Note: Descriptions are shown in the official language in which they were submitted.
CA 02595444 2007-07-24
PAVING JOINT MORTARS
The present invention relates to paving joint mortars. More particularly, the
present
invention relates to polymer powders redispersible in water and their use in
paving jointing
mortars containing mineral binders.
Paving joint mortar is understood by one skilled in the art as joint mortar
commonly used
in the open air for jointing paving stones, natural stones and natural stone
slabs, concrete stone
slabs and concrete paving stones, mosaic flooring and mosaic paving, composite
stone, natural
stone paving, paving flag, large stone paving and small stone paving, cobble
stone paving, erratic
block paving, wooden paving and decking as well as cement clinker paving,
among others. Such
paving is used, for example, for pedestrian areas, roads, foot paths, cycling
paths, access ways,
gutters, and parking areas, as well as in garden architecture. The paving is
introduced
predominantly by garden designers and road builders by way of a so-called
"loose construction
method", which is the most commonly used and one of the oldest methods of
construction for
such surfacing. In this method, the stones to be laid are placed onto a loose
bed of chippings,
sand or granules and subsequently jointed. The joint width may range, for
example, from a few
millimeters to a few centimeters. This type of construction responds to static
or dynamic stresses
by elastic deformation. Thermal impact is eliminated by unhindered deformation
without
stresses occurring. The paving cover remains basically permeable to water. It
is generally
perceived as a disadvantage in that the jointing material can be washed out
from the joint or
sucked up, for example, by sweeping machines. As a consequence, the stones may
lose their
hold. In addition, weeds can grow in these joints in the case of sparse
traffic, something that is
often perceived as undesirable, particularly in the case of natural stone
surfaces.
Sand is the most commonly used jointing material, and can be introduced in
powder
form, for example, by means of a broom. It adapts without problem to the
movement of the
slabs and to the subgrade. An embodiment based on this is described in EP 1
484 295 Al,
wherein a small portion of fibrous substances is mixed with the sand. Still,
in this type of
construction the above mentioned disadvantages of the state of the art
persist.
In DE 44 21 970 Al a jointing material and its use for jointing natural stone
or synthetic
stone paving is described. The jointing material includes a mixture of quartz
sand with an
addition of silica dust and a liquid polymer binder. The binder is typically
composed of a
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mixture of polybutadiene, boiled linseed oil and isoparaffinic hydrocarbon
mixtures. This
mixture is swept with a broom as a soil-moist mass into the dry joints,
compacted with a
vibrating plate, and subsequently scraped off with a rubber scraper. This type
of jointing material
is consequently time-consuming to produce and apply. Moreover, such systems
can have low
strength levels.
DE 102 49 636 Al describes a similar approach. Here, functionalised polymer
powders
redispersible in water are mixed with jointing sand. The polymer powders self-
crosslink in
acidic or slightly alkaline medium, resulting in permanent compaction of the
joint filling
compound. Water permeability of the moulded body produced is improved by using
the
crosslinking polymer powder. The 636 publication does not describe how the
jointing sand and
the polymer powder are mixed and introduced into the joints. Strengths, such
as tensile strength
in bending and compressive strength, are not indicated. Conventional, non-
crosslinking polymer
powders cannot be used. Moreover, required conditions such as the pH-range
must be accurately
maintained in order to guarantee cross-linking.
In another approach, sand is mixed with approximately 20 to 40% by weight of
cement
and other additives, for example, cellulose fibers, in order to increase
durability and strength. As
a result, the paving joints become more durable and washable. Also, nothing
will grow in them.
As a result of the high rigidity of the joints, such joint filling materials
are suitable only for a
'bound' method of construction where paving stones are laid onto a rigid
subgrade such as a
concrete slab. This subgrade or support layer underneath the paving must be
produced in a
manner particularly resistant to deformation using appropriate materials and
requires accurate
planning. Still, stresses frequently occur, which may be due to changes in
temperature. This
frequently causes cracks and joints to loosen, resulting in the stones
becoming detached. For this
reason, two-component (2K) jointing mortars based on resin are very frequently
used for this
bound method of construction. These mortars do not respond in an elastic
manner to stress, but
rather in a rigid manner comparable to concrete surfaces. However, such
systems are expensive,
complicated to apply, and cannot be used for a non-bound method of
construction.
JP 2285103 describes the use of silica sand and rubber powder as aggregates, a
styrene
acrylate copolymer dispersion, and Portland cement as binders. The joint
filling material is first
sprayed and then the joints are filled with it. After filling, the surface
then has to be sprayed with
a cleaning agent and cleaned with a polishing machine. This jointing material
consists of two
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components and therefore needs to be thoroughly mixed by stirring, meaning
additional effort is
required. Moreover, the subsequent cleaning process is time consuming to
execute.
In order to produce a single component mortar that has been improved with a
polymer,
polyvinyl alcohol in powder form can be added to a paving joint dry mortar
with approximately
2 to 7% by weight of cement. The paving joint dry mortar scattered into the
joint is then wetted
with water from the outside. Although this is simple to handle, the water
cannot penetrate into
the deeper layers due to the polyvinyl alcohol swelling rapidly on contact
with water, resulting in
an uneven and unsatisfactory introduction of water into the mortar. Moreover,
polyvinyl alcohol
provides a greasy consistency and tends to easily form foam. During continued
contact with
water, polyvinyl alcohol is also washed out over time, which may result in
embrittlement of the
paving joint.
In one embodiment, the present invention provides a single component paving
jointing
dry mortar in powder form for the loose method of construction. The mortar is
simple to handle
and apply. The applied mortar exhibits an increased durability, certain
flexibility, as well as a
corresponding compressive and tensile strength in bending. Moreover, the
paving joint mortar
possesses good flank adhesion, that is, a good adhesion to the paving stone
that is resistant to
mechanical stresses such as those caused by sweeping machines, high pressure
cleaning
machines, and/or driving rain. It also provides for easy removal by washing of
contamination
from paving jointing mortar residues on the paving stones, thereby simplifying
subsequent
cleaning considerably.
In another embodiment the present invention provides paving joint mortars
having
polymer powders redispersible in water. The paving joint mortar can also
having one or more
mineral binders in an amount of about 0.5% by weight or more, based on the
desired paving
jointing dry mortar, as well as one or more additives and, optionally, further
components. The
paving joint mortar can be introduced into a joint in powder form and
subsequently watered, or it
can be mixed with water before introduction and added to the joint in paste
form.
In one aspect, paving joint mortars having the polymer powder redispersible in
water can
have one or more mineral binders in about 0.5 to about 30% by weight. In
another aspect, the
one or more mineral binders are present in an amount of about 1.0 to about 20%
by weight. In
even another aspect, the binders are present in an amount of about 1 to about
10% by weight. In
another aspect the binders are present in an amount of about 1 to about 5% by
weight. In one
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embodiment, the amount of additives in the paving joint mortars is about 30 to
about 99% by
weight. In another aspect, the amount of additives is about 50 to about 98% by
weight. In even
another aspect, the amount of additives is about 60 to about 95% by weight. In
a further aspect,
the amount of additives is about 70 to 90% by weight. In one embodiment, the
amount of
polymer powder redispersible in water present in the paving joint mortar is
about 0.5 to about
20% by weight. In another aspect, the amount of polymer powder is present in
an amount of
about 1.0 to about 15% by weight. In a further aspect, the amount of polymer
powder is present
in an amount of about 0.5 to about 10% by weight. In another aspect, the
amount of polymer
powder is present in an amount of about 2 to about 7% by weight. Other
optional components
can be present in the paving joint mortar in an amount of about 0 to about 25%
by weight. In
one aspect, other components are present in an amount of about 0 to about 20%
by weight, based
on the paving jointing dry mortar, respectively.
Suitable mineral binders include at least (a) hydraulically binding binders
such as cement,
(b) latent hydraulic binders such as acidic blast-furnace slag, pozzolans
and/or metakaolin,
and/or (c) non-hydraulic binders that react under the influence of air and
water, such as calcium
hydroxide and/or calcium oxide.
In one embodiment, cement such as Portland cement (e.g., according to EN 196
CEM I,
II, III, IV and V), calcium sulfate in the form of a-hemihydrate and/or 0-
hemihydrate and/or
anhydrite and/or alumina melt cement can be the hydraulically binding binder.
Pozzolans such
as metakaolin, calcium metasilicate and/or volcanic slag, volcanic tuff,
trass, fly ash, blast
furnace slag and/or silica dust can also be used as a latent hydraulic binder,
which, together with
a source of calcium such as calcium hydroxide and/or cement, reacts
hydraulically. Lime in the
form of calcium hydroxide and/or calcium oxide, for example, can be used as
non-hydraulic
binder reacting under the influence of air and water. In one embodiment, the
systems are based
on Portland cement or a mixture of Portland cement, alumina melt cement and
calcium sulfate,
where latent hydraulic and/or non-hydraulic binder can optionally be added to
either system.
Examples of suitable additives (sometimes also referred to as fillers) include
quartzitic
and/or carbonaceous sands and/or meals such as quartz sand and/or ground
limestone,
carbonates, silicates, chalk, layer silicates and/or precipitated silicic
acids. In addition, light
weight fillers such as hollow microspheres of glass, polymers such as
polystyrene spheres,
aluminosilicates, silicon oxide, aluminium silicon oxide, calcium silicate
hydrate, aluminium
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silicate, magnesium silicate, aluminium silicate hydrate, calcium aluminium
silicate, calcium
silicate hydrate, silicon dioxide andlor aluminium iron magnesium silicate but
also clays such as
bentonite can be used. It is also possible for the fillers and/or light weight
fillers to possess a
natural or artificially produced color.
Polymer powders redispersible in water according to the invention can contain
at least
one polymer based on vinyl acetate, ethylene vinyl acetate, ethylene vinyl
acetate vinyl versatate,
ethylene vinyl acetate vinyl chloride, ethylene vinyl chloride, vinyl acetate
vinyl versatate,
(meth)acrylate, ethylene vinyl acetate (meth)acrylate, vinyl acetate vinyl
versatate
(meth)acrylate, vinyl acetate maleic acid and vinyl acetate maleic acid ester,
vinyl acetate vinyl
versatate maleic acid and vinyl acetate vinyl versatate maleic acid ester,
vinyl acetate
(meth)acrylate maleic acid and vinyl acetate (meth)acrylate maleic acid ester,
styrene acrylate
andlor styrene butadiene, wherein vinyl versatate is a C4- to C12- vinyl
ester. The polymer
powders can also contain about 0 to about 50% by weight of additional monomers
such as
monomers with functional groups. In another aspect, the polymers can contain
about 0 to about
30% by weight of additional monomers. In even another aspect, the polymers can
contain about
0 to about 10% by weight of additional monomers.
Polymer powders redispersible in water according to the invention can be based
on one or
several polymers. These polymers can be produced, for example, by emulsion
polymerisation,
suspension polymerisation, microemulsion polymerisation and/or inverse
emulsion
polymerisation. If necessary, the polymers can also exhibit a heterogeneous
morphology
obtained by selecting the monomer and the production process. Subsequent
drying takes place,
for example, by spray drying, freeze drying, fluid bed drying, roller drying
and/or rapid drying.
In one embodiment the polymer powders are produced by emulsion polymerisation
and spray
drying.
Examples of suitable classes of monomers for producing these polymers include
linear or
branched CI- to C20- vinyl ester, ethylene, propylene, vinyl chloride,
(meth)acrylic acid and their
linear or branched Cl- to C20- alkyl esters, (meth)acrylamide and
(meth)acrylamide with N-
substituted linear or branched C1- to C20- alkyl groups, acrylonitrile,
styrene, styrene derivatives
andlor dienes such as 1,3-butadiene. In one embodiment, the vinyl esters are
linear or branched
Cl- to C12- vinyl esters such as vinyl acetate, vinyl stearate, vinyl formate,
vinyl propionate,
vinyl butyrate, vinyl pivalate, vinyl laurate, vinyl-2-ethyl hexanoate, 1-
methyl vinyl acetate
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and/or C9-, Cto- and/or Clt- vinyl versatate, vinyl pyrrolidone, N-vinyl
formamide, N-vinyl
acetamide, as well as vinyl esters of benzoic acid and p-tert.-butyl benzoic
acid. In another
embodiment, the vinyl esters are vinyl acetate, vinyl laurate and/or vinyl
versatate. Examples of
Cl- to C12- alkyl groups of (meth)acrylic acid esters and N-substituted
(meth)acrylamides include
methyl groups, ethyl groups, propyl groups, n-butyl groups, i-butyl groups,
tert.-butyl groups,
hexyl groups, cyclohexyl groups, 2-ethyl hexyl groups, lauryl groups, stearyl
groups, norbornyl
groups, polyalkylene oxide groups and/or polyalkylene glycol groups. In one
embodiment, the
alkyl groups are methyl groups, butyl groups, and/or 2-ethyl hexyl groups. In
another
embodiment, the alkyl groups are methyl methacrylate, n-butyl acrylate, tert.-
butyl methacrylate
and/or 2-ethyl hexyl methacrylate.
Additional monomers such as monomers with functional groups can be
incorporated by
polymerization. For example, it is possible to copolymerize maleic anhydride,
unsaturated
dicarboxylic acids and their branched or linear Cl- to C20- esters, such as
itaconic acid, maleic
acid and/or fumaric acid as well as their esters, multiply ethylenically
unsaturated copolymers
such as e.g. divinyl adipate, diallyl maleate, allyl methacrylate or triallyl
cyanurate, divinyl
benzene, butane diol-1,4-dimethacrylate, triethylene glycol dimethacrylate,
hexane diol
diacrylate, functional vinyl monomers and/or (meth)acrylate monomers
containing alcoxy silane
groups, glycidyl groups, epihalohydrin groups, carboxyl groups, amine groups,
hydroxyl groups,
ammonium groups and/or sulfonic acid groups. In one aspect the functional
monomers can be
hydroxyl propyl (meth)acrylate, N-methylol allyl carbamate, methyl
acrylamidoglycolic acid
methyl ester, N-methylol (meth)acrylamide, vinyl sulfonic acid, acrylamido
glycolic acid,
glycidyl (meth)acrylate, 2-acrylamido-2-methyl propane sulfonic acid,
(meth)acryloxypropyl
tri(alkoxy)silane, vinyl trialkoxysilane, vinyl methyl dialkoxysilanes;
methoxy groups, ethoxy
groups and/or iso-propoxy groups being used as alkoxy groups; acetyl
acetoxyethyl
(meth)acrylate, diacetone acrylamide, acrylamido glycolic acid, methyl
acrylamido glycolic acid
methyl ester, alkyl ether, N-methylol (meth)acrylamide, N-methylol allyl
carbamate, esters of N-
methylol (meth)acrylamide and of N-methylol allyl carbamate, N-[3-(dimethyl
amino)propyl]methacrylamide, N-[3-(dimethyl amino)ethyl]meth-acrylamide, N-[3-
(trimethyl
ammonium) propyl]methacrylamide chloride and/or N,N-[3-chloro-2-hydroxypropyl)-
3-
dimethyl ammonium propyl](meth)acrylamide chloride. In one aspect the
proportion of these
comonomers is approximately 0 to 30% by weight. In another aspect, it is
approximately 0 to
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20% by weight. In even another aspect it is approximately 0.1 to 10% by
weight, based on the
total proportion of monomer. Care should be taken to ensure that the
proportion of free carboxyl
groups is not higher than approximately 10% by weight; in another aspect not
higher than
approximately 5% by weight; and in even another aspect not higher than
approximately 3% by
weight.
Choice of initiator system used for polymerisation is not restricted. Thus,
all known
initiator systems can be used.
In one embodiment the glass transition temperature ("Tg") of the emulsion
polymer is
within approximately -60 C to 80 C. In another embodiment the temperature is
approximately
-30 C to 50 C. In even another embodiment the temperature is approximately -20
C to 40 C.
The glass transition temperature Tg of the copolymers produced and
consequently the
emulsion polymers can be calculated empirically as well as determined by
experiments from the
monomers used. Using the Fox equation (T.G. Fox, Bull. Am. Phy. Soc. (serli)
1, p. 123 (1956)
and ULLMANNS ENZYKLOPADIE DER TECHNISCHEN CHEMIE, Vol. 19, 4th Ed., Verlag
Chemie,
Weinheim, 1980, pp. 17-18), they can be calculated empirically: 1/Tg = XA /
TgA + xB / TgB +...
+ xõ / Tg,,, with XA , xB ... the mass fractures of the monomers A, B, ...
used (in % by weight)
and TgA, TgB ... the glass transition temperatures Tg in Kelvin of the
homopolymers of A, B, ...
concerned. These are listed in, for example, ULLMANNS ENZYKLOPADIE DER
TECHNISCHEN
CHEMIE, VCH, Weinheim, Vol. A21 (1992), p. 169. Another possibility for
determining the
glass transition temperatures Tg of the copolymers is experimental
determination, for example,
by DSC, the average temperature being used (midpoint temperature according to
ASTM D3418-
82).
Emulsion, suspension, microemulsion and/or inverse emulsion polymers produced
can be
stabilised with one or more higher molecular compounds, such as one or more
protective
colloids. The quantity of stabilizing systems used is approximately 1 to 30%
by weight. In
another aspect the amount used is approximately 3 to 15% by weight, based on
the proportion of
monomer used.
Typical water-soluble organic polymeric protective colloids include higher
molecular
compounds. These include natural compounds such as polysaccharides, including
chemically
modified ones, synthetic higher molecular oligomers and polymers having no or
only a slight
ionic character, and/or polymers produced with monomers having an at least
partially anionic
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CA 02595444 2007-07-24
character and, e.g., by radical polymerisation in situ in the aqueous medium.
It is also possible
for only one stabilising system to be used or for different stabilising
systems to be combined.
Useful polysaccharides and their derivatives include polysaccharides and
polysaccharide
ethers soluble in cold water such as cellulose ether, starch ether (amylose
and/or amylopectin
and/or their derivatives), guar ether and/or dextrins. It is also possible to
use synthetic
polysaccharides such as anionic, non-ionic or cationic heteropolysaccharides
such as xanthan
gum or wellan gum. The polysaccharides can, but need not, be chemically
modified, e.g., with
carboxymethyl groups, carboxyethyl groups, hydroxyethyl groups, hydroxypropyl
groups,
methyl groups, ethyl groups, propyl groups and/or long-chain alkyl groups.
Further natural
stabilising systems consist of alginates, peptides and/or proteins such as
gelatin, casein and/or
soy protein. Examples include dextrins, starch, starch ether, casein, soy
protein, hydroxyl alkyl
cellulose and/or alkyl hydroxyalkyl cellulose.
Synthetic stabilising systems include one or several polyvinyl pyrrolidones
and/or
polyvinyl acetals having molecular weights of approximately 2000 to 400,000;
fully or partially
saponified and/or modified fully or partially saponified polyvinyl alcohols
with a degree of
hydrolysis of approximately 70 to 100 mole %, or in another aspect
approximately 80 to 98 mole
%, and a viscosity according to Hoppler in a 4% aqueous solution of about 1 to
50 mPas, or in
another aspect approximately 3 to 40 mPas (measured according to DIN 53015 at
20 C); as well
as melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates,
block copolymers
of propylene oxide and ethylene oxide, styrene-maleic acid copolymers andlor
vinyl ether-maleic
acid copolymers. Higher molecular oligomers may include non-ionic, anionic,
cationic and/or
amphoteric emulsifiers such as alkyl sulfonates, alkyl aryl sulfonates, alkyl
sulfates, sulfates of
hydroxyl alkanols, alkyl disulfonates and alkyl aryl disulfonates, sulfonic
fatty acids, sulfates and
phosphates of polyethoxylated alkanols and alkyl phenols, as well as esters of
sulfosuccinic acid,
quatemary alkyl ammonium salts, quaternary alkyl phosphonium salts,
polyaddition products
such as polyalkoxylates, e.g., adducts of 5 to 50 mole ethylene oxide and/or
propylene oxide per
mole of linear and/or branched C6- to C22- alkanols, alkyl phenols, higher
fatty acids, higher fatty
acid amines, primary and/or secondary higher alkyl amines. The alkyl group can
be a linear
and/or branched C6- to C22- alkyl group in each case. Synthetic stabilising
systems include
partially saponified and/or modified polyvinyl alcohols, it being possible for
one or several
polyvinyl alcohols to be used together, if necessary with small quantities of
suitable emulsifiers.
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Synthetic stabilising systems further include modified and/or non-modified
polyvinyl alcohols
with a degree of hydrolysis of 80 to 98 mole % and a viscosity according to
Hoppler as 4%
aqueous solution of I to 50 mPas and/or polyvinyl pyrrolidone.
According to a specific embodiment, an ionic polymer obtained by radical
(co)polymerisation of olefinic monomers in water wherein at least part of the
olefinic monomers
containing an ionic group is used as the stabilising system. Such systems are
typically obtained
in situ, it being possible for (meth)acrylic acid, monomers with sulfonic acid
groups and/or
cationic monomers, for example, to be used as monomers with an ionic group,
such as described
in EP-A 1098916 and EP-A 1109838.
Moreover, polymers containing carboxyl group based on monocarboxylic and/or
dicarboxylic acids or their anhydrides, for example, polyacrylic acids, can be
used as stabilising
systems. However, care should be taken to ensure that the quantity of such a
stabilising system
and/or the quantity of polymer powder re-dispersible in water used is not
chosen too large so as
not to influence the hydration of the mineral binders and its processing in an
excessively
negative manner.
A film forming aid and/or a coalescing agent can also be added to the polymer
powders
redispersible in water. The amount can be approximately 0 to 5% by weight, or
in another
aspect, approximately 0 to 2% by weight, based on the copolymer content.
Polymer powders redispersible in water include those with a low proportion of
organic
volatile components (VOC), such as those possessing a boiling point of less
than 250 C at
normal pressure. These include, for example, non-reacted monomers and non-
polymerisable
contaminants contained in the monomers and by-products of the polymerisation.
VOC content
of the polymer powders redispersible in water amounts to less than
approximately 5000 ppm, in
another aspect less than 2000 ppm, in even another aspect less than 1000 ppm,
and in another
aspect less than approximately 500 ppm, based on polymer content.
Other components such as additives can be added to the polymer powders
redispersible in
water, with their addition occurring before, during and/or after drying. The
types of these
components used are numerous. Liquid components can be added before or during
drying, but
can also be sprayed onto the powder subsequently. Components in powder form
can be added
during or after spray drying, but can also be added during dispersion mixing
before the drying
step.
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One embodiment includes the addition of at least one further organic component
with
functional groups. This can be part of the polymer powder re-dispersible in
water and/or can be
mixed with the paving joint dry mortar as a separate component. If this
component is liquid, it
can be added to the polymer powder redispersible in water during its
production or transformed
into powder form. When used in powder form, it can be mixed with the polymer
powder
redispersible in water and/or the paving jointing dry mortar. Useful organic
components with
functional groups react in an alkaline medium either with itself andlor other
compounds.
Examples of such compounds include crosslinking agents such as epoxides, epoxy
resins,
oligoamines and/or polyamines, bifunctional masked aldehydes with at least 3
carbon atoms,
silanes, siloxanes, isocyanates which can be used together with hydroxy
compounds such as
polyols, if necessary, boric acid and/or borax and/or compounds with
carbodiimide groups,
carboxyl groups and/or epichlorohydrin groups.
Functional groups of these organic components and of the (co-)polymerisable
monomers
with functional groups include silane groups such as alkoxy silane groups,
glycidyl groups,
epihalohydrin groups, N-methylol groups, carboxyl groups, amine groups,
hydroxyl groups,
ammonium groups, ketone groups, acid anhydride groups, acetoacetonate groups,
sulfonic acid
groups, amide groups, amidine groups, imine groups, ester groups, carboxyl
groups, carbonyl
groups, aldehyde groups, sulfate groups, sulfonate groups and/or thiol groups.
In one aspect the
functional groups are silane groups, epoxy groups, epihalohydrin groups and/or
amine groups.
The paving joint mortar can also contain further components in typical
quantities. It is
advantageous if they are present in powder form. If they are by nature liquid,
they can be
adsorbed onto a matrix or embedded in a matrix in order to be able to handle
them in powder
form. There are no essential limitations regarding the type of these further
components. Non-
limiting examples of such further components are colour pigments, cellulose
fibers, water-
soluble polymers, in particular fully or partially saponified and, if
necessary, modified polyvinyl
alcohols, polyvinyl pyrrolidones, polyalkylene oxides and polyalkylene
glycols, the alkylene
group typically being a C2- and/or C3- group, which includes also block
copolymers, thickening
agents, water retention agents, alkyl hydroxyalkyl ethers and/or alkyl
hydroxyalkyl
polysaccharide ethers such as such as cellulose ether, starch ether and/or
guar ether, the alkyl
group and hydroxyalkyl group typically being a Cl- to C4- group, synthetic
polysaccharides such
as anionic, non-ionic or cationic heteropolysaccharides, in particular xanthan
gum or wellan
CA 02595444 2007-07-24
gum, wetting agents, dispersing agents, cement liquefiers, polycarboxylates,
polycarboxylate
ethers, polyacrylamides, hydrophobing agents such as silanes, silane esters,
siloxanes, silicones,
fatty acids and/or fatty acid esters, air pocket formers, rubber powders,
biocides, herbicides,
fungicides, defoaming agents, fragrances for keeping animals away, additives
for reducing
sedimentation, segregation and/or efflorescence such as compounds based on
natural resins, in
particular rosin and/or its derivatives, setting and solidification
accelerators, setting retarders
and/or powders which have an alkaline reaction with, water such as oxides
and/or hydroxides of
alkali salts and/or alkaline earth salts such as calcium hydroxide, calcium
oxide, sodium
hydroxide and/or potassium hydroxide and/or aluminium hydroxide.
In principle, all organosilicone compounds can be used as silanes, silane
esters, silicones
andlor siloxanes. However, it is advantageous, though not compelling for the
boiling point of the
organosilicon compound used not to be too low at normal pressure, for example,
approximately
100 C and more. The organosilicon compounds may be soluble, insoluble or only
partially
soluble in water. Useful compounds can have no or only limited solubility in
water. These may
consist of silicic acid esters with the formula Si(OR')4, organoxysilanes with
the formula
Si(OR')4_õ where n = 1 to 3, polysilanes with the formula R3Si(SiR2)õSiR3
where n= 0 to 500 or
in another aspect n = 0 to 8, disiloxanes, oligosiloxanes and polysiloxanes of
units with the
general formula R HaSi(OR')e)OH)f0(4-c-d-e-fln where c = 0 to 3, d = 0 to 2, e
= 0 to 3, f = 0 to 3
and the sum of c+d+e+f is a maximum of 3.5 per unit, R' representing identical
or different alkyl
radicals or alkoxy alkylene radicals with 1 to 4 C-atoms (e.g., methyl or
ethyl) and R being
identical or different and representing branched or non-branched alkyl
radicals with 1 to 22 C-
atoms, cycloalkyl radicals with 3 to 10 C-atoms, alkylene radicals with 2 to 4
C-atoms, aryl
radicals, aralkyl radicals, alkyl aryl radicals with 6 to 18 C-atoms. The
above mentioned radical
R can be substituted with halogens such as F or Cl, with ether groups,
thioether groups, ester
groups, amide groups, nitrile groups, hydroxyl groups, amine groups, carboxyl
groups, sulfonic
acid groups, carboxylic anhydride groups and carbonyl groups. R can also have
the meaning
OR' in the case of polysilanes.
Further components also include polysaccharide ethers such as cellulose ether
and/or
starch ether, hydrophobing agents such as silanes, silane esters, fatty acids
and/or fatty acid
esters, agents for reducing efflorescence, for example, those based on natural
resins, cellulose
fibres, defoaming agents andlor pigments.
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The proportion of these additional components may be very small, for example,
for
surface-active substances, based on the paving jointing dry mortar, and be
within the region of
approximately 0.01% by weight or more, in another aspect approximately 0.1% by
weight and
more, but should not typically exceed approximately 2% by weight, in another
aspect
approximately 1% by weight. On the other hand, the proportion of mixed
pigments can be
higher, but should be not more than approximately 25% by weight, in another
aspect not more
than approximately 20% by weight, and in even another aspect not more than
approximately
15% by weight. The proportion of hydrophobing agents is approximately 0.05 to
approximately
3% by weight, in another aspect approximately 0.1 to approximately 2% by
weight and in even
another aspect approximately 0.2 to approximately 1% by weight. The content of
the other
components is between approximately 1% by weight and approximately 15% by
weight, in
another aspect between approximately 2 and approximately 10% by weight, based
on the paving
joint dry mortar.
As a rule, it is beneficial for the user if the paving jointing mortar is
scattered as paving
jointing dry mortar into the empty joints or swept into them with a broom, and
water then
subsequently added, for example, over the surface. Such addition of water over
the surface
without subsequent mixing of the mortar is sufficient to both re-disperse the
polymer powder re-
dispersible in water in this compact environment and distribute it in the
matrix. On setting and
drying of the paving jointing mortar, a water-insoluble film is then formed.
This thus increases
the cohesion of the set paving joint mortar.
When introducing water over the surface, suitable methods include those in
which the
paving jointing dry mortar scattered or swept in is not damaged. For example,
this can be
accomplished with a gentle introduction of water in the form of a spray mist
and/or surface
watering. The method of water introduction is not restricted in any way as
long as it does not
damage the paving jointing mortar introduced. This can be achieved with a lawn
sprinkler, a
water sprinkler, a garden hose with or without distributor nozzle and/or a
watering can. It is
advantageous to set the duration of watering such that the water penetrates
through the entire
paving jointing dry mortar, providing the mortar with sufficient water for
hydration down to the
subgrade. If too much water is added, the excess seeps into the subgrade,
usually without
negative consequences. If insufficient water is added, only the upper part of
the paving jointing
mortar is hydrated. During later watering, either artificially or by rain or
dew, further water can
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then diffuse through the mortar set at the surface and penetrate into deeper
layers. However, it is
also possible for the water to pass into the paving jointing dry mortar
through the subgrade, thus
causing hydration.
According to a further embodiment, the paving jointing dry mortar is first
stirred with
water and introduced into the joints as stirred mortar. In the case of this
variation, however, it is
helpful to adjust the quantity of water in such a way that the stirred mortar
receives an easily
processable consistency in order to be introduced into the joints without
running off.
Paving jointing mortar containing the polymer powder re-dispersible in water
that can be
used according to the invention typically exhibits a high level of
wettability. The polymer
powder re-dispersible in water re-disperses without additional shearing forces
and mixing
processes and subsequently forms a water-insoluble film. Thus, polymer powders
re-dispersible
in water results in none or only minor disadvantages vis-a-vis emulsifier-
stabilised dispersions
with the physical values of the set paving jointing mortar, even though these
systems have
previously been thoroughly mixed in order to guarantee a corresponding
homogeneity of the
mortar. Nevertheless, the end properties of the paving jointing mortar are
entirely comparable in
spite of a much simpler introduction and processing.
The invention will be explained in further detail by way of the following
examples.
Example 1- Production and watering by spray mist of paving joint dry mortar
introduced by
scattering
Mortar prisms were produced in order to investigate the introduction by
scattering and
watering of joints under conditions which are as clearly defined as possible.
From this it was
possible to subsequently determine physical values such as the tensile
strength in bending and
the compressive strength.
A paving joint dry mortar was prepared by mixing homogenously in an agitator
5% by
weight of Portland cement CEM 142.5 N, 87% by weight of quartz sand with a
sieve line of
0.063 to 1.5 mm, 3% by weight of a calcium carbonate (Durcal 10) and 5% by
weight of a
polymer powder redispersible in water. A comparative example was carried out
using in place of
the polymer powder a partially saponified polyvinyl alcohol with a degree of
hydrolysis of 88
mole % and a viscosity of 4mPas (according to Hoppler as 4% aqueous solution,
measured
according to DIN 53015 at 20 C) (in the following tables referred to as
"PVOH"). Another
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comparative example was carried out entirely without polymer powder, the
omitted polymer
quantity being replaced by quartz sand.
500g of the dry mortar produced were then scattered into a 4cm x 4cm x 16cm
metal
prism mould, the inside wall of the prism mould having been painted with mould
oil as release
agent using a painter's brush. The dry formulation was compacted by manually
shaking and
tapping for 10 seconds. The surface of the dry mortar scattered in was
smoothed off with a
trowel.
A spray bottle typically used for spraying plants was used for watering. The
water cone
formed during spraying was adjusted so that the water was sprayed selectively
onto the mortar
surface from a distance of 10cm. The spray duration was 5 to 10 minutes,
depending on how
well the surface was wetted and the water was able to penetrate inside. The
necessary quantity of
water was determined by way of a separate test wherein the surface was damaged
periodically
using a fine spatula and the depth of water penetration assessed optically
until the water had
reached the lowermost layer of the paving jointing mortar.
During watering the following assessments were carried out: (a) wetting of the
surface
(i.e., how well the water is absorbed by the joint during the entire watering
process), (b) water
saturation (i.e., how much water can be sprayed continually onto the prism
until water floats on
the surface), (c) bubble formation (i.e., whether bubbles rise to the surface
during or immediately
after spraying on of the water, which may have a negative influence of the
surface properties),
and (d) cleaning after contamination (i.e., how simply the prism mould could
be cleaned after
releasing the prisms). These assessments provide a good indication regarding
the behavior of the
watered paving joint mortar on the surface of the paving stones.
18 hours after completion of the introduction of water, the prisms were
released and
stored at 23 C and a relative atmospheric humidity of 50% (standard climate).
Table 1
Table 1 indicates the quantities of water sprayed onto the different paving
jointing
mortars containing the polymer powders re-dispersible in water EVA-1, EVA-2
and St/Ac and
the comparative samples PVOH and without polymer powder and assessment of the
different
paving stone joints during watering a).
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EVA-1 EVA-2 St/Ac PVOH Without
Quantity of water 9 9 9 12 9
(% by wei t
Water saturation (% 7 7 5 6 None
by weight)
Wetting of surface Excellent Excellent Average Excellent Excellent
Spray duration 5 5 10 8 5
(min)
Bubble formation None None None Strong None
Cleaning after Excellent Excellent Excellent Smeared Excellent
contamination b)
a) The polymer powders re-dispersible in water EVA-1, EVA-2 and St/Ac consist
of different spray-dried dispersions stabilised with polyvinyl alcohol based
on
ethylene-vinyl acetate (EVA-1 and EVA-2) copolymers and styrene-acrylate
copolymers (St/Ac).
b) "Excellent" means that cleaning caused no problems whatsoever and the
residues were easily removed by washing. "Smeared" means that the residual
layer could be removed only after intensive cleaning.
c) PVOH represents partially hydrolysed polyvinyl alcohol.
d) P.P. represents "polymer powder".
Table 2
Table 2 illustrates the results of repeated watering of the paving joint
mortar in the prism
mould at intervals of one hour. Four prisms were produced per composition, one
being put aside
after each watering cycle for removal from the mould after 18 hours and
assessed. The
percentage indicated below provides details of the proportion of prisms which
formed a compact
unit and did not disintegrate. Moreover, the surface of the last prism was
assessed after a storage
period of 4 days for its surface hardness and surface hydrophobicity.
Quantity of EVA-1 St/Ac PVOH c) Without P.P. water d)
1 Watering 3 60% 60% 20% 95%
2 Watering 6 95% 70% 70% 100%
3 Watering 9 100% 100% 75% 100%
4 Watering 12 100% 100% 90% 100% 7d
CA 02595444 2007-07-24
Surface hardness e Hard Average Hard Soft
Surface h dro icity 5 min 30 sec 30 sec 0 sec
d) Indicated in % by weight.
e) The surface hardness was assessed by scratching with a pointed metal rod.
f) To assess the surface hydrophobicity, 1 ml of water was placed drop-wise
onto
the surface using a pipette and the time was measured by which all the water
had
been absorbed by the subgrade.
Tables 1 and 2 show, among other things, that paving joint mortar containing
partially
hydrolysed polyvinyl alcohol exhibits the greatest water requirement. In
contrast to paving
jointing mortars prepared without polymer powder or with polymer powders
redispersible in
water (EVA-1, EVA-2 and St/Ac), the paving joint mortar with PVOH absorbs a
relatively large
amount of water at its surface, preventing the water from reaching the
underlying layers. Thus,
the mineral binder does not set and the organic binder does not form a film,
resulting in a lack of
strength of these layers.
Even if wetting of the dry mortar is excellent, the unset paving jointing
mortar may
exhibit a moderate hydrophobicity as shown by the example of EVA-1. This
contributes to less
dirt penetrating into the joints and being washed away, particularly in the
case of an inclination
and/or fairly strong rain.
Table 3
Tensile strengths in N/mm2 determined at different storage periods by bending
of the
mortar prisms obtained, in line with EN13892-2.
Storage time in a EVA-1 EVA-2 St/Ac PVOH Without P.P. standard climate
1 day 0.07 0.06 0.04 0.22 0.18
3 days 0.56 0.43 0.51 0.97 0.35
7 days 1.67 0.99 1.50 1.80 0.50
14 days 2.07 1.05 1.69 - g 0.45
28 days 2,19 0.99 1.57 - g 0.40
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Table 4
Compressive strength in N/mm2 determined after different storage periods by
bending of
the mortar prisms obtained, in line with EN13892-2.
Storage time in a standard EVA-1 EVA-2 St/Ac PVOH Without p.p.
climate
1 day 0.20 0.16 0.17 0.16 0.26
3 days 1.24 0.94 1.00 1.28 0.75
7 days 5.52 2.37 3.18 2.99 1.02
14 days 6.15 2.63 3.21 - g) 0.93
28 days 5,41 2.44 2.98 - g) 0.77
g) No values available.
Tensile strength and compressive strength are excellent measures for assessing
cohesion
of the watered paving jointing mortar. The values given in Tables 3 and 4
clearly show the
additional cohesion achieved by adding polymer powder redispersible in water
versus those
containing only mineral binder (indicated by "without polymer powder"). These
high values are
highly surprising since the dry mortar was merely watered without mixing the
mortar. Mixing
enhances the redispersion of the polymer powder redispersible in water,
guaranteeing good
distribution of the redispersion achieved. The cohesion achieved is sufficient
to prevent damage,
for example, in the case of impact or expert cleaning with sweeping machines
or high pressure
cleaners. The corresponding early strength values additionally provide the
paving jointing mortar
applied with sufficient protection against driving rain and hail. The polymer
powder
redispersible in water used provides the paving joint mortar also with a good
flank adhesion such
that the joint does not detach itself from the paving stone. The low
proportion of mineral binder
guarantees the required flexibility needed to survive deformations of the
subgrade without
cracking. As a result of the controlled optimisation of the types and
quantities of hydraulically
binding binder used and of the polymer powder redispersible in water, it is,
moreover, possible to
correspondingly optimize flexibility, tensile strength and compressive
strength, as well as tensile
bond strength in line with users' requirements without having to change
processing.
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Example 2- Stirring of paving stone joint mortar with water before application
The paving joint dry mortar produced according to Example 1 is stirred with
water for
one minute using a propeller stirrer at 900 rpm, the amount of water adjusted
for consistency.
During this process, care was taken in mixing that the resulting mortar was
not too thin but also
not too highly viscous, and could be introduced into a prism box as described
in Example 1 by
simply using a trowel. Prior to addition to the box, the mixed paving joint
mortar was allowed to
mature for 3 minutes and was then stirred once more for 15 seconds. Following
the introduction
of the mortar, the surface of the mortar was smoothed off with a trowel. The
storage conditions
were handled in a manner analogous to Example 1.
Quantities of water used for adjusting the consistency of the different
samples of EVA-1,
St/Ac and the comparative sample without polymer powder and tensile strength
in bending and
compressive strengths after different storage periods, in N/mm2, in line with
EN13892-2 are
illustrated in Table 5 below.
Table 5
Storage time in a Tensile strength in bending Compressive strength
standard climate /mm2 (N/mm2
EVA-1 St/Ac Without EVA-1 St/Ac Without
d) d)
Quantity of water (% 9.5 9.5 15 9.5 9.5 15
by weight)
1 day 0.26 0.30 0.04 0.35 0.49 0.32
3 days 2.13 2.39 0.30 4.11 4.75 0.54
7 days 3.77 3.58 0.10 9.23 7.36 0.74
Table 5 illustrates that by mixing the paving joint dry mortar with water
prior to
introduction into the joints, the physical values obtained are slightly higher
than by introduction
of water over the surface according to Example 1. Consequently, by using
paving joint dry
mortar according to the present invention, the user has the choice of choosing
either an extremely
simple and convenient type of application involving dry introduction with
subsequent surface
watering, or by externally mixing the paving joint dry mortar with water and
subsequent
introduction to obtain even higher physical strength values.
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Although the present invention has been described and illustrated in detail,
it is to be
understood that the same is by way of illustration and example only, and is
not to be taken as a
limitation. The spirit and scope of the present invention are to be limited
only by the terms of
any claims presented hereafter.
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