1、Designation: D7954/D7954M 15D7954/D7954M 15aStandard Practice forMoisture Surveying of Roofing and Waterproofing SystemsUsing Non-Destructive Electrical Impedance Scanners1This standard is issued under the fixed designation D7954/D7954M; the number immediately following the designation indicates the
2、year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice applies to techniques that use non-de
3、structive electrical impedance (EI) scanners to locate moisture andevaluate the comparitive moisture content within insulated low-slope roofing and waterproofing systems.1.2 This practice is applicable to roofing and waterproofing systems wherein insulation is placed above the deck and positionedund
4、erneath and in contact with electrically nonconductive single-ply or built-up roofing and waterproofing membranes and systemssuch as coal tar, asphalt, modified bitumen, thermoplastics, spray polyurethane foam, and similar electrically non-conductivemembrane materials. This practice is also applicab
5、le to roofing and waterproofing systems without insulation placed abovemoisture absorbing decks such as wood, concrete, or gypsum, that are in contact with single-ply or built-up roofing andwaterproofing membranes as described above.1.3 This practice is applicable to roofing and waterproofing system
6、s incorporating electrically nonconductive rigid boardinsulation made from materials such as organic fibers, perlite, cork, fiberglass, wood-fiber, polyisocyanurate, polystyrene, phenolicfoam, composite boards, gypsum substrate boards, and other electrically nonconductive roofing and waterproofing s
7、ystems suchas spray-applied polyurethane foam.1.4 This practice is not appropriate for all combinations of materials used in roofing and waterproofing systems.1.4.1 Metal and other electrically conductive surface coverings and near-surface embedded metallic components are not suitablefor surveying w
8、ith impedance scanners because of the electrical conductivity of these materials.1.4.2 Black ethylene propylene diene terpolymer (EPDM) produces false positive readings when tested because of the materialshigh dielectric constant.This practice is not appropriate for use with black EPDM, any membrane
9、s containing black EPDM, orblack EPDM coatings because black EPDM gives false positive readings.1.4.3 Aluminum foil on top-faced insulation, roofing, or waterproofing membranes gives a false positive reading and is notsuitable for surveying with impedance scanners; however, liquid-applied aluminum p
10、igmented emulsified asphalt-based coatingsshall not normally affect impedance scanner readings.1.4.4 See A1.4 for some cautionary notes on roofing anomalies and limitations that affect the impedance test practice.1.5 Moisture scanners using impedance based technology are classified as EI scanners.NO
11、TE 1The term capacitance is sometimes used when describing impedance scanners. Capacitance scanners are purely capacitive as they do not havea resistive component. Impedance scanners combine both capacitance and resistance for testing; thus, they are well suited to the measurement of differenttypes
12、of materials and constructions found in roofing and waterproofing systems as the combination of both components allows for a more versatiletesting, calibration, and measurement arrangement.1.6 This practice also addresses necessary verification of impedance data involving invasive test procedures us
13、ing core samples.1.7 This practice addresses two generally accepted scanning techniques for conducting moisture surveys using electricalimpedance scanners:1.7.1 Technique AContinuous systematic scanning and recording (see 8.2), and1.7.2 Technique BGrid format scanning and recording (see 8.3).1.8 Thi
14、s practice addresses some meteorological conditions and limitations for performing impedance inspections.1.9 This practice addresses the effect of the roofing or waterproofing construction, material differences, and exterior surfaceconditions on the moisture inspections.1 This practice is under the
15、jurisdiction of ASTM Committee D08 on Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.20 on RoofingMembrane Systems.Current edition approved Feb. 15, 2015June 1, 2015. Published March 2015June 2015. Originally approved in 2014. Last previous edition approved in 2014201
16、5 asD7954/D7954M 14.D7954/D7954M 15. DOI: 10.1520/D7954_D7954M-15.10.1520/D7954_D7954M-15A.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possibl
17、e to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
18、Conshohocken, PA 19428-2959. United States11.10 This practice addresses operating procedures, operator qualifications, operating methods, scanning, surveying, andrecording techniques.1.11 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. The val
19、ues statedin each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining valuesfrom the two systems may result in non-conformance with the standard.1.12 This standard does not purport to address all of the safety concerns, if any, associated w
20、ith its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Caution should be taken when accessing, walking, or using scanning equipment on the roofing orwaterproofing su
21、rfaces, or elevated locations, when using ladders, and when raising and lowering equipment to elevated locations.2. Referenced Documents2.1 ASTM Standards:2C1616 Test Method for Determining the Moisture Content of Organic and Inorganic Insulation Materials by WeightD1079 Terminology Relating to Roof
22、ing and WaterproofingD7438 Practice for Field Calibration and Application of Hand-Held Moisture MetersE2586 Practice for Calculating and Using Basic StatisticsF2659 Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement and Other FloorSlabs and Screeds Using a
23、Non-Destructive Electronic Moisture MeterNOTE 2See A1.3 for other referenced documents.3. Terminology3.1 For definitions of terms used in this practice, refer to Terminology D1079.3.2 Definitions of Terms Specific to This Standard:3.2.1 comparative moisture, content, nqualitative characterization of
24、 moisture content in relative terms (that is, low, medium,and high levels of moisture).3.2.2 core sample, nsmall specimen of insulation and membrane having a minimum of 2-in. 50-mm diameter obtained bycutting through these components down to the deck and removing them from the roofing section under
25、test.3.2.2.1 DiscussionCore samples are used to verify the membrane and insulation composition and ascertain information on their condition.3.2.3 detect or detection, v or nfor the purpose of impedance scanning, the condition at which there is a consistent indicationthat an elevated level of impedan
26、ce reading is present within the roofing or waterproofing system.3.2.4 false-positive, adjreading that indicates that elevated moisture is present when it is not.3.2.4.1 DiscussionFor example, a false positive in roofing for impedance scanning may be returned when some other electrically conductive
27、materialis present in the roofing system.3.2.5 gravimetric analysis, ndetermination of moisture content by weight of a material by comparing wet weight to over dryweight expressed as a percentage.3.2.6 moisture content, MC, nmass of moisture per unit mass of dry material.3.2.6.1 DiscussionThe moistu
28、re content is usually expressed as a percentage by weight and determined gravimetrically.3.2.7 roof assembly, nassembly of interacting roof components including the roof deck, air or vapor retarder, insulation andmembrane, or primary roof covering designed to weatherproof a structure.3.2.8 roof sect
29、ion, nportion of a roof that is separated from adjacent portions by walls or expansion joints with no changesin the components throughout the section.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Stand
30、ardsvolume information, refer to the standards Document Summary page on the ASTM website.D7954/D7954M 15a24. Summary of Practice4.1 This practice covers a procedure in which a specifically developed non-destructive electronic impedance (EI) based moisturescanner is used in conjunction with interpret
31、ive data and invasive verification practices to detect and evaluate the moistureconditions within low-sloped roofing and waterproofing systems by non-destructively measuring the electrical alternating current(ac) impedance.4.2 This practice is intended to be used in conjunction with the impedance sc
32、anner manufacturers operation instructions andguides.5. Significance and Use5.1 Excess moisture trapped in roofing or waterproofing systems can adversely affect performance and lead to premature failureof roofing or waterproofing systems and its components. It also reduces thermal resistance, result
33、ing in reduced energy efficiencyand inflated energy costs. Impedance scans can be effective in identifying concealed and entrapped moisture within roofing orwaterproofing systems.5.2 This practice is intended to be used at various stages of the roofing and waterproofing systems life such as: during
34、or atcompletion of installation of roofing or waterproofing system to determine if there was moisture intrusion into the roofing orwaterproofing system or materials for quality control purposes, underlying materials, at regular intervals as part of a preventativemaintenance program, and before re-ro
35、ofing or repair work to aid in condition assessment, or before replacement or repair work,or combinations thereof, to assist in determining the extent of work and replacement materials.5.3 This practice alone does not determine the cause of moisture infiltration into roofing or waterproofing systems
36、; however,it can be used to help tracing excess moisture to the point of ingress.6. Apparatus6.1 EI ScannerThis apparatus shall be specifically developed to detect and evaluate non-destructively comparative moistureconditions within roofing and waterproofing systems.FIG. 1 Typical Non-Destructive Mo
37、isture ScannerD7954/D7954M 15a36.1.1 Principles of OperationThe EI of a material varies in proportion with the materials moisture content. The EI ofmaterials such as those listed in 1.2 and 1.3 in the roofing or waterproofing system directly under the footprint of the scanner ismeasured by creating
38、an alternating electric field that penetrates the materials under test. The small alternating current (ac) flowingthrough this field is inversely proportional with the impedance of these moisture-absorbing materials. The instrument determinesthe currents amplitude and converts this value to a compar
39、ative moisture value.6.1.1.1 The depth of the signal penetration varies depending on the sensitivity and signal strength settings of the scanner as wellas the composition of materials, thickness, and moisture content of the roofing or waterproofing system under test.6.1.2 Apparatus Requirements:6.1.
40、2.1 The moisture scanner shall be capable of sending signals non-destructively into the materials below the surfacing andthe scanner.6.1.2.2 The moisture scanner shall have integrated adjustable calibration ability for the differing composition, thickness, densityof materials, and moisture condition
41、s that can be encountered in roofing or waterproofing assemblies.6.1.2.3 The moisture scanner shall have a display giving comparative readings of moisture conditions of materials found inroofing and waterproofing systems.6.2 Scanner TypesTwo types of impedance scanners are commercially available:6.2
42、.1 Handheld scanner designed to be used for point readings on a grid system, and6.2.2 Mobile-wheeled scanner, which can be rolled across the roofing or waterproofing to obtain continuous readings as thescanner moves over the surface.NOTE 3See A1.1 and A1.2 for examples of typical handheld and mobile
43、-wheeled types of impedance scanners.7. Operator Qualifications and Referenced Materials7.1 The operator shall:7.1.1 Be familiar with the use of the impedance scanner;7.1.2 Have knowledge of and available for reference at the roof site a copy of the manufacturers operating and calibrationinstruction
44、s for the impedance scanner used;7.1.3 Have knowledge of how and under what circumstances the impedance scanning system can be used, as well as itslimitations;7.1.4 Have a thorough understanding of the construction and components used in the roofing or waterproofing system assemblyunder test, such a
45、s types of membranes, roofing insulations, decking, and attachment;7.1.5 Confirm the composition of the roofing or waterproofing assembly and endeavor to obtain historical data regarding theconstruction, age, and performance of the roofing or waterproofing assembly; and7.1.6 Have a thorough understa
46、nding and knowledge of roofing and waterproofing technology including types of roofing orwaterproofing membranes and materials, decks, insulation materials, system assemblies and construction procedures, equilibriummoisture content, moisture migration in buildings, as well as health and safety requi
47、rements when carrying out roofing orwaterproofing moisture surveying.7.2 Data InterpreterIndividuals interpreting the field data shall have knowledge of: impedance scanner principles ofoperation, moisture migration transport mechanisms, environmental effects, oven dry and equilibrium moisture conten
48、ts (EMC),thermal resistance ratios (TRR), verification methods, and roofing and waterproofing construction as it applies to moisture analysisand gravimetric analysis to diagnose and interpret the readings from the roofing or waterproofing system surveyed.NOTE 4See A1.4 for additional information on
49、technique and anomalies.8. Impedance Scanning Techniques8.1 Two techniques, (A) and (B), for conducting moisture surveys using impedance scanners are:8.2 Technique AContinuous Systematic Scanning and RecordingThis practice involves moving (rolling) the impedancescanner in a systematic and continuous row-by-row manner when traversing the roof surface.8.2.1 As the scanner is rolled along each run or row in a systematic fashion, continuous impedance readings shall be displayedon the scanners meter. These readings shall be visually observed by the
