Plastic and nonmetallic article shaping or treating: processes – Direct application of electrical or wave energy to work – Producing or treating inorganic hydro-settable material
Reexamination Certificate
1999-08-02
2004-08-24
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of electrical or wave energy to work
Producing or treating inorganic hydro-settable material
C264S069000, C264S071000, C264S162000, C264S256000, C264S333000
Reexamination Certificate
active
06780369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention generally relates to a method for finishing a plastic concrete mixture. More particularly, the present invention relates to a method for introducing and consolidating a dry shake aggregate additive into plastic concrete mixtures using a vibrational finishing tool.
2. Description of the Prior Art
In constructing concrete structures, such as concrete slabs and the like, certain conventional procedures involve placing a plastic concrete mass inside of a form and finishing the top surface in various well known manners and permitting the concrete to harden with no vibration of the concrete mass whatsoever. Other procedures involve the use of vibrators placed temporarily into or upon the concrete mass at various locations, with the surface being finished by using various combinations of striking off the surface and/or troweling operations, including the use of hand trowels, powered rotary trowels and the like. It is also generally known that, if not worked, the surface of wet concrete would take on a highly undesirable rough and uneven finish which, after partial setting of the concrete, would render the surface difficult if not impossible to finish to the desired smooth and even consistency.
The conventional process for pouring and finishing concrete is labor intensive and consists of the steps of:
1. Pouring fresh concrete into forms.
2. Screeding or striking off the concrete to preliminarily level the surface of the concrete.
3. Tamping the concrete i.e., with a bull float or similar device to bring the finer aggregates to the surface.
4. Applying a “dry shake” aggregate to harden and/or color the concrete.
5. Moving a bull float over the surface of the wet concrete to mix the “dry shake” with the upper layer of the concrete.
6. Moving another rectangular tool such as a hand trowel or fresno, over the bull floated concrete.
7. Allowing the concrete to dry an amount sufficient to support the weight of an individual.
8. Utilizing a power trowel to put a smooth finish on the surface of the concrete.
The above described conventional method of finishing concrete is labor intensive. Accordingly, it would be very desirable to provide an improved method for finishing concrete that would permit concrete to be finished in a substantially shorter period of time. It would also be desirable to provide a method that would permit concrete to be finished with a surface which is very level, and would produce a highly polished surface finish. Therefore, it is a principal object of the invention to provide an improved method and apparatus for finishing freshly poured concrete.
After concrete is initially laid, it must be worked while it is wet in order to provide a smooth, homogeneous mixture. Working the concrete helps settle the concrete and helps densify and compact the concrete during finishing. The working also removes air voids and brings excess water and fine aggregates to the surface for subsequent finishing. After the initial finishing stages are complete, a more detailed work frequently commences, generally by means of a hand-held float to further compact the concrete for purposes including the driving of suspended gravel downwards. This floating help develop a wetted surface slurry or soup-like finish, while further driving out air pockets and the like for preparing the surface for final finishing. A bull float is most often used for this stage of compacting and smoothing the concrete. The bull float is a rectangular piece of material made from pinewood, magnesium or material other than iron or steel. (Iron “seals” concrete, which is not desirable during initial floating).
This floating is often accompanied by some sort of vibration of the concrete. In the above-described process, various large vibrating devices may be beneficially employed. Illustrative embodiments of such large vibrating tampers or the like may be seen in U.S. Pat. No. 3,306,174 to Wardell, U.S. Pat. No. 2,289,248 to Davis, U.S. Pat. No. 1,955,101 to Sloan, and U.S. Pat. No. 2,209,965 to Mall. These devices generally include a rather large flat base plate, a heavy and bulky vibratory mechanism disposed thereon, and an elongate handle attached thereto for moving the large plate across the concrete surface. Such devices are generally intended to provide a general smoothing and compacting operation over a large area.
After the concrete is floated, and a slurry forms, the surface of the concrete has a slight water sheen. The water sheen will evaporate from the surface of the concrete, leaving no apparent water sheen on the concrete surface. The speed of evaporation is dependent on ambient conditions such as temperature, humidity and exposure to wind or direct sunlight. It is at this point, i.e., when the water sheen has just disappeared from the concrete surface, that a “dry shake” hardener may be applied to the concrete.
In the related art, diverse attempts have been made to control and modify the characteristics including the surface characteristics of concrete flooring, road beds or the like with different types of additives. U.S. Pat. No. 4,746,788, to Shaw et al discloses a process for producing a concrete surface of seeded exposed aggregate using small, rounded aggregate (preferably sand) which is broadcast over the upper surface of the pour and thereafter mixed into the cement paste of the concrete pour matrix. A surface retarder and vapor barrier is applied for a short-term (approximately 4 to 24 hours) and removed and the concrete is thereafter cured by fogging or with a soaker hose and, after approximately 30 days, the surface residue is removed with a steam/acid wash to expose the finished floor.
Another method of producing a sand/cement upper surface is disclosed in U.S. Pat. No. 4,281,496, to Danielsson in which larger aggregate is allowed to settle, producing a thin upper layer formed substantially of sanded cement which is thereafter floated to remove surface irregularities. After curing 1 to 5 days, the upper surface is treated in a grinding operation to produce a flat, porous surface having a sanded quality.
Another technique involves the application of an excessively dry top dressing mix while the concrete base is still wet. Water rising from the base concrete penetrates into the topping and the two bond together. The top stratum of the conglomerate can then be wetted and floated to achieve a smooth finish. Such a system is shown by Sloan in U.S. Pat. No. 2,078,289. Reardon, in U.S. Pat. No. 2,853,928, discloses a method for curing concrete in which a dry powder composition is spread over the top of the wet concrete to absorb the excess moisture. The dry powder, however, is not blended into the concrete base and after the concrete is cured for a sufficient length of time, the dry powder is removed by vacuuming or sweeping. That composition is approximately 80 parts silica and about 20 parts salt. It is further known to apply a dry shake into a concrete base to control the concrete surface moisture. The dry shake may be incorporated to produce a monolithic cementitious floor by using various processes.
The American Concrete Institute (ACI) has approved an application procedure (No. 302) for adding a dry shake hardener to concrete. This procedure includes the following steps. Immediately after the slab surface has been floated, the first shake is applied in a uniform application by hand, spreader or other suitable method placing the material on the edges of the slab first. A mechanical spreader gives better results and is highly recommended. The first shake is allowed to remain unworked on the surface until it has absorbed moisture as evidenced by a change to a darker color. Then, it is floated with a hand or power float. Immediately after floating in the first shake, the second shake is applied, again placing the material on the edges of the slab first. The second shake is applied and floated in a like manner.
A problem with prior methods of finishing concrete is that moisture may evaporate quickly from the surface of the concrete suc
Darrow Darrell
Davis Michael
Face, Jr. Samuel A.
Francis David
Rogers, Jr. Glenn F.
Bolouc David J.
Clark Stephen E.
Face International Corp.
Poe Michael I.
Silbaugh Jan H.
LandOfFree
Method of finishing plastic concrete mixture does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of finishing plastic concrete mixture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of finishing plastic concrete mixture will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3360299