Road structure – process – or apparatus – Process – In situ treatment of earth or roadway
Patent
1985-11-29
1987-12-15
Leppink, James A.
Road structure, process, or apparatus
Process
In situ treatment of earth or roadway
404 97, 404103, 404117, E01C 1929, E01C 2100
Patent
active
047129433
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of levelling or smoothing concrete in the casting of large concrete areas, and to a machine intended herefor, said machine being adapted for movement over a concrete surface without the use of screed guide support means or like devices.
Concrete is today normally smoothed and levelled with the aid of finishing boards which run on a screed guide system comprising a plurality of beams. The assembly and dismantling of such screed guide systems is both laborious and time consuming, and hence expensive. When there is no particular demand for the surface of the concrete to be truly smoothed, the use of such a screed guide can be dispensed with, while in other cases the use of such a guide may prove difficult or impossible. The task of levelling or smoothing concrete by hand without the aid of screed guide support means is today effected with the use of a scraper or scraper-like implements, which are heavy to handle.
It is known to remove excess or surplus water from concrete surfaces by means of so-called vacuum treatment processes, in order to improve the quality of concrete in a concreted area and to accelerate hardening of the concrete. With present day vacuum-treatment techniques the concrete is treated in sections, with the aid of vacuum mats or plates which are moved from position to position over the concrete surface.
In addition to the aforesaid suction mats it is known from Swedish Pat. No. 137,965 to use in such vacuum treatment processes a device in the form of a small suction box adapted for movement over the surface of the concrete. When using this device it is only possible to vacuum treat a very small area of the concrete surface at a time; alternatively the device may possibly be used for continuous vacuum treatment while being moved over a very flat concrete surface. This latter alternative, however, assumes that the vacuum is maintained at an extremely low level, see for example Column 1, lines 44-46. A vacuum of this low level results in an excessively poor vacuuming effect when seen from a practical viewpoint. If a higher vacuum is used, however, the device is pressed firmly against the surface of the concrete by the atmospheric pressure and cannot be moved thereacross.
The German patent specification No. 709 278 describes a compacting vibratory device in the form of an extremely heavy belt-driven earth vibrator. This is intended for compressing and compacting masses in the construction of dams and like structures for example, and cannot be used to level or smooth fluid concrete.
The U.S. Pat. No. 2,025,703 describes a relatively heavy rotatable vibratory roller operative to compact a plastic or pliable stratum. According to FIGS. 6-11 of this patent it is possible to use two mutually connected rollers, with or without encircling belts. These rollers lie very close together and because of their weight function as a surface compactor. The sole purpose for using two rollers is to prevent material from flowing up behind the first, vibrating roller, cf. page 2, Col. 2, lines 9-17. The described device is adapted for use in conjunction with a plastic or pliable material which was generally used at the time of this patent. The modern concrete grades used today, however, have a much higher water content or contain plasticizers, which render the concrete grades highly fluid so that they behave almost as a liquid. Apparatus which operate in accordance with the aforesaid surface compacting principles cannot be used with concrete of such high fluid consistency, such concrete being far from plastic or pliable.
An object of the present invention is to provide a technique with which even highly fluid concrete masses can be levelled and smoothed without any appreciable manual contribution thereto and without the use of screed guide supports for strikers, punners or like devices. This object is achieved in accordance with the invention by smoothing or levelling the concrete with the aid of a machine so constructed that it floats lightly even on a highly fluid concret
REFERENCES:
patent: 699694 (1902-05-01), Longenecker
patent: 1945145 (1934-01-01), Gordon
patent: 2025703 (1935-12-01), Baily et al.
patent: 3515042 (1970-06-01), Austin
patent: 4088077 (1978-05-01), von Beckmann
Leppink James A.
Smith Matthew
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