Ferguson, Ian Francis (14 Chadwick Crescent, Oxford Park Dewsbury, West Yorkshire WF13 2JF, GB)
| 1. | A cement formulation for use in the manufacture of concrete, said formulation comprising: a) cement; b) calcium carbonate (limestone); and c) ground granulated blast furnace slag. |
| 2. | The formulation of claim 1, further comprising an admixture agent for aiding consolidation of the formulation during manufacture. |
| 3. | The formulation of claim. 2, wherein the admixture agent is a polycarboxylate superplasticizer. |
| 4. | The formulation of claim 3, wherein the polycarboxylate superplasticizer has a comb polymer structure having (i) carboxylic acid anhydride, free carboxylic acid or its ammonium, alkali or alkaline earth metal salt of carboxylic acid units; and (ii) C2Cs oxyalkylene units therein. |
| 5. | The formulation of claim 4, wherein the carboxylic acid units or oxyalkylene units are pendant to the polymer backbone structure and wherein the oxyalkylene units provide a majority of the molecular weight of the comb polymer. |
| 6. | The formulation of any of claims 2 to 5, wherein the amount of admixture agent in solution is 1060% by weight solids . |
| 7. | The formulation of claim 6, wherein the amount of admixture agent is 2050% by weight solids. |
| 8. | The formulation of any preceding claim, wherein the cement formulation comprises cement in an amount of between 5 and 30 wt % of the formulation. |
| 9. | The formulation of claim 8, wherein the formulation comprises cement in an amount of between 5 and 20 wt %. |
| 10. | The formulation of claim 9, wherein the formulation comprises cement in an amount of between 7 and 17 wt %. |
| 11. | The formulation of any preceding claim, wherein the cement comprises Portland Cement. |
| 12. | The formulation of any preceding claim, wherein the cement comprises Portland Limestone Cement which comprises Portland Cement mixed with calcium carbonate. |
| 13. | The formulation of claim 12, wherein the Portland Limestone Cement comprises between 2 and 20 wt % of calcium carbonate. |
| 14. | The formulation of any preceding claim comprising a number of different size grades of calcium carbonate. |
| 15. | The formulation of any preceding claim wherein the ground granulated blast furnace slag is as described in British Standard BS 6699. |
| 16. | The cement formulation of any preceding claim wherein ground granulated blast furnace slag comprises an amount of at least 30 wt % of the formulation. |
| 17. | The formulation of claim 16, wherein ground granulated blast furnace slag comprises an amount of between 30 and 80 wt% of the formulation. |
| 18. | A concrete formulation for producing a concrete composition when mixed with a quantity of water, said formulation comprising the cement formulation of any preceding claim and fine (xfines'l and coarse aggregates. |
| 19. | The concrete formulation of claim 18, wherein the fines may comprise material such as from naturally occurring or marine sources together with any crushed rock fines or crushed stone material. |
| 20. | The concrete formulation of claim 18 or 19, wherein fines comprise an amount of between 20 and 80 wt % of the concrete formulation. |
| 21. | The concrete formulation of claim 18 or 19, wherein fines comprise in an amount of between 25 wt % and 55 wt% of the formulation. |
| 22. | The concrete formulation of any of claims 18 to 21, wherein, when mixed with an appropriate quantity of water to form a concrete composition, the cement formulation forms an amount of between 10 and 25 wt%. |
| 23. | The concrete formulation of any of claims 18 to 22, wherein the coarse aggregate material comprises an amount of between 20 and 80 wt % of said concrete formulation. |
| 24. | A concrete composition comprising the concrete formulation of any of claims 18 to 23 and water. |
| 25. | The concrete composition of claim 24, wherein water comprises an amount of between 2 and 20 wt % of the composition. |
| 26. | The concrete composition of claim 25, wherein water comprises between 4 and 10 wt %, of the composition. |
| 27. | A concrete body or structure made in accordance with any of the above listed compositions and formulations as set out in any of claims 1 to 26. |
| 28. | A method of manufacturing concrete compositions using the compositions/formulations as set out in any of claims 1 to 26. |
| 29. | A method of manufacturing a concrete body or structure using the compositions/formulations as set out in any of claims 1 to 26. |
| 30. | A cement formulation, a concrete formulation or a concrete composition substantially as herein described with reference to the accompanying drawings . |
The present invention relates to concrete compositions, concrete formulations for producing concrete compositions when mixed with water, cement formulations for use in producing concrete compositions, concrete bodies, concrete structures, methods of manufacturing concrete compositions and methods of manufacturing concrete bodies and structures.
Concrete is used in many areas of the construction industry, for example in the construction of buildings, and bridges. Pre-formed concrete bodies, such as paving slabs, are known for providing surfaces and pre-formed concrete bodies are also employed for decorative purposes or as ready made elements of structures such as buildings.
There are known a number of concretes having differing compositions depending upon the application in which the concrete is used. Such concrete compositions comprise cement, fine aggregate, coarse aggregate and water and optionally other additives. Cement, fine aggregate (λfines') and coarse aggregate can be provided as a concrete formulation which when mixed with water provides a concrete composition. This composition then sets to produce concrete.
There are known concrete compositions which when set result in concrete having considerable strength. However, such concretes may still not be as strong as might be desired for some applications. Concrete is often employed in applications where it is subjected to considerable forces . In order to compensate for this concrete bodies may need to be of a substantial size to provide the required strength. Additionally, concrete bodies may be employed in situations where they are subjected to considerable wear and tear, such as weathering. Known concretes may not withstand such wear and tear as well as may be desired.
Further, whilst many different mixes with different properties are known and in use, high strength mixes having a low cost factor are few and far between and highly sought after.
The present invention aims to address at least one disadvantage associated with known concrete whether discussed herein or otherwise. Preferred embodiments aim to provide high strength at relatively low cost.
According to a first aspect of the present invention there is provided a cement formulation for use in the manufacture of concrete, said formulation comprising:
a) cement;
b) calcium carbonate (limestone) ; and
c) ground granulated blast furnace slag.
Suitably, the cement formulation comprises cement in an amount of between 5 and 30 wt % of the formulation, preferably in an amount of between 5 and 20 wt %, for example in an amount of between 7 and 17 wt %. Suitably, the cement comprises Portland Cement. The Portland Cement may be as described in BS EN 197: CEM I.
The cement may comprise Portland Limestone Cement which comprises Portland Cement as detailed above mixed with calcium carbonate. The Portland Limestone Cement may be as detailed in BS EN 197: CEM II.
Where the Cement comprises Portland Limestone Cement the cement may comprise between 2 and 20 wt % of calcium carbonate. Where the Cement comprises Portland Limestone Cement the wt % values of cement in the composition may be based on the amount of Portland Cement in the Portland Limestone Cement and not on the total weight of the Portland Limestone Cement.
The cement formulation may comprise a number of different size grades of calcium carbonate.
All grades of calcium carbonate will comprise powdered calcium carbonate. By powdered calcium carbonate it is meant calcium carbonate having a particle size of less than lmm. Such calcium carbonate may be comprised by a Portland Limestone Cement.
Suitably, the cement formulation comprises calcium carbonate in an amount of between 2 and 30 wt % of the formulation, preferably between 10 and 20 wt %.
Where the cement comprises Portland Limestone Cement the wt % values for calcium carbonate in the formulation suitably include the calcium carbonate in that cement. Suitably, the ground granulated blast furnace slag is as described in British Standard BS 6699.
Suitably, the cement formulation comprises ground granulated blast furnace slag in an amount of at least 30 wt % of the formulation, preferably in an amount of between 30 and 80 wt%, for example around 50 wt %.
The cement formulation may further comprise an admixture agent for aiding consolidation of the formulation during concrete manufacture.
Suitably, the admixture agent comprises a polycarboxylate.
The admixture agent may be any suitable polycarboxylate.
Preferably, the admixture agent is a polycarboxylate superplasticizer. This term means and includes polymers or copolymers, and solutions thereof, preferably having a comb structure, which contain groups for attaching to cement particles and groups for dispersing the attached cement particle within an aqueous environment.
Preferably, the PCS has a comb polymer structure having (i) carboxylic acid anhydride, free carboxylic acid or its ammonium, alkali or alkaline earth metal salt of carboxylic acid units; and (ii) C2-C5 oxyalkylene units therein and wherein the carboxylic acid units or oxyalkylene units are pendant to the polymer backbone structure and wherein the oxyalkylene units provide a majority of the molecular weight of the comb polymer. The preferred amount of polymer or copolymer in solution is 10-60%, and more preferably 20-50%, by weight solids, majority of the molecular weight of the polymer.
The molecular weight of the comb polymers suitable in the present invention for modifying cementitious compositions typically have a weight average molecular weight of from about 2,000 to 200,000, preferably from about 2,000 to 100,000 and most preferably from about 2,000 to 75,000. Preferably, although not necessarily, at least about 50, or even up to 90 percent, by weight of the molecular weight of the polymer is attributable to the molecular weight of the EO units therein.
It will be understood that when an oxyalkylene chain is pendant through a carboxylic acid anhydride (e.g. maleic acid unit) or free carboxylic acid (e.g. acrylic acid unit) , not all acid units may be utilized in such linkage and remain as acid units .
Polycarboxylate superplasticizer polymers contemplated for use in the present invention preferably comprise at least 50% by weight of (poly) oxyalkylene units forming the major component. Thus, the polymer structure of the superplasticizers may contain other copolymerizable units, provided the above preferred requirement is met. For example, the copolymer may further have styrene, methyl vinyl ether, vinyl pyrrolidone and the like, as part of the polymer structure.
The admixture agent may comprise an ethylene oxide/propylene oxide polycarboxylate. According to a second aspect of the present invention there is provided a concrete formulation for producing a concrete composition when mixed with a quantity of water, said formulation comprising:
i) a cement formulation comprising (a) cement, (b) calcium carbonate, and (c) ground granulated blast furnace slag; and
ii) fine (''fines') and coarse aggregates.
An admixture agent for aiding consolidation of the formulation during manufacture may further be provided.
Preferably, the cement formulation comprises a cement formulation according to the first aspect.
The fines may comprise material such as from naturally occurring or marine sources together with any crushed rock fines or crushed stone material.
Suitably, the concrete formulation comprises fines in an amount of between 20 and 80 wt% of the formulation. The concrete formulation may for example comprise fines in an amount of around 25 wt % or around 55 wt% of the formulation.
Suitably, the concrete formulation (cement, fines, coarse aggregate and water) comprises the cement formulation in an amount of between 10 and 25 wt % of said concrete formulation. Suitably, the components of the cement formulation are present in the cement formulation of the concrete formulation in the amounts specified for the cement formulation in the first aspect.
The concrete formulation may comprise aggregate material. The aggregate material may comprise fines from suitable recycled or waste material.
The concrete formulation may comprise the coarse aggregate material in an amount of between 20 and 80 wt % of said concrete formulation, for example in an amount of around 40 wt %.
According to a third aspect of the present invention there is provided a concrete composition comprising: i) a cement formulation comprising (a) cement, (b) calcium carbonate, and (c) ground granulated blast furnace slag and;
ii) fine aggregate ( ^fines' ) and coarse aggregate iii) water.
An admixture agent for aiding consolidation of the formulation during manufacture may further be provided.
Preferably, the cement formulation comprises a cement formulation according to the first aspect.
The components of the concrete composition detailed as (i) and (ii) may comprise a concrete formulation according to the second aspect. Suitably, the fines are as described in the second aspect.
Suitably, the concrete composition comprises fines in an amount of between 20 and 80 wt% of the composition.
Suitably, the components of the cement formulation are present in the cement formulation of the concrete composition in the amounts specified for the cement formulation in the first aspect.
The concrete composition may comprise coarse aggregate material which may be as described in the second aspect.
The concrete composition may comprise the coarse aggregate material in an amount of between 20 and 80 wt % of said concrete composition, for example in an amount of around 18 wt %.
The concrete composition may comprise water in an amount of between 2 and 20 wt % of the composition, preferably between 4 and 10 wt %, for example around 8 wt % or 10 wt %.
The invention also extends to concrete bodies and concrete structures made in accordance with any of the above listed compositions and formulations, as well as to methods of manufacturing concrete compositions and methods of manufacturing concrete bodies and structures using the compositions/formulations.
For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:
Figure 1 shows a molecular structure of a suitable polycarboxylate admixture; and
Figure 2 illustrates formation of the molecular structure of the admixture.
In the description which follows, examples of concrete compositions, concrete formulations for producing concrete compositions when mixed with water and cement formulations for use in producing concrete compositions are disclosed. In each case, the compositions and formulations are referred to as tri-blend powder formulations. These tri- blend powder formulations are then preferably combined with an EO/PO (ethylene oxide/propylene oxide) polycarboxylate admixture, that binds aggregate (coarse and fine) together in an efficient manner to form a concrete.
The tri-blend concrete uses a combination of cement, Calcium Carbonate (also referred to as Limestone powder) and slag. More specifically the cement is suitably Portland Limestone Cement (which is a blend of Portland Cement and Limestone Powder - blended or inter-ground) together with Ground Granulated Blast furnace Slag, or Portland Cement with Limestone Powder (Calcium Carbonate) and Ground Granulated Blast furnace Slag (GGBS) . The blend types are further enhanced by the inclusion of a suitable super plasticising admixture, such as an EO/PO (ethylene oxide/propylene oxide) Polycarboxylate Comb superplasticising admixture. However, in any such arrangements in which a mechanical compaction process is used the admixture is an optional ingredient and may be omitted. In mechanically compacted mixes the tri-blend has been found to work adequately without the admixture. Where a superplasticizing admixture is used, such an admixture comprises a polycarboxylate superplasticizer (which may be referred using the acronym "PC" or "PCS". Such a PCS means and includes polymers or copolymers, and solutions thereof, which typically have a comb structure and contain groups for attaching to cement particles and groups for dispersing the attached cement particle within an aqueous environment. The comb structure of the PCS has (i) carboxylic acid anhydride, free carboxylic acid or its ammonium, alkali or alkaline earth metal salt of carboxylic acid units; and (ii) C2-C5 oxyalkylene units therein and wherein the carboxylic acid units or oxylakylene units are pendant to the polymer backbone structure and wherein the oxyalkylene unit provide a majority of the molecular weight of the comb polymer. Typically, the amount of polymer or copolymer in solution is between 10 and 60% by weight solids majority of the molecular weight of the polymer.
The molecular weight of the comb polymers suitable for modifying cementitious composition typically have a weight average molecular weight of from about 2000 to 200,000, preferably from about 2,000 to 100,000 and most preferably from about 2,000 to 75,000. Generally, between 50 to 90% by weight of the molecular weight of the polymer is attributable to the molecular weight of the EO units therein, EO referring to Ethylene Oxide which forms the side chain - the teeth of the polymer structure. It will be understood that when an oxyalkylene chain is pendant through a carboxylic acid anhydride (e.g. maleic acid unit) or free carboxylic acid (e.g. acrylic acid unit) , not all acid units may be utilized in such linkage and remain as acid units.
Carboxylate superplasticizer polymers contemplated for use in embodiments of the present invention preferably comprise at least 50% by weight of (poly) oxyalkylene units forming the major component. Thus, the polymer structure of the superplasticizers may contain other copolymerizable units, provided the above preferred requirement is met. For example, the copolymer may further have styrene, methyl vinyl ether, vinyl pyrrolidone and the like, as part of the polymer structure.
The base technology is that alumina sulphate (present in the GGBS) reacts with calcium carbonate (Limestone Powder) which increases the presence of hydrates, the EO/PO Polycarboxylate admixture significantly reduces the water demand of the concrete mix whilst the comb polymers act in such a way that they attach themselves to the cement grain whilst attracting water molecules resulting in steric repulsion force.
The Concrete Mix Designs detailed herein are examples of designs employed in accordance with the invention and are not intended to be limiting.
According to a first embodiment of the invention a wet vibrated concrete mix is disclosed. Wet vibrated concrete is typically wet by its nature, has a Slump Workability in the range 25mm - Collapsed (300mm) and has a water: cement ratio range 0.45 - 0.8; the produced concrete would typically be placed into a mould or formwork and be mechanically or manually vibrated (or in the case of Self Compacting Concrete, would self-compact without mechanical or manual vibration) .
The Mix Design employed in self-compacting concrete in this instance is as follows:
* This is a Portland Cement, inter-ground or blended, with Limestone Powder (otherwise referred to as Calcium Carbonate) .
** Not necessarily included for mechanically or manually vibrated concrete mixes .
In a second embodiment, a semi-dry Vibro-Pressed process is used. In this process, concrete type is typically "just moist" by its nature with a consistency measured by producing a cohesive ball when compressed by squeezing with your hand - often referred to as earth- moist concrete; its water to cement ratio is in the range 0.30 - 0.45. The produced concrete would typically be used to produce concrete block paving, walling or other suitable products in a Vibro-Press (combined vibration with hydraulic pressing action) machine.
The mix design employed in this instance is as follows :
** Optional
In a third embodiment, a hydraulic wet pressed flag and curb type mix is provided. In this type of mix, the concrete commences with wet concrete at a water : cement ratio in the range of 0.8 to 1. The concrete is processed through a hydraulic press machine where the larger part of the water within the concrete is pressed out until the concrete is fully consolidate within its mould; the resulting concrete is formed to paving flag, curb stone, walling or other suitable produce shape - the produced concrete is now in semi-dry condition with a reduced water to cement ratio in the range of 0.32 to 0.42 .
Hydraulic Wet Pressed Flag & Kerb
Definition: This concrete type commences with wet concrete at a water: cement ratio in the range 0.8 - 1.0. the concrete is processed through a hydraulic press machine where the larger part of the water within the concrete is pressed out until the concrete is fully consolidate within its mould; the resulting concrete is formed to paving flag, kerb stone, walling or other product shape - the produced concrete is now in semi-dry condition with a reduced water : cement ratio in the range 0.32 to 0.42 .
The Mix Design employed in this instance is as follows:
** Optional Referring now to Figure 1, there is shown the molecular structure of a suitable Polycarboxylate admixture.
The molecular structure of the admixture is such that the molecules attach themselves to the cement grains, whilst the hydrophilic character of the admixture attracts water molecules present within the wet concrete mix. Neighbouring cement particles are kept apart, thereby releasing bound water.
Figure 2 illustrates the formation of the molecular structure of the admixture.
The properties of Portland Limestone Cement as disclosed in the embodiments above, are similar to those of Portland Cement described in BS EN 197-CEM 1 and indeed is specified in BS EN 197-CEM 11. This cement is either blended at source with Limestone powder (Calcium Carbonate) or inter-ground in process to a given percentage by mass typically in the range of 2 to 20%. Typical properties of the Portland Limestone Cement are shown below: Portland cement used in the mixtures is a commonly available material used in a production of conventional concretes, its specification is detailed in BS EN 197-CEN 1. Typical properties of Portland cement are given below: The Limestone powder/Calcium Carbonate utilised in embodiments of the invention is a mineral material that can be added to Portland cement at source by way of blending (blended or inter-ground) to produce PLC, also it can be blended with Portland cement and ground granulated Blast Furnace slag at the point of concrete production in order to produce tri-blend concrete.
• Limestone Synonyms:
Limestone, calcium carbonate, precipitated calcium carbonate, ground/pulverized calcium carbonate, PCC< GCC, calcite, limestone, crushed marble, ground limestone, lime, chalk, whiting, champagne chalk, French chalk, albacar, and aeromatt
• Limestone Formula:
CaCO3
• Limestone Description :
Produced by crushing, grinding, precipitation, and classifying high purity, white, calcite limestone
Typical purity of Limestone Powder is 95 - 99.9% pure properties of Limestone Powder are described below:
In the above examples, some specific examples of formulations have been set out. However, it should be appreciated by the man skilled in the art that the invention is not limited to these particular ratios and formulations. In fact, a range of formulations may in general be used and fall within the scope of the present invention.
Suitably, the cement formulation comprises ground granulated blast furnace slag in an amount of at least 30 wt % of the formulation, preferably in an amount of between 30 and 80 wt%, for example around 50 wt %. The proportion of slag is significant and generally of a much higher proportion to that which has been utilised in the prior art. As a result of the specific combination of the three elements (Portland cement, Limestone powder, ground granulated Blast Furnace slag) the physical strength exhibited by the concrete is much higher than would be expected by a man skilled in the art. Further, the use of such a low cost ingredient as slag in a relatively high percentage also makes the particular tfi-blend mix extremely commercially attractive as it may be a lower cost product.
Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.