# US 5,704,972 A · Product and process for strong light-weight aggregate

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- Number: US 5,704,972 A
- Document ID: US5704972A
- Status: Granted
- Kind: A
- Application number: 08/787,605
- Filed: 1997-01-23
- Granted: 1998-01-06
- Earliest claimed: 1997-01-23
- Assignees: Trans Ash, Inc.
- Inventors: Daniel P. Ivkovich
- Web page: https://patentgrep.com/patent/US5704972A

## CPC

- C04B 18/027: {Lightweight materials}
- C04B 28/18: containing mixtures of the silica-lime type
- Y02W 30/91: Use of waste materials as fillers for mortars or concrete
- Y10S 106/01: Fly ash
- Y10S 264/49: Processes of using fly ash
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The present invention provides a method and mixture for use in forming strong light-weight aggregate and includes by weight about; 68% to 95% fly-ash, 2% to 10% hydrated lime, and 3% to 12% alkali hydroxide such as Sodium Hydroxide. While many types of fly-ash may be used, Type F or Type C fly-ash are preferred. The admix is mixed with water to form a slurry including water in a range of 10% to 25% by weight of the dry mixture and the slurry is then compacted. The compacted slurry is then cured such as by using a rotary kiln or by in situ open air curing. The cured slurry is then allowed to hydrolyzed to form a hard material which then may be crushed and optionally screened to form an aggregate having a particular size or range of sizes.

## Claims

### Claim 1

A method for making aggregate comprising:
(a) preparing a mixture comprising by weight about, 68% to 95% fly-ash, 2% to 10% hydrated lime, and 3% to 12% alkali hydroxide;
(b) preparing a slurry by adding water to the mixture of (a) in a range of 10% to 25%;
(c) compacting said slurry;
(d) introducing the compacted slurry into a rotary means to rotate the compacted slurry to form pellets; and
(e) removing the pellets from the rotary means and allowing them to hydrolyze.

### Claim 2 (depends on 1)

A method as claimed in claim 1 wherein step (d) comprises introducing the compacted slurry from step (c) into a rotary kiln wherein the compacted slurry is rotated and heated such that it is pelletized.

### Claim 3 (depends on 2)

A method as claimed in claim 2 wherein the slurry is compacted and introduced into the rotary kiln by way of an auger or an extruder.

### Claim 4 (depends on 2)

A method as claimed in claim 2 wherein the compacted slurry is rotated and heated for a period of time between 2 and 30 minutes and at a temperature between 150 and 1000 degrees Fahrenheit.

### Claim 5 (depends on 2)

A method as claimed in claim 2 further comprising the step of crushing the pellets to form the aggregate.

### Claim 6

A method for making aggregate comprising:
(a) preparing a mixture comprising by weight about, 68% to 95% fly-ash, 2% to 10% hydrated lime, and 3% to 12% alkali hydroxide;
(b) preparing a slurry by adding water to the mixture of (a) in a range of 10% to 25%;
(c) forming a compacted slurry in situ by spreading the slurry on a level surface and then compacting the slurry by rolling.

### Claim 7 (depends on 6)

A method as claimed in claim 6 wherein the slurry is compacted by rolling using a vibratory roller.

### Claim 8 (depends on 6)

A method as claimed in claim 6 further comprising the step of forming a hydrolyzed product by curing and hydrolyzing the compacted slurry in situ by letting the compacted slurry sit until it has cured, hydrolyzed, and hardened.

### Claim 9 (depends on 8)

A method as claimed in claim 8 further comprising the step of excavating the hydrolyzed product and crushing and screening the excavated hydrolyzed product to form the aggregate.

### Claim 10 (depends on 9)

A method as claimed in claim 9 wherein the hydrolyzed product has at least a 2000 PSI compression strength.