CA1062830A - Lightweight cement composition of enhanced trowelability - Google Patents
Lightweight cement composition of enhanced trowelabilityInfo
- Publication number
- CA1062830A CA1062830A CA222,302A CA222302A CA1062830A CA 1062830 A CA1062830 A CA 1062830A CA 222302 A CA222302 A CA 222302A CA 1062830 A CA1062830 A CA 1062830A
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- CA
- Canada
- Prior art keywords
- weight
- cement
- volume
- expanded
- amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
ABSTRACT
The trowelability of lightweight aggregate-containing, low density cement compositions (e.g. Portland cement-expanded vermiculite composition(s) is enhanced by the incorporation therein of a polymer of ethylene oxide. The composition has particular utility in the lining of in-ground swimming pools where the composition is to be applied by trowel to other than horizontal surfaces.
The trowelability of lightweight aggregate-containing, low density cement compositions (e.g. Portland cement-expanded vermiculite composition(s) is enhanced by the incorporation therein of a polymer of ethylene oxide. The composition has particular utility in the lining of in-ground swimming pools where the composition is to be applied by trowel to other than horizontal surfaces.
Description
This invention relates to novel lightweight aggregate-containing, hydraulic cement compositions having improved properties. More particularly, this invention concerns novel compositions containing hydraulic cement as a binder and additionally a lightweight aggregate such as expanded vermiculite or perlite to which have been added a polymer of ethylene oxide to enhance certain properties thereof.
In the construction of in-ground swimming pools wherein a water-impermeable membrane such as a plastic film is employed as a liner, it is highly desirable to protect the membrane from being punctured by irregular-ities in the surface of the cavity, e.g. rocks or shale, against which the membrane is placed. One method of providing such protection is by pouring and screeding a layer of sand on the bottom or horizontal surface adjacent the liner. In another method, a layer of lightweight, inert foraminous part-iculate material such as expanded vermiculite, perlite, etc., is employed which not only covers the surface irregularities but also provides a more "cushioned" and less abrasive surface for the easily-perforated liner. On the non-horizontal surfaces of the cavity formed to receive the liner in in-ground pool construction, it has been the practice to trowel a layer of wet sand to provide the necessary protection. The applied sand, however, when dried has a tendency to fall off of the surface, exposing the liner to the rocks or other surface irregularities. To avoid this problem, a binder such as Portland cement can be mixed with the sand. A more advantageous protective coating can be prepared from a mixture of such a binder with the aforemention-ed lightweight foraminous material, for example, expanded vermiculite aggre-gate. Such a coating is less abrasive to the liner than sand and also has insulating properties that the sand coating does not. The foraminous material in the coating renders it porous thus permitting water which has seeped be-tween the liner and the coating to drain through the coating. The highly porous nature of the coating also protects it from being washed out by rising water tables during wet months of the year. The composition containing the -1- ~
~06Z~330 foraminous aggregates have however, been found to be difficult to trowel onto the non-horizontal surfaces of the cavity. Attempts at trowelling such com-positions on other than horizontal surfaces often results in severe tearing, sagging and general unmanageability of the applied product.
Accordingly, the invention provides a dry, settable, composition with a density after setting of less than 50 pounds per cubic foot containing a hydraulic cement, a lightweight, inert, low density, foraminous particulate aggregate selected from the group consisting of expanded vermiculite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said particulate material.
Thus, it has been found that the trowelability of such cementing compositions containing a hydraulic binder and lightweight foraminous aggre-gates such as expanded vermiculite, perlite, shale, etc., is enhanced by the incorporation therein of relatively small amounts of high molecular weight polymers of ethylene oxide. The presence of a small amount of such polymers was found to enable placement and trowelability of compositions having ratios of such aggregates to cement either too difficult or impossible to produce or place on non-horizontal surfaces.
Another aspect of the invention provides the method of constructing in-ground structures comprising the steps of: (a) forming a cavity in the ground having a desired configuration; (b) trowelling a smooth, wet mixture containing a hydraulic cement, a lightweight, inert, low density, foraminous, particulate aggregate selected from the group consisting of expanded vermicu-lite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, water, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said aggregate to enhance the trowelability of the wet mix over the interior surface of said cavity; and (c) thereafter placing a water-impermeable membrane over the trowelled mixture.
The compositions to which the ethylene oxide polymers are added
In the construction of in-ground swimming pools wherein a water-impermeable membrane such as a plastic film is employed as a liner, it is highly desirable to protect the membrane from being punctured by irregular-ities in the surface of the cavity, e.g. rocks or shale, against which the membrane is placed. One method of providing such protection is by pouring and screeding a layer of sand on the bottom or horizontal surface adjacent the liner. In another method, a layer of lightweight, inert foraminous part-iculate material such as expanded vermiculite, perlite, etc., is employed which not only covers the surface irregularities but also provides a more "cushioned" and less abrasive surface for the easily-perforated liner. On the non-horizontal surfaces of the cavity formed to receive the liner in in-ground pool construction, it has been the practice to trowel a layer of wet sand to provide the necessary protection. The applied sand, however, when dried has a tendency to fall off of the surface, exposing the liner to the rocks or other surface irregularities. To avoid this problem, a binder such as Portland cement can be mixed with the sand. A more advantageous protective coating can be prepared from a mixture of such a binder with the aforemention-ed lightweight foraminous material, for example, expanded vermiculite aggre-gate. Such a coating is less abrasive to the liner than sand and also has insulating properties that the sand coating does not. The foraminous material in the coating renders it porous thus permitting water which has seeped be-tween the liner and the coating to drain through the coating. The highly porous nature of the coating also protects it from being washed out by rising water tables during wet months of the year. The composition containing the -1- ~
~06Z~330 foraminous aggregates have however, been found to be difficult to trowel onto the non-horizontal surfaces of the cavity. Attempts at trowelling such com-positions on other than horizontal surfaces often results in severe tearing, sagging and general unmanageability of the applied product.
Accordingly, the invention provides a dry, settable, composition with a density after setting of less than 50 pounds per cubic foot containing a hydraulic cement, a lightweight, inert, low density, foraminous particulate aggregate selected from the group consisting of expanded vermiculite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said particulate material.
Thus, it has been found that the trowelability of such cementing compositions containing a hydraulic binder and lightweight foraminous aggre-gates such as expanded vermiculite, perlite, shale, etc., is enhanced by the incorporation therein of relatively small amounts of high molecular weight polymers of ethylene oxide. The presence of a small amount of such polymers was found to enable placement and trowelability of compositions having ratios of such aggregates to cement either too difficult or impossible to produce or place on non-horizontal surfaces.
Another aspect of the invention provides the method of constructing in-ground structures comprising the steps of: (a) forming a cavity in the ground having a desired configuration; (b) trowelling a smooth, wet mixture containing a hydraulic cement, a lightweight, inert, low density, foraminous, particulate aggregate selected from the group consisting of expanded vermicu-lite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, water, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said aggregate to enhance the trowelability of the wet mix over the interior surface of said cavity; and (c) thereafter placing a water-impermeable membrane over the trowelled mixture.
The compositions to which the ethylene oxide polymers are added
-2-- .~
according to the invention comprise a hydraulic cement binder such as Port-land cement to which is added the desired proportion of inert lightweight foraminous particulate aggregate, and sufficient water to give the desired fluidity to the wet mix. Expanded vermiculite is the preferred inert foraminous aggregate for use in the present invention. The exact proportion of foraminous aggregate employed will vary according to the desired degree of "cushion" wanted in the set coating but in general between about 1 and 25, preferably about 4 and 16 parts by volume of vermiculite will be employed per part by volume of cement. Also, the precise amount of water to be employed will also vary according to the degree of fluidity desired in the mix. Workable mixtures will, however, normally require the use of between about 2 and 5 gallons of water for each cubic foot of foraminous aggregate present. In addi~ion to expanded vermiculite, other inert lightweight foraminous particulate materials such as expanded perlite and expanded shale can be employed. The set compositions will generally have a dry density of less than about 50 lbs. per cubic foot, more often about 15 to 35 lbs. per cubid foot. Additional ingredients such as sand, air-entraining agents, etc., - 2a -can be employed in the compositions of the invention.
The ethylene oxide polymers useful in the invention are the well known water-soluble organic polymers having a molecular weight ranging from, e.g. lO0,000 to 6,000,000 or more. The polymers are preferably incorporated in the composition in finely divided form in an amount of from about 0.01 to about 2 percent, preferably from about 0.05 to about 1 percent by weight based on the inert lightweight foraminous aggregate present in the composit-ion. The preferred polymers for use in the invention have a molecular weight of less than 1,000,000 with polymers having a molecular weight in the range of about 100,000 to 400,000 being especially preferred.
The following examples serve to illustrate the invention.
Example To a paddle type mixer are added 25 gallons of water followed by one cubic foot of Portland cement. Eight cubic feet of expanded vermiculite to which had previously been added 100-110 cubic centimeters of a polymer of ethylene oxide having an approximate molecular weight of 200,000 is then slowly added while the mixer is rotated. After approximately one minute, the mixture is conveyed to an excavation in the ground formed to receive the lining element of an in-ground swimming pool. Following application of the wet mix by trowel, a smooth, porous, nonabrasive coating is formed having a compressive strength in the range of 90 to 125 pounds per square inch and a dry density of less than 50 pounds per cubic foot, the liner can be installed over the coating when either wet or dry.
The lightweight, low-density compositions of the invention have obvious utility in applications other than in-ground swimming pool construct-ion, for instance, as lightweight insulating concretes in roof, wall, etc., construction.
according to the invention comprise a hydraulic cement binder such as Port-land cement to which is added the desired proportion of inert lightweight foraminous particulate aggregate, and sufficient water to give the desired fluidity to the wet mix. Expanded vermiculite is the preferred inert foraminous aggregate for use in the present invention. The exact proportion of foraminous aggregate employed will vary according to the desired degree of "cushion" wanted in the set coating but in general between about 1 and 25, preferably about 4 and 16 parts by volume of vermiculite will be employed per part by volume of cement. Also, the precise amount of water to be employed will also vary according to the degree of fluidity desired in the mix. Workable mixtures will, however, normally require the use of between about 2 and 5 gallons of water for each cubic foot of foraminous aggregate present. In addi~ion to expanded vermiculite, other inert lightweight foraminous particulate materials such as expanded perlite and expanded shale can be employed. The set compositions will generally have a dry density of less than about 50 lbs. per cubic foot, more often about 15 to 35 lbs. per cubid foot. Additional ingredients such as sand, air-entraining agents, etc., - 2a -can be employed in the compositions of the invention.
The ethylene oxide polymers useful in the invention are the well known water-soluble organic polymers having a molecular weight ranging from, e.g. lO0,000 to 6,000,000 or more. The polymers are preferably incorporated in the composition in finely divided form in an amount of from about 0.01 to about 2 percent, preferably from about 0.05 to about 1 percent by weight based on the inert lightweight foraminous aggregate present in the composit-ion. The preferred polymers for use in the invention have a molecular weight of less than 1,000,000 with polymers having a molecular weight in the range of about 100,000 to 400,000 being especially preferred.
The following examples serve to illustrate the invention.
Example To a paddle type mixer are added 25 gallons of water followed by one cubic foot of Portland cement. Eight cubic feet of expanded vermiculite to which had previously been added 100-110 cubic centimeters of a polymer of ethylene oxide having an approximate molecular weight of 200,000 is then slowly added while the mixer is rotated. After approximately one minute, the mixture is conveyed to an excavation in the ground formed to receive the lining element of an in-ground swimming pool. Following application of the wet mix by trowel, a smooth, porous, nonabrasive coating is formed having a compressive strength in the range of 90 to 125 pounds per square inch and a dry density of less than 50 pounds per cubic foot, the liner can be installed over the coating when either wet or dry.
The lightweight, low-density compositions of the invention have obvious utility in applications other than in-ground swimming pool construct-ion, for instance, as lightweight insulating concretes in roof, wall, etc., construction.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A dry, settable, composition with a density after setting of less than 50 pounds per cubic foot containing an hydraulic cement, a lightweight, inert, low density, foraminous particulate aggregate selected from the group consisting of expanded vermiculite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said particulate material.
2. The composition of claim 1 wherein the said hydraulic cement is Portland cement.
3. The composition of claim 1 wherein the amount of said aggregate ranges from about 4 to 16 parts by volume per part by volume of said cement.
4. A wet, settable slurry containing an hydraulic cement, a light-weight, inert, low density, foraminous particulate aggregate selected from the group consisting of expanded vermiculite, expanded perlite and expanded shale in an amount of from about 1 to about 25 parts by volume per part by volume of said cement, water, and from about 0.01 to about 2 percent by weight of ethylene oxide polymer based upon the weight of said particulate material to enhance the trowelability of the wet mix.
5. The slurry of claim 4 wherein the amount of water present ranges between about 2 and 5 gallons per cubic foot of foraminous aggregate present.
6. The slurry of claim 4 wherein the amount of said ethylene oxide present ranges between about 0.05 and 1 percent by weight.
7. The mass of claim 1 wherein said polymer has a molecular weight of less than about 1 million.
8. The mass of claim 1 wherein the said polymer has a molecular weight of between about 100,000 and 400,000.
9. The method of constructing in-ground structures comprising the steps of: (a) forming a cavity in the ground having a desired configuration;
(b) troweling a smooth, wet mixture containing an hydraulic cement, a light-weight, inert, low density, foraminous, particulate aggregate selected from the group consisting of expanded vermiculite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, water, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said aggregate to enhance the trowelability of the wet mix over the interior surface of said cavity; and (c) thereafter placing a water-impermeable membrane over the trowelled mixture.
(b) troweling a smooth, wet mixture containing an hydraulic cement, a light-weight, inert, low density, foraminous, particulate aggregate selected from the group consisting of expanded vermiculite, expanded perlite and expanded shale in an amount of from about 1 to 25 parts by volume per part by volume of said cement, water, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based upon the weight of said aggregate to enhance the trowelability of the wet mix over the interior surface of said cavity; and (c) thereafter placing a water-impermeable membrane over the trowelled mixture.
10. The method of claim 9 wherein said cement is Portland cement.
11. The method of claim 9 wherein the particulate aggregate is expanded vermiculite and amount of water in the mixture ranges between about 2 and 5 gallons per cubic foot of vermiculite.
12. In the construction of in-ground structures wherein a water-imper-meable membrane is placed adjacent a cavity formed in the ground, the improve-ment which comprises forming a porous protective layer having a dry density of less than 50 pounds per cubic foot between said cavity and said membrane, said layer containing Portland cement, expanded vermiculite in an amount of from about 1 to 25 parts by volume per part by volume of said cement, and from about 0.01 to about 2 percent by weight of a polymer of ethylene oxide based on the weight of said particulate material.
13. A lightweight porous mass having a density of less than about 50 pounds per cubic foot and containing Portland cement, from about 1 to 25 parts by volume of expanded vermiculite per part by volume of said cement, and from about 0.01 to 1 percent by weight of a polymer of ethylene oxide based on the weight of vermiculite.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US45737874A | 1974-04-02 | 1974-04-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062830A true CA1062830A (en) | 1979-09-18 |
Family
ID=23816491
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA222,302A Expired CA1062830A (en) | 1974-04-02 | 1975-03-17 | Lightweight cement composition of enhanced trowelability |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1062830A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6290769B1 (en) | 1999-06-22 | 2001-09-18 | Siplast, Inc. | Lightweight insulating concrete and method for using same |
-
1975
- 1975-03-17 CA CA222,302A patent/CA1062830A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6290769B1 (en) | 1999-06-22 | 2001-09-18 | Siplast, Inc. | Lightweight insulating concrete and method for using same |
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