DISPERSIONS AND THE USE THEREOF IN CONCRETE MIXTURES

DISPERSIONS ET LEUR UTILISATION DANS DES MELANGES DE BETON

English Abstract

An aqueous dispersion containing a latex, an alkaline earth metal formiate,
cellulose ether and lauryl sulphonate can be added to a
concrete mixture as an auxiliary agent to make the concrete more flexible and
reduce shrinkage during setting. Adding the dispersion to
concrete mixtures allows also addition of fillers hitherto regarded as toxic
to cement.

French Abstract

Une dispersion aqueuse contenant un latex, un formiate de métaux alcalino-terreux, de l'éther cellulosique et du sulfonate de lauryle, peut être ajoutée à un mélange de béton sous forme d'auxiliaire pour rendre le béton plus souple et réduire le retrait pendant le durcissement. Cette adjonction permet également d'utiliser dans le mélange de béton des matières de charge qui jusqu'alors étaient considérés comme toxiques pour le ciment.

Claims

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WHAT IS CLAIMED IS:
1. An aqueous dispersion comprising:
- 83.0-96.0 wt-% (percent by weight), based on the total weight of
the dispersion, water;
- 1.0-6.0 wt-% based on the total weight of the dispersion, of a 30-70
wt-% aqueous, synthetic latex;
- 1.0-7.2 wt-%, based on the total weight of the dispersion, of an
alkaline earth metal formate; and,
- 0.02-0.12 wt-%, based on the total weight of the dispersion, lauryl-
sulfonate;
whereby the weight of all components of the dispersion totals 100 wt-%.
2. The aqueous solution of claim 1, further comprising:
- 0.2-1.2 wt-%, based on the total weight of the dispersion, of a
cellulose ether.
3. The aqueous solution of claim 1, further comprising:
- 0.6-1.2 wt-%, based on the total weight of the dispersion, of a
preservative agent.
4. The aqueous solution of claim 1, further comprising:
- 0.25-0.6 wt-% based on the total weight of the dispersion, of a
foam separator.
5. The aqueous solution of claim 1, further comprising:
- 0.2-1.0 wt-%, based on the total weight of the dispersion, of a 50-
60 wt-%, aqueous paraffin emulsion.

6. The aqueous dispersion according to claim 1, comprising:
- 85.0-90.0 wt-% of water;
- 2.0-5.0 wt-% of 30-70 wt-% aqueous, synthetic latex;
- 2.0-6.0 wt-%, of metal formate;
- 0.3-1.0 wt-%, of cellulose ether;
- 0.03-0.08 wt-% of lauryl-sulfonate;
- 0.8-1.0 wt-%, of said preservative agent;
- 0.3-0.5 wt-% of foam separator; and,
- 0.5-0.8 wt-% of an aqueous paraffin emulsion
whereby the weight of all components of the dispersion totals 100 wt-%.
7. The aqueous dispersion according to claim 1, wherein a polystyrene-
butadiene latex is used as said synthetic latex and as preservative agents 2-n-
octyl-4-isothiazole-3-one dissolved in propyl glycol are used.
8. A concrete mixture comprising:
- 0.01-0.5 liter per kg cement of a dispersion according to any one of
claims 1 to 7;
- cement;
- a filling agent; and
- water.

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9. The concrete mixture according to claim 8, wherein the filling agent is at
at least one of non-contaminated soil, contaminated soil, bauxite, laterite,
and
ash.
10. The concrete mixture according to claim 8, wherein at least a portion of
the required content of water is in the filling agent.
11. A concrete mixture according to any one of claims 8 to 10, containing:
- 0.05-0.151iter per kg cement of said dispersion.
12. Use of a concrete mixture according to any one of c!aims 8 to 11, for the
production of a building material.
13. Use according to claim 12, wherein said building material is selected from
the group consisting of stones and slabs.
14. Use of a concrete mixture according to any one of claims 8 to 11, for the
construction of street, road or fastening construction.
15. The concrete mixture of claim 9, wherein said ash is vulcanized ash.
16. The concrete mixture of claim 9, wherein said ash is combustion ash.
17. A procedure for the production of concrete building material and
components of a!l kinds, wherein excavated earth and/or filling agents, which
are available at the building site are used as a filling agent for the
production of
the concrete mixture according to any one of claims 8 to 11.

Description

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Title: Dispersions and the use thereof in concrete mixtures
The invention relates to aqueous dispersions, with which the concrete can be
made more
flexible and with which the shrinkage of the concrete mixture can be reduced
during setting
and with which it is possible to use filling agents in the concrete mixtures
hitherto regarded as
toxic to cement.
In the course of growing industrialization in most countries of the world and
the continuously
rising desire for mobility of the human beings, the street and road
construction is of a growing
importance.
The mostly required road construction material is bitumen. Bitumen has the
advantage, that it
has enough flexibility to adapt to the movement of the subsoil, so that the
roads, which are
built with it, do not form any cracks and/or edge projections. Furthermore, a
bitumen layer has
proven to be exceptionally resistant to abrasion so that the streets with a
bitumen layer last for
a long time.
The disadvantage bitumen has however is its very high price and the fact that
this petroleum
derivative is not available in many countries of the world. Additionally, in
many countries of
the south and far eastern hemisphere, bitumen is not suitable as a
construction material for
road construction purposes due to the fact that it lacks a resistance to heat.
An alternative road construction material for bitumen is concrete. In
comparison to bitumen,
concrete is a material, which is remarkably lower in price, and the kind of
material needed for
concrete mixtures, cement, water and filling agents as for example sand are at
least more
available than bitumen in large parts of the world. As an additional aspect,
concrete does not
turn soft even at extreme exposure to sunlight.

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To be able to build roads made of concrete, the subsoil under a concrete slab
has to be very
solid. Otherwise the concrete slabs will either break or they will set locally
in such a way that
edge projections may occur, which may present an extreme stress factor for the
motor vehicle
as well as for the drivers thereof.
The process of hardening the subsoil is an extremely cost effective procedure,
whereby as a
rule the grown soil has to be replaced by a compressable material, as for
example sand.
There have been many tests with additives to make concrete that flexible, that
it may reach the
flexibility of bitumen.
From the AU-A-35121/93 a mixture is known, for example, which is added to a
concrete
mixture to make the concrete more flexible and reduce shrinkage during
setting.
The mixture mainly consists of two components, whereas the one component
consists mainly
of chloride salts and the other component is an alkali silicate (waterglass),
preferably sodium
silicate. The two components are premixed and then added to the concrete
mixture made of
cement, water and sand to then use the same for the road construction for
example.
This procedure has the disadvantage that the two components of the mixture
already react
with each other during the process of premixing already and that the silicate
already starts
setting before it comes into contact with the concrete mixture so that the
actual effect of this
mixture in the concrete mixture is limited.
Furthermore some problems may occur by the fact that waterglass is rated as a
dangerous
substance and may only be processed by using gloves, safety glasses and an
apron and that the
respective safety precautions have to be taken during transport.
It is therefore required to find an auxiliary agent, which is rated as not
being dangerous and
which is generally recognized as being safe for the environment, and which
also makes
concrete more flexible and reduces shrinkage of the concrete mixture during
setting.
This task is solved according to the invention by providing an aqueous
dispersion, which
contains:

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a.) 83,0-96,0 wt-% (percent by weight), related to the total weight of the
dispersion,
water,
b.) 1,0-6,0 wt-%, related to the total weight of the dispersion, of a 30-70 wt-
% aqueous,
synthetic latex,
c.) 1,0-7,2 wt-%, related to the total weight of the dispersion, of an
alkaline earth metal
formate, preferably calcium formate,
d.) if need be, 0,2-1,2 wt-%, related to the total weight of the dispersion,
of a cellulose
ether,
e.) 0,02-0,12 wt-%, related to the total weight of the dispersion, lauryl-
sulfonate,
f.) if need be, 0,6-1,2 wt-%, related to the total weight of the dispersion,
of a commonly
used preservative agent,
g.) if need be, 0,25-0,6 wt-%, related to the total weight of the dispersion,
of a commonly
used foam separator,
h.) if need be, 0,2-1,0 wt-%, related to the total weight of the dispersion,
of a, preferably
50-60 wt-%, aqueous paraffin emulsion, whereby the total weight of all
components of
the dispersion has to add up to 100 wt-%.
Preferably the aqueous dispersion according to the invention contains:
- 85,0-90,0 wt-% of component a,
- 2,0-5,0 wt-% of component b,
- 2,0-6,0 wt-%, of component c,
- if need be, 0,3-1,0 wt-%, of component d,
- 0,03-0,08 wt-% of component e,
- if need be, 0,8-1,0 wt-%, of component f,
- if need be, 0,3-0,5 wt-%, of component g,

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- if need be, 0,5-0,8 wt-%, of component h,
whereby the total weight of all components of the dispersion has to adti up to
100 wt-%.
Preferably, a polystyrene-butadine-copolymer latex is used as a synthetic
latex, as an alkaline
earth metal calcium forrnate and as preservative agents 2-n-octyl-4-
isothiazole-3-one
dissolved in propyl glycol.
A further subject matter of the invention is a concrete mixture containing:
a.) 0,01-0,5 1 preferably 0,05-0,15 1 of the dispersion according to the
invention per kg cement
b.) cement,
c.) filling agent
d.) if need be, water,
whereas the components of the concrete mixture are used in the usual amounts
and the
respective concrete, which has set.
The concrete mixture according to the invention is preferably produced in such
a way that the
filling agent and, if need, be water are mixed with each other and after that
the dispersion
according to the invention is added. Any other order of mixing the components
is also
possible.
A further subject matter of the invention is the production of construction
material, preferably
slabs or stones, from the concrete mixture according to the invention.
The concrete mixture according to the invention can further be used for all
kinds of concrete
building, preferably street and road construction and fastening construction,
in such a way that
a further subject matter of the invention is this use and the respective
concrete building,
preferably street and road construction and other fastening coverings or
building.
With the dispersion according to the invention the following advantages are
achieved:

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- To a concrete mixture only one auxiliary agent has to be added, which does
not have to
be premixed to make the concrete more flexible and to reduce the shrinkage
during setting.
Because of that the costs for freight and storage are reduced.
- The dispersion according to the invention is not classified as a dangerous
material,
which results in the fact that it can be processed without protection
measures.
- The dispersion according to the invention is generally recognized as safe
for the
environment.
- A concrete mixture according to the invention sets very quickly.
- With the dispersion according to the invention, it is possible to produce a
concrete
mixture with filling agents, which hitherto had been regarded as toxic to
cement.
- As a filling agent in the concrete mixture, the common kinds of sand, but
furthermore
also every kind of soil, contaminated or not contaminated, and/or materials
such as bauxite,
laterite, vulcanized ash, bimos and ash from combustion plants are used.
- If the water part of the filling agent is sufficient to cover the amount of
water needed
of the concrete mixture according to the invention, then no amount of water
has to be added to
the concrete mixture according to the invention.
- With the concrete mixture according to the invention construction material
and
concrete building components of any kind can be produced, preferably street
and road layers,
in such a way that the excavated earth of the building site and/or sand or
soil-like material,
which are available at the building site, can be used as filling agents
instead of the common
filling agents commonly used in the concrete mixture.
Example 1
To be able to check how far the mechanic characteristics, especially the
elasticity and the
shrinkage of a concrete has been changed by the dispersion according to the
invention and

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how far it was possible to reduce the shrinkage of the concrete mixture, a
test with and
without the addition of the aqueous dispersion was performed.
Initially a concrete mixture was produced, which contained the following
components:
- 20 kg cement,
- 100 l of sand a
- 5 liters of water.
After that the concrete mixture was divided in the relation of 1:1 and filled
into two separate
vats.
One of the concrete mixtures was left as it was, while the other concrete
mixture was mixed
with a liter of the dispersion according to the invention, which was composed
of the
following:
a.) 87,6 wt-% (percent by weight), related to the total weight of the
dispersion,
water,
b.) 4,0 wt-%, related to the total weight of the dispersion, of a 50 wt-%
aqueous,
synthetic styrol/butadine latex,
c.) 5,0 wt-%, related to the total weight of the dispersion, calcium formate,
d.) 1,0 wt-%, related to the total weight of the dispersion, cellulose ether,
e.) 1,0 wt-%, related to the total weight of the dispersion, 2-n-octyl-4-
isothiazol-3-one
dissolved in propylene glycol,
f.) 0,39 wt-%, related to the total weight of the dispersion, poly(dimethyl
siloxane),
g.) 0,01 wt-%, related to the total weight of the dispersion, lauryl
sulfonate,

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h.) 1,0 wt-%, related to the total weight of the dispersion, of a 60 wt-%,
aqueous paraffin
emulsion.
After that the concrete mixtures'according to the invention and the
conventional conciete
mixture were each poured into wood moulds with the measures 50x20x1 cm
(length, width,
depth), in which the concrete mixture set, respectively. 10 slabs were
produced respectively.
A visual assessment of the concrete slabs resulted in the fact that the
concrete slabs according
to the invention had shrunk less than the conventional concrete slabs.
After that 10 concrete slabs were clamped in a tight manner into a testing
machine at the one
face of the plank and at the other face of the plank, 45 cm away from the
location of clamping,
were increatingly exposed to pressure with a hydraulic die, until they broke.
During this test
the deformation of the concrete slabs were measured optically.
It appeared that the concrete slabs according to the invention comprised a
higher ductility
before the fracture of 2,5 on average.
Example 2:
As mentioned already before, it is possible to use substances as filling
agents in concrete
mixtures with the dispersion according to the invention, which were hitherto
regarded as toxic
to cement.
To illustrate this fact, three concrete mixtures were produced, which each
contained 20kg of cement and 5 liters of water. As a filling agent mixture 1
contained 100 liters of commercially available building sand, mixture
contained
2 100 liters of excavated native soil of a building site and mixture contained
3 100 liters of ash from a combustion plant.
The concrete mixtures were intensively premixed in a concrete mixing machine
and then
mixed in a vat with a liter of the dispersion according to example 1 and
moulded into slabs in
the moulds described in example 1, in which the concrete mixtures set.

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A visual assessment of 10 concrete slabs respectively resulted in the fact
that the shrinkage of
the concrete mixtures was low in all cases during setting.
After that, the slabs were subjected to the most different mechanical testing
procedures as for
example resistance to pressure, ductility and surface hardness, whereby it
appeared that the
mechanical characteristics of all concrete slabs showed good results in
comparison.