Effects of workmanship on membrane performance

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Effects of workmanship on membrane performance

Mailvaganam, N. P.; Collins, P.

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Effe c t s of w ork m a nship on m e m bra ne pe rform a nc e

N R C C - 4 1 7 1 4

M a i l v a g a n a m , N . P . ; C o l l i n s , P .

S e p t e m b e r 1 9 9 6

A version of this document is published in / Une version de ce document se trouve dans:

Concrete Repair Bulletin, 9, (5), September/October, pp. 22-24, September 01,

1996

The material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42

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ｉｖｾｃｃＧＭ

<i/7/L/-Effects of workmanship

on membrane perrormance

Noel P. Mailvaganam

P.G.Collins

-A

parking structure slab must protect the spacebelow and serve as a structural diaphragm and wearing surface. These functions require a deck to be impervious to liquids and able to stop water from seeping through cracks. Elastomeric

mem-branes are frequentlyｵｳ･､ｾｴｹｰｩ｣｡ｬｬｹ in conjunction

with joint systems and sealants-to provide the needed protection.

The degree of protection actually provided by the installed membrane is, however, influenced by a num-berofjob site variables, including ambient conditions (temperature and relative humidity), application prac-tice, and control of the installation process. Poor judgement and practice in these areas will usually lead to pronounced defects which wi II act as weak sites during the service life ofthe membrane.l,2Defects can

occur in numerous forms, including uncured (wet) areas, uneven coloring, over-cured material (exces-sively hard), surface pinholes, blisters, craters, and delaminations.

The findings reported in this article arc the results ofa study to determine the extent to which the water-proofing properties ofcold liquid applied membrancs may be compromised by poor workmanship and indif-ferent quality control.

Material assessment

Membrane selection should be based on careful study of material properties and an evaluation of its perfor-mance under conditions similar to those in the tended application. Prediction of a membrane's in-stalled perfonnance based on measurement ofmaterial properties under lab conditions is difficult.

Most standard tests used for the selection and specification of these membranes do not define per-formance limits, In the absence ofperforrna neelimits, these test criteria serve at best as a screening

mecha-nism for selection, but provide limited assurance that an applied membrane will perform as claimed by the manufacturer. Thus, the main guide to be relied upon for proper membrane installation is the manufacturer's application instructions. It is therefore worthwhile to determine the nature, magnitude, and duration of deleterious effects that may arise when manufacturer's specifications relating to application parameters are ignored for the sake ofexpediency.

Research findings

The following data are drawn from research into the effects on-site application variables may have on the . physical and mechanical properties of cold liquid-applied elastomeric membranes. To insure representa-tive sampling, the four urethane-based membranes selected for the investigation were determined to have significant market share. The tested systems and their corresponding labels were:

M

1

two-component polyurethane

M2

two-component polyurethane

M3

one-component polyurethane

M4

two-component epoxy-urethane

The effects produced were measured after subjecting the membrane systems to conditions that simulated the following installation factors:

1

Incorrect proportioning of membrane components

2

Poor mixing ofmembrane components

3

Varying the time interval of application after mixing

Perfonnance, tensile strength, and elongation are good indicatorsofwaterproofing capabilities. The effects ofproportioning and mixing errors on these properties were evaluated bycomparing membranes incorporat-ing these crrors with correctly proportioned andTnixcd

specImens.

Table 2. Effect 01 Mixing on Permeance 01 Waterproofing Membranes

• Polyurethane

.- --- .

-Permeance Ix 10 ' g/Pa·s·mll_{- -}

-.-Sv

stem

Poor Mixing Correct Mixing

MI 12 Component PW) 2.37 2 17 M2 (2 Component PU') 2.34 2 50

I

M3 11 Component PW} 373 1.00

j

M4 (Epoxy·Urethanel 2.10 I 43 L_ . _ . _ . _ - - - - -.

Table 1. Effect 01 mix proportioning on permeanee 01 waterprooling membranes

·PolyureUlane

._-- - - -

_.-

-_._----Permeance

Ix

10' g/Pa+m'l

Sv

stem

_{Excess Resin Correct Excess} Proportions Hardener Ml (2 Component PU'I 2.51 2.17 2.06 M2 12 Component PWI 4.20 250 176 M3(1 Componellt PU'I 2.20 1.00 152 M4(Epoxy·Urethanel

182

1.43 140 . _

-Figure 1, Development 01 elongation

(%)

under conditions 01

excess resin, correct proportioning, and excess hardener

Figure 2. Development oltensile strength (MPa) underconditions 01

excess resin, correct proportioning, and excess hardener

... Excess resin

_ _ Correct proport',ons

••ｾ •• - Excess hardener

Ml

M2

20 ₂₀

ro

...

0.. 15

1"···

ro

15 ｾ 0..

Eo

10

.

..

ｾ ₁₀

"

ｾ

:

,

..

.../

Eo

...

... ... ...

5

.

:' <::

ｲｲｾｾＢＢ

-...----.-...-.

In

_"

_ｾ

5 '''-0 ₀ ｾＭ｟ＮＭｉＭＭ 0 10 20 30 _{0 10 20 30}

Age (days)

_{Age (daysl}

MJ

M4

20 - 20

ro

15

_ro

15 0.. 0.. :;;: 10 ｾ ｾ

....

10 Co

/--

...

"

..

--

..

-

,

...

Eo

ｾ

..

' _ｾ ...

...

ｾ 5 _{... ｾ} 5

ｾ

...

ｾ

•.•••

.. -_ ....

_.-

..

-In In ." 0 "

...

_Ｍｾ 0 , 0 10 20 30 0 10 20 30

Age (days I

Age (days)

... Excess resin _ _ Correct proportions

Ml

ＶＰＰＭＮＭＭＭＭＭＭＭＭＭｾ 30 30 10 20

Age (days)

.' •••• Excess hardener '. ...

ｾ

..

ＺｾＮｾＮｾＮｾｾｾＮｾＺＮｾｾＮｾｾＮｾｾＮｾＮＺＺＺＮｾＮＺＮＺＧＮＺＧ

.. 0 + - - - 1 - - - + - - - <

o

10 20

Age (days)

o

+---I----...f---<

o

M2

M4

6 0 0 , - - - , . . 400 <:: o Ｎｾ

g

200 OJ 6 0 0 . . - - - ,

ｾ

i

400

ＢＢＺｾｾＺ

:.::.:.:,:,:.:.:.:" ••_

"

ｾ 200 30 30

--...

excess resin value \. 10 20

Age (days)

10 20

Age (days)

ｾ

400

ｾ｟

_ _'"""'....__...

ｾ｟

g _.w ••••••ＺﾷＺﾷｾﾷ ｾＬＬｾ ｾ 200 0 0

MJ

600

...

400

"

0

.'"

'"

C> <::

-...

,

0 200 W 0 0

Incorrect proportions

Deviations from the manufacturer's

compo-nent proportions can have serious effects

on both the mechanical properties of the

membrane and its waterproofing perfonnance

(Figures 1,2).

The penneance data shows

that for all four materials tested, excess resin

produced higher system penneance than did

excess hardener. Catalyzed,

single-compo-nent systems are quite vulnerable to

varia-tion in proporvaria-tioning and mixing since they

rely on complete dispersion of the proper

amount of catalyst to initiate the curing

reaction. The effects of proportioning and

mixing on two-component systems are

var-ied and depend upon the chemistry of the

components. Since waterproofing character

is a primary requirement of parking garage

membrane systems, the variation in per-meance values observed is significant enough to impair long-term perfonnance.

Poor mixing

In the field, poor mixing can occur in a

num-berofways:

Mixers with poor mixing action are

often used

The hardener component is added

halfway through the mixing cycle

The manufacturer's stipulated mixing

time is not met

The consequences of such mistakes on the coating is significant. As the permeance

values show, the tendency for ingress of

water (and hence chloride ions) is increased (Table 2).

Poor mixing of membrane components

appears to have a significant effect on

elon-gation capacity, which governs

crack-bridg-ing properties

(Figure

3). Since this

prop-erty influences a membrane's ability to re-main functional in the parking garage

envi-ronment (which may include winter and high

temperature summer conditions), the impor-tance of site supervision to ensure proper mixing cannot be over-emphasized.

The effects of poor mixing on the early

mechanical properties of some of the coat-ings were drastic. Compared to specimens which were correctly mixed, the tensile strength values for some incorrectly mixed

coatings could not be obtained until 28 days

(Figure

4). Such delayed tensile strength

development can result in damage caused by stress from post-installation construc-tion activity of other trades. Foot traffic and items dragged across the poorly cured coal-ing can cause damage which will result in deterioration. The durability of the coating is, therefore, significantly compromised.

Figure 3. Development of elongation (%) under co nditions of poor mixin gand correct mixin g

. ---- -- - Poor mixing conditions

Correct mixing conditions

Ml

M2

500 500

ｾ

.

.

400 400

.

Ji

ifi

ｾＭ｟ＮＭ

c: ₃₀₀ c: ₃₀₀ 0 0 .';:; ＭＮｾＭＭ

..

-

...

ｾ

..

-.-.

.';:;

.-.-....

_-.

_{c_._} OJ OJ C> C> c: ₂₀₀ c ₂₀₀ 0 0 w w 100 100

a

0 0 10 20 30 0 10 20 30

Age (days)

Age (days)

M3

M4

500 400 #. 400 #. 300

ｾ

c: 300 c:

.

0 0 Ｎｾ

-

.';:; 200

.

OJ

.

ＭＭＭＭｾＮ｟Ｎ｟

...

_

....

_

...

C>

-

C> c: ₂₀₀ c: 0

.

0

i:Ii

poor mixing •

.

iIi

100

100 value*

0 0

0 10 20 30 0 10 20 30

Age ldaysl

Age ldays)

*

Under poor mixing conditions. the elongation value for

M3

could not be obtained until 28 days.

Varying time interval

Thetime interval between mixing and

appli-cation ofthe membrane affects the degree of

adhesion to the concrete substrate. This is

a concern particularly in summer and when

large size batches are used. The exothcrm

developed during the mixing of some of the

coating components, particularly ifthey ha ve

been stored in trucks exposed to high

sum-mertime temperatures, may well shorten the

"pot life"ofthemix. This will cause

applica-tion problems due to poor sprayability and

is likely to reduce theadhesion ofthe coating

to the concrete because the polymerization

reaction may have proceeded to an advanced

stage.

4

The optimal time interval aftermixing

is less than thirty minutes.

Conclusion

Most systems were affected by many of the

factors investigated; some systems showed

thatthey were especially prone to site abuse,

particularly at early ages.

A

surprising result

was the magnitude of variation in response

between the different chemistries tested.

This variation demonstrates that the test

data typically reported in material data sheets

are not consistently reliable indicators of

installed perfonnance. The protection that

elastomeric membranes provide depends not

only on their material properties, but also on

how well they are installed.D

I. Feldman, D., "Durability of Polymers Used in the Building IndustryY."Canadian Building Construction Congress. Montreal, pp. 167-174, November 27-29,1988. 2. Davis, A. and Sims, D.:'Wcathering of

Polymers." Applied Science Publishers, London and New York, pp. 34-29, 198.3 .3 Mailvaganam,N.? and Collins,PG,

"Effect of Ambient Application Factors on the Performance of ElaSlOmeric Water-proofing Membranes." submitted to

Journal ofｐｲｯｬ･｣ｴｩｾ･ Coalingsand Linings.

May 1995

4 Soebbl1lg J.B .."TIpson lmprovlllg ApplicatIOn of Plural Component Polyure-thane Linings(0Plpell1lcs."Joumalof

Protective Coatings andLinings.May 1994.

Noel Mailvaganam is the senior research officer ofthe Repair Technologies and Strategies Pro-gram ofCanada 's National Research Council's (NRC) Institute for Research in Construction, Ottawa, Canada.

P. G. Collins is the technical officer of the Repair Technologies and Strategies Program.

References

Correct mixing conditions

M2

20 -16

.f?

ｾ 12 .J::: ..-Cl

...

-

...

c: ₈

...

---Q) ｾ

r

en 4 0 30 0 10 20 30

Age (days)

M4

20 ｾ 16 ::E ₁₂ .;:; en 8 c: ｾ V; 4 ...-_

...

---0 I I 30 0 10 20 30

Age (daysl

poor miXing

value"·---10 20

Age (days I

/---....

.

M3

4 O+'----f---+---i

o

." •..••• Poor mixing conditions

Figure 4. Development oftensilestrength (MPa) under conditions of poor mixing and correct mixing

_ _ _ _ _ _ _ _ _ _ _ _•• _ _ｾ ....J 4 8 0+---+---+---1

o

M1 20 , - - - . . . , 2 0 . . , - - - ; 16 ｾ :::2: 12 10 20

Age (days)