Special Glues of Interest to Builders
(The second of two articles)
In Our last issue, We wrote about First, however, it is of interest to note The results for the first four sets of 'Aerolite' and 'Aerodux'
synthetic re- one of the reasons why 'Aerolite' showed sin glues of particular interest to the such outstanding qualities in the tests. building industry. Brief details were given of their manufacture, characteristics and
with specific examples application
of structures in which they had been used to advantage.
The illustration indicates how this glue behaved in comparison with a convention- al glue of the same type.
The fact that the Aerolite' has not crazed is due to the patented GB Hardeners with which it is In this article more detailed information used. These hardeners cause setting at a will be submitted of their qualities, and uniform rate throughout the resin mass reference will be made to various tests and full gap-filling requirements thus pre carried out by highly competent and well sent no problem, uneven setting being the know authorities.
specimens are shown in table and 2 together with the corresponding figures the time of preparation and after storage obtained with control specimens tested at
under normal laboratory conditions. Each result is the mean of 12 tests.
Note that even after two years under exposed tropical conditions the 'Aerolite" joints continued to exceed specification by a wide margin, The two phenol-formalde- hyde resins, which remain satisfactory in cause of crazing. Other urea-formalde- close contact joints, fail significantly in
Table 1
Close Contact Specimens, Failing Load (lb.) (Note: BS. 1204 calls for a minimum figure of 600 lb )
Anursive —
UREA-
PHENOL- FORMALDEHYDE FORMALDEHYDE
RIORCINKLE FORMALDEHYDE
!Adhesive Acrolite" Adhesive Adhesive Adhesive Adhesive
Table 2
Gap Specimens-Farling Load (lb.i (Note: BS.1204 calls for a minimum figure of 450 lb)
UREA- FORMALDEHYDE
PHENOL-
Resorcin01.- FORMALDEHYDE FORMALDEHYDE
ADHESIVE:-
Adhesive?" Aerolite” Adhesive, Adehsive AdhesivejAdhesive
A
300
B
C
*E*
3:00
* B*
C'
'D'
E'
Control Specimens
Control Specimens
At time of preparation
764
४।
716
746
687
i
702
At time of preparation
555
545
466
456
596
312
After 6 months at R A.E.
803
739
704
774
728
699
After 6 mths at R.A.E.
530
609
496
425
600
508
12
750
779
749
778
682
673
12
Th
H
559
586
466
434
600
472
..
TK 24
757
814
737
789
754
709
IR
582
575
448
418
644
478
732
749
674
772
715
713
24
579
563
478
417
608
495
|
Exposed Specimens
After 6 mths, at TTE., Nigeria
Exposed Specimens
765
843
701
775
729
709
After 6 mths at TTE., Nigeria
502
543
454
355
599
485
12
++
18
24
.י
I
685
790
663
732
714
692
12
476
566
434
366
552
450
T
+
11
656
754
654
724
734
695
[]
687
659
705
706
681
[* 24
446
557
466
373
606
473
358
307
T
584
454
Tropical exposure tests made
in-
hardeners
by the hyde glues achieve gap-filling properties British Royal Aircraft Establishment have by the addition of materials called fillers shown these glues to be markedly superior china clay, cereal flour etc.-and and we are indebted to the Establishment variably deteriorate in the course of time. for permission to quote from their find-
The result of using the GB ings.
and not adding fillers is that the inexpen- sive Aerolite' is equal to and sometimes
much more superior to the
expensive synthetic glues known as resorcinol and phenol formaldehydes.
The tests referred to are being carried out at the Tropical Testing Estatblishment, Nigeria (with control specimens stored under normal laboratory conditions in England being subjected to parallel tests) and have been planned to cover a five The results given here are year period. for the first two years of that period.
The adhesives under test comprise six cold setting proprietary brands of which two art urea-formaldehydes (one being 'Aerolite'), two phenol-formaldehyde TC- sins and two resorcinol formaldehyde re- sins.
Two special boxes of a type know to simulate aircraft wing conditions were used to store the test specimens and the boxes mounted about three feet from the ground and exposed to the hot, damp conditions prevailing in the jungle. Temperatures between રી during the two years varied An effective demonstration of the superior gap-filling properties of Aerolite 306 and minimum of 60 F and a maximum of hardener GBP.X. Even in a
while 91° F.
relative humidity ranged very thick
from 54 to 100 percent. The highest solar application (bottom) this combination of resin and adhesive has not crazed where. temperature recorded was 91 F. Record- us another urea-formaldehyde glue used ers placed inside the boxes showed that, r mixed-application' hardener and here, temperature varied from 60° F to filler (top) has crazed within few 106' F with relative humidity ranging
with
months.
a.
from 51 to 95 percent.
-
65
Table 3 Single Lap Joint. European Redwood
Axial Load Parallel to Grain
Number of nails Safe Loud Connection
or bolts
fb.
cffc
Nails
4.092" da.
152
2.82
Nails in pre-
bored holes Screws in pre-
bored holes
6/ 092" dia.
228
4 22
4. No. 4 (IOS)
dia.)
152
2.82
11" dia. (largest
bolt possible!
1150
21 3
Bulldog Con-
nector Split Ring
Connector Lrea-Formal- dehyde glue
2)* connector÷}”
bolt
1140
21.1
24"
2080
38 5
Aerolite 300
*2500
46.4
Bolis
'This is 45% of mean failing load of twelve specimens having Jin. lap. The basic stress in tension of European Redwood is 1200 psi. hence a full 3 in × 14 in. section will carry 5400 lb. safe load
Table 4
Double Lap Joints. European Redwood
Axial Load Parallel to Grain
Number of naild Safe Load Connection
or belts
lb.
effic. *
Nails
8 - 092′′ dia
304
564
Nails in pre- bared holes Screws in pre- bored holes
Bolts Bulldog Con-
12. - 092" dia.
456
844
No 4 (108)
dia.)
104
5.65
1.- 1" dia
1150
213
2}' connectors –
nector
4 boll
1035
197
21"
NOI
possible
Aerolite 300
6070
1125
Split Ring
Connector Crea-Formal· dehyde Glue
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