Altering the properties of concrete by altering the quality or geometry of the intergranular contact of filler materials

• US 3,917,781 A
• Filed: 06/21/1972
• Issued: 11/04/1975
• Est. Priority Date: 12/19/1969
• Status: Expired due to Term

• Current Assignee: Lester H. Gabriel, Wilfred Ernest Willis
• Original Assignee: Lester H. Gabriel, Wilfred Ernest Willis
• Inventors: Gabriel, Lester H., Willis, Wilfred Ernest
• Primary Examiner(s): White, Robert F.
• Assistant Examiner(s): Hoag, Willard E.
• Application Number:
  US05/264,785
• Time in Patent Office: 1,231 Days
• Field of Search: 264/69,71,72,240,DIG.43,333,256,232,340 106/97,98,112,120
• US Class Current: 264/71
• CPC Class Codes: B28B 23/0081 Embedding aggregates to obtain particular properties
• CPC Class Codes: C04B 40/0028 Aspects relating to the mixing step of the mortar preparation

Abstract

A method for preparing and molding concrete so as to impart great strength per weight, minimize or otherwise alter shrinkage and creep, reduce porosity and give a superior as-molded surface. Aggregates are dry mixed with cement (or cement-filler mixture) in a preparation such that the bulk volume of dry cement (or cement-filler mixture) is approximately equal to the volume of void space which the aggregates would have if the cement were not present. A mold is filled with the resultant dry mixture, the ingredients of which are so proportioned that a particular geometry of particle contact is achieved upon compaction. The quality and geometry of this contact (coupled with the properties of the particular filler materials) determine the properties of the finished product. Then, with no disturbance to this compacted structure of particle contact, water is injected and distributed by a self-metering process dependent upon capillary action which itself is dependent upon the geometry of particle contact. With the assistance or opposition of gravitational forces and with or without increased pressure differential, this water is introduced in a manner such that the water sweeps the air from the remaining voids and ejects that air into the atmosphere. The resultant wet, compact mixture is then cured in the mold or forms.

Claims

1. IN A METHOD FOR PREPARING CONCRETE WHEREIN GRADED DRY AGGREGATE IS DRY MIXED WITH DRY CEMENT COMPOSITION IN A PREPARATION SUCH THAT (1) THE INDIVIDUAL PARTICLE OF THE CEMENT COMPOSITION ARE UNIFORMLY SMALLER THAN THE INDIVIDUAL PARTICLES OF THE AGGREGATE AND ARE SMALLER THAN THE INDIVIDUAL VOID SPACES BETWEEN THE ADJACENT AGGREGATE PARTICLES OF THE CEMENT-FREE DRY COMPACTED AGGREGATE, AND (2) THE BULK VOLUME OF DRY COMPACTED CEMENT COMPOSITION IN THE FINISHED CONCRETE IS APPROXIMATELY EQUAL TO THE BULK VOLUME OF TOTAL VOID SPACE IN TE DRY COMPACTED CEMENT-FREE AGGREGATE, THE MOLD THEN FILLED WITH THE RESULTANT DRY MIXTURE, AND THE DRY MIXTURE COMPACTED IN THE MOLD TO REDUCE SUBSTANTIALLY THE

2. The method of claim 1 wherein said vertical vibrating at low frequency is accompanied by horizontally vibrating said dry mixture at a high-frequency rate at least as great as 4000 cycles per minute.

3. The method of claim 2 wherein said horizontal high-frequency vibrating is accompanied by applying vertical pressure to said dry mixture.

4. In a method for preparing concrete wherein graded dry aggregate is dry mixed with dry cement composition in a preparation such that (1) the individual particles of the cement composition are uniformly smaller than the individual particles of the aggregate and are smaller than the individual void spaces between the adjacent aggregate particles of the cement-free dry compacted aggregate, and (2) the bulk volume of dry compacted cement composition in the finished concrete is approximately equal to the bulk volume of total void space in the dry compacted cementfree aggregate, the mold filled with the resultant dry mixture, and the dry mixture in the mold compacted to reduce substantially the volume of void space and to force the aggregate particles into direct contact with each other and the cement composition particles into the spaces between the aggregate particles, preparatory to adding water and curing the resultant wet compact mixture, the improvement in which the compacting step comprises vibrating said dry mixture horizontally at a high frequency rate of at least 4000 cycles per minute.

5. The method of cLaim 4 wherein the vibrating is accompanied by applying vertical pressure to said dry mixture.

6. The method of claim 4 wherein the vibrating is followed by applying vertical pressure to said dry mixture.

7. A method for preparing concrete, comprising dry mixing a graded dry sand with dry hydraulic cement in a preparation such that (1) the individual cement particles are uniformly smaller than the individual sand particles and are smaller than the individual void spaces lying between the adjacent sand particles, when the sand is compacted, and (2) the bulk volume of dry compacted cement in the finished concrete is approximately equal to the bulk volume of total void space in the dry compacted sand, filling the mold with the resultant dry mixture, compacting the dry mixture in the mold to reduce substantially the volume of void space and to force the sand particles into direct contact with each other and the cement particles into the spaces between the sand particles, providing a positive escape path to the surrounding atmosphere for the air present in the compacted dry mixture, adding water and distributing it with the aid of the inherent capillary action of the mixture while preventing the water from blocking the escape path as long as there is air to escape by it, so that the water sweeps the air from the remaining voids and ejects that air by means of the positive escape path into the atmosphere, the amount of water added being determined by the final volume of the void space and the inherent capillary action, which ceases when the initially remaining voids have had their air replaced with the water, and curing the resultant wet compact mixture in the mold until it has gained sufficient strength for safe removal, whereby the shrinkage of the hydrating cement during curing results in preloading the points of contact between the sand particles.

8. A method for preparing and molding concrete so as simultaneously to impart great strength per weight, miminize shrinkage, reduce porosity and give a superior asmolded surface, comprising dry mixing graded dry sand and graded dry gravel with dry hydraulic cement in a preparation such that (1) the individual particles of cement are uniformly smaller than the individual sand particles and are smaller than the individual void spaces between the adjacent sand particles of the cementfree dry compacted sand, (2) the individual sand particles are uniformly smaller than the individual gravel particles and are smaller than the individual void spaces between the adjacent gravel particles of the compacted dry gravel by itself, (3) the bulk volume of dry compacted cement in the finished concrete is approximately equal to the bulk volume of total void space in the compacted cement-free sand, and (4) the bulk volume of the combined dry compacted sand and dry compacted cement is approximately equal to no less than the bulk volume of void space in the compacted gravel, filling the mold with the resultant dry mixture, compacting the dry mixture in the mold while inhibiting segregation, to achieve greater density of the cement, and to reduce the volume of void space, forcing the cement particles into the void spaces between the sand particles and at least filling the void spaces between the gravel particles with the sand particles, providing a positive escape path to atmosphere for such air as is present in the compacted dry mixture, adding water and distributing it with the aid of the inherent capillary action of the mixture while preventing the water from blocking the escape path as long as there is air requiring escape, so that the water sweeps the air from the remaining voids and ejects the air by means of the positive escape path into the atmosphere, the amount of water added being determined and metered by the inherent capillary action and the final volume of the void space, the addition of water ceasing when the initially remaining voids hAve had their air replaced with the water, and curing the resultant wet compact mixture in the mold until it has gained sufficient strength for safe removal, whereby the shrinkage of the hydrating cement during curing results in preloading the points of contact between the sand and the gravel particles.