US1297080A - Method of mixing concrete and similar cementitious materials. - Google Patents

Description

H. P. BROWN. NG CONCRETE AND SIMILAR CEMENTITIOUSMATERIALS.

METHOD OF MIXI "APPLICATION FILED nc.24; I914.

' Patented Mar. 11,1919.

WITNESSES v gamma/r01? ATTORNEY HAROLD P. BROWN, OF NEW YORK, N. Y.

Specification of Letters Patent.

Application filed December 24, 1914. Serial No. 878,849.

To all whom it may concern.

Be it known that I, HAROLD P. BROWN, a citizen of the United States, and a resident .of the borough of Manhattan of the city of New York, in the State of New York, have invented certain new and useful Improveinents in Methods of Mixing Concrete and Similar Cementitious Materials, of which the following is a specification, reference being had to the accompanying drawing, forming a part hereof.

This invention, while concerned incidentally with the provision of new apparatus for carrying on the mixing of concrete, is concerned particularlywith a new and improved method for producing a cementitious conglomerate, composed generally of water,

' sand, stone and cement, or other suitable material'sfin proper proportions, which shall possess all of those properties which are generally recognized to be desirable in concrete. One of the greatest difliculties in placing concrete which shall be strong, hard and water-proof, is due to the time which usually elapses between the hydration and the set ting, it being well known that the sooner the concrete sets, the more effective the bond.

During the time of the conveying of the con.

crete from the mixer to the place where it is to be applied, it is evident that the n'uxture must remain as a plastic solid and no portion thereof must be permitted to set.

This plastic condition can be maintained by the presence of an excess of water which is undesirable for the reason that hydration is more effective when just the right amount of *water is combined with the constituents of the concrete. Or such plastic condition can be maintained by continuous mechanical agitation, stirring or other mixing, in a tube leading from the mixer to the Point of application. It is the object of this invention to improve the character of cement, not by shortening the elapsed time between the mixing and the placing (for that is obviously impossible) but by making it unnecessary to add an excessive amount of water to prevent premature setting. In accordance with the invention, the concrete is mixed in the presence of a hot elastic gaseous element under more or less pressure,which has the peculiar property of accelerating or assisting hydra tion during the mixing and of accelerating drying and crystallization after theconcrete is placed, the hydration being effected with just the right amount of water and the premature setting being prevented bythe peculiar action of this gaseous element on the mass. In practice, dry superheated steam has been found to be the most inexpensive and eliicient element, although as this description proceeds it will be evident that heated compressed air or gas will satisfy many of the specified requirements.

The steam at suitable pressure is piped source to assist the hydration during the mixing and appears to bring about some physical or chemical inter-action between the materials which, when hydration is completed, will maintain the plasticity of the mass until it is deposited at the desired place. The effect of the steam, the heat and the pressure on the concrete after placing seems to be to dry and crystallize it so that the setting is completed within a comparatively short time and a. very dense, nonporous and somewhat vitreous monolithic structure is developed.

Furthermore, the said dry superheated steam in addition to increasing the crystallizing process and maintaining the temperature during transit, also opens up the pores of the cement to perfectly hydrate it and opens up the pores oi; the sand and pebbles while Patented Mar. 11, 1919.

" into the mixer drum from any available I the pressure forces the perfectly hydrated I cement into these pores and hence produces a coating which adheres firmly to the sand and pebbles, causing them to compactly unite during the setting period.

Suitable apparatus for practising the imis rotated and the mixture therein thoroughly agitated. It will be obvious that any other form of apparatus for mixing theconcrete may be employed.

The trunnions a of the drum a are tubular in the illustrated embodiment and have connected thereto steam pipes f and f which are coupled to a steam supply. pipe 9 leading from. any available source of steam, such as the boiler h. To secure the be t results, it is desirable to have a superheater i interposed in the steam line a. drain pipe or separator 76 communicating With the line between the superheater and the boiler h. Suitable valves'are indicated generally at f f 9 and k, for controlling the passage of fluid through the respective portions of the system and an adjustable pressure regulating valve is shown at 9. For

instance, by means of the-valve it becomes v possible to regulate the quantity of steam Icy-passed through the super-heater t. The use of the remaining valves will be evident to one skilled in the art.

In operation, the materials are introduced into the drum n as through a trap a -'a-nd steam is admitted into the drum through the pipe connections 7', f, or through either one. Where the materials are at a. low temperature, it Will be desirable to pass steam through the drum for short time before the mixing operation is commenced.

As has been noted before, the presence or steam under pressure during the mixing ofthe materials has proved to be very effective in producing concrete With such properties as are recognized to be desirable. However, the presence of heat in some other "form dun ing this mixing ope-ration falls Within the scope of, this invention as the results obtained in practice are believed to be due partially to the presence of heat and pressure and partially to the use of an elastic gaseous element.

While the apparatus illustrated herein is believed to be new when considered with re spect to the interrelation or" the separate elements, it is obvious that modifications in the structure of each or" the elements and changes in the arrangement and connections be made Without departing from the ating conditions specified in the appended claims.

Although a variety of types of mixers may be used in'pertormin this method, mixers designed to raise the concrete materials and to then permit them to fall through the atmosphere of the gaseous medium and thus be completely subjected to the action thereof are round to be most suitable. Such mixers are those with blades secured to the interior of the rotary drum or those with agitating paddles.

In order to avoid excess'of Water in the concrete,. in case the steam is used as a gaseous medium, it is advisable to have dry "iper-heated steam. The super-heater and separator illustrated lend themselves readily to the production of'such steamu, in the absence of super-heater, steam of high pressure Wir -drawn to low pressure .through regulating valve, may also be used.

I claim as my invention:

1. The method of mixing concrete and similar cementitious material which consists in applying superheated steam to the ingredients during mixing.

2. The method of mixing concrete and similar cementitious material which consists in submitting the ingredients to be mixed to pressure and applying superheated steam to said ingredients during the mixing opera- 'tion.

This specification signed and witnessed this 7th day of December, A. D. 1914.

HABULD P. BROVJN.

Signed in the presence oi deems Costner.

Aurrronr Tnoarrson.

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