass (Weight)Determine the unit mass (weight) of the concrete sample in accord
17、ance with T 121M/T 121. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 356-6 AASHTO 8. PREPARATION OF TEST EQUIPMENT 8.1. Preconditioning the Water: 8.1.1. Prior to opening the test chamber, clo
18、se all valves except the valve positioned between the test chamber and the hydraulic cylinder. Remove the lid of the test chamber by loosening the wing nut at the top, thereby releasing the steel crossbar used to secure the lid. Tilt the lid and remove it from the chamber by aligning the flat sides
19、of the lid with the flat sides of the test chamber. 8.1.2. Completely fill the test chamber with deionized water. Remove the pressure gauge and replace it with a plug capable of withstanding a 101 kPa (30 in Hg) vacuum. Apply Teflontape to the plug, prior to installation. Place the vacuum lid over t
20、he top of the test chamber. It may be necessary to apply vacuum grease to the O-ring of the vacuum lid to prevent leakage. 8.1.3. Engage the vacuum by turning on the power and opening the valves connecting the vacuum lid to the vacuum hose and the vacuum hose to the vacuum. The vacuum gauge should r
21、ead approximately 91 kPa (27 in Hg). Apply the vacuum until air bubbles being pulled to the surface are no longer visible; this may be done overnight. The vacuum is applied to remove as much air as possible prior to the determination of an initial value. 8.1.4. Disengage the vacuum by closing the va
22、lves previously opened and turning off the power. The gauge should return to zero. Apply Teflontape to the pressure gauge and replace the plug with the pressure gauge. Replace the vacuum lid with the test chamber lid; do not secure the lid. 8.2. Bleeding the SystemThe system is bled to remove all en
23、trapped air bubbles that may have developed throughout the workings of the high-pressure air meter. This is done by forcing water through the system. 8.2.1. Close the valve positioned between the test chamber and the hydraulic cylinder. Open the drainage valve positioned at the bottom of the test ch
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