Puncture resistance
RECOMMENDATIONS
Puncture of a bridge membrane defeats the
Until a membrane has been field tested, its ser-
purpose of its existence.
vice life remains unknown. Laboratory tests can
The potential for puncture is significant in the
help rank membranes according to individual
bridge deck construction environment.
properties, but exposure to the complex combina-
Puncture resistance is an important property of
tion of natural forces is essential for proving a
a good sheet membrane.
material's durability. Therefore, it is recommended
The lack of consensus on a test standard for the
that a field study be instituted to monitor the in-
evaluation of sheet membranes indicates the
stallation/design process and long-term perfor-
need for a uniform methodology for puncture
mance of bridge membranes in New England.
resistance evaluations.
Sheet membranes are one type of waterproof-
The proposed test method more closely approxi-
ing--liquid applied membranes are the other. It is
mates field conditions. The test apparatus is
recommended that a parallel test be conducted on
relatively inexpensive, commercially available,
liquid membranes to complete the picture.
and portable. Specimen preparation is relatively
simple.
LITERATURE CITED
The puncture test results obtained during this
evaluation show that the proposed test method
ASHRAE (1997) Fundamentals Handbook. Ameri-
is adequate to rate membranes according to
can Society of Heating, Refrigerating and Air-Con-
their puncture resistance.
ditioning Engineers, Inc., Atlanta, Georgia, p. 22.17
The bridge designer must consider the results
ASTM (1993a) D2523, Standard practice for test-
from the various test types along with other
ing load-strain properties of roofing membranes.
factors relevant to the selection of sheet mem-
Annual Book of ASTM Standards, Vol. 04.04, Ameri-
branes, such as cost, environmental friendliness,
can Society for Testing and Materials, West
and durability.
Conshohocken, Pennsylvania.
ASTM (1993b) C794, Standard test method for
Water vapor permeability
adhesion of elastomeric joint sealants. Annual Book
All six membranes are very good vapor retard-
of ASTM Standards, Vol. 04.07, American Society
ers. Their permeance ranged from 0.01 to 0.05
for Testing and Materials, West Conshohocken,
perm and varied by a factor of five, instead of
Pennsylvania.
the factor of 333 originally indicated in the
ASTM (1993c) D4885, Standard test method for
manufacturers' data.
determining performance strength of
The modified-cup test procedure has potential,
geomembranes by the wide strip tensile method.
but our apparatus needs some refinement. This
Annual Book of ASTM Standards, Vol. 04.08, Ameri-
procedure provides both a water weight loss
can Society for Testing and Materials, West
and a desiccant weight gain across a specimen
Conshohocken, Pennsylvania.
without the need for humidity control. The
ASTM (1993d) D638, Standard test method for
weight loss should equal the weight gain if leak-
tensile properties of plastics. Annual Book of ASTM
age is controlled and the sample absorbs no
Standards, Vol. 08.01. Designation. American Soci-
moisture.
ety for Testing and Materials, West Conshohocken,
Manufacturers seem to prefer the ASTM E96
Pennsylvania.
(Water-Cup Method B) and we see no reason to
ASTM (1993e) D882, Standard test method for ten-
change that. However, all bridge membranes
sile properties of thin plastic sheeting. Annual Book
should be subjected to the same test method and
of ASTM Standards, Vol. 08.01, American Society
test conditions if reliable comparisons are to be
for Testing and Materials, West Conshohocken,
made between them. It would be best if all test-
Pennsylvania.
ing were done by one highly qualified lab that
ASTM (1993f) D0412, Standard test method for
is aware of the potential for errors when using
vulcanized rubber and thermoplastic rubbers and
ASTM E96.
thermoplastic elastomers--Tension. Annual Book
21
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