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Characteristics of the mechanically fastened joints of one-layer bitumen sheets

Abstract

The system of mechanic fastening is one of the most frequently used variants of roof membrane stabilization against the impacts of wind sucking. With the growing number of applications of mechanically fastened roofs the number of defects is also growing. We particularly see them in the joints of waterproofing membranes. The contribution is thus dedicated to examination of mutual dependence between the type of the carrier and the strength characteristics of mechanically fastened joints of these sheets. Bitumen sheets with different types of carrier used for one-layer mechanically fastened waterproofing membranes of flat roofs were chosen as samples. The above mentioned dependence is frequently stated in the practice, but is not explicitly documented. The aim of the contribution is to confirm or refute a hypothesis that a relation between the bitumen sheet carrier type and the strength of their joints exists. The results were arranged on the base of statistic evaluation of data obtained by laboratory measurement.

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Characteristics of the mechanically fastened joints of one-layer bitumen sheets

Author: Petříček, Tomáš; Kacálek, Petr; Hlavačka, Tomáš
Publisher: EDP Sciences
Year: 2016
DOI: 10.1051/matecconf/20179303007
Source: https://dspace.vut.cz/bitstreams/91a4b31f-47ac-42f5-9480-4489d20efebe/download
Cha ac e is ics o he mechanically as ened
join s o one-laye bi umen shee s
Tomáš Pe říček1,*, Pe Kacálek1, and Tomáš Hla ačka1
1B no Uni e si y o Technology, Facul y o Ci il Enginee ing,
Ins i u e o Building S uc u es, Ve eří 95, 602 00 B no, Czech Republic
Abs ac . The sys em o mechanic as ening is one o he mos equen ly
used a ian s o oo memb ane s abiliza ion agains he impac s o wind
sucking. Wi h he g owing numbe o applica ions o mechanically
as ened oo s he numbe o de ec s is also g owing. We pa icula ly see
hem in he join s o wa e p oo ing memb anes. The con ibu ion is hus
dedica ed o examina ion o mu ual dependence be ween he ype o he
ca ie and he s eng h cha ac e is ics o mechanically as ened join s
o hese shee s. Bi umen shee s wi h di e en ypes o ca ie used o one-
laye mechanically as ened wa e p oo ing memb anes o la oo s we e
chosen as samples. The abo e men ioned dependence is equen ly s a ed
in he p ac ice, bu is no explici ly documen ed. The aim o he
con ibu ion is o con i m o e u e a hypo hesis ha a ela ion be ween he
bi umen shee ca ie ype and he s eng h o hei join s exis s. The esul s
we e a anged on he base o s a is ic e alua ion o da a ob ained by
labo a o y measu emen .
1 In oduc ion
The applica ion o he single-laye mechanically as ened bi umen shee sys em is a quick
and p og essi e one, which equi es high echnological discipline. High quali y bi umen
shee s o a leas 0.5 mm hickness a e equi ed as s anda d o he applica ion o single-
laye sys ems. The bi umen shee s also need o be o a su icien quali y ha hey a e
weldable and lexible o e he long e m. The shee s a e mos ly ein o ced wi h
a combina ion o PES leece s eng hened wi h glass ib es laid in one o bo h di ec ions.
O e laps o a leas 120 mm wide a e ecommended o he shee s.
Whole su ace mel ing o he join is essen ial o he wa e p oo ing capabili ies o he
sys em as well as o he ans e o wind load o ces. A c i ical poin wi h ega ds o he
wind load esis ance o a join is he p esence o a as ening elemen .
2 Fas ening o bi umen shee join s
To ensu e he join is sealed co ec ly he su ace a ea along he en i e join leng h o bo h
shee s need o be hea ed o mel ing poin . The as ening elemen is no placed in he cen e
* Co esponding au ho : [email p o ec ed]
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© The Au ho s, published by EDP Sciences. This is an open access a icle dis ibu ed unde he e ms o he C ea i e
Commons A ibu ion License 4.0 (h p://c ea i ecommons.o g/licenses/by/4.0/).
o he join bu is loca ed 10 mm (o 20 mm) om he edge o he lowe shee , whe eby he
en i e su ace a ea o he join is able o ake he s ain o he as ening elemen . The e ec s
o linea shea ing ( ea ) o ce and he angen ial o ces (peel esis ance) a e he e o e
applied in a ying deg ees o he o e lap o e he en i e su ace a ea o he join .
Acco ding o ČSN EN 13707 [1] manu ac u e s o bi umen shee s a e obliged
o p oduce hem wi h su icien esis ance agains angen ial o ces (De e mina ion o peel
esis ance in join s acco ding o ČSN EN 12316-1 [2]) and linea shea esis ance when
joined oge he (De e mina ion o shea esis ance acco ding o ČSN EN 12317-1 [3], [4]).
A mechanically as ened bi umen shee join aces a combina ion o bo h he abo e
s esses. As angle β g ows (see Fig. 1), he le el o peel s ess g ows, whe eas whe e angle
β (Fig. 2) is minimized, he linea shea o ce ( ea ) g ows. Wi hin his con ex , he peel
esis ance es o a join is o pa icula impo ance when e alua ing he quali y o he
bi umen subs ance used [5].
Fig. 1. P e ailing angen ial (peel) o ce. Sou ce: [6].
Fig. 2. P e ailing linea shea ( ea ) o ce. Sou ce: [6].
The ca ie in he bi umen shee gua an ees he s eng h p ope ies, olume s abili y,
i o ms he base o he bi umen shee du ing p oduc ion and also aps and ans e s ensile
s esses and edis ibu es he s ess caused by in e nal and ex e nal o ces.
The esul an mechanical and s eng h cha ac e is ics o he ca ie depend on he
ma e ial base o he ib es, hei mu ual di ec ion and on he p opo ion o he applied ille
o hei connec ion. App oxima e compa ison o he p ope ies o ca ie s a e shown
in Table 1.
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Table 1. App oxima e compa ison o s eng h and duc ili y o he mos o en used ca ie s
Sou ce: [6].
Ca ie ype
Squa e
weigh S eng h Duc ili y
g/m2
longi udinal
di ec ion
[kN.m/-1]
ans e sal
di ec ion
[kN.m/-1]
longi udinal
di ec ion
[%]
ans e sal
di ec ion
[%]
Glass leece (Vlis)* 60-110 min. 3.6-8.6 min. 2.6-4.8 1.2-1.4 1.2-1.4
Glass wo en ab ic ( ug)** 152-200 min. 18-21 min. 20-24 2-3 2-3
PES leece*** 120-250 8.6-19 4.6-14 20-35 23-37
Combined**** 160-180 min. 9.6-13.3 min. 6.8-8.1 min. 23 min. 25
* Johns Man ille, DH se ies ** Sain Globain Ve o ex
*** Johns Man ille, 032 se ies **** Johns Man ille, 054 se ies
Tes s desc ibing ensile p ope ies p o ide compa ison o he in luence o he ca ie on
he o e all s eng h pa ame e s o a bi umen shee : he highes ensile s eng h and duc ili y
speci ied in he longi udinal and ans e sal di ec ion. The g aph in Fig. 3 shows
compa ison o mechanical p ope ies o ca ie s and bi umen shee s wi h he espec i e
ca ie s.
Fig. 3. Compa ison o mechanical p ope ies o ca ie s and bi umen shee s wi h espec i e ca ie s
a he empe a u e o +20 °C Sou ce: [6].
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3 Expe imen al measu emen
A p essu e chambe was used in which he composi ion o a oo memb ane om a eal
join segmen o mechanically as ened wa e p oo ing could be subjec ed o de ined
s esses. This wind load es is de ined in he App o al Guideline o sys ems
o mechanically as ened wa e p oo ing memb anes ETAG 006 [7].
Fo he expe imen al measu emen s es s we e ca ied ou on a s anda d ensile es ing
machine. The specimens we e oo memb ane segmen s, no jus he wa e p oo ing
memb ane. Two me al as ening s ips in he a ms o he uppe g ip o he machine held
he wa e p oo ing memb ane in place. These a ms ans e ed he o ce o he applied s ess
o es ma e ial. A pad, o which he wa e p oo ing memb ane was as ened by he mal
insula ion, was clamped in o he lowe g ip. As he lowe g ip o he ensile es ing machine
eceded i caused s ess on he join and subsequen ly i s up u e.
The es specimens we e p epa ed acco ding o composi ion a ian S1 i.e. analogically
o a oo wi hou he mal insula ion wi h he wa e p oo ing memb ane mechanically
as ened o OSB boa d o 22 mm hickness. The as ening elemen o he ha d base was
a sc ew wi h a me al o al washe . The edge o he p essu e washe o he as ening elemen
was loca ed 10 mm om he edge o he lowe bi umen shee . The use o he o al p essu e
washe was in en ional because i p o ides be e p essu e on he lowe shee due o i s
la ge su ace a ea. As a esul , he up u e o he es specimens was dependen on he
pa ame e s o he bi umen shee a he han on he ailu e o he as ening elemen .
Th ee bi umen shee a ian s we e chosen as he wa e p oo ing memb anes:
1. Tes specimen B - SBS modi ied bi umen shee 5.2 mm hick, ca ie : PES 180 g/m2
ein o ced longi udinally wi h glass ib es, lexibili y a low empe a u es: -25 °C, join
leng h 100 mm
2. Tes specimen E - SBS modi ied bi umen shee 5.2 mm hick, ca ie : PES 230 g/m2,
un ein o ced, lexibili y a low empe a u es: -25 °C, join leng h 100 mm
3. Tes specimen F - SBS modi ied bi umen shee 5.2 mm hick, ca ie : PES 180 g/m2,
ein o ced on bo h sides wi h glass ib es, lexibili y a low empe a u es: -25 °C, join
leng h 100 mm
Fig. 4. Tes specimen - composi ion a ian S1. Sou ce: [8].
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Fig. 5. Tes specimen in he ensile es ing machine du ing es ing. Sou ce: [8].
4 E alua ion
App oxima ely 10 specimens we e used o each es sample. The inal o ce is in he o m

xx

, whe e
x
is he a i hme ic a e age and

x

is he p obable measu emen
e o . The la e was de e mined on he basis o he e o heo y o he de ia ions o he
a i hme ic a e age using he o mula:
 

.
1
1
3
2
1
2





n
i
ixx
nn
x

(1)
5 Resul s o he expe imen al measu emen and discussion
In he specimens wi h lowe squa e weigh (B and F) unsealing o he join occu ed and he
es ended in ea ing o he ca ie on he base o he as ening elemen and in sepa a ion
o he wa e p oo ing laye om he base (Fig. 6). The s eng h o specimen E exceeded he
ange o he es ing machine (max. ensile 2,000 N), he cohe ence o he specimen E was
so high ha no unsealing o he join occu ed in some o he samples (Fig. 7).
We can assume on he base o he esul s o he expe imen al measu emen ha he
s eng h o a mechanically as ened join g ows wi h he squa e weigh o he PES ug used
in he bi umen shee ca ie . Specimen E (un ein o ced PES ug, 230 g/m2) achie ed he
highes s eng h alues, he esul s o specimen B (PES ug longi udinally ein o ced wi h
glass ib e, 180 g/m2) we e by app oxima ely 13 % lowe . Specimen F (PES ugs ein o ced
wi h glass ib e on bo h sides 180 g/m2) showed he lowes s eng h, he alues we e
by app oxima ely 20 % lowe compa ed o specimen E.
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De ailed esul s and compa ison o he esul s o all he specimens a e shown in Table 2.
Fig. 6. Typical damage o he join on specimen B. Sou ce: [8].
Fig. 7. No damage o he join on specimen E is isible a he maximum ensile. Sou ce: [8].
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Table 2. Compa ison o he es specimens
Tes specimen: B E F
Bi umen subs ance: SBS modi ied
Flexibili y a low
empe a u es: -25 °C
Shee hickness: 5.2 mm
Ca ie : PES longi udinally
ein o ced, 180 g/m2
PES 230 g/m2, no
ein o ced
PES ein o ced on
bo h sides, 180 g/m2
O e lap wid h: 100 mm
The highes ensile
s eng h:
longi udinally: 900
(± 200) N/50mm,
ans e sally: 700
(± 150) N/50mm
longi udinally: 950
(± 200) N/50mm,
ans e sally: 850
(± 150) N/50mm
longi udinally: 900
(± 200) N/50mm,
ans e sally: 650
(± 150) N/50mm
Duc ili y:
longi udinally and
ans e sally:
50 (± 10) %
longi udinally and
ans e sally:
50 (± 10) %
longi udinally and
ans e sally:
45 (± 10) %
Mean alue: 1,624.5 N 1,856.8 N 1,488.3 N
S anda d de ia ion: 127.6 N 97.4 N 131.6 N
Va ia ion coe icien : 7.9% 5.2% 8.8%
Highe squa e weigh o he PES ug inc eases esis ance o a bi umen shee agains
mechanical damage ( ea ing agains he shank o he p essu e washe o he as ening
elemen ) when exposed o s ess. Fo combined ca ie s manu ac u e s p esen hei o al
squa e weigh s, i.e. he PES ug including he ein o cemen glass ib es. In he ins ance
o he PES ug ein o ced on bo h sides he p opo ion o he glass ib es in he o al weigh
o he ca ie is highe , so he weigh o he PES ug i sel is lowe . This migh explain why
he bi umen shee wi h longi udinally ein o ced PES ug (specimen B) achie ed highe
s eng hs han he shee wi h a PES ug ein o ced in bo h di ec ions (specimen F).
In he bi umen shee s ein o ced wi h combined ca ie no g adual c acking o he
indi idual glass ib es ha ein o ce he ca ie was isible du ing ensioning and be o e he
up u e. In he case o he combined ca ie s he pa ame e s depend on he pa icula ype –
squa e weigh , loca ion and connec ion o he ein o cemen ib es o he PES ug a ec he
esul ing s eng hs and duc ili y o he ca ie .
The esul s o his compa ison should howe e be unde s ood in wide con ex – on he
base o he abo e desc ibed esul s applica ion o bi umen shee s wi h ca ie s o non
ein o ced PES ugs canno be p e e ed. Applica ion o combined ca ie s in single-laye
mechanically as ened sys ems p o ides i eplaceable ad an ages.
6 Conclusion
The pe o med measu emen s showed ha he s eng h o a join o mechanically as ened
bi umen shee g ows wi h he squa e weigh o he PES ug used in he ca ie o he
bi umen shee .
In combined ca ie s he o al weigh is lowe ed by he weigh o he glass
ein o cemen ib es, which migh lead o educ ion o he inal s eng h compa ed o
an un ein o ced ca ie . Applica ion o combined ca ie s in single-laye mechanically
as ened sys ems howe e p o ides i eplaceable ad an ages.
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This pape has been wo ked ou unde he p ojec No. LO1408 "AdMaS UP - Ad anced
Ma e ials, S uc u es and Technologies", suppo ed by Minis y o Educa ion, You h and Spo s unde
he „Na ional Sus ainabili y P og amme I”.
Re e ences
1. ČSN EN 13707+A2, Wa e p oo ing shee s and oils – Rein o ced oo wa e p oo ing
bi umen shee s – De ini ions and cha ac e is ics (The Ins i u e o Technical
S anda diza ion, Me ology and S a e Tes ing, P ague, 2009)
2. ČSN EN 12316-1, Wa e p oo ing shee s and oils – Pa 1: Roo wa e p oo ing
bi umen shee s – De e mina ion o peel esis ance o join s (Czech S anda ds
Ins i u ion, P ague, 2000)
3. ČSN EN 12317-1, Wa e p oo ing shee s and oils – Pa 1: Roo wa e p oo ing
bi umen shee s – De e mina ion o shea esis ance in join s (Czech S anda ds
Ins i u ion, P ague, 2000)
4. R. Smolka, T. Pe říček, P. Kacálek, en iBUILD 2014 - Buildings and En i onmen
(B no, 2014)
5. T. Pe říček, P. Kacálek, R. Smolka, AMS 1041, 71-74 (2014)
6. J. Plachý, Bi umen shee join s unde he in luence o empe a u e and ime in he
composi ion o single-memb ane oo s (Doc o al hesis, B no Uni e si y
o Technology, Facul y o Ci il Enginee ing, B no, 2005)
7. ETAG 006. Eu opean Technical App o al Guideline – Sys ems o Mechanically
Fas ened Flexible Roo Wa e p oo ing Memb anes (Eu opean O ganisa ion o
Technical Assessmen - EOTA, B ussels, 2000)
8. T. Pe říček, Adhesion o join s o mechanically as ened bi umen shee s (Doc o al
hesis, B no Uni e si y o Technology, Facul y o Ci il Enginee ing, B no, 2013)
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