ASTM C1699-08
(Test Method)Standard Test Method for Moisture Retention Curves of Porous Building Materials Using Pressure Plates
Standard Test Method for Moisture Retention Curves of Porous Building Materials Using Pressure Plates
SIGNIFICANCE AND USE
The purpose of this test is to obtain, by means of a specified laboratory procedure, the values of the equilibrium moisture content at higher RH levels ((≈ 95 to 100%). These values are used either as means to characterize the material or as material characteristics needed as input to appropriate computer models that can simulate wetting or drying potential of individual building materials or material assemblies under specified environmental conditions.
SCOPE
1.1 This test method specifies a laboratory procedure for the determination of the water retention curve (or moisture storage capacity) of porous building materials at very high relative humidity (RH) levels (≈ 95 to 100% RH) corresponding to the capillary moisture region of the sorption isotherm. This is achieved by using the pressure plate test apparatus. This technique was originally developed to study soil moisture content and eventually had been adapted to building construction materials.
1.2 At higher RH levels (≈ 95 to 100% RH) of the sorption isotherm (see Test Method C 1498), use of climatic chamber is not an option. This technique uses overpressure to extract water out of the pore structure of porous materials until equilibrium between the moisture content in the specimens and the corresponding overpressure is achieved. Using the pressure plate extractors, equilibrium can only be reached by desorption.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 prior to use.
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Designation:C1699–08
Standard Test Method for
Moisture Retention Curves of Porous Building Materials
Using Pressure Plates
This standard is issued under the fixed designation C 1699; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D 2325 Test Method for Capillary-Moisture Relationships
for Coarse- and Medium-Textured Soils by Porous-Plate
1.1 This test method specifies a laboratory procedure for the
Apparatus
determination of the water retention curve (or moisture storage
D 3152 Test Method for Capillary-Moisture Relationships
capacity) of porous building materials at very high relative
for Fine-Textured Soils by Pressure-MembraneApparatus
humidity (RH) levels (' 95 to 100% RH) corresponding to the
E 337 Test Method for Measuring Humidity with a Psy-
capillary moisture region of the sorption isotherm. This is
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
achieved by using the pressure plate test apparatus. This
peratures)
technique was originally developed to study soil moisture
content and eventually had been adapted to building construc-
3. Terminology
tion materials.
3.1 Definitions of Terms Specific to this Standard:
1.2 At higher RH levels (' 95 to 100% RH) of the sorption
3.1.1 desorption isotherm—the sorption isotherm measured
isotherm (see Test Method C 1498), use of climatic chamber is
exclusively during the hygroscopic desorption process started
not an option. This technique uses overpressure to extract
from the condition of full water saturation of the material.
water out of the pore structure of porous materials until
3.1.2 sorption isotherm—relationship between the relative
equilibrium between the moisture content in the specimens and
humidity (see Test Method E 337) and the equilibrium mois-
the corresponding overpressure is achieved. Using the pressure
ture content of the material, at a specified temperature.
plate extractors, equilibrium can only be reached by desorp-
3.1.3 pressure-plate facility—Heavy steel vessel capable of
tion.
holding different pressure levels.
1.3 The values stated in SI units are to be regarded as
3.1.4 moisture content, by mass—mass of water retained in
standard. No other units of measurement are included in this
the specimen divided by the dry mass of the specimen.
standard.
1.4 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 The purpose of this test is to obtain, by means of a
responsibility of the user of this standard to establish appro-
specified laboratory procedure, the values of the equilibrium
priate safety and health practices and determine the applica-
moisture content at higher RH levels ((' 95 to 100%). These
bility of regulatory limitations prior to use.
values are used either as means to characterize the material or
2. Referenced Documents as material characteristics needed as input to appropriate
2 computer models that can simulate wetting or drying potential
2.1 ASTM Standards:
of individual building materials or material assemblies under
C 1498 Test Method for Hygroscopic Sorption Isotherms of
specified environmental conditions.
Building Materials
5. Apparatus
5.1 Pressure vessel—Heavy-duty steel vessels of approxi-
mately 305 mm in diameter and about 75 mm or 250 mm high
with heavy top lid tightly-held against O-ring gasket by
ThistestmethodisunderthejurisdictionofASTMCommitteeC16onThermal
clamping bolts (see Fig. 1).
Insulation and is the direct responsibility of Subcommittee C16.33 on Insulation
Finishes and Moisture. 5.2 Porous ceramic plates—Thisistheplateuponwhichthe
Current edition approved Oct. 15, 2008. Published November 2008.
specimens sit and is composed of microscopic pores allowing
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Withdrawn. The last approved version of this historical standard is referenced
the ASTM website. on www.astm.org.
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C1699–08
FIG. 1 Pressure Plate Test Apparatus
only water to flow through it. The plate assembly is exposed to 7.3 Forvacuumsaturation(seeNote2),followsteps7.3.1to
anoverpressurethatcanbeadjusted,whiletheothersideofthe 7.3.3
plate is always at atmospheric pressure resulting in a pressure
7.3.1 Place them in a vacuum chamber (that is, desiccator
difference over the plate and the specimens. equipped with outflow knob and connected to vacuum pump)
5.3 Balance—An analytical balance capable of weighing
and evacuate for 24 hours. This ensures that no air remains in
within 1 mg shall be used.The accuracy of the balance shall be the pores when specimens are being saturated.
at least 6 0.1 percent of the total specimen weight.
7.3.2 Evacuate distilled water by pumping air out for 1 to 2
5.4 Drying oven—A ventilated drying oven, capable of hours.
maintaining the required drying temperature within 62K for
7.3.3 Use this water to saturate the specimens under
temperatures less than 75°C and 64K for temperatures above
vacuum. The assembly remains under vacuum for at least 3
75°C , and a relative humidity of less than 10%, shall be used.
days or until no air bubbles are observed. Keep the specimens
In warm-humid laboratory environment or at low drying
fully submerged in the vacuum chamber until ready for
temperatures, it will be necessary to provide a supply of dried
measurement. This minimizes the amount of drying that can
air to achieve the less than 10 % relative humidity specification
occur.
in the drying oven.
7.4 For capillary saturation (see Note 3), specimens shall be
5.5 Desiccator equipped with outflow knob—Used as a
immersed completely in distilled water (kept at room tempera-
vacuum chamber to remove air (that is, evacuate) from the
ture) until a constant weight is attained.
water and evacuate specimens.
7.5 Soak the porous ceramic plate(s) in distilled water for a
5.6 Kaolin paste and acetate fabric—This clay paste en-
minimum of 8 hours.
sures good hydraulic contact between plate/specimen. The
7.6 Prepare the kaolin paste by mixing 125g of kaolin
acetate fabric prevents contamination of the specimens by the
powderwith150gwaterandapplyitdirectlyontothesaturated
clay.
plate.
5.7 Pressure source—Compressed air or nitrogen in cylin-
7.7 Cover the paste with a layer of acetate cloth to prevent
ders, or high-pressure air compressor.
the kaolin from sticking to the specimens.
5.8 Pressure manifold—Assembly of conduits and valves
7.8 Remove excess water off specimen surfaces by patting
regulating the air supplied to the extractors.
on a damp sponge and record specimen masses.
7.9 Press each specimen firmly on the acetate cloth ensuring
6. Test Specimens
good contact and also removal of any air bubbles underneath.
6.1 A test specimen shall be cut to approximately 15 cm
7.10 Close the pressure plate extractor lid after ensuring
and have a thickness as minimal as possible (' 5mm,
good connection of the outflow tube to the ceramic plate.
depending on the structure of the material) to reduce the time
NOTE 1—ypically, the f
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