WO2008089250A2

WO2008089250A2 - Lightweight cementitious material and method of making

Info

Publication number: WO2008089250A2
Application number: PCT/US2008/051187
Authority: WO
Inventors: Matthew Piazza
Original assignee: Carpentercrete, Llc
Priority date: 2007-01-17
Filing date: 2008-01-16
Publication date: 2008-07-24
Also published as: WO2008089250A3

Abstract

A lightweight cementitious material is produced by combining concrete mixture, non-ionic surfactant and water in a mixture. The concrete mixture includes cement and aggregate materials. The mixture is mixed allowing the cement to be naturally hydrated thereby increasing the temperature of the mixture. The increase in temperature causes the surfactant to reach its cloudpoint resulting in the surfactant foaming and dropping out of solution. The surfactant bubbles produced during the foaming are incorporated in the voids between the cement and the aggregate materials. The mixture cures to a desired hardness and the result is a lightweight concrete material.

Description

Lightweight Cementitious Material and Method of Making

Field of the Invention The present invention relates generally to building materials and, more specifically, to a composition for use in producing building materials and a method for producing the composition.

Background of the Invention Concrete is formed from cement, water and any of a plurality of different aggregate materials. When combined, the cement and water bind the aggregate materials together until the composition cures to form concrete. The type of aggregate material selected for use in a particular concrete mixture is dependent on the desired properties had by the resulting concrete. For example, the aggregates used in conventional, "normal weight" concrete may include sand, gravel, limestone whereas for concrete termed "lightweight" or "ultra-lightweight" the aggregate materials used may include clay, crushed brick, vermiculite, perlite, etc. The drawback associated with normal concrete is a higher weight as compared to lightweight concretes. However, the use of lightweight aggregates material to make ultra-light weight concrete adds to the cost of production and may require the addition of costly admixtures for production thereof. Therefore, it is desirable to produce a lightweight concrete material using aggregates that are typically associated with "normal weight" concrete material. A composition and method according to invention principles satisfies these needs and remedies the above-noted drawbacks.

Summary of the Invention

A lightweight concrete material is produced without using any light weight aggregate materials. Cement, aggregate materials, water and non-ionic surfactant are combined in a mixture. The water naturally hydrates the cement thereby raising the temperature of the mixture. The increase in temperature causes the surfactant to drop out of solution and form surfactant foam bubbles. The resulting surfactant bubbles are distributed throughout the mixture between the aggregate materials filling any voids therebetween. The resulting concrete is an ultra lightweight concrete. Grouts can be made via a similar method. A method of producing a lightweight cementitious material includes the activities of combining cement, aggregate materials, water and non-ionic surfactant into a composite mixture and mixing the composite mixture resulting in hydration of the cement and increasing a temperature of the mixture to a predetermined temperature causing the non-ionic surfactant to breakdown and drop out of solution forming bubbles of non-ionic surfactant molecules. The surfactant bubbles are incorporated by mixing into voids between the cement and aggregate materials and the resulting mixture is cured until a desired hardness is reached resulting in a lightweight concrete material.

A lightweight cementitious mixture includes cement, aggregate materials, a non-ionic surfactant and water wherein mixing of the cement, aggregate materials, non-ionic surfactant and water causes the non-ionic surfactant to change state and form bubbles of non-ionic surfactant which are incorporated into voids formed between the cement and aggregate materials.

Brief Description of the Drawings

In order that the invention may be more fully understood, it will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 is a flow diagram detailing the method of producing the lightweight cementitious material according to the principles of the invention.

Description of the Invention

The following description describes the principles of the invention. This discussion should not be construed, however, as limiting the invention to those particular embodiments discussed. Practitioners skilled in the art will recognize numerous other embodiments as well with reference to the drawings and the following description.

The method shown in Figure 1 provides for the creation of a true light weight concrete or grout without using any light weight aggregates. A light weight cementitious mixture can be achieved by mixing a very high proportion of a non-ionic surfactant into a grout or concrete mix (including cement and/or gypsum, sand, and gravel). Additionally, depending on the need of the user, additional materials such as structural fibers may be included during the mixing process shown in Figure 1 and described hereinafter.

At step SlOl, concrete mix, water and non-ionic surfactant are combined into a mixture and mixed together. The concrete mix includes predetermined amount of cement and predetermined amount of aggregate materials such as sand and gravel. The use of concrete mix as an element of the composition is described for purposes of example only and one skilled in the art will appreciate the ability to substitute concrete mix with any cementitious material mixture that may be combined with water and non-ionic surfactant as described herein. Other aggregate materials may be used in producing the lightweight concrete mixture including at least one of vermiculite, shale, slate, plastic, clay, perlite, limestone, sandstone and any ceramic materials. While other aggregate materials may be used in this method of producing a lightweight cementitious building material, the use of sand and gravel significantly reduce the cost associated with the resulting material. This reduction in cost is associated with sand and gravel being typically used to make "normal weight" or "medium weight" concrete. Additionally, the mixing in step SlOl maybe performed manually or by an automated device able to combine these elements into a composite mixture, for example a static mixer. Additionally, a high speed mixer may be employed to combine the concrete mix, surfactant and water. Use of a high speed mixer increases the speed at which the elements of the mixture are combined with one another and may directly impact the formation of the resulting lightweight concrete. The use of a high speed mixer decreases the amount of time need to produce the lightweight concrete material.

The mixing step SlOl causes the natural hydration resulting from the combination of water with cement to raise the temperature of the mixture as in step S 102. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products. The chemical reaction of hydration releases heat and causes the temperature increased seen in step S 102. However, natural hydration of the cement occurs after a dormant period of approximately 1 - 3 hours whereby there is no chemical reaction and no temperature increase occurring between the water and the cement. If the mixing step of SlOl is performed in a high speed mixer, the hydration process occurs at a faster rate and thus increases the rate of temperature increase in the mixture. The friction generated during the high speed mixing of the elements shown in SlOl circumvents the dormant period and allows for the rapid increase in temperature in the mixture. As the temperature of the mixture increases, the surfactant in the mixture is caused to reach its "cloudpoint" as shown in step S 103. The cloudpoint temperature, generally 75 degrees Celsius (or higher), is the temperature at which the surfactant drops out of solution and the solution becomes turbid. When the cloudpoint is reached and the surfactant drops out of solution, the surfactant is caused to breakdown into individual surfactant molecules and a large amount of surfactant foaming takes place. The resulting surfactant foam are microscopic bubbles of non-ionic surfactant molecules that appear on the surface of the mixture and, upon continued mixing, are incorporated within the mixture and fill the void spaces in a concrete mix as in step S 104. The addition of a curing agent and/or accelerating agent also circumvents the dormant period associated with mixing the cement by increasing the temperature of mixture at a greater rate as compared to solely using mixing device. The quicker the non-ionic surfactant reaches its cloudpoint, the quicker the foam is produced and can be incorporated into the mixture.

The incorporation of microscopic bubbles to fill voids in the mixture is similar to the use of an air-entraining agent which artificially injects air bubbles into a cementititious mixture to increase the strength of the resulting composition. However, the use of an air entraining agent would not be able to incorporate the amount of air bubbles as compared to the non-ionic surfactant molecules that are incorporated by the method of Figure 1. Specifically, the amount of air-entraining agent that would needed to produce composition such as the one produced herein would be so great that the resulting composition would not be able to cure or be used for its intended purpose to produce a lightweight cementitious mixture. The present method provides natural production of non-ionic surfactant bubbles upon the surfactant reaching its cloud point which are then incorporated within the mixture by the mixing process. Moreover, the resulting composition produced using the method in Figure 1 results in a composition that is more dense because the non-ionic surfactant molecules are filling any voids between the cement and aggregate materials. The individual non- ionic surfactant molecules force out and replace the water molecules that conventionally fill the voids in conventional cementitious compositions. The result is a stronger, more dense but lighter weight cementitious material.

The incorporation of these microscopic surfactant bubbles result in a mixture that has an increased volume as compared to heretofore produced concrete (or other cementitious) mixtures. Consequently, the weight of the subject mixture is much lighter than can normally be achieved using aggregates that up until now were used to make heavier weight concrete. For example, the mix may be at least 40% lighter than standard concrete, or the equivalent of approximately 87 lbs. per cubic foot. This method of producing lightweight concrete thereby results in a lower overall cost for the mix. Another benefit to producing concrete using this method is an increased tensile strength due to the incorporation of the surfactant foam bubbles into the mixture to fill voids prior to curing thereof. The resulting strength of a material formed from using the mixture described herein exceeds 5000 psi. Moreover, the material maybe be modified using simple woodworking tools including have screws and nails being supported by the material. The material may also be cut or otherwise shaped using other woodworking tools such as a saw or drill. The method further reduces costs that are typically associated with foam or cellular concrete in that the foam in the present method is naturally produced as result of the high non-ionic surfactant concentration which reaches a cloudpoint, drops out of solution and is broken down into a plurality of individual non-ionic surfactant molecules forming bubbles that produces the foam. No additionally chemistry or machines are required beyond conventional mixing equipment.

The method described above and shown in Figure 1 may be accomplished by using a non-ionic surfactant and forcing the surfactant to reach the cloudpoint in the cementitious mixture. For example, a suitable surfactant compound may include alcohol ethoxylates and octyl phenol ethoxylate with ethyleneoxide or octyl phenol. The ethylene oxide (EO) chain of the surfactant molecule is the hydrophilic portion of the molecule. The larger the EO chain of the particular surfactant increases the water solubility of the surfactant. In the case of a non-ionic surfactant, ethylene oxide is the reactive chemical which is added to the base alcohol and amines to form ethoxlated non-ionic surfactant. These surfactants are typically used in the agricultural industry as wetting agents for use in wetting out hydroponics. Specifically, these surfactants are generally used with water soluble mixtures and/or oil-in- water concentrates. However, in the hydroponics, the acceptable ratio of surfactant is approximately eight (8) ounces of surfactant per one hundred and twenty-five (125) gallons of water. The method shown in Figure 1 utilizes much higher ratios of surfactant to water. For example the present method may include a surfactant to water ratio ranging substantially between 1:1 and 8:1 or greater. Additionally, a surfactant as described above for use in the agricultural industry is only effective at a temperature below the cloudpoint because they are used to reduce the surface tension of a mixture. The benefit of the surfactant in the present mixture is realized when the cloudpoint is reached or exceeded and the surfactant drops out of solution and is broken down into individual surfactant molecules that form bubbles, the surfactant molecules are then recombined into the mixture producing a lightweight cementitous mixture.

Additionally concrete additives may be added during the mixing process of

Figure 1. Depending on the need of the user producing the lightweight cementitious material using the method of Figure 1, the user may include at least one of such as super plasticizers, fast curing agents (accelerators), or any other additive known for use in producing a concrete (or other cementitious) mixture.

When the mixing of the elements and incorporation of the produced surfactant foam bubbles are complete, the resulting lightweight composition can be poured into any mold in any shape. The lightweight concrete mixture may then be left to cure for the desired amount of time and used for its intended purpose. Alternatively, if the aggregate materials used in the method described above are vermiculite or other aggregates knows to be associated with making "lightweight concrete", the present method results in a super-lightweight concrete material that has increased strength as compared to previously produced lightweight concretes.

It may be appreciated by those skilled in the art that the description and drawings show the use of the system of the present invention in the context of forming an elevated deck above a foundation floor. It is to be understood that the system and its method of use may be repeated, for example, on the elevated deck as completed, in use on subsequent superposed floors, such that elevated concrete decks may be successively formed one above another in accordance with the invention as described, and is not limited to a single story above, for example, a basement.

While certain novel features of this invention have been shown and described and are pointed out in the annexed claims, the invention is not intended to be limited to the detailed description set forth above, since it will be understood by those skilled in the art that various omissions, modifications, substitutions and changes in the form and details of the system and its components and the methods of forming the elevated concrete deck can be made by those skilled in the art without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. A method of producing a lightweight cementitious material comprising the activities of: a. Combining cement, aggregate materials, water and non-ionic surfactant into a composite mixture; b. Mixing the composite mixture resulting in hydration of the cement and increasing a temperature of the mixture to a predetermined temperature causing the non-ionic surfactant to breakdown and drop out of solution forming bubbles of non-ionic surfactant molecules; c. Incorporating, by mixing, the surfactant bubbles into voids between the cement and aggregate materials; u. Curing the resulting mixture until a desired hardness is reached resulting in a lightweight concrete material.

2. The method as recited in claim 1, wherein the aggregate materials include at least one of sand, gravel, clay, sandstone and brick.

3. The method as recited in claim 1 , further comprising the activity of adding concrete additives prior to the activity of mixing.

4. The method as recited in claim 3, wherein the concrete additives include at least one of super plasticizers, accelerators.

5. The method as recited in claim 1, wherein said activity of combining includes combing the surfactant and water in a ratio ranging between 1 : 1 and 8:1.

6. The method as recited in claim 1, wherein said activity of mixing further comprises the activity of circumventing a dormant period associated with the mixture by at least one of mixing the mixture in a high speed mixer and adding an accelerating agent to the mixture.

7. A lightweight cementitous composition comprising cement, aggregate materials, water and a non-ionic surfactant, said composition produced by: a. Combining cement, aggregate materials, water and non-ionic surfactant into a composite mixture; b. Mixing the composite mixture resulting in hydration of the cement and increasing a temperature of the mixture to a predetermined temperature causing the non-ionic surfactant to breakdown and drop out of solution forming bubbles of non-ionic surfactant molecules; c. Incorporating, by mixing, the surfactant bubbles into voids between the cement and aggregate materials; d. Curing the resulting mixture until a desired hardness is reached resulting in a lightweight concrete material.

8. The composition of claim 7, wherein a dormant period associated with the mixture is circumvented by at least one of mixing the mixture in a high speed mixer and adding an accelerating agent to the mixture.

9. A lightweight cementitious mixture comprising, cement, aggregate materials, a non-ionic surfactant and water wherein mixing of said cement, aggregate materials, non-ionic surfactant and water causes said non-ionic surfactant to change state and form bubbles of non-ionic surfactant which are incorporated into voids formed between the cement and aggregate materials.

10. The lightweight cementitious mixture of claim 9, further comprising a curing agent to cure said mixture into a desired hardness and producing a lightweight cementitious composition.

11. The composition as recited in claim 9, wherein said aggregate materials include at least one of sand, gravel, clay, sandstone and brick.

12. The composition as recited in claim 9, further comprising at least one of super plasticizers, accelerators.

13. The composition as recited in claim 9, wherein said surfactant and water are in a ratio ranging between 1 : 1 and 8:1.