BACKGROUND OF THE INVENTION

There exists various cementitious compositions, particularly plaster, and concrete or mortar mixes made therefrom. These substances are routinely used for a variety of patching applications, including filling exposed areas in airport runways, roadways, and the like. Additionally, they are used to finish the exterior surfaces of houses, roofs, as well as being favorably employed as light weight floors, and decking.

Depending on the nature that a particular cementitious composition is used for, it is often supplemented with chemicals that permit the composition to be employed for that particular application. Thus, plasticizing agents are often included because they tend to increase the strength of the cementitious composition, decrease the time it takes for the composition to set, and further contribute other desirable qualities. For instance, U.S. Patent No. 3,997,353 describes an early setting cement that neither substantially expands nor shrinks when used in a variety of purposes and contains calcium aluminate and calcium sulfate.

A key feature of any cementitious composition is its strength. One means whereby cementitious compositions are reinforced is to incorporate in them natural or synthetic fibers. For example, U.S. Patent No. 4,199,366 describes fiber reinforced cement-like material. Natural fibers such as cellulose, cotton and silk are well known, and have been widely used. Additionally, man-made fibers of polyamide, polyester, and polypropylene have also been used.

Generally, however, man-made fibers are better reinforcing agents when compared to their naturally occurring counterparts.

In addition to the fibers described above, adjuvants such as cellulose waste, wood chips, and other fillers are frequently added to reinforce cementitious compositions. Also, glass fibers, polyvinyl alcohol fibers, or mixtures of these can be employed as reinforcing additives. However, these latter fibers are ideal in instances where a significant degree of flexibility is sought in the final composition.

Additional elements found in cementitious compositions are an adhesive binder, sand, lime and clay. While silica sand is most convenient and inexpensive, a variety of different types of sands composed of siliceous materials can often be utilized. Generally, the sand must be of a particular particle size which enables the composition to be employed for a particular task. Most cementitious compositions incorporate an amount of lime sufficient to impart a degree of workability to the composition. Clay is further added to give the composition body, as well as to provide a surface for pigment absorption.

Despite the existence of numerous cementitious compositions, none of them exhibit high strength when applied in a thin layer, set rapidly, are long lasting, and are capable of retaining added colored pigments. Further, none of the presently available cementitious compositions can be used both to cover asphalt surfaces, as well act as a filler for patching holes in roads, runways and the like. Generally, if a cementitious composition has one or more

desirable properties, the composition is not rapid setting. Most cementitious compositions require weeks, if not months, to properly set.

SUMMARY OP THE INVENTION

A cementitious composition having sealing and patching properties, particularly useful for sealing surfaces of asphalt, cement or the like, or patching highways, airport runways and similar surfaces. It is composed of an adhesive bonder, vinyl acetate, a wood product, cement, clay, strengthening fibers, sand and lime, and water. Additionally, substances that facilitate application of the composition are included.

The components of the composition coact to form a resilient yet flexible material, particularly when applied as a thin layer, and have the appealing property of setting in as short a time as five minutes. Further advantages of the composition are that it is capable of pigment retention, thereby imparting to the composition a pleasing appearance. Moreover, by varying the amount of one or more components that comprise the composition, particular applications are enhanced, as well as the ease with which it can be employed in different environmental settings.

DETAILED DESCRIPTION OP THE INVENTION

The cementitious composition described herein is comprised of solids and liquids. These components can be kept separately, and combined prior to use to form the composition.

Solids comprising the composition are cement, clay, sand, fibers, and lime. It should be noted that a variety of different types of cements can be utilized. This includes Portland cement, alumina cement, iron Portland cement, trass cement and blast furnace cement.

The second solid component, clay, acts as a moisture filler, imparting to the composition body, and, moreover, provides an adhesive surface, particularly for dyes, should they be added to color the composition. The third solid component, fibers, are responsible for a significant amount of the strength, and partial flexible nature of the composition. It is anticipated that a variety of synthetic or naturally occurring fibers can be utilized. Typical natural fibers are cellulose, cotton, and silk. Man-made fibers are polyamide, polyester, and polypropylene.

Polypropylene fibers are particularly desirable because they impart a degree of strength and flexibility not found in the other fibers. Moreover, it is further desired that the polypropylene fibers should be approximately one-eighth to three-fourths inches long.

It should be noted that in addition to the above described fibers, it may also be possible to use glass fibers, particularly alkali-resistant glass fibers. However, because of the relatively high cost of these fibers, it is anticipated that they will not be routinely employed.

The fourth solid constituent, sand, primarily functions as an adhesive element, allowing for aggregation and setting of the cementitious composition when the latter is used to coat porous surfaces, roads, airport runways and the like. A variety of materials are usable under the term "sand."

While silica sand will most frequently be utilized because it is easy to obtain and inexpensive, other materials, silicas or non-silicas, may be favorably employed. Examples of non-silicas materials.include, but are not limited to, fly ash, and volcanic glasses. If silica sand is utilized, it is preferred that it be 90 grit - 16 grit in size. This size distribution has been found to be particularly favorable for numerous applications of the cementitious composition. However, it should be noted that by varying the size of the sand particles, it may be possible to extend the uses of the composition to instances where it may coat, or act to fill holes in surfaces that can be similarly repaired with conventional cementitious compositions.

The final solid component is lime. It is anticipated that lime will be added to the composition for most uses; however, it should be noted that it may be omitted without affecting the overall properties of the composition. The function of lime is twofold; first, its interaction with the other components of the composition considerably increases the workability of the composition. And, second, it enhances the cover retention properties of the composition. In the former instance, for some applications, lime will not increase the workability of the composition because of its tendency to incorporate air. The second category of components, or liquids, comprises an adhesive bonder, a wood product soil stabilizer, and optionally, a liquid additive for enhancing the fluid quality of the cementitious composition, thereby enabling it to be readily applied, particularly if the composition is pumped.

A variety of common bonders can be utilized in the cementitious composition. Most of these are sold under trade names well known to those in the art. Similarly, there exists a large number of liquid additives that facilitate pumping the composition. A further benefit associated with the use of such additives is that they simultaneously act as low-foaming agents, and heat retardants. The former feature is particularly attractive in those instances where the composition is applied via pumping. A number of liquid additives are shown in D.S. Patent

No. 4,265,674. Additionally, a further liquid additive that performs satisfactorily is sold under the trade name of Vinyl Glaze, (Tibbetts Co., Santa Ana, California). Vinyl Glaze is predominantly vinyl acetate. It is particularly desirable to add Vinyl Glaze in those instances where the cementitious composition is applied in warm climates.

The third liquid additive comprises a variety of what are known in the art as soil stabilizers. When added to the composition, they increase its strength and hardness. Moreover, they considerably decrease the cure time of the composition for particular applications. Indeed, the cure time for patches is reduced from weeks to hours. Suitable soil stabilizers are sold under the trade names GP or GPS (Cold Bond Co.) . The solid and liquid components can be kept separate until just prior to use, whereupon they are combined in the presence of water and mixed, followed by the addition of further water. The mixture is stirred, agitated, or similarly treated to effect a homogeneous composition and thereafter employed for a particular job.

It is important to note that by varying the amounts of the various solids or liquids, it is possible to impart to the composition properties that favor its use for a particular application. However, for most uses the formulation will be about: 15 gallons bonder

15 gallons wood product (soil stabilizer) 500-600 lbs. cement 600-1000 lbs. sand 2 lbs. fiber

50 lbs. lime (optional)

10 gallons Vinyl Glaze additive (optional) water to 200 gallons The composition can be applied using a variety of techniques, each of which will be suitable for a particular job application. Thus, it is anticipated that it will be either poured, pumped, or sprayed, depending on whether it is being used to fill holes, seal surfaces, or the like. Recall that the applicability of the composition is facilitated in particular weather environments by the addition of organic additives which aid in its fluid application. Thus, it is anticipated that chemicals sold under the trade name Vinyl Glaze will be added to the composition should it be pumped or sprayed. The latter additives can be added to the composition after the other components have already been prepared.

It will be further noted that by varying the amounts of either the powder or liquid components, the composition can be optimally suited for specific applications. For instance, if the composition is used to seal a relatively

smooth asphalt surface, it can be applied about 1/64 of an inch thick. However, should the surface exhibit discontinuities, particularly pitting and the like, then proportionally more sand, or sand with different grit size is anticipated to be favorably employed.