METHOD OF DETECTING A LEAK IN A LIQUID APPLIED MEMB
RANE Technical field This invention relates to a method of detecting a l
eak in a water impermeable liquid applied membrane, preferably on a roof, using voltage to gen
erate a current through any defects which can be detected by sensors on top of the mem
brane. Background of the invention The failure to detect, find and correct membrane def
ects during and as soon after its installation as possible, can cause premature failure.
Problems include design deficiencies, faulty application of the membrane system and damage
by subsequent tradesmen. Roof designs incorporating a waterproofing membranes under
a green roof, insulation layer, wear‐course, or topping slab greatly exacerbate the
problem of leak locating. The early detection of leaks in waterproof membranes is crucial
during construction and for effective roof maintenance. Leaks in conventional roof assemblie
s allow moisture to accumulate under the membrane in the underlying components such
as protection boards and insulation. Accumulated water in insulation compromises
its thermal properties. Accumulated water in construction materials can cause
rotting and other damage which is very costly to repair. Low voltage electrical conductance testing is often u
sed to detect and locate leaks in waterproof membranes. The principle technique of the
conductance leak location method is to establish an electrical potential between the elec
trically insulating membrane and the underlying roof substrate. A controlled surface coveri
ng of water forms the conductive path horizontally across the membrane to any membrane brea
ch. At a breach location, the test instrument detects the electrical path that is formed
through the water leaking to the conductive substrate below. Low voltage electrical methods to detect and locate
breaches are effective; however they require a controlled surface covering of water forms
the conductive path horizontally across the membrane. This brings the disadvantage of having
access to water, requires a uniform distribution of water, potentially damages to area be
low due to leakage of the applied water and fails to detect leakage around uneven surf
aces. Further, they require an electrically conductive surfa
ce immediately below and in intimate contact with the membrane. Membranes in conventional
assemblies are made from thermoplastic materials like PVC and polyolefins. Thes
e membranes are adhered with adhesives or mechanically fastened to non‐conductive
materials such as plywood substrate or protection boards which inhibit electric conductanc
e testing. US2014361796 A1 discloses a method of detecting a leak in such a membrane ba
sed on thermoplastic material on a roof using low voltage that addresses the problem of said
inhibition. It teaches the attachment of the membrane to the roof support substrate by an ad
hesive layer that includes electrically conductive material onto a conductive primer. This br
ings the disadvantage of having to apply an adhesive layer in an additional step, that
might be prone to failure, on top of the applied conductive primer. Aim to provide a method for leak detection on water
proof membranes that does not rely on the application of water for detection purposes and
does not require the application on a conductive adhesive layer. Summary of the invention According to one aspect of the invention there is p
rovided a method of detecting a leak in a liquid applied water impermeable membrane comprising t
he following steps: a) applying a water impermeable membrane M onto an
electrically conductive layer ECL located on a support substrate SuS by the applicatio
n of a reactive composition in liquid form on the electrically conductive layer ECL and le
tting the applied composition cure; b) applying electrical voltage between a conductive d
etector CD on top of the water impermeable membrane M and the electrically conductive
layer ECL such that current will flow between the electrically conductive layer ECL an
d the conductive detector CD through any leak located within the water impermeable membran
e M; c) sensing the current between the electrically condu
ctive layer ECL and the conductive detector CD so as to detect any leak. According to another aspect of the invention there i
s provided an epoxy resin composition comprising ‐at least one liquid epoxy resin LER; ‐at least one amine hardener AH; ‐4.50 to 9.00 wt.‐%, based on the total weight
of epoxy resin composition, of carbon fibers CF with a length of 40 ‐ 200 ^m. Preferred embodiments of the composition are reproduce
d in the dependent claims. The invention is elucidated below comprehensively. A way of performing the invention In step b), electrical voltage is applied between a
conductive detector CD on top of the water impermeable membrane M and the electrically con
ductive layer ECL such that current will flow between the electrically conductive layer E
CL and the conductive detector CD through any leak located within the water impermeable
membrane M. Preferably, the electrical voltage is applied by usin
g a voltage higher than 600 V, preferably higher than 2 kV, more preferred between 5 and 10
kV. Hence it is preferred, if in step b), current will
flow between the electrically conductive layer ECL and the conductive detector CD through the air,
preferably by an electric arc, of any leak located within the impermeable membrane M. The conductive detector CD is preferable a portable
device. Preferably, in step c), the conductive detector CD detects the current CD with a
n electrode brush, preferably an electrode brush with conductive metal bristles. It is
further preferred, that in step c), the current is detected on a dry water impermeable membr
ane M. A suitable conductive detector CD is Buckleys’ Dry Roof Pro2 flat electr
onic roof leak detector unit from Buckleys (UVRAL) Ltd. Preferably the leak detection is carried out by sens
ing the current between the electrically conductive layer ECL and the conductive detector CD using a conductor app
lied on top of the water impermeable membrane M which is connected
to the voltage potential and includes a sensor in the detector device to detect
the current that is created through the water impermeable membrane M by the leak. In step a), a water impermeable membrane M is appli
ed onto an electrically conductive layer ECL located on a support substrate SuS by the
application of a reactive composition in liquid form. In this document the term “water impermeable liquid
applied membrane” preferably refers to a material which is applied in liquid form as a
layer onto a substrate, and which cures to form an elastic membrane making the substrate waterpr
oof. In this document, the term “polyurethane polymer”
includes all polymers prepared by the so‐called diisocyanate polyaddition process. It inclu
des isocyanate‐functional polyurethane polymers obtained by reacting polyisocyanates and poly
ols, which may also be called prepolymers and are polyisocyanates themselves. The reactive composition is preferably a material whi
ch is applied in liquid form as a layer onto a substrate, and which cures to form an elasti
c membrane making the substrate waterproof. The reactive composition preferably has a water conte
nt of less than 10 wt.‐%, preferably less than 5 wt.%, more preferably less than 3 wt.%,
based on the total weight of the composition. Preferably, the reactive composition is selected from
the list consisting of reactive one‐part polyurethane compositions, reactive two‐part polyureth
ane compositions and reactive two‐ part polyurea compositions, preferably reactive one‐p
art polyurethane compositions. Preferably, the reactive one‐part polyurethane compos
ition contains: ‐at least one isocyanate‐functional polyurethane po
lymer; and ‐at least one latent hardener. The isocyanate‐functional polymer is preferably liqui
d at room temperature. Preferred are isocyanate‐functional polymers of low
viscosity, preferably with a viscosity of less than 50 Pa∙s, more preferably less than 30 P
a∙s, particularly less than 20 Pa∙s, measured by a cone‐plate‐viscometer with a cone diameter o
f 25 mm, cone angle of 1° at a cone‐ plate‐distance of 0.05 mm and a shear rate of 10
s‐1 at 20 °C. The isocyanate‐functional polymer preferably has an
NCO‐content in the range of 1 to 8 weight‐%, preferably 1.5 to 6 weight‐%. The isocyanate‐functional polymer preferably has an
average molecular weight M
n in the range of 1'000 to 15'000 g/mol, preferably 1'500 to
12'000 g/mol. The isocyanate‐functional polymer is preferably obtai
ned from the reaction of an aliphatic isocyante, preferably isophorone diisocyanate, and at
least one polyol. Preferably, the reaction is done in a molar NCO/OH
ratio of at least 3/1, preferably in the range of 3/1 to 10/1, more preferably 3/1 to 8/1.
The reaction between isocyanate and the polyol is pr
eferably conducted in the absence of moisture at a temperature in the range of 20 to 16
0 °C, preferably 40 to 140 °C, possibly in the presence of a suitable catalyst. The polyol is preferably selected from the group con
sisting of polyether polyols, polyester polyols, polycarbonate polyols and polyacrylate polyols
. Preferred are polyether polyols, preferably with repet
itive units selected from 1,2‐ ethyleneoxy, 1,2‐propyleneoxy, 1,3‐propyleneoxy, 1,2
butyleneoxy and 1,4‐butyleneoxy. Particularly preferred are 1,2‐propyleneoxy units, op
tionally in combination with some 1,2‐ ethyleneoxy units at the end of the chains. Further
particularly preferred are 1,4‐ butyleneoxy units. Preferred are polyetherpolyols with a content of unsa
turation below 0.02 mEq/g, preferably below 0.01 mEq/g. Preferred are polyoxypropylene diols or triols, which
optionally are ethyleneoxide‐ endcapped, with an OH‐number in the range of 10 t
o 250 mg KOH/g, preferably 20 to 125 mg KOH/g. The polyol preferably has an average OH‐functionalit
y in the range of 1.7 to 3. Particularly preferred are polyoxypropylene diols, whic
h optionally are ethyleneoxide‐ endcapped, with an average molecular weight M
n in the range of 450 to 12'000 g/mol, preferably 1'000 to 6'000 g/mol. Particularly preferred are further trimethylolpropane o
r glycerine started polyoxypropylene triols, which optionally are ethyleneoxide‐endcapped,
with an average molecular weight M
n in the range of 3'000 to 8'000 g/mol. Particularly preferred are further poly(oxy‐1,4‐buty
lene) diols, particularly with an OH‐ number in the range of 50 to 180 mg KOH/g, particu
larly with an average molecular weight M
n in the range of 650 to 2'000 g/mol. Preferred latent hardeners are blocked amines which h
ave a blocked, hydrolytically activatable amino group and either at least one furt
her blocked, hydrolytically activatable amino group or at least one reactive group R which
is selected from the group consisting of hydroxyl group, mercapto group and secondary amino gr
oup. The blocked, hydrolytically activatable amino group of
the blocked amine is selected, in particular, from the group consisting of enamino grou
ps, oxazolidino groups, ketimino groups and aldimino groups. Such blocked amines are
substances known in polyurethane chemistry which are used as so‐called latent harden
ers in compositions containing isocyanate groups. In the present document, "oxazolidino group" refers t
o both tetrahydrooxazole groups (5‐ ring) and tetrahydrooxazine groups (6‐ring). Preferably, the blocked, hydrolytically activatable ami
no group of the blocked amine is an aldimino group. The blocked amine can be obtained, in particular, fr
om the condensation reaction of a primary or secondary amine with a ketone or aldehyde
. Particularly suitable as ketones are acetone, methyl ethyl ketone, methyl propyl ketone, m
ethyl isopropyl ketone, methyl isobutyl ketone, methyl pentyl ketone, methyl isopenty
l ketone, diethyl ketone, dipropyl ketone, diisopropyl ketone, dibutyl ketone, diisobutyl
ketone, cyclopentanone, cyclohexanone and actetophen. Particularly suitable as
aldehyde are formaldehyde, acetaldehyde, propanal, 2‐methylpropanal, butanal, 2
methylbutanal, 2‐ethylbutanal, pentanal, 2‐methylpentanal, 3‐methylpentanal, 4‐met
hylpentanal, 2,3‐dimethylpentanal, hexanal, 2‐ethyl ‐hexanal, heptanal, octanal, nonan
al, decanal, undecanal, 2‐methyl‐ undecanal, dodecanal, methoxyacetaldehyde, cyclopropaneca
rboxaldehyde, cyclopentanecarboxaldehyde, cyclohexanecarboxaldehyde, dip
henylacetaldehyde, benzaldehyde and substituted benzaldehydes. A blocked amine having at least one oxazolidino grou
p can be obtained in particular from the condensation reaction of at least one hydroxyamin
e in which the hydroxyl and primary amino groups are separated by an optionally substitut
ed ethylene or trimethylene radical, with at least one ketone or aldehyde, in particular
formaldehyde or one of the enolizable ketones or aldehydes mentioned; The aldehydes, in par
ticular 2‐methylpropanal, are particularly suitable. Particularly suitable as hydroxy
amine are diethanolamine and diisopropanolamine, which lead to hydroxyoxazolidines f
rom which polyoxazolidines can easily be prepared, for example by reaction with a
polyisocyanate or a polyester. A blocked amine having at least one ketimino or ald
imino group can be obtained in particular from the condensation reaction of an amine
having at least one primary amino group with at least one ketone or aldehyde, as ment
ioned above. If a ketone is used to block a primary amino group, a ketimino group is formed,
while an aldimino group is formed when an aldehyde is used. Most preferred, the latent hardener is a blocked ami
ne having at least one aldimino group. Preferably, said blocked amine is present in an amou
nt that the ratio between the total number of aldimine groups to the total number of is
ocyanate groups is in the range of 0.3 to 1, preferably 0.4 to 1, more preferably 0.5 to 1.
Preferably, the reactive one‐part polyurethane compos
ition further contains fillers. Suitable fillers are ground or precipitated calcium carbonates
(chalk), which are optionally surface coated with a fatty acid such as stearate, barium s
ulfate (barytes), slate, silicates (quartz), magnesiosilicates (talc) or alumosilicates (clay, kaoli
n), dolomite, mica, glass bubbles, silicic acid, particularly highly dispersed silicic acids from
pyrolytic processes (fumed silica), carbon black, microspheres, pigments, particularly titanium di
oxide or iron oxides, or flame‐ retarding fillers such as aluminium hydroxides, partic
ularly aluminium trihydroxide (ATH), magnesium dihydroxide, antimony trioxide, antimony pent
oxide, boric acid, zinc borate, zinc phosphate, melamine borate, melamine cyanurate, ethylen
ediamine phosphate, ammonium polyphosphate, di‐melamine orthophosphate, di
‐melamine pyrophosphate, hexabromocyclododecane, decabromodiphenyl oxide and tris
(bromoneopentyl) phosphate. Preferred fillers are chalk, barytes, fumed silica an
d/or ATH. Preferably, the reactive one‐part polyurethane compos
ition further contains plasticizers. Suitable plasticizers are phthalates, particularly diis
ononyl phthalate (DINP) or diisodecyl phthalate (DIDP), hydrogenated phthalates, particularly
hydrogenated DINP, which is diisononyl‐1,2‐cyclohexane dicarboxylate (DINCH), ter
ephthalates, particularly bis(2‐ ethylhexyl) terephthalate or diisononyl terephthalate,
hydrogenated terephthalates, particularly bis(2‐ethylhexyl)‐1,4‐cyclohexane dicar
boxylate, trimellitates, adipates, particularly dioctyl adipate (DOA), azelates, sebacates
, citrates, benzoates, glycol ethers, glycol esters, organic sulfonates or phosphates, parti
cularly diphenylcresyl phosphate (DPK), polybutenes, polyisobutenes or plasticizers obtained fr
om natual fats or oils such as epoxidized soy or linseed oil. Preferably, the reactive one‐part polyurethane compos
ition further contains catalysts. Suitable catalysts for the acceleration of the latent
hardeners, preferably aldimine hydrolysis, are acid catalysts, particularly carboxylic
acids or sulfonic acids, preferably aromatic carboxylic acids such as benzoic acid or sa
licylic acid. Suitable catalysts are catalysts for the acceleration
of the reaction of isocyanate groups, particularly metal catalysts, preferably dialkyltin com
plexes, in particular dibutyltin or dioctyltin carboxylates or acetoacetonates such as dib
utyltindilaurate (DBTDL), dibutyltindi(acetoacetate) (DBT(acac)
2 ) or dioctyltindilaurate (DOTDL), or amine catal
ysts, preferably tertiary aminoethers, in particular 2,2'‐d
imorpholinodiethylether (DMDEE). Preferably, the reactive one‐part polyurethane compos
ition further contains additives selected from the group consisting of UV stabilizers,
wetting agents, flow enhancers, leveling agents, defoamers, deaerating agents and bioc
ides. A preferred reactive one‐part polyurethane compositio
n contains: ‐ An amount of isocyanate‐functional polymers in
the range of 15 to 80 weight‐%, particularly 20 to 50 weight‐%, in relation to the
total composition. ‐ An amount of latent hardener, preferably aldimine
s, in the range of 0.5 to 25 weight‐%, preferably 1 to 20 weight‐%, in relation to the t
otal composition. ‐ An amount of plasticizers in the range of 0 to
40 weight‐%, preferably 10 to 30 weight‐%, in
relation to the total composition. ‐ An amount of fillers in the range of 0 to 80
weight‐%, preferably 20 to 60 weight‐%, in relation to the total composition. Preferably, the fi
ller contains at least one flame‐retarding ingredient, more preferably aluminium trihydroxide (ATH
). The composition preferably contains a low amount of
volatile organic solvents with a boiling point at atmospheric pressure below 200 °C. Preferab
ly, it contains not more than 200 g of such volatile organic solvents, more preferably not m
ore than 150 g, per liter of the total composition. Such a composition is particularly suitab
le as coating for the waterproofing of buildings. The reactive one‐part polyurethane composition is pr
eferably formulated as a single‐pack composition, prepared by mixing all ingredients under
exclusion of moisture to obtain a macroscopically homogeneous fluid or paste and stored
in a moisture‐tight container at ambient temperatures. A suitable moisture‐tight conta
iner consists preferably of an optionally coated metal or plastic. It is preferably
a bucket, a barrel, a hobbock, a bag, a sausage, a cartridge, a can, a bottle or a tube.
The process of curing begins when the reactive one
part polyurethane composition is applied and gets in contact with moisture, especially
atmospheric moisture. Upon curing, the isocyanate groups react under the influence of m
oisture with the hydrolyzing latent groups of the latent hardener, preferably hydrolyzing
aldimine groups. Further, isocyanate groups react with each other under the influence of
moisture. As a result of these reactions, the composition cures to form an elastic material.
The reactive one‐part polyurethane composition is pr
eferably applied at ambient conditions, preferably in a temperature range of ‐1
0 to 50 °C, more preferably ‐5 to 45 °C, particularly 0 to 40°C. The curing of the composition preferably also takes
place at ambient conditions. The reactive one‐part polyurethane composition prefer
ably has a sufficient open time to allow precise positioning and large surface applicatio
ns and a fast‐curing progress, whereby the composition soon becomes tack‐free and shows a
fast build‐up of mechanical strength and elasticity. "Open time" is the time period, within which the ap
plied composition can be processed or reworked without any negative effect. It is over whe
n the viscosity of the composition due to progressing curing has risen too much, at the la
test when a skin is formed on the surface. The time period, until a skin is formed on the sur
face, is called "skin formation time" or "skinning time". In step a), the water impermeable membrane M obtaine
d from the reactive composition in liquid form is applied onto an electrically conductiv
e layer ECL. Preferably, the electrically conductive layer ECL has
a resistance to ground of less than 10
9 ohm, preferably less than 10
6 ohm, most preferably between 10
4 ohm and 10
3 ohm Preferably, conductive layer ECL has a layer thicknes
s in the range of 20 to 5000 ^m, preferably 150 to 1000 ^m, more preferably 250 to 500 ^m. Preferably, conductive layer ECL is applied onto the
support substrate SuS by spraying, brushing or pouring. To form an even layer, the con
ductive layer ECL can then optionally be spread before curing to the desired layer thickness
with a suitable tool, preferably as a squeegee, a toothed trowel, a spatula, a roller, a
brush or a draw down bar. The electrically conductive layer ECL is located on
a support substrate SuS, either in direct contact or via one or more additional layers of mat
erial. Such additional layers of material are preferably layers of cured synthetic resin layers
. Preferably the electrically conductive layer ECL is n
ot tacky. Preferably it is not able to function as an adhesive to bond the water impermeabl
e membrane M to the support substrate SuS. Preferably, the electrically conductive layer ECL is
a synthetic resin layer, preferably selected from the list consisting of epoxy resins, polyurethan
es, polyureas, polymethacrylates, polyacrylates, cementitious hybrid systems and polymer
modified cementitious mixtures (PCC). Preferably the electrically conductive layer ECL is e
poxy resin layer, preferably obtained from a two‐part epoxy composition, more preferably
a two‐part epoxy composition as mentioned below. Preferably, the electrically conductive layer ECL cont
ains one more conductive additives, preferably selected from the group consisting of carb
on fibers, carbon black, graphite, silicon carbide, metal oxides, metals such as iron,
ammonium salts, heavy metal‐containing or metal‐containing fillers, especially antimony‐ a
nd tin‐containing fillers based on titanium dioxide or mica, ionic liquids, ionic and nonionic s
urfactants, melamine sulfonates and polycarboxylate ethers, preferably carbon fibers. It is especially preferred if the electrically conduc
tive layer ECL is epoxy resin layer obtained from a two‐part epoxy composition containing carbon
fibers. Even though for the inventive method any suitable electrically conductive layer ECL
described above can be used, the inventors have developed a particularly suited composi
tion for said electrically conductive layer ECL. Another aspect of the present invention is therefore
an epoxy resin composition comprising: ‐at least one liquid epoxy resin LER; ‐at least one amine hardener AH; ‐4.50 to 9.00 wt.‐%, based on the total weight
of epoxy resin composition, of carbon fibers CF with a length of 40 ‐ 200 ^m, preferably 50 ‐ 150 ^m, more preferably 60 ‐ 120 ^m. Preferred one liquid epoxy resin LER are in particul
ar aromatic epoxy resins, especially the glycidyl ethers of: – bisphenol A, bisphenol F or bisphenol A/F, where
A stands for acetone and F for formaldehyde, which served as reactants for the prepa
ration of these bisphenols. In the case of bisphenol F, positional isomers may also be
present, especially derived from 2,4'‐ or 2,2'‐hydroxyphenylmethane. – dihydroxybenzene derivatives such as resorcinol, h
ydroquinone or catechol; – further bisphenols or polyphenols such as bis(4
hydroxy‐3‐methylphenyl)methane, 2,2‐ bis(4‐hydroxy‐3‐methylphenyl)propane (bisphenol C),
bis(3,5‐dimethyl‐4‐ hydroxyphenyl)methane, 2,2‐bis(3,5‐dimethyl‐4‐hydro
xyphenyl)propane, 2,2‐bis(3,5‐ dibromo‐4‐hydroxyphenyl)propane, 2,2‐bis(4‐hydroxy
3‐tert‐butylphenyl)propane, 2,2‐ bis(4‐hydroxyphenyl)butane (bisphenol B), 3,3‐bis(4
hydroxyphenyl)pentane, 3,4‐bis(4‐ hydroxyphenyl)hexane, 4,4‐bis(4‐hydroxyphenyl)heptane,
2,4‐bis(4‐hydroxyphenyl)‐2‐ methylbutane, 2,4‐bis(3,5‐dimethyl‐4‐hydroxyphenyl)
‐2‐methylbutane, 1,1‐bis(4‐ hydroxyphenyl)cyclohexane (bisphenol Z), 1,1‐bis(4‐hy
droxyphenyl)‐3,3,5‐ trimethylcyclohexane (bisphenol TMC), 1,1‐bis(4‐hydro
xyphenyl)‐1‐phenylethane, 1,4‐bis[2‐ (4‐hydroxyphenyl)‐2‐propyl]benzene (bisphenol P), 1
,3‐bis[2‐(4‐hydroxyphenyl)‐2‐ propyl]benzene (bisphenol M), 4,4'‐dihydroxydiphenyl (
DOD), 4,4'‐dihydroxybenzophenone, bis(2‐hydroxynaphth‐1‐yl)methane, bis(4‐hydroxynaph
th‐1‐yl)methane, 1,5‐ dihydroxynaphthalene, tris(4‐hydroxyphenyl)methane, 1,1,
2,2‐tetrakis(4‐ hydroxyphenyl)ethane, bis(4‐hydroxyphenyl) ether or bi
s(4‐hydroxyphenyl) sulfone; – condensation products of phenols with formaldehyde
that are obtained under acidic conditions, such as phenol novolaks or cresol novolak
s, also called bisphenol F novolaks; – aromatic amines such as aniline, toluidine, 4‐a
minophenol, 4,4'‐ methylenediphenyldiamine, 4,4'‐methylenediphenyldi(N‐me
thyl)amine, 4,4'‐[1,4‐ phenylenebis(1‐methylethylidene)]bisaniline (bisaniline
P) or 4,4'‐[1,3‐phenylenebis(1‐ methylethylidene)]bisaniline (bisaniline M). A preferred liquid epoxy resin is a liquid resin ba
sed on a bisphenol, in particular a bisphenol A diglycidyl ether and/or bisphenol F diglycidyl ethe
r, as are commercially available, for example, from Dow, Huntsman or Momentive. These liqui
d resins have a viscosity that is low for epoxy resins and good properties as a coati
ng when cured. They may contain proportions of solid bisphenol A resin or novolak gl
ycidyl ethers. Preferred amine hardener AH are selected from the li
st consisting of: ‐ aliphatic, cycloaliphatic or arylaliphatic primary
di‐ or triamines, especially isophorone diamine (IPD) and m‐xylylenediamine (MXDA)
, ‐ ether group‐containing aliphatic primary di‐ o
r triamines, ‐ polyamines containing secondary amino groups, pref
erably 2‐piperazin‐1‐ylethylamine, and ‐ adducts of these amines with epoxides or epoxy
resins, in particular adducts with diepoxides or monoepoxides. More preferred, the amine hardener AH consists of a
mixture of said list. Most preferred, the amine hardener AH consists of a
mixture of: ‐ aliphatic, cycloaliphatic or arylaliphatic primary
di‐ or triamines, especially isophorone diamine (IPD) and m‐xylylenediamine (MXDA)
, and ‐ polyamines containing secondary amino groups, pref
erably 2‐piperazin‐1‐ylethylamine. The carbon fibers CF have a length of 40 ‐ 200
^m, preferably 50 ‐ 150 ^m, more preferably 60 ‐ 120 ^m. Fibers longer than 200 ^m have the disadvantage that they tend to set up
and stick out vertically of the applied and cured epoxy
resin composition. The length of the carbon fibers can for example be determined by micro
scopy. Preferably, the carbon fibers CF have a diameter of
2 ‐ 12 ^m, preferably 3 ‐ 10 ^m, more preferably 4‐7 ^m. The length and diameter of the carbon fibers ca
n for example be determined by microscopy. It is further preferred if the carbon fibers CF hav
e an electrical resistivity of less than 5 mΩ*cm, preferably less than 3 mΩ*cm, more prefera
bly less than 2 mΩ*cm. The carbon fibers CF are present in an amount of 4
.50 to 9.00 wt.‐%, based on the total weight of epoxy resin composition. As can be seen i
n table 1 in the comparison of Ex.1 and Ex.2 with Ref.5 – Ref.7, an amount of less than
4.50 wt.‐% lead to an insufficient conductivity. The comparison of Ex.1 and Ex.2 with R
ef.8 indicates that an amount of more than 9.00 wt.‐% leads to a too high viscosity tha
t is disadvantageous for the mixing of the epoxy resin composition. It is preferred if the amount of carbon fibers CF
is 5.00 to 8.00 wt.‐%, 5.25 to 7.00 wt.‐%, 5.25 to 6.00 wt.‐%, based on the total weight of
epoxy resin composition. As can be seen in table 1 in the comparison of Ex.1 with Ex.2, said
ranges are preferred with respect to good conductivity in combination with low viscosity. It wa
s further found that the adhesion of an applied water impermeable liquid membrane directly ont
o the cured composition based on Ex.1 showed the same good adhesion as the cured com
position based on Ref.1 not containing carbon fibers. The comparison of Ex.1 and Ex.2 with Ref.2 and Ref.
3 further shows that compositions containing carbon black either showed no sufficient c
onductivity or a too high viscosity. Preferably, the epoxy resin composition is a two‐pa
rt composition consisting of a first part containing the at least one liquid epoxy resin LER
and a second part containing the at least one amine hardener AH. Preferably the carbon fibers
CF are present in the first part. Preferably the two parts are stored in separate cont
ainers. Preferably, the epoxy resin composition has a water
content of less than 5 wt.‐%, preferably less than 3 wt.%, based on the total weight of the
composition. Preferably, the epoxy resin composition has, 2 minute
s after mixing all the components, a viscosity of less than 15’000 cP, preferably less
than 12’500 cP, more preferably less than 10’000 cP, using a Brookfield DV1 Viscometer with
a HB‐04 spindle @ 100 rpms at 23 °C. The support substrate SuS is preferably part of a w
aterproofing system. The support substrate SuS is preferably part of a b
uilding, such as balcony, a terrace, a roof, particularly a flat or a slightly sloping roof, a r
oof garden, in the inner parts of a building of a
floor, preferably a roof, particularly preferred a fl
at roof. The support substrate SuS is preferably made of a m
aterial selected from the list consisting of: – metals and alloys, such as aluminium, copper, ir
on, steel, nonferrous metals, including surface‐finished metals and alloys, such as galvaniz
ed metals or chrome‐plated metals; – asphalt; – bitumen; – concrete, lightweight concrete, mortar, cement, fi
ber cement, brick, adobe, tile, slate, gypsum, gypsum panels, or natural stone, such as gra
nite or marble; – repair or levelling compounds based on PCC (poly
mer modified cement) or ECC (epoxy modified cement); – timber, plywood, paper, cardboard, wood materials
bonded with organic resins, resin‐ textile composites or so‐called polymer composites;
– insulating foams, particularly out of EPS, XPS,
PUR, PIR, rock wool, glass wool or foamed glass; More preferably, the support substrate SuS is selecte
d from the list consisting of metals, alloys, asphalt, bitumen, concrete, gypsum, timber and
plywood. The reactive composition is preferably applied by spr
aying or pouring onto a flat or slightly sloped surface. To form an even coating, the reactiv
e composition can then optionally be spread to the desired layer thickness with a suitabl
e tool, preferably as a squeegee, a toothed trowel, a spatula, a roller, a brush or a
draw down bar. Preferably, the reactive composition is applied in a
layer thickness in the range of 0.5 to 3.5 mm, preferably 1.0 to 2.5 mm. If the support substrate SuS is part of a waterproo
fing system, the reactive composition is preferably applied by pouring it onto the electricall
y conductive layer ECL located on a support substrate SuS, followed by spreading it evenl
y to the desired layer thickness. In a preferred waterproofing system, a fibre reinforc
ement mesh is used. The fibre reinforcement mesh is preferably worked into a first
layer of the reactive composition as long as the composition is still liquid, preferably
by incorporating it thoroughly into the liquid layer with a roller or a brush. After the c
uring of the reactive composition with the incorporated fibre reinforcement mesh, a next layer o
f the reactive composition is preferably applied, and the reactive composition is c
ured. The fibre reinforcement mesh is preferably a non‐wo
ven polyester fibre mesh, or more preferably a non‐woven glass fibre mesh. Examples The following examples illustrate the present inventio
n without being limiting. Carbon black powder Raven 500 Carbon Black Powder, Birla Carbon Carbonfibres MFIM56R‐080 milledcarbonfibres electricalresistivit :15 ly A‐part compositions of the inventive compositions Ex
.1 and Ex.2 and reference compositions Ref.1 – Ref.8 were prepared by additio
n of the conductive materials (carbon black powder or carbon fibres) to the A‐component
of the product Sikalastic® EP Primer/Sealer, by weight percentage based on the tota
l weight of the obtained composition after addition of the conductive material. For carbon
black powder, three samples were prepared at 5 wt.‐%, 10 wt.‐%, and 15 wt.‐% o
f carbon black powder, based on the total weight of the obtained composition. For samples with
carbon fibres six samples were prepared at 2 wt.‐%, 4 wt.‐%, 6 wt.‐%, 8 wt.
%, 10 wt.‐%, and 15 wt.‐%, based on the total
weight of the obtained composition. Each composition
was then mixed at 700 rpms with a cowles type blade for 30 minutes. Compositions contai
ning 10 wt.‐% carbon black,15 wt.‐% carbon black and 15 wt.‐% of carbon fibres, based
on the total weight of the obtained composition, were too high in viscosity for mixing.
These A‐part compositions were not evaluated further. After mixing, the remaining A‐part composition were
evaluated for uniformity and viscosity measurements were taken using a Brookfield DV1 Viscom
eter @ 23 °C (HB‐04 spindle @ 100 rpms). Each measurement was recorded. The results
of the viscosity measurements of said A‐part compositions are shown in table 1 (“
Viscosity”). The A‐part compositions described above were then m
ixed with the B‐component of Sikalastic® EP Primer/Sealer (B‐part) in a mix rat
io so that the amount of component A without the added conductive material (pure A‐compon
ent of Sikalastic® EP Primer/Sealer) to the B‐component (A‐component: B‐component) was
3:1 by weight. The compositions were mixed for 2 minutes by hand to achieve a unif
orm mixture. Each sample was applied to paper substrate using a 1/8th inch notched squeeg
ee and then back‐rolled with a 3/8th of an inch paint roller to smooth out notch marks
from the squeegee. Each sample was allowed to fully cure for 24 hours. In addition, th
e viscosity of the composition Ex.1 was determined 2 minutes after the mentioned mixing by h
and and was found to be 3500 cP. The conductivity was tested using a Buckleys’ Dry
Roof Pro2 flat electronic roof leak detector unit. The grounding wire was secured to one
corner of the applied and fully cured composition. The unit was set to output 7.56 kV fro
m the electrode. The electrode, a 150 mm long stainless‐steel drum‐brush, was swept acro
ss the coating to measure the conductivity. The unit is set to detect a current o
f 200 µA or more by emitting an audible alarm. Each sample was checked over the entire surfa
ce area of the applied composition to assure uniform conductivity. The results are shown in
table 1 (“Conductivity”). After the conductivity was verified, a reactive compo
sition in liquid form (Sikalastic®‐641) was applied directly over the above mentioned fully
cured composition of Ex.1 and Ex.2 using a ½ inch nap roller to a coat weight of ap
proximately 1.25 mm. Sika Reemat Premium, a chopped strand fiberglass mat, was applied to the
wet coating and back rolled to embed the reinforcement, then allowed to cure for 24 hrs.
After 24 hours of cure a second coat of Sikalastic‐641 was applied on top of the reinforcem
ent to a coat weight of approximately 0.75 mm (total thickness of the system approximately
2.00 mm). The system was then allowed to cure for 72 hours. The system was then checked for conductivity to ensu
re membrane integrity. As before, the grounding wire was secured to one exposed corner of
the (conductive) fully cured composition, and the electrode was swept across the
surface of the cured Sikalastic‐641 membrane. No conductivity was observed indicating zero
voids in the Sikalastic‐641 membrane. Damage to the Sikalastic‐641 membrane was
simulated by making a 2‐inch razor cut and a thumbtack pierce through the system
all the way down to the primer layer. The system was then checked with the Buckleys’ lea
k detector unit for conductivity. The signal was observed over both simulated damage condit
ions and not in any other section of the system. Compositions Ref.1 and Ex.1 were also evaluated for
the strength/quality of adhesion of the Sikalastic 641 membrane coated over the cured composi
tions. Compositions Ref.1 and Ex.1 were applied to a standard concrete block and allowe
d to cure for 24 hours and a Sikalastic 641 membrane was applied on top as mentioned above
for the conductivity testing and allowed to fully cure for 2 weeks. Adhesion was eva
luated using an Elcometer 510 Automatic Pull‐Off Adhesion Gauge in accordance with
ASTM D7234‐21 for both compositions Ref.1 and Ex.1. No significant difference
of adhesion values was observed, indicating the addition of the carbon fibres had no
detrimental effect on adhesion. The results are shown in table 1 (“Adhesion”).
n i o i s i s p . e 0 h 5 d . . d . d . s d . d . d p . . n . n . n . n . n . n 0 5 d . d n . n d 2 A ~ 2 ~ ) t r r r t a a a r t r t r t r a m p p a a a r a p o c B B p B p B p p p B B + + A ( A + ( A + B A + B A + B + + A + A A ( A ( n n ( o i o n ( ( ( ( n n t i o n n n n o i o i i t s i i s ti o i t o i t o i t o i t ti o o s o i s i s ti p p p o s i o s i s o s o o p o p m p p p p m m m o m o m m m m oc oc n oc c l c o o i l a l c l oc l oc l oc l l a l a t a i t t a s o o t t o t a t a o t a t a t t o t t o o t p % % t o t o t o t t ‐ % %‐ %‐ m ‐ .t ‐ . %‐ . %‐ . %‐ . %‐ . .t .t o A c t .t t n w w t t t t t 2 w 9 w w w w w 2 w 9 r e n 7 5 8 . 7 . 7 4 9 8 5 2 6 5 8 . 7 . a p‐ o . p 3 ( 6 ( 9 ( . 1 . . . ( 2 ( 4 ( 5 ( 6 ( 9 ( A m o A A t A t A c t o n n n t A t A A A t A t t t t e e n e n e n e n e n n e e n n e n d n e o o n p o p n o n n n o o p o o o p p d p d m m o m p p p o m a o m o m m m o m o c o c l o a c c i n c i n i c n c n c o n c ni ni r n i e t k k c k c i s i s i s ni s s e s e d a c al al al e r e r e r e r r b m b b i r bi e n e n b b n i f bi f bi f bi f f n f i m v i n t o o c b u r b o r b n a r a o n b o n o n o o n r b r b r b r b o r b r e a r a t e d d a c c c a a a a c c n % % c c c c % o % ‐ ‐ .t ‐ .t % ‐ % ‐ % ‐ %‐ ‐. %t o t ‐ .t n c . o t . w w w t . w t . w t . w t = w w w . N 5 0 1 5 1 2 4 6 8 0 1 5 1 d .n 1 . f 2 . 3 4 5 , 1 e f . f . f . f 6 . f 7 . f 1 . 2 . 8 . f e R e R e R e R e R e R e R x E x E e l R b a T