Testing Water Absorption in Cold Liquid-Applied Waterproofing: An Exploratory Study

Background

The wrinkled appearance of cold liquid-applied membranes that have absorbed water, termed “braining,” is familiar to those who investigate waterproofing failures. Deterioration of cold liquid-applied membranes due to water absorption has been described by Laaly and Serenda [1], and by the authors [2]. Water absorption in similar materials, cold liquid-applied deck coatings, is described by Mailvaganam et al. [3].

FIG. 4—Plus 3/16 confinement.

This study explores water absorption by subjecting specimens to a cycle of water immersion and drying over an extended period. The testing is not a duplication of actual construction conditions; however, it may be more similar to real conditions than is typical in laboratory water absorption testing. The accelerated oven curing used in tests cited in ASTM C 836 was not used. Oven curing is likely significant

500

——— Sample a|

——— Sample 81

Sample C|

to-

0 ‘

0 2 4 6

SampU Diam«t*r uni

FIG. 5—Average flow rate vs, sample diameter.

500

300

200

100

0

——— Sample A

———- Sarnie В

SampleC

.*’** ^ ——-

‘ ————- ~——————————– *——

0 1/16 1/8 Э/16

Shun Spac* (in)

FIG, 6—Average flow rate vs. shim space,

TABLE 7—Test cycle.

Week #

Condition

Temperature

1

Water Immersion

50°C (122°F)

2

Air Drying

Room Temperature—Office Environment

3

Water Immersion

Room Temperature—Office Environment

4

Air Drying

Room Temperature—Office Environment

in the test performance of some materials because ASTM C 836 allows as low as 80 % non-volatile content. As required in referenced test methods, oven curing at 37.8°C (100°F) to 70°C (158°F) is likely effective in driving off volatiles and completing the cure of materials. Our decision to omit oven curing had the advantage of more closely replicating construction conditions. Omitting oven curing had the disadvantage that for some products, the weight changes measured would include both weight loss due to loss of volatile components and possible weight gain due to water absorption.