Note: Descriptions are shown in the official language in which they were submitted.
~275775
1 FIELD OF INVENTION
This invention relates to a novel kit of components
for providing a resilient patch in the repair of spauled
or broken concrete.
BACKGROUND OF INVENTION
It is a common problem in the repair of broken concrete
that it is difficult to provide a patch that will permanently
adhere to the main body of concrete to be repaired. Concrete
normally expands and contracts in response to changes in
the ambient temperature. While this expansion and contraction
can be a cause of damage to concrete (especially in cold
climate), such as cracking or spauling of the surface,
it contributes as well to the degradation of repairs.
The most common type of concrete repair comprises the addition
13 of a lap coat of a mixture Gf concrete similar in composition
to that of the concrete body being repaired. Such a lap
coat provides a poor bond however. It will be appreciated
by those skilled in the art that normally a poor bond is
created at the interface of like materials and that a more
effective bond is provided where a layer of glue is applied
to each body to be joined and the interface between the
two bodies comprises an adhesive bridge Eormed when the
two layers of glue are ~oined together.
In the art of concrete patching it has therefoxe been
taught to apply an adhesive bridge to the body of concrete
to be repaired formed from an epoxy resin or the like and
to thereafter apply a patching compouncl such as concrete.
Normally an adhesive bridge formed from epoxy resin or
the like when first applied has a low viscosity and when
completely dry is rigid and brittle. Although such an
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1 adhesive bridge provides a more effective bond with the
patching material, when the concrete body expands and contracts
in response to changes in the ambient temperature, the
adhesive bridge will crack due to its brittle nature.
It will be appreciated by those skilled in the art that
when the adhesive bridge cracks the bond formed thereby
between the concrete body and the patching material is
disrupted. The repaired surface will then be affected
by spauling and cracking and the problem will have returned.
An example of an adhesive bridge being provided as
a bonding interface between a concrete body and a patching
compound may be seen in Japanese Letters Patent 60,195,269
to Tao Gosei Chem Ind Ltd. -- a coating material having
a viscosity of 300 C.P.S. or more is applied to the damaged
portion, for example cracks, blisters, peeling, of reinforced
concrete structures. This undercoating of epo~y resin
is applied to the damaged portion prior to application
of the patching material.
In United Kingdom Letters Patent 2,030,986 B it is
disclosed at page 2 line 15 that it is usual to provide
the concrete surface with a so called "adhesive bridge".
The invention therein discloses that it is unnecessary
to provide an adhesive bridge when the binder mixture of
the invention is applied directly to the damaged concrete.
United States Letters Patent 3,966,657 describes a
filling compound to be applied to concrete surfaces -- according
to the invention therein the extension of the curing time
of the compound in response to decreases in the ambient
temperature may be compensated for by selecting and adding
a diluent to the resin or hardener blend so that when the
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1 resin blend and the hardener blend are intermixed a heat
exchange is produced which counteracts the effect of the
ambient temperature.
It is therefore an object of this invention to provide
a kit of pre-mixed components comprising a bonding agent
and a patching compound which when applied to a concrete
body provides a resilient patch which will not break down
in response to the expansion and contraction of the concrete
body according to changes in the ambient temperature.
It is a further object of this invention to provide
a kit of components for patching a broken concrete body,
the kit having a bonding agent and a patching mixture which
may be more effectively applied to the concrete body in
a bonding interface.
Further and other objects of the invention will be
apparent to those skilled in the art from the following
Summary of Invention and Detailed Description thereof.
SUMMARY OF INVENTION
According to one aspect of the invention there is
provided a kit for repairing spauled or broken concrete
comprising:
a) a pre-mixed bonding agent for ul-iformly coating
the concrete surface to be repaired; said bonding agent
comprising more than one premixture containing an expoxy
resin and hardening agent separately contained until mixed
together prior to use; said epoxy resin also blended with,
a diluent, a filler, a binder, and a thickening agent;
said hardening agent also blended with a diluent, a first
accelerator, a second accelerator, a binder and a thickening
.~gent; whereby when the epoxy resin mixture and the hardening
~27577~
1 mixture are mixed a bonding agent is formed having a viscosity
characterized by good adhesion when first applied to a
concrete surface and when said bonding agent drles having
resilient characteristics;
b) a patching compound used in conjunction with said
bonding agent comprising at least two premixtures containing
an epoxy resin and a hardening agent separately contained
until mixed together prior to use; said epoxy resin also
blended with aggregate material, and preferably pigments;
said hardening agent preferably alone but may also be blended
with aggregates and pigments whereby when the epoxy resin
mixture and the hardening agent mixture are mixed a patching
compound is formed having viscosity characteri2ed by good
adhesion when first applied to said bonding agent and
when said patching compound dries having resilient
characteristics;
c) whereby the bonding interface formed between said
bonding agent and said patching compound is characterized
by a generally uniform interface, and whi.ch interface is
resilient, responding to freeze/thaw cycles resulting in
the expansion and contraction of the substrate concrete
body being repaired, thereby increasing the life of the
patch applied.
BRIEF DESCRIPTION OF DRAWINGS
Figure l is a schematic view of a concrete body having
a damaged area.
Fi~ure 2 is a schematic vi.ew of the damaged area in
Figure l having a bonding agent applied thereto.
Fiqure 3 is a schematic view of the damaged area in
Figure l having an adhesive bridge applied thereto as taught
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1 by the prior art.
Figure 4 is a schematic view of the damaged area shown
in Figure l having applied thereto the bonding agent shown
in Figure 2 and a patching compound.
- 5 DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
~ ith reference to Figure l there is shown a concrete
body 10 having a damaged area 15, as for example by spauling
or cracking of the surface 12 of the concrete body 10.
Normally the surface 16 of the damaged area 15 is cleaned
prior to any patching -- for example a wire brush or the
like may be used to debrade loose material. Nonetheless
the surface 16 will have irregular undulations comprising
pockets 20, 30, 40, and 50 and projections as at 35. With
reference to Figure 3 there is shown the damaged area 15
having applied thereto an adhesive bridge L composed only
of the combination of epoxy and hardener as normally applied
by men skilled in the art. As a result of the exothermic
reaction of the epoxy and the hardener when first combined,
the viscosity of the said combination when applied to the
surface 12 decreases to a value less than that of the epoxy
resin without the hardener. The low viscosity oE the adhesive
bridge L when first applied to the sur~ace 12 of the damaged
area 15 results in weeping of the material L. Portions
of the damaged area 15 which are generally vertically inclined
may not be coated as at projection 45. As best illustrated
ln Figure 3, the adhesive bridge L is not of a unifrom
thickness or consistency -- air bubbles may be trapped
within recesses 50, 40 and projections 35 may not be coated;
thereby reducing the quality of the bonding interface with
any patching coat applied to the adhesive bridge L.
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1 With reference to Figure 2 there is shown a layer of a
bonding agent M as taught herein applied to the surface 12 of
the damaged area. The said layer M has a generally uniform
thickness, for example as at projection 45. As a result of
the uniform thickness of the layer of the bonding agent M,
the quantity of trapped air (as illustrated by recesses 50,
40) is reduced and projections ~as for example at 45) are
more uniformly coated. The quality of the bonding interface
with any patching coat applied to the bonding agent M is
thereby improved. In this regard, reference is made to
Figure 4-- wherein there is shown a patching coat P applied
to the surface presented by the layer of the bonding agent M.
In Figure 4 patching compound P is shown
applied to the bonding agent M as referred to in Figure 2.
Exaggerated zones A and B are illustrated to depict the
total encapsulation with epoxy ladened material of each
granule within the patching compound, even at the boundary
of the bonding agent layer, unlike that of the generally
taught adhesive bridge (as illustrated in Figure 3)
wherein particles of a similar patch would come into
direct contact with cracks and crevices of the damaged
surface 15.
Preferably the I.ayer of bond:i.ng ayent M. is
characterized by the following constituents:
TABI.E 1 - BONDING AGENT
EPOXY COMPONENTS
TRADE
ITEM DEscRIPTION % BY WEIGHT GENERIC DESCRIPTION
1 "DER 331" 24.4 Liquid Epoxy Resin
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1 Trade
ItemDescription % By WeightGeneric ~escription
Der is a registered
trade mark of the DOW
Chemical Company of
Midland Michigan
2"TOLUOL" 6.5 Diluent
3"ATOMITE" 17.8Calcium Carbonate
(a registered trade mark (Fine Ground Calcium
of Thompson Weinman and Carbonate)
Company)
4"MULTIFLEX MM" 3.0Precipitated Calcium
Carbonate
Multiflex MM is a
registered trade mark
of the Diamond Shamrock
Corporation of Cleveland, Ohio
5"CALEDRIA" 1.2 Thickening Agent
HARDENER COMPONENTS
Trade
I-temDescription % ~y ~eigh~~Ll~ C~LLe~LQ~
6"VERSAM:[DE l.~()" L~.0Ikl.tclener; :I.ow v:i.scos:Lty
Polyam.ide Resin
7 "TOLUOL" 7.1 Diluent
8"DMP 30" 1.0 Accelerator
a registered 2,4,6-Tri(demethyl-
trade mark of Rohm aminomethylphenol)
& Haas Company of
Philadelphia P.A.
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9"NONYL PHENOL" 12.1Accelerator; high
viscosity
(mixture of predominantl
para-substituted monoalk~
phenols)
10"ATOMITE" 11.9Calcium Carbonate
(fine ground calcium
(a registered trade mark carbonate)
of Thompson, Weinman and
Company)
11"MULTIFLEX MM" 1.8Precipitated Calcium
Carbonate
Multiflex MM is a
registered trade mark
of the Diamond Shamrock
15Corporation of Cleveland, Ohio
12 'CALEDRIA" 1,2 Thickening Agent
Preferably the Layer of Patching agent is
characterized by the following consti-tuents:
20TABLE 2 - PATCHING COMPOUND
EPOXY COMPONF,NTS
TR~DF
ITEMDE.'C ~IP'~IQ~ Y_~EI~ e~ ' CAI~
1"71 SILICA SAND" 39.3
2"#30 SILICA SAND" 39.3
3"ARALDITE 507" 9.3Modifi.ed low viscosity
a registered trade epoxy resin (low
mark of the Ciba-Geigy tendency to crystalize)
Corporation. Ardsley, N.Y.
4"TITANIUM DIOXIDE" 0.2Whitening Agent
, ~ .
~7S'775
Trade
Item Description % By Weight Generic Description
"CARBON" 0.1 Blackening Agent
~aRDEN~R COMPON~NTS
Trade
Item Descrip~ion % By Weight Generic Description
6 "ARALDITE 1l,8 Liquid Hardener-
~Y 955" Modified liquid polyamid
a registered trade
mark of the Ciba-Geigy
Corporation. Ardsley, N.Y.
With reference to Tables 1 and 2, testing
various proportions and components has, unexpectedly,
shown that the proportions and components in the above-
mentioned tables offer the exact characteri.stics sought;
namely, resiliency, economy, durability and ease of use.
With reference to the admixture in Table l, a bonding
agent suitable for use as an adhesive bridge is thereby
provided having characteristics of resiliency and
sufficient v.iscosi-ty for coveri.ng the damat3c-~d area
is vertically i.nc~irleci. ~:Lth rc-f.ererlce t..o the
admixture in Table 2, a patching compound is
thereby provided having adhesive characteristics,
resiliency, and sufficient viscosity for covering the
damaged area of a concrete body without the
assistance of forms. The adhesive characteris-tics
of the bonding agent and the patching compound
provide for a generally uniform bonding interface between
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l the two.
With reference to the admixture in Table l, it has
been found that by incorporating nonyl phenol as a secondary
accelerator, that the resulting admixture has less of a
tendency to crystalize at low temperature, thereby enhancing
the resiliency of the bonding agent. Normally a mixture
of epoxy resin and hardener when first mixed together has
a low viscosity because of the exothermic reaction. Accordingly,
many coats of the epoxy-hardener mixture are required to
achieve sufficient coverage of the damaged area. Unexpectedly,
according to the present invention, the addition of binding
and thickening agents, preferably calcium carbonate and
caledria, provides for a bonding agent suitable for use
as an adhesive bridge having viscous characteristics suitable
for applying the bonding agent in a single coat of generally
uniform thickness. With reference to the patching compound
disclosed in Table 2, the same is epoxy based. Unexpectedly,
the epoxy based patching compound provides an admixture
which is easily applied -- once dry the combination in
the kit of the epoxy based patching compound and the epoxy
based bonding agent provides a patch which is extremely
durable and has a tendency not to breakdown with the expansion
and contraction of the concrete body according to changes
in the ambient temperature.
As many changes can be made to the preferred embodiments
without departing from the scope oE the invention, it is
intended that all matter contained herein be interpreted
as illustrative on the invention and not in a limiting
sense.
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