.*^T °F **

s ffc

If) NBS TECHNICAL NOTE 863

U.S. DEPARTMENT OF COMMERCE/ Nation:

m

Fatigue Tests ot Bituminous
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards 1 was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology,

the Institute for Computer Sciences and Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United

States of a complete and consistent system of physical measurement; coordinates that system

with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Measurement Services and the following divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Nuclear

Sciences 2 — Applied Radiation 2 — Quantum Electronics 3 — Electromagnetics 3 — Time

and Frequency * — Laboratory Astrophysics 3 — Cryogenics 3. THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational institutions, and Government; provides

advisory and research services to other Government agencies; and develops, produces, and

distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials and the following divisions: Analytical Chemistry — Polymers — Metallurgy — Inorganic Materials — Reactor

Radiation — Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to promote

the use of available technology and to facilitate technological innovation in industry and

Government; cooperates with public and private organizations leading to the development of

technological standards (including mandatory safety standards), codes and methods of test; and provides technical advice and services to Government agencies upon request. The Institute consists of a Center for Building Technology and the following divisions and offices: Engineering and Product Standards — Weights and Measures — Invention and Innovation — Product Evaluation Technology — Electronic Technology — Technical Analysis — Measurement Engineering — Structures, Materials, and Life Safety* — Building

Environment * — Technical Evaluation and Application 4 — Fire Technology.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides technical services designed to aid Government agencies in improving cost effec- tiveness in the conduct of their programs through the selection, acquisition, and effective

utilization of automatic data processing equipment; and serves as the principal focus within

the executive branch for the development of Federal standards for automatic data processing

equipment, techniques, and computer languages. The Institute consists of the following

divisions

Computer Services — Systems and Software — Computer Systems Engineering — Information Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and

accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and

a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum

accessibility to the scientific information of the world. The Office consists of the following

organizational units: Office of Standard Reference Data — Office of Information Activities — Office of Technical

Publications — Library — Office of International Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

a Part of the Center for Radiation Research.

3 Located at Boulder, Colorado 80302.

* Part of the Center for Building Technology.
ml Bureau of Standards

Li&icny Fatigue Tests of Bituminous

MAY2oi97S/lembrane Roofing Specimens

US'? 53

1976,

George F. Sushinsky

Mechanics Division

Institute for Basic Standards

National Bureau of Standards

Washington, D.C. 20234

Robert G. Mathey

Structures, Materials and Safety Division

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

>^Uu\jjuoXj srurfju

J

<sru> * ?&3

<°'j\

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Issued April 1 975
National Bureau of Standards Technical Note 863

Nat. Bur. Stand. (U.S.), Tech. Note 863, 32 pages (April 1975) CODEN: NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1975

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.46:863). Price $1.15
CONTENTS

Page

1. INTRODUCTION 1

2. TEST SPECIMENS 2

3. TEST EQUIPMENT k

3.1 Fatigue Equipment h

3.1.1 Tensile Fatigue k

3.1.2 Flexural Fatigue 6

3 .

Flexure Fixture 6

3 .

3

Environmental Chamber 6

k. TEST PROCEDURES 9

U.l Tensile Fatigue 9

h . 2 Flexural Fatigue 9

5

.

EXPERIMENTAL RESULTS 10

5.1 Tensile Fatigue 10

5 .

Flexural Fatigue IT

6. DISCUSSION AND RECOMMENDATIONS IT

6.1 Proposed Performance Criteria 2T

6.1.1 Tensile Fatigue 2T

6.1.2 Flexural Fatigue 2T

T . ACKNOWLEDGMENT 2T

8. REFERENCES 28

in

FATIGUE TESTS OF

BITUMINOUS MEMBRANE ROOFING SPECIMENS

by

George F. Sushinsky and

Robert G. Mathey

ABSTRACT

Tensile and flexural fatigue tests were performed on built-up roof membrane specimens (ASTM Designation: D2523-70)

fabricated from four different material systems. The tensile

fatigue tests were run under cyclic load control conditions

while specimens tested in flexural fatigue were run under

cyclic midspan displacement control. Tests were run at ambient

laboratory conditions, generally TO ± 2°F (21 ± 1°C), and at

± 2°F (-18 ± 1°C). Curves based on the experimental results

are plotted relating the peak load or displacement to the

median fatigue lifetimes for specimens fabricated from each

material. Performance criteria for roof membranes subject to

fatigue loading are recommended.

Key Words: Bituminous roof membranes; fatigue testing; flexural

fatigue; performance criteria; roofing; temperature effects;

tensile fatigue; test methods.

1. INTRODUCTION

8 2 1

In 1972 over 3.5 billion square feet (3.x x 10 m ) of bituminous

built-up roof membranes were applied to buildings in the United States.

While the membrane represents only one component in a roof system , it

is the membrane that provides protection to a building's contents and

occupants from the weather. Traditionally, roof membranes have been

described by prescriptive-type specifications for the materials

The units used for physical quantities in this paper are given in both

the U. S. Customary Units and in the International System of Units (Si).

Conversion factors can be found in ASTM Standard Metric Practice Guide,

ASTM Designation E-380-72.

2Bituminous built-up roof system is a term used to describe roofs in

which the waterproofing membrane is composed of layers of reinforcing

felts adhered together with a bituminous material. The membrane is

generally installed over insulation but is sometimes applied directly

to the roof deck.
comprising the membranes. The use of prescriptive-type specifications

tends to hinder innovation in systems design and the implementation of

new materials in built-up roof systems.

The performance of the bituminous membrane has been considered for

many years only from a practical viewpoint, that is, observation of

its durability under in-service conditions. Only recently have some of

the properties and characteristics of bituminous built-up roofs been

described quantitatively [l] . Prior to this, a few quantitative

guidelines have been available to predict the performance of built-up

roof membranes. The lack of performance criteria probably represents

;he largest single constraint to the introduction of new and innovative

systems into the roofing industry.

In an attempt to develop the "art" of roofing into more of a science, research was conducted at the National Bureau of Standards to

develop performance criteria which would contain quantitative definitions

on a roof membrane's overall ability to perform under in-service conditions.

An important intent in the performance approach is to provide a basis

for evaluating roofing membranes with reasonable assurance that the

membrane will perform satisfactorily over its intended period of use,

As part of the research program, preliminary performance criteria were recommended for bituminous membrane roofing [l]. These criteria

recommend levels of performance for nine of the twenty attributes that were identified for laboratory study as affecting the performance of

roof membranes under service conditions. Two of the attributes which

were identified for laboratory study were tensile fatigue strength and

flexural fatigue strength.

This report describes the development of performance criteria

based on the fatigue behavior of conventional types of roof membranes.

The objectives of this study were to measure the tensile and flexural

fatigue strengths of conventional roofing membranes, to develop methods

of tests for measuring these engineering properties and to recommend

the levels of performance included in the performance criteria.

2. TEST SPECIMENS

The specimens tested in this investigation were die cut from fourply membranes and conformed to standard size specimens such as those

described in ASTM D-2523 [2]. The specimen geometry is shown in Figure

1. The specimens represented four different types of four-ply membranes,

Four types of roofing felts and two types of bitumen were used in the

fabrication of the test specimens^. The four types of roof membranes

Figures in brackets refer to literature references given in Section 8.

kDetails of specimen fabrication will be given in a report, "Tensile

Properties of Built-Up Roof Membranes" by Robert G. Mathey to be

published.
1.0 0"

1.005"

10"

Figure 1 - Built-up roof membrane specimen geometry (ASTM Designation:

D2523-70).
are given in Table 1. Specimens are identified using the appropriate

Table 1 - Roof Membrane Material Combinations and Membrane Designation

ASTM ASTM Membrane

Felt Designation Matrix Designation Designation

Organic D22T Coal-tar pitch DU50, Type A A

Organic D226, 15 lb type Asphalt D312, Type I B

Asbestos D250, 15 lb type Asphalt D312, Type I C

Glass D2178, Type I Asphalt D312, Type I D

membrane designation letter code followed by a 2 digit number. The

specimens tested were fabricated with the across machine (transverse)

direction of the felts oriented in the direction along the longitudinal

axis of the specimens . All specimens were fabricated in an identical

manner except the specimens to be tested in flexural fatigue. These

specimens contained a 0.010-in (0.03-cm) diameter copper wire at midsection

that spanned the length of the specimen.

3. TEST EQUIPMENT

3.1 Fatigue Equipment

The test program was conducted using the fatigue equipment available

so, the National Bureau of Standards' Engineering Mechanics Laboratory [3].

3.1.1 Tensile Fatigue

Tensile fatigue tests were run with the actuator from the 10,000

lbf (UU,500 N) capacity fatigue machine mounted in a test stand (Figure 2)

These tests were conducted under load control conditions with the span

adjusted to a 5,000 lbf (22,200 N) maximum load. In order to further

reduce the maximum load capacity of the fatigue test set-up, while

attempting to maintain the accuracy of the applied load, the actuator

was connected to a ten-to-one lever arm. This provided for a possible

maximum load of 500 lbf (2,200 N) to the specimens.

The specimens were clamped in 2-in (5.1-cm) wide tension grips, so that the length of the specimen between grips was 7.0-in (17.8-cm).

The upper grip was attached to the end of the lever arm through a steel

5 Roofing felts are made on a moving belt and formed in rolls generally

36-in (91-cm) wide and of various lengths. The across machine (transverse)

direction is the direction across the width of the felt. The strength of

a felt oriented in the across machine direction is generally weaker than

in its machine (longitudinal) direction. This is a result of the

preferred orientation of the fibers of the felt in the direction along

the material's length.
CDa

cu6

•HO

CUaen

cuG

cdu§

cu6

a.3

CU

CO

•u

CO

cu u

cu

•Hu

•H

COc

cu H

I CN

cuu

00 •H
pull rod which swivelled on a "ball and socket joint. The lower grip was rigidly attached to the test frame. The test set-up is shown in

Figure 2.

An aluminum tensile coupon with physical dimensions similar to the

specimens was instrumented with resistance strain gages to check the

amount of in-plane and out-of-plane bending introduced by the test

system. Adjustments were made to the test system so that the bending

strain in each direction was less than 5% of axial strain under static

loading conditions.

The test system was calibrated to determine the correspondence

between the machine set point dial setting and applied static loads to

U00 lbf (1,800 N). A 500 lbf (2,200 N) capacity load cell was used for

this purpose. The uncertainty of the static loads applied to the

specimen was less than 1 percent of the prescribed load. Using techniques

described by Robinson [h] , the inertial effects of the lever arm on the

applied waveform amplitude and shape were checked at frequencies up to

15 Hz. No qualitative distortional effects on the waveform were noted.

3.1.2 Flexural Fatigue

Three point bending (flexural) fatigue tests were run under controlled displacement conditions in a 50,000 lbf capacity (222,000 N) fatigue

machine for tests at ambient conditions and a 2,000 lbf (9,900 N) capacity

fatigue machine for tests at ± 2°F (18 ± 1°C) (Figures 3a

and 3b respectively). Applied displacements of each machine were checked quasistatically against readings from a dial gage graduated in

0.001 in (0.003 cm) increments. The differences between. these readings

and the prescribed deflections were less than 1 percent of the prescribed

deflections.

3 . 2 Flexure Fixture

Flexural fatigue tests were performed in the fixture shown in

Figure k. The loading member and the end supports were made from 1.5-

in (3.8-cm) diameter aluminum rod. The span length of the fixture was 7.0-in (17.8-cm). The specimens were restrained from slipping at the

support by clamping pressure applied at the supports and by plates

0.09^-i'n (0.02-cm) thick clamped to the ends of the specimen and wedged

against the supports of the fixture. The ends of the specimen were allowed to rotate at the supports.

3.3 Environmental Chamber

Two test chambers were used for the tests at 0°F (-l8°C). One

chamber was made with a wood shell insulated internally and externally

with 2-in (5-cm) thick insulating foam plastic; the other chamber was made from an insulating foam plastic. In both chambers all joints and

edges were sealed to minimize leakage. Each chamber was conditioned
Figure 3 - Flexural fatigue test set-ups for roof membrane specimens.

7
hi

• • *

• • • •

• •

'? ** * | :

.

'v ',v

' H

Figure 4 - Fixture used in testing roof membrane specimens in flexure,

8
using a commercial refrigeration unit and circulating fan. Temperature

was measured with a thermocouple taped to the gage section of the

specimen. Temperature was controlled and recorded by a time-proportioning,

recording controller. An initial temperature between 0°F (-l8°C) and

-2°F (-19°C) with a time variation of 1°F (0.6°C) was used in each test.

Temperatures were maintained within these limits for the duration of

each test.

k. TEST PROCEDURES

Tensile fatigue tests and flexural fatigue tests were performed on

four types of four ply built-up roof membranes. These tests were run at

ambient laboratory conditions, generally TO ± 2°F (21±1°C), and at

+ 2°F (-18+ 1°C). Triplicate tests were run at each of three load

levels and at two temperatures on the four different types of membrane

specimens. Specimens tested under ambient laboratory conditions were

stored prior to testing at ^2°F (6°C) while those tested at the lower

temperature were stored at -6°F (-21°C) prior to testing. These storage

conditions facilitated handling of the specimens and the environmental

conditioning of the specimens to be tested at the cold environment.

U.l Tensile Fatigue

All tensile fatigue tests were run under load control in the setup shown in Figure 2. A specimen was placed in the grips and a small

tensile load, 5 lbf (22 N), was applied. The specimen was held at this'

load level until it attained the desired test temperature. It was maintained under these conditions for an additional period of at least

30 minutes prior to the start of fatigue testing.

Fatigue loads were based on the average static strengths of similar

specimens [l]. The peak fatigue loads were approximately 80, 60, and kO

percent of the average static strengths of specimens of each material

type. The minimum load in the fatigue cycle was 10 percent of the

maximum applied fatigue load. The cyclic load waveform was a haversine.

Tests were run at frequencies of 10 Hz for tests at ambient laboratory

conditions and 15 Hz for tests at 0°F (-l8°C). Failure was defined as separation of the specimen into two pieces.

k.2 Flexural Fatigue

Roof membranes have very little flexural stiffness, which resulted

in large deflections in the static flexural tests [l] at low loads.

Therefore, it was decided to conduct the flexural fatigue tests under

center-span displacement control. Test set-ups for flexural fatigue

tests at ambient laboratory temperatures and ± 2°F (-18 + 1°C) are shown in Figures 3a and 3b respectively. Specimens were first clamped

in the test fixture. The 0.010-in (0.03-cm) diameter copper wire,

placed in the specimen during fabrication, was connected to the machine

interlock completing an electrical circuit. Each specimen was held at
zero displacement until it attained the desired test temperature, and

then maintained at this temperature for 30 minutes prior to the start of

the fatigue test.

Tests "were run with positive and negative peak center-span displacements

of 0.20, 0.15 and 0.125-in (0.51, 0.38 and 0.32-cm). These displacements

were chosen to produce failures at about 5,000, 50,000 and 500,000

cycles respectively as based on preliminary test results using specimens

fabricated from material B.

Test frequency was dictated by the available equipment. For tests

at ambient laboratory temperatures, the test frequency was limited to 2,

3, and k Hz for positive and negative peak center-span displacements of

0.20, 0.15, and 0.125-in (0.51, 0.38, and 0.32-cm) respectively by the

displacement-frequency characteristics of the 50,000 lbf (222,000 N)

fatigue machine. At 0°F (-l8°C), for tests in the 2,000 lbf (8,900 N)

fatigue machine, frequency was not a limiting constraint. For these

tests, restraint was imposed by the environmental chamber which could

maintain temperature for only about 18 hours. For positive and negative

peak center-span displacements of 0.20, 0.15, and 0.125-in (0.51, 0.38

and 0.32-cm) the low temperature tests were run at 7.5 Hz.

The cyclic waveform for all the flexure tests -was a full sine wave

cycled between the positive and negative peak displacement values.

Specimens were cycled until failure. This occurred when the wire in the

center of the specimen broke, interrupting the circuit to the machine

interlock. Wire breakage occurred as damage propagated through the

thickness of the specimen from the two outer felt plies to the two inner

felt plies. Complete physical separation of the specimens into two

parts did not necessarily result at this point, but irreparable damage

was always evident and separation did occur within minimal additional

effort.

A limited amount of data relating the static load at the peak

displacement versus the number of fatigue cycles was taken for specimens

being tested at ambient temperatures. These data were taken by intermittently stopping the flexural fatigue tests and recording static loads

using a 75 lbf (330 N) load cell and associated instrumentation.

5. EXPERIMENTAL RESULTS

5.1 Tensile Fatigue

Specimen designations, test conditions and fatigue lifetimes for

specimens run under load controlled tensile fatigue are given in Tables

2 and 3. Replicate specimens are grouped as indicated by a single digit

appended to the specimen number. The median fatigue lifetime of each

group of replicate specimens is indicated in the last column of each

table. Graphical data based on the median fatigue lifetimes of these

specimens are presented in Figures 5 through 8. Figures 5 and 6 represent

10
Table 2 - Results of Tensile Fatigue Tests on Roof Membrane Specimens

Percent of

Specimen average static Cyclic load Cycles to

number failure load limits Frequency Temperature failure

Ibf Hz

A-51-1

A-5 2-1

A-53-1

A-57-2

A-58-2.

A-60-2

A-61-3

A-63-3

A-6U-3

B-90-1

B-91-1

B-93-1

B-86-2

B-9^-2

B-96-2

B-95-3

B-97-3

B-98-3

B-92-U

C-80-1

C-82-1

C-81+-1

C-85-2

C-86-2

C-89-2

C-91-3

C-95-3

C-98-3

C-100-3

C-90-3

D-92-1

D-96-l

D-9T-1

D-93-2

D-9^-2

D-98-2

D-95-3

D-99-3

D-100-3

D-91-^

81 5.0-50.0 22-220 10

81 5.0-50.0 22-220 10

81 5.0-50.0 22-220 10

57 3.5-35.0 16-160 10

57 3.5-35.0 16-160 10

57 3.5-35.0 16-160 10

111 2.5-25.0 11-110 10

kl 2.5-25.0 11-110 10

kl 2.5-25.0 11-110 10

83 ' 5.0-50.0 22-220 10

83 5.0-50.0 22-220 10

83 5.0-50.0 22-220 10

58 3.5-35.0 16-160 10

58 3.5-35.0 16-160 10

58 3.5-35.0 16-160 10

k2 2.5-25.0 11-110 10

k2 2.5-25.0 11-110 10

k2 2.5-25.0 11-110 10

33 2.0-20.0 9-90 10

83 3.0-30.0 13-130 10

83 3.0-30.0 13-130 10

83 3.0-30.0 13-130 10

55 2.0-20.0 9-90 10

55 2.0-20.0 9-90 10

55 2.0-20.0 9-90 10

kl 1.5-15.0 7-70 10

ill 1.5-15.0 7-70 10

Hi 1.5-15.0 7-70 10

ill 1.5-15.0 7-70 10

ill 1.5-15.0 7-70 10

86 6.0-60.0 27-270 10

86 6.0-60.0 27-270 10

86 6.0-60.0 27-270 10

57 i+.0-i|0.0 18-180 10

57 U.O-ilO.O 18-180 10

57 il.O-ilO.O 18-180 10

43 3.0-30.0 13-130 10

U3 3.0-30.0 13-130 10

ii3 3.0-30.0 13-130 10

80 5.5-55.0 2i|-2U0 10

°F °C median

70 21 63900

70 21 70600 70600

72 22 71600

72 22 252000 252000

72 22 290000

72 22 153000

68 20 25ii0000 (1)

68 20 i|220000 U220000 (1)

72 22 i|250000 (1)

70 21 11200

70 21 10700 10700

70 21 6850

70 21 6U6OO

70 21 80il00 80i|00

68 20 137000

72 22 975000

68 20 1110000 1110000

68 20 1280000

70 21 1150000 1150000 (1)

68 20 16300

68 20 8i+20

68 20 13200 13200

68 20 101000

68 20 103000 103000

72 22 17ii000

72 22 28il000

72 22 i|20000

72 22 161000

73 23 236000 236000

72 22 lil2000

70 21 12il0 12U0

68 20 1000

68 20 3930

70 21 18200

70 21 U1200

68 20 32900 32900

72 22 157000

68 20 708000

68 20 267000 267000

70 21 Qkho 8Uii0

(l) No visible evidence of specimen damage.

11
Table 3 - Results of Tensile Fatigue Tests on Roof Membrane Specimens

Percent of

Specimen average static Cyclic load Cycles to

number failure load limits Frequency Temperature failure

lbf N Hz °F °C median

A-82-1 83 22-220 98-980 15 -1 -18 23

A-81-1 83 22-220 98-980 15 -1 -18 230 126

A-80-1 83 22-220 98-980 15 -1 -18 13

A-92-1 83 22-220 98-980 15 -18 280

A-T9-2 59 15.5-155 69-690 15 -1 -18 396000

A-87-2 59 15-5-155 69-690 15 -2 -19 1270000

A-93-2 59 15.5-155 69-690 15 -2 -19 U09000 1^09000

A-90-3 U2 11-110 1+9-^90 15 -1 -18 2920000 (1)

A-9i+-3 U2 11-110 U9-U90 15 -2 -19 3330000 3330000 (1)

A-91-3 U2 11-110 U9-U90 15 -2 -19 5950000 (1)

B-56-1 82 22-220 98-980 15 -1 -18 1150 1150

B-67-1 82 22-220 98-980 15 -2 -19 650

B-69-1 82 22-220 98-980 15 -2 -19 1170

B-68-2 58 15.5-155 69-690 15 -2 -19 212000

B-55-2 58 15.5-155 69-690 15 -1 -18 98200

B-61-2 58 15.5-155 69-690 15 -2 -19 197000 197000

B-65-3 kl 11-110 U9-U90 15 -3 -19 2060000 (1)

B-57-3 kl 11-110 1*9-U90 15 -2 -18 45^0000 (1)

B-58-3 kl 11-110 U9-U90 15 -3 -19 1+530000 U530000 (1)

C-73-1 82 15-150 67-670 15 -1 -18 110

C-102-1 82 15-150 67-670 15 -1 -18 2000

C-65-l 82 15-150 67-670 15 -1 -18 1000 550

C-60-1 82 15-150 67-670 15 -1 -18 55

C-61-2 58 10.5-105 1+7-vro 15 -1 -18 180000 199000

C-62-2 58 10.5-105 1+7-^70 15 -1 -18 17^000

C-63-2 58 10.5-105 U7-1+70 15 -1 -18 218000

C-6U-2 58 10.5-105 l+T-l+TO 15 -1 -18 U99000

c-69-2 kl 7.5-75 33-330 15 -1 -18 2U80000 (1)

C-66-3 kl 7-5-75 33-330 15 -1 -18 U820000 (1)

C-67-3 kl 7.5-75 33-330 15 -2 -19 3550000 3550000 (1)

D-81-1 80 11.5-115 51-510 15 -1 -18 15

D-65-l 80 11.5-H5 51-510 15 -1 -18 1U0

D-67-l 80 11.5-115 51-510 15 -1 -18 28 28

D-72-1 80 11.5-115 51-510 15 -1 -18 7

D-77-l 80 11.5-115 51-510 15 -1 -18 370

D-82-2 56 8-80 36-360 15 -1 -18 26800

D-66-2 56 8-80 36-360 15 -1 -18 3U600 58800

D-6U-2 56 8-80 36-360 15 -1 -18 126000

D-63-2 56 8-80 36-360 15 -18 82000

D-68-3 38 5.5-55 2H-21+0 15 -1 -18 1230000 (1)

D-70-3 38 5.5-55 2U-2U0 15 -2 -19 UU60000 (1)

D-73-3 38 5.5-55 2H-2U0 15 -2 -19 3290000 3290000 (1)

(l) No visible evidence of specimen damage,

12
ct

t <L!_ oI—

LU

I u

>

a

•H

4-) CO

4-1 CO

cu&0

CtJ M

0>>«

CU 42

4-1

M-lo

4-> c

cuo

(-1 cuex

CO3

COn

cu>

COd

cu6

•H

CJCU . ex /—s CO CJ

M-lo iHCN

cu v-/ e

•H Pn

4J o

cu

4-1 O •H r~

.H

4J

CU CO 3

OC -a

•H cO 4J o

CO t-H

4-t cu C u

CO 3

•H rH 'a •H

cu CO

IT)

CU3

00

•H

o o o O

avoi juvis govajAV jo iNajaad

oCO

13
fa o

-"b

•^ on o Z3<

u.O

it/) o

avcn J.N3DiHd

u

CO

CO 13

COou

•HU

cO -J

CO

<uM

cO

!-i cu>

COC

OJ

CJU

CUa.

CO3

CO CO LU d) O -i > — u> CO U c

cu

Ik

•H

.CJ CUa.

CO

M-lo

cue

CU00

CO • 4-1 /-\ U C o

co •H CO

T3 rH

CU 1 I

CUu3

00

•H

fa
<u_OI—

t/3

>-

*qi ' avoi >iV3d

CN1

F=4 oO

•u

to x)

cOO

cuM

•H

•U

CO

^!

co

cuP, 13

CU •H

rH

apCO

CO

COu

cu>

COa

cu6

•HO

CUP.

CD IWo

cua

•HU

CU

CU3

60

•HU

CO

cfl •H'd

cu

cu3

t>0 •H

15
jqi ' avoi »v3d

K . o /~\ oCO

tH1 >-• o

>oO o 1 4J

CO

COO

a>3 o

60

•H

4-> cd

«4-l

CO

a)

"* •H o LU P.

ac CX

r>

CO _i CO < 3

CO u. >

CO \—

CO or~ m a> LU S 1 •H > a

(X

u CO

<4-t o

CN a) o e

•H

4J

•H

iH

CD3

00

•H ^TM 4J o cd f—

M-l

flCO •H

<D o 1 o 00

OJ

S-i 3

60

•H

16
comparative data of the median fatigue lifetimes based on percentages of

the average static strength for each membrane type, while Figures 7 and

8 represent comparative data of the median fatigue lifetimes "based on the actual peak fatigue loads at ambient temperatures and 0°F (-l8°C)

respectively.

5.2 Flexural Fatigue

Specimen designations, test conditions, and fatigue lifetimes for

specimens run under displacement controlled flexural fatigue are given

in Tables h and 5. Replicate specimens are grouped as indicated by a single digit appended to the specimen number. The median fatigue lifetime of each group of replicate specimens is indicated in the last

column of each table. Graphical data based on the median fatigue lifetimes of these specimens are presented in Figures 9 through 12. Figures

9 and 10 represent comparative data of the median fatigue lifetimes

based on percentages of the maximum static midspan deflection for each

membrane type [l], while Figures 11 and 12 represent comparative data of

the median fatigue lifetimes based on the applied peak midspan deflections

at ambient laboratory temperatures and 0°F (-l8°C) respectively.

Compliance data relating the static flexural loads to the number of

fatigue cycles for a given displacement are given in Table 6.

6. DISCUSSION AND RECOMMENDATIONS

Fatigue loading in a roofing membrane encompasses the spectrum from

low cycle, large amplitude fatigue caused by foot traffic to wind induced

high frequency vibrations at small amplitudes as well as thermally

induced load cycling. Therefore, performance guidelines for rocf membranes

should consider their fatigue properties.

Membrane material types A, B, C, and D were chosen to be evaluated

since they represent commonly used roof membranes with known in-service

performance histories. Generally, four-ply roof membranes similar to

those designated as A, B, and C have demonstrated satisfactory performance

in-service under varying climatic conditions and roof loadings. All of

the membranes have experienced some degree of splitting in cold climates.

However, splitting appears to have been more prevalent in membranes

having low tensile strengths and large coefficients of thermal expansion

such as some two-ply membranes and some of those similar to type D. A

new type of glass felt having a higher tensile strength compared to the

other roofing felts [l] has been developed recently. Although preliminary

static tensile and flexural data have been favorable for membranes

fabricated from this felt it has not been evaluated in fatigue.

The following recommendations present performance guidelines based

on the data available at this point. Minimum levels of acceptable

performance were selected such that membrane types A, B, and C satisfied

the proposed performance criteria. Roof membranes made from other

materials that equal or exceed these fatigue performance guidelines

IT
Table k - Results of Flexure Fatigue Tests on Roof Membrane Specimens

Specimen

number

Peak

deflection

Percent of static

deflection at maximum load Frequency- Temperature

Cycles to

failure

in percent Hz °F median

A-58W-1 0.20 0.51 18

A-65W-1 0.20 0.51 18

A-6UW-1 0.20 0.51 18

A-68W-2 . 0.15 0.38 Ik

A-69W-2 0.15 0.38 Ik

A-62W-2 0.15 O.38 Ik

A-70W-3 0.125 0.32 11

A-71W-3 0.125 0.32 11

A-72W-3 0.125 0.32 11

B-73W-1 0.25 0.6U 31

B-72W-1 0.25 0.6k 31

B-69W-1 0.25 0.6k 31

B-70W-2 0.20 0.51 25

B-67W-2 0.20 0.51 25

B-66W-2 0.20 0.51 25

B-62W-3 0.15 0.38 19

B-63W-3 0.15 0.38 19

B-61+W-3 0.15 0.38 19

B-59W-I1 0.125 0.32 15

B-58W-U 0.125 0.32 15

B-^kV-k 0.125 0.32 15

B-65W-5 0.10 0.25 12

C-65W-1 0.20 0.51 25

C-61+W-1 0.20 0.51 25

C-66W-1 0.20 0.51 25

C-69W-2 0.15 0.38 19

C-73W-2 0.15 0.38 19

C-71W-2 0.15 0.38 19

C-68W-2 0.15 0.38 19

C-70W-3 0.125 0.32 15

C-7W-3 0.125 0.32 15

C-61W-3 0.125 0.32 15

D-61W-1 0.20 0.51 33

D-60W-1 0.20 0.51 33

D-58W-I 0.20 0.51 33

D-57W-2 0.15 0.38 25

D-55W-2 0.15 0.38 25

D-53W-2 0.15 0.38 25

D-50W-3 0.125 0.32 20

D-59W-3 0.125 0.32 20

D-51+W-3 0.125 0.32 20

2.0 72 22 Il60 1160

2.0 72 22 5ko

2.0 72 22 2620

3.0 73 23 8260 8260

3.0 73 23 10900

3.0 72 22 6200

k.O 72 22 12800 12800

k.o 72 22 li+300

k.O 72 22 11200

2.0 72 22 1170

2.0 72 22 7730

2.0 72 22 2660 2660

2.0 72 22 U880

2.0 72 22 7370

2.0 72 22 7260 7260

3.0 72 22 60200

3.0 68 20 20600

3.0 70 21 51100 51100

k.O 72 22 65000

k.O 68 20 80500 80500

k.O 70 21 99*+00 k.O 72 22 703000 703000(2)

2.0 72 22 1850

2.0 72 22 1580

2.0 72 22 1780 1780

3.0 72 22 63U0

3.0 72 22 13800 11+100 3.0 72 22 1^1+00 3.0 66 19 5920

k.O 70 21 53700

k.O 72 22 16200

k.O 72 22 39900 39900

2.0 72 22 12100 12100

2.0 72 22 3880

2.0 70 21 1U100

3.0 72 22 61100

3.0 72 22 3U800 3U800

3.0 72 22 25900

k.O 72 22 669000 (2)

k.O 70 21 653000 653000(2)

k.O 72 22 590000 (2)

(1) W indicates specimens fabricated with copper wire inserted between the

center plies.

(2) No visible evidence of specimen damage.

18
Table 5 - Results of Flexure Fatigue Tests on Roof Membrane Specimens

Percent of

Specimen Peak maximum static Cycles to

number deflection deflection Frequency Temperature failure cm percent Hz °F median

A-56w-r x; 0.20 0.51 50 7.5 -18 16000 16000

a-6iw-i 0.20 0.51 50 7.5 -18 16100

a-6ow-i 0.20 0.51 50 7.5 -18 790

A-73W-2 0.15 0.38 38 7.5 -18 60

A-55W-2 0.15 0.38 38 7.5 -1 -18 60 60

A-57W-2 0.15 0.38 38 7.5 -0.5 -18 80

A-50W-3 0.125 0.32 30 7.5 -2 -19 11+6000 11+6000 A-53W-3 0.125 0.32 30 7.5 -2 -19 19I+OO A-52W-3 0.125 0.32 30 7.5 -2 -19 19^000

B-51W-1 0.20 0.51 50 7.5 -1.5 -19 30

B-76W-I 0.20 0.51 50 7.5 -1.5 -19 ^0 1+0 B-77W-I 0.20 0.51 50 7.5 -18 190

B-83W-2 0.15 0.38 38 7.5 -1.5 -19 70

B-7I1W-2 0.15 0.38 38 7.5 -1 -18 21100

B-82W-2 0.15 0.38 38 7.5 -1.5 -19 230 230

B-78W-2 0.15 0.38 38 k.O '-18 13150

B-85W-3 0.125 0.32 30 7.5 -18 35000

B-81W-3 0.125 0.32 30 7.5 -1 -18 7^0

B-79W-3 0.125 0.32 30 7.5 -1 -18 21+200 21+200

C-57W-1 0.20 0.51 67 7.5 -1.5 -19 Ho

C-7I1W-I 0.20 0.51 67 7.5 -18 10 25

C-53W-2 0.15 0.38 50 7.5 -1.5 -19 26

C-83W-2 0.15 0.38 50 7.5 -18 50 50

C-80W-2 0.15 0.38 50 7.5 -18 50

C-52W-3 0.125 0.32 ko 7.5 -1 -18 70

C-81+W-3 0.125 0.32 ko 7.5 -0.5 -18 1+530 C-81W-3 0.125 0.32 ko 7.5 -0.5 -18 250 250

D-75W-I 0.20 0.51 61 7.5 -18 90

D-7I+W-I 0.20 0.51 67 7.5 -0.5 -18 1380

D-82W-1 0.20 0.51 67 7.5 -1 -18 500 500

D-72W-2 0.15 0.38 50 7.5 -2 -19 10600

D-70W-2 0.15 0.38 50 7.5 -0.5 -18 16000 13000

D-78W-2 0.15 0.38 50 7.5 -18 15500

D-71W-2 0.15 0.38 50 7.5 -0.5 -18 9190

D-76W-3 0.125 0.32 1+0 7.5 -1.5 -18 66800 66800

D-79W-3 0.125 0.32 1+0 7.5 -1.5 -18 1+8900 D-83W-3 0.125 0.32 1+0 7-5 -2 -19 222000

(2)

(2)

(1) W indicates specimens fabricated with copper wire inserted between the

center plies.

(2) Delamination of felts on initial loadings.

19
E

3

E

•HX

COE

4-1o

c

0)

CJu

01fX

en3

CO

0)>

c

(UE

•Ho

OJPu

CO

4-1o u

E CM

0) h 4-1 „

W CTJ

CTJ C

oH

CO 0) £! H X) 14_| 0) Q)

3

«)

•H

NOUD31d3a NVdSQIW OIIVIS dO lN3Dd3d

20
«to

>o

u

•r-t 4-> cd

4-> CO§

B

•HX

cda

C

CU

CJu

0)D,

CO3

"o COU

cu UJ >

ct-) CO _j c

cu < e

u- •HO

o1—

cua

CO •

CO U-t O

UJ O o

—J

(

)

cu ro

CO >- 6 -H o LJ •H 1

14-1 lJ-i •H oo

cu3 4-1 60 CO •Hu C m o

<4-l •H

•u c o

CO cu •H H

-d 4-1 cu cu g "3 o

.H

cuM

3

00

fe

NOI1331d3a NVdSaiW DI1V1S dO iN3D83d

21
PEAK DEFLECTION AMPL I TUDE , IN.

o

n

-<n

r—m

C

TOm

22
o00

r-t

I v—

OO

c

o

•HU

O

CD iH

IW

CU 13

CTJ CUp, 13

0) H

-H

P-P

ca

en3

enM

0)>

c

CDB

•H

cj

CDP

W

CU6

•H

CU

<U3

•H

C

ctj •H

-T3CU S

CN

cu

•H

ui'aanindwv NOin3id3a W3d

23
W

fpO

H

oooo

w

ION

JO

S!

I 00

roo

o

vji

to

ION

ON

s:

i IO

O

OO

ro

>

io

I oo

o

VJ)

00OO

>

I ON

OO

s:

Iro

>

i vji OO

£.

I

H 'T) (D ID O p

c+ *" o

3

TO

>-3 &

H

ftON

I a

onvji ro H ON -p- M H vji ro on .p- O O ON -J -p- ro oo-^i ro o o o o woo ro o 00 w w o

o o o o o o o On O O moo o o o O H O O O H1 O O H O H -J o o

O 00 VJI —

5

VJI O U1VO O

vji O ON 00

HMUI ow ro poo00

bd

1 viCO

Si

1jrO

ro -p- -p- p- o -Pw

iON

1 OO

ro vji o —3 CO

H

O IO

>

I

SJ

i 00

OVIOM

VJI

o ro -p- on

>

iON

VO

s;

I ro

ro o -pHo

o -<i

>

i ON

i

o

a

1

i-b

CD

tr< o

p

p<

d-O

t)

(Do

(DM>H

CD

Co VJI vji H H

ovo ro^o o

yi-io ro o o o o o

o o o o o

roo ro On O

o o

O O H

H H H p- ro oo O vo oo

00 O ON VO VJI VJI VJI VJI o o O o o o -p- o

O O O H o o o H o o

o

P

c+H-

(TO

n>o

o oo -P--J oo CO o vji ro o -p-vo o o oo oo o

h ro o oo -p- 2

H H OO 00 oo O 00 00 H ON ON

ro vji o ro oo m -p- -p- ocoor H 00 -P- o o\o\-pVJ1 o

O CO—

J

w

I VJI •p- s:

I-ptD

ION

-P- s:

i oo

>

I —1

ro

s:

i 00

>

ION

ro

=S

1ro

>

i ON

Ps;

i

w

0) a*

CD4 tD

13

roH

oo

VO VJI -P- H VJI ro H

vo vo vji co ro I-1 ro h -p" o o ro vji H o o

o o o o o o o o

o o o o o H o o o H

o

o

ESc+

H-D

£ M

c» o vji vji on—q vo o ON ON O

Cb • VJI VJI VJI VJI

ro ro ro oo -p- o -p- vo vo oo oro ro -p- o —1 vo -pH VJI H on ro ro i-1 ro oo on ro oo m ON ON o o o o O 00 ro —J O O O H o o o H o o H

o vo o ro

4=- -P" VJI o o —] oo

o oo vji vo

VJI ON CO O CO--) j=-

r-1 ro O 00 O

vji Oo O CD VO

o

2i*
o

c—

a

P

aj En

<L> -P

<P<!o

•H

-PO

0) H

«H

<u o

,M

CD ftOP

TJ

o3o

1-3

p

P

COM

•HP

oj H

0)

ffi

cti P

cd

VO

<D H

Eh

a

CD fn S <D •H £

CD 3

ft c

o

(!) ^

6 CD •H P

<-> H

<v 3

ft c

o

•H

,y p

01 0) ft H

(D T3

CM o

CM

i-l

rH O O

O oo VO tr— H

I vo

VO

VO

I O

o o

JI

VO

I o

H o oo o

oo OJ H

1^-lAmO

H O O O

o o o O O ,* H J" H H

t— CO H O

CM H

VD J- W O

t— VO O

vo CO

1ACO O

H

o o o H O O

o o o o o

t— O ON VO H H H ON 00-*

oo ro H

\OHfflO

00 00 H

co t— -3- o

i o o o

o o o

o UN o\ M501A

OJ CM

ON t— OJ CO CO

0J OJ OJ H H

\OVO lAJ-^

; O O O O

o o o o

On O O O

to W 04-

t— H VO

0J 00 00

vo oj co oo o

00 OJ H H

CO UN_d- oo o

oo3

VO

I o

t— oo oo o

OJ H H

vo oo oo o

CO

oo o

OJ o

OJ

I OO

-* VO t- O

-d- 00 OJ

oo

I JUN

I Q

t— OJ OJ OJ

OJ OJ OJ 0J

ooovoo vo un i/n un

o i-H O O O O r-H O O O H O HOOIA H O O O

CO O O CO O O O O O O O UN O O O LT\ OO OJ OJ CO o ir\ t— ON OVflr- OHO rH H OJ oo oo o oo oo OO t-CO _* CO O VO H H C11A H 00 UN OO OOCO

OJ

I oot—

I o

OO

I o

t—

I o

oo vo o

0O H

ir\ u>

t- oo o

I o

VO

I o

0O CO o

UN 00

oj co o

VO H H O

00 00 00

CO t-t-O

I ON

C— CM OJ OJ CO

OJ OJ OJ CM H

VO LT\ UN UN.3-

H CO

oo

oo VO

OJ

I o\ VO

H O OJ H O O rH O O O H O O O O

o t— O O O O O O O O o

O H -3- rH lf\ O H O VO o o

UNVO _* CM 00 VO i-l 00 1ACVI t- H H H VO CM ion t—

CO

OO

oo

I

I o

CMOOo

UN

CM

<Ho"

H

I ESHVO

I n

CO

OO

o

OJ

oo

I o

LTN

I ft

CMOO

UN

CM

25
possess adequate material properties in fatigue to allow their consideration as suitable roof membrane materials. The fact that these guidelines may not represent the absolute minimum for membrane material

properties in fatigue is a question that can be resolved only by further

qualitative in-service testing.

The tensile fatigue properties of the roof membranes were closely

related to the static tensile strength of the roof membrane. In-service

the largest tensile forces on the roof membrane probably occur during

the low cycle fatigue due to thermal cycling. Fortunately, the static

tensile strengths of roof membranes A, B, and C at 0°F (-l8°C) are more

than three times their strengths at T0°F (21°C). This is probably due

to the increased stiffness of the membrane matrix material at low

temperatures. Thus, performance guidelines should be stated in terms of

test results at 0°F (-l8°C). Based on the available data, it is concluded

that an adequate tensile fatigue performance criterion for roof membrane

specimens requires a fatigue lifetime of at least 10 tension-tension

cycles at a peak cyclic test load of 100 lbf {kkO N) at 0°F (-l8°C).

Furthermore, this criterion should be augmented in terms of the load

carrying capability of the felt material which is better reflected in

the data at 70°F (21°C), at which temperature the matrix material has

softened considerably. This data indicates an adequate lifetime performance

criterion of 105 tension-tension cycles at a peak cyclic test load of 20

lbf (89 N).

The performance criteria for roof membranes subjected to flexural

fatigue are not as clearly defined. Large amplitude deflections of some roof membranes at 0°F (-l8°C) result in data scatter that is difficult

to analyze. In particular, the brittle glassy nature of the coal tar

matrix in membrane series A resulted in felt delamination at a peak

deflection amplitude of 0.20-in (0.51-cm) with a simultaneous shattering

and loss of the matrix material. This loss of material effectively

relaxed the remaining felt plies thus lowering the applied loads to the

specimens and affecting the amount of fatigue damage and the medium of

damage propagation. This is shown by the high lifetime points in both

Figures 10 and 12 for material A. In service, this matrix material

remains in situ and reforms its adhesive bond with the felts as the

temperature rises. This healing process is a desirable characteristic

of the coal tar roofing membrane.

The trends of medium flexural fatigue lifetime data are presented

in Figures 11 and 12. Based on these, the recommended performance

criterion for the flexural fatigue properties of membrane specimens

requires a fatigue lifetime of 10 cycles at an alternating positive and

negative peak midspan deflection of 0.125-in (0.32-cm) at T0°F (21°C).

At 0°F (-18°C) a fatigue lifetime of 250 cycles at an alternating

positive and negative peak midspan deflection of 0.125-in ( 0.32-cm)

represents a minimum criterion.

26
6.1 Proposed Performance Criteria

The minimum performance criteria for roof membrane specimens

subjected to fatigue are summarized below.

6.1.1 Tensile Fatigue

Based on the available data, minimum tensile fatigue performance ^ criteria for the membrane types tested require a fatigue lifetime of 10

tension-tension cycles at a peak cyclic test load of 100 lbf (UUO N) at

0°F (-l8°C) and 105 tension-tension cycles at a peak cyclic test load of

20 lbf (89 N) at T0°F (21°C).

6.1.2 Flexural Fatigue

Based on the available data, minimum flexural fatigue performance,

criteria for the membrane types tested require fatigue lifetimes of 10

and 250 cycles at an alternating positive and negative peak midspan

deflection of 0.125-in (0.32-cm) for test temperatures of T0°F (21°C)

and 0°F (-l8°C) respectively.

The observations stated above and the recommended performance

criteria are based on results of tests on four ply membrane specimens

(ASTM Designation: D2523-70) with the longitudinal axis oriented in the

across machine direction.

7 . ACKNOWLEDGMENT

The work described in this paper was jointly sponsored by the

Owens-Corning Fiberglas Corporation and the National Bureau of Standards,

The authors wish to acknowledge the financial support of Owens-Corning

Fiberglas Corporation in conducting the research described in this

paper. In particular, they wish to express their sincere thanks to

Miles E. Jacoby of the Owens-Corning Fiberglas Corporation, Product

Testing Laboratories, who served as project coordinator, for his valuable

technical and administrative assistance.

27
8. REFERENCES

[l] Mathey, Robert G. and Cullen, William C, Preliminary Performance

Criteria for Bituminous Membrane Roofing, NBS Building Science

Series 55 » November 197^.

[2] Recommended Practice for Testing Load-Strain Properties of Roof

Membranes, ASTM Designation D-2523-70, Part 11, ASTM Book of

Standards, 1973.

[3] Chwirut, D. J., (coordinator), Research and Testing Facilities of

The Engineering Mechanics Section, National Bureau of Standards,

Washington, D. C, NBS Spec. Publ. 370, January, 1973.

[k] Robinson, D. C, Determination of Dynamic Loads in a High-Frequency

Direct-Stress Fatigue Machine, NBS TN 578, June, 1971.

28
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS Tech. Note 8632. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Fatigue Tests of Bituminous Membrane Roofing Specimens

5. Publication Date April 1975

6. Performing Organization Code

7. AUTHOR(S)

George F. Sushinsky and Robert G. Mathey

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP) 13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Tensile and flexural fatigue tests were performed on built-up roof membrane specimens

(ASTM Designation: D2523-70) fabricated from four different material systems. The

tensile fatigue tests were run under cyclic load control conditions while specimens

tested in flexural fatigue were run under cyclic midspan displacement control.

Tests were run at ambient laboratory conditions, generally 70 ± 2°F (21 ± 1°C) , and

at i 2°F (-18 ± 1°C) . Curves based on the experimental results are plotted

relating the peak load or displacement to the median fatieue lifetimes for specimens

fabricated from each material. Performance criteria for roof membranes subject to

fatigue loading are recommended.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Bituminous roof membranes; fatigue testing; flexural fatigue; performance criteria;

roofing; temperature effects; tensile fatigue; test methods.

18. AVAILABILITY \^2 Unlimited

I

' For Official Distribution. Do Not Release to NTIS

I XI Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. C13. 46:8b3

I ! Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

32

22. Price

$1.15

USCOMM-DC 29042-P74

TimeWasWhen

Energy Was

Cheaper

...but that's all changed now.

Today, increased energy costs—caused by in- creasing demand—boost the price of consumer

goods, fuel inflation, and hurt our balance of payments.

That's why conserving energy is a must today,

especially for you in the business and industry

community which uses two thirds of our nation's energy. Now . . . there's a book to tell you how to do

it. It's called EPIC—the Energy Conservation

Program Guide for Industry and Commerce. Pre- pared for you by the Commerce Department's

National Bureau of Standards in cooperation

with the Federal Energy Administration. EPIC is a comprehensive handbook that can

help you establish or improve an energy conservation program in your organization. Not only industry and commerce but also hospitals, universities, research institutes, ANY or- ganization that uses energy—and has to pay

the bills—will want a copy of EPIC. EPIC outlines in detail the steps in setting up

an energy conservation program.

It contains a checklist of more than 200 Energy

Conservation Opportunities—suggestions to save

U.S. DEPARTMENT OF COMMERCE / National

energy in a dozen different areas. EPIC's actual case histories of energy saving

actions help you estimate your potential for saving energy—and reducing costs. And EPIC contains much more—financial analysis procedures to evaluate projects, sources of information on energy conservation, engineering

data and factors, an energy conservation bib- liography.

Make EPIC part of your plan to control energy use and costs. Make EPIC part of your contri- bution to using energy resources wisely ... so we can keep America working and growing.

To order your copy of EPIC, send $2.50 per copy (check, money order or Superintendent of Documents Coupons) to Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

Ask for NBS Handbook

115, EPIC, C13. 11:115. Discount of 25% on

orders of 100 copies or more.

Bureau of Standards FEDERAL ENERGY ADMINISTRATION / Conservation and Environment
this little booklet

can change the lives

of thousands of

American Indians

if it gets into the right hands

This booklet locates forty Indian industrial parks on reservations from New York to Florida to the

Pacific Northwest, and outlines the business advantages to locating a plant or offices on any one of them.

Favorable lease terms, significant tax benefits, easy access to markets, abundant natural resources, complete planning assistance—and a rich source of willing and able employees are waiting.

It's an opportunity to make a most profitable business investment—and change the lives of thousands

of American Indians. But nothing much will happen unless we get this booklet into the right hands. Are they your hands, or those of someone you know?

r

I'm interested. Send your booklet "Indian Industrial Parks" to me, today.

Name Title Address

City State Zip

and send a copy to someone I know, today.

Name Title Address

City

%

State Zip

Office of Public Affairs, Economic Development Administration, Room 7019, U.S. DEPARTMENT OF COMMERCE, Washington, D.C. 20230. /! fv L . i * U.S. GOVERNMENT PRINTING 0FFICE:1975- 583-019/18
NBS TECHNICAL PUBLICATIONS

PERIODICALS JOURNAL OF RESEARCH reports National Bureau

of Standards research and development in physics,

mathematics, and chemistry. It is published in two sections, available separately:

• Physics and Chemistry (Section A)

Papers of interest primarily to scientists working in these fields. This section covers a broad range of physical and chemical research, with major emphasis on

standards of physical measurement, fundamental constants, and properties of matter. Issued six times a

year. Annual subscription: Domestic, $17.00; Foreign,

$21.25.

• Mathematical Sciences (Section B)

Studies and compilations designed mainly for the mathematician and theoretical physicist. Topics in mathematical statistics, theory of experiment design, numerical analysis, theoretical physics and chemistry, logical design and programming of computers and computer

systems. Short numerical tables. Issued quarterly. Annual subscription: Domestic, $9.00; Foreign, $11.25. DIMENSIONS/NBS (formerly Technical News Bulletin) —This monthly magazine is published to inform

scientists, engineers, businessmen, industry, teachers,

students, and consumers of the latest advances in science and technology, with primary emphasis on the work at NBS. The magazine highlights and reviews such

issues as energy research, fire protection, building tech- nology, metric conversion, pollution abatement, health and safety, and consumer product performance. In addition, it reports the results of Bureau programs in measurement standards and techniques, properties of matter and materials, engineering standards and services, instrumentation, and automatic data processing. Annual subscription: Domestic, $9.45; Foreign, $11.85.

NONPERIODICALS

Monographs—Major contributions to the technical liter- ature on various subjects related to the Bureau's scientific and technical activities. Handbooks—Recommended codes of engineering and

industrial practice (including safety codes) developed

in cooperation with interested industries, professional

organizations, and regulatory bodies.

Special Publications—Include proceedings of confer- ences sponsored by NBS, NBS annual reports, and other

special publications appropriate to this grouping such

as wall charts, pocket cards, and bibliographies.

Applied Mathematics Series—Mathematical tables, manuals, and studies of special interest to physicists, engineers, chemists, biologists, mathematicians, computer programmers, and others engaged in scientific and technical work.

National Standard Reference Data Series—Provides

quantitative data on the physical and chemical properties of materials, compiled from the world's literature and critically evaluated. Developed under a world-wide

program coordinated by NBS. 'Program under authority

of National Standard Data Act (Public Law 90-396). NOTE: At present the principal publication outlet for

these data is the Journal of Physical and Chemical

Reference Data (JPCRD) published quarterly for NBS

by the American Chemical Society (ACS) and the American Institute of Physics (AIP). Subscriptions, reprints, and supplements available from ACS, 1155 Sixteenth

St. N. W., Wash. D. C. 20056.

Building Science Series—Disseminates technical infor- mation developed at the Bureau on building materials, components, systems, and whole structures. The series presents research results, test methods, and performance criteria related to the structural and environmental functions and the durability and safety characteristics of building elements and systems.

Technical Notes—Studies or reports which are complete

in themselves but restrictive in their treatment of a

subject. Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under pro- cedures published by the Department of Commerce in Part 10, Title 15, of the Code of Federal Regulations. The purpose of the standards is to establish nationally

recognized requirements for products, and to provide

all concerned interests with a basis for common under- standing of the characteristics, of the products. NBS

administers this program as a supplement to the activities of the private sector standardizing organizations. Federal Information Processing Standards Publications (FIPS PUBS)—Publications in this series collectively constitute the Federal Information Processing Standards Register. Register serves as the official source of information in the Federal Government regarding stand- ards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended,

Public Law 89-306 (79 Stat. 1127), and as implemented

by Executive Order 11717 (38 FR 12315, dated May 11, 1973) and Part 6 of Title 15 CFR (Code of Federal

Regulations). Consumer Information Series—Practical information, based on NBS research and experience, covering areas

of interest to the consumer. Easily understandable language and illustrations provide useful background

knowledge for shopping in today's technological

marketplace.

NBS Interagency Reports (NBSIR)—A special series of interim or final reports on work performed by NBS for

outside sponsors (both government and non-government). In general, initial distribution is handled by the

sponsor; public distribution is by the National Technical Information Service (Springfield, Va. 22161) in paper

copy or microfiche form.

Order NBS publications (except NBSIR's and Biblio- graphic Subscription Services) from: Superintendent of Documents, Government Printing Office, Washington,

D.C.. 20402. BIBLIOGRAPHIC SUBSCRIPTION SERVICES

The following current-awareness and literature-survey

bibliographies are issued periodically by the Bureau:

Cryogenic Data Center Current Awareness Service A literature survey issued biweekly. Annual subscription: Domestic, $20.00; foreign, $25.00.

Liquefied Natural Gas. A literature survey issued quarterly. Annual subscription: $20.00. Superconducting Devices and Materials. A literature

survey issued quarterly. Annual subscription: $20.00. Send subscription orders and remittances for the pre- ceding bibliographic services to National Technical Information Service, Springfield, Va. 22161.

Electromagnetic Metrology Current Awareness Service Issued monthly. Annual subscription: $100.00 (Special rates for multi-subscriptions). Send subscription order and remittance to Electromagnetics Division, National Bureau of Standards, Boulder, Colo. 80302.
U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C. 20234

OFFICIAL BUSINESS

Penalty for Private Use. $300

POSTAGE AND FEES PAID

U.S. DEPARTMENT OF fOMMERCE

COM-215

FOURTH CLASS MAIL

U.S.MAI

^6-191*