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

• US 3,927,163 A
• Filed: 12/19/1969
• Issued: 12/16/1975
• Est. Priority Date: 01/21/1969
• 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): Auville, Gene
• Application Number:
  US04/886,556
• Time in Patent Office: 2,188 Days
• Field of Search: 264/333,71,128,69 18/DIG.62
• US Class Current: 264/71
• CPC Class Codes: B28B 23/0081 Embedding aggregates to obtain particular properties
• CPC Class Codes: B28B 7/465 Applying setting liquid to dry mixtures
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 40/0028 Aspects relating to the mixing step of the mortar preparation
• CPC Class Codes: Y10S 264/43 Processes of curing clay and concrete materials
• CPC Class Codes: Y10S 425/012 Destructible mold and core

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 preordered 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. A METHOD FOR PREPARING CONCRETE COMPRISING DRY MIXING GRADED DRY AGGREGATE 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 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 CEMENT-FREE AGGREGATE, 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 AGGREGATE PARTICLES INTO DIRECT CONTACT WITH EACH OTHER AND THE CEMENT COMPOSITION PARTICLES INTO THE SPACES BETWEEN THE AGGREGATE PARTICLES, PROVIDING A POSITIVE ESCAPE PATH FOR THE AIR PRESENT IN THE COMPACTED DRY MIXTURE, ADDING WATER DISTRIBUTING IT WITH THE AID OF THE INHERENT CAPILLARY ACTION OF THE MIXTURE WHILE PREVENTING THE WATER FROM BLOCKING THE ESCAPE PATH ALONG 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 POSI:

TIVE ESCAPE PATH INTO THE ATMOSPHERE, THE AMOUNT OF WATER ADDED BEING DETERMINED BY 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, SAID CURING RESULTING IN PRELOADING OF THE POINTS OF CONTACT BETWEEN THE AGGREGATE PARTICLES BY VIRTUE OF SHRINKAGE OF THE HYDRATING CEMENT.

2. The method of claim 1 wherein:

the aggregate comprises both fine and cOarse aggregate, each well graded, the individual void spaces contained in the compacted dry coarse aggregate by itself are larger than the individual particles of the fine aggregate and can contain them, the void space contained in the compacted dry fine aggregate by itself being sufficient to contain all of the cement composition, the dry compacted volume of the fine aggregate being equal to no less than the volume of space in the voids in the dry compacted coarse aggregate, the bulk volume of the cement composition in the finished concrete being approximately equal to the bulk volume of total void space in the dry compacted cement-free fine aggregate.

3. The method of claim 2 wherein the cement composition in the finished concrete approaches its densest possible state.

4. The method of claim 2 wherein one component of said aggregate is much lighter in weight than another component thereof and the lighter-weight component is small enough in particle size so that the forces of apparent viscous drag in the fluid-like dry mixture before compaction exceed the apparent buoyancy forces in the dry mixture.

5. The method of claim 2 wherein one component of said aggregate is much lighter in weight than another component thereof and the size and quantity of the lightweight component are such that it can fit completely within the void spaces of said other component, the quantity and proportion of said other component being such that the particles thereof touch each other in the completed mix.

6. The method of claim 1 wherein the positive escape path is provided along mold surfaces and the water is added internally of said dry mixture and sweeps the air outwardly to said positive escape path.

7. The method of claim 1 wherein the positive escape path is provided along one face and the water is added to an opposite face only and sweeps the air out principally through said one face at said positive escape path.

8. The method of claim 7 wherein the water is added to the bottom of the mold, along watercourses provided by the mold and the top surface of the mixture is directly exposed to the atmosphere to provide the positive escape path.

9. The method of claim 1 wherein the water is added on a top surface, the step of adding water being preceded by covering the top surface with a layer of sand, to hold said top surface in place while the water is added.

10. The method of claim 1 comprising increasing the said preloading by accelerating the cure, thereby increasing compressive and flexural tensile strength of the finished concrete.

11. The method of claim 10 wherein said cement composition comprises a mixture of cement particles and filler particles of substantially the same order of particle size as the cement particles.

12. A method for preparing and molding concrete so as simultaneously to impart great strength per weight, minimize shrinkage, reduce porosity and give a superior as-molded surface, comprising dry mixing graded fine dry aggregate and graded coarse dry aggregate with cement composition in a preparation such that (1) the individual particles of the cement composition are uniformly smaller than the individual particles of the fine aggregate and are smaller than the individual void spaces between the adjacent fine aggregate particles of the cement-free dry compacted fine aggregate, (2) the individual particles of the fine aggregate are uniformly smaller than the individual particles of the coarse aggregate and are smaller than the individual void spaces between the adjacent coarse aggregate particles of the compacted dry coarse aggregate by itself and (3) 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 compacted cement-free fine aggregate, and so that the bulk volume of dry-compacted fine aggregate plus the dry compacted cement is approximately equal to no less than the bulk volume of void space in the compacted coarse aggregate, filling the mold with the resultant dry mixture, compacting the dry mixture in the mold substantially to restrain segregation, to achieve greater density of the cement, and to reduce the volume of void space in a geometrically stable particle configuration, by forcing the cement composition particles into the void spaces between the fine aggregate particles and filling the void spaces between the coarse aggregate particles with the fine aggregate particles, providing a positive escape path 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 that 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, which ceases when the initially remaining voids have had their air replaced with the water, and curing the geometrically stable resultant wet compact mixture in the mold until it has gained sufficient strength for safe removal, said curing resulting in preloading of the points of contact between the aggregate particles by virtue of shrinkage of the hydrating cement.

13. The method of claim 12 comprising interlocking the aggregate particles by employing aggregate particles that are generally angular in shape rather than well rounded.

14. The method of claim 12 wherein the cement composition is in a dry compacted state at the end of the compacting steps and approaches the densest possible state in the finished concrete.

15. The method of claim 12 wherein one component of said aggregate is much lighter in weight than another component thereof and the lighter-weight component is small enough in particle size so that the forces of apparent viscous drag in the fluid-like dry mixture before compaction exceed the apparent buoyancy forces in the dry mixture, thereby enabling molding without segregation of the component parts and providing a geometrically stable and constrained particle structure during the step of adding water.

16. The method of claim 12 wherein one component of said aggregate is much lighter in weight than another component thereof and the size and quantity of the lightweight component are such that, as a consequence of the compacting steps, the lighter-weight component fits completely, and is for all time constrained, within the void spaces of said other component, the quantity and proportion of said other component being such that the particles thereof touch each other in the completed mix.

17. The method of claim 12 wherein the positive escape path is provided along the top by direct exposure to the atmosphere and the water is added from the bottom.

18. The method of claim 17 wherein the adding of water is preceded by providing the bottom surface with a corrugated contact surface to aid in the distribution of the water.

19. The method of claim 17 wherein the adding of water is preceded by providing the bottom surface with a screened contact surface to aid in the distribution of the water.

20. The method of claim 12 wherein the positive escape path is provided along mold surfaces and the water is added through perforated conduits inside the mold and surrounded by the compacted dry mix.

21. The method of claim 20 wherein said conduits are directly surrounded by sand separating them from the compacted dry mix.

22. The method of claim 12 wherein said cement composition comprises a mixture of cement particles and filler particles of substantially the same order of particle size as the cement particles.

23. The method of claim 12 wherein the water is added to the top surface.

24. The method of claim 23 wherein the top surface is covered with a porous surcharged load before the water is added.

25. The method of claim 24 wherein the surcharged load is sand.

26. The method of claim 23 wherein the water is added slowly from one region only of said top surface at a rate slow enough to prevent water entrapment of the air in the mixture'"'"''"'"'s voids.

27. The method of claim 23 having the step of recomposing the top surface after the water is added and before curing.

28. The method of claim 27 wherein the recomposition is done by troweling.

29. The method of claim 12 wherein the step of adding water includes adding simultaneously means for accelerating the rate of hydration of the cement.

30. A method for molding concrete so as to simultaneously impart great strength per weight, minimize shrinkage, reduce porosity and give a superior as-molded surface, comprising adding cement composition to fine aggregate in a bulk volume approximately equal to the bulk volume of void space which would exist in the compacted cement-free fine aggregate, to make a dry mortar, the individual particles of the cement composition being uniformly smaller than the individual particles of the fine aggregate and being uniformly smaller than the individual void spaces between the adjacent fine aggregate particles of the cement-free compacted fine aggregate, adding said mortar to optimally graded coarse aggregate in a bulk volume approximately equal to at least the bulk volume of void space which would exist in the compacted mortar-free coarse aggregate, the individual particles of the fine aggregate being uniformly smaller than the individual particles of the coarse aggregate and smaller than the individual void spaces between the adjacent coarse aggregate particles of the compacted mortar-free coarse aggregate, dry mixing the cement composition and fine and coarse aggregates, filling the mold with the resultant dry mixture, compacting the dry mixture in the mold to minimize segregation and to achieve the optimum volume of void space in a geometrically stable particle configuration, by forcing the cement composition particles into the void spaces between the fine aggregate particles and filling the void spaces between the coarse aggregate particles with the mortar mix, providing a positive escape path for such air as remains in the compacted dry mixture, adding water and distributing it by the inherent capillary action of the dry mixture, while preventing plugging of the escape path wherever air remains to be displaced by the water, so that the water sweeps the air from the remaining voids and ejects that air by the positive escape path into the atmosphere, the amount of water added being determined and metered by the inherent capillary action, and curing the resultant geometrically stable wet compact mixture in the mold until it has gained sufficient strength for safe removal, said curing resulting in preloading the points of contact between the aggregate particles by shrinkage of the hydrating cement.

31. The method of claim 30 interlocking the aggregate particles by using aggregate particles that are generally angular in shape rather than well rounded.

32. The method of claim 30 wherein said curing is accelerated, thereby increasing flexural tensile strength and compressive strength due to extraordinary preloading of the points of contact between the aggregate particles by more rapidly hydrating the cement.

33. The method of claim 32 wherein said curing is accelerated by adding cure accelerators to the water before distributing it.

34. The method of claim 33 wherein said cement composition is made up of a mixture of cement and filler, both having substantially the same order of particle size.