Method for in-situ manufacture of a lightweight fly ash based aggregate
First Claim
1. A method of making loose aggregate particles consisting of the steps of:
- forming a mixture by mixing ingredients consisting essentially of;
water,cementitious reactive powder consisting essentially of fly ash and a calcium sulfate selected from the group consisting of calcium sulfate hemihydrate, calcium sulfate dihydrate, and mixtures thereof, and optional silica fume,an alkali metal salt of citric acid selected from the group consisting of sodium citrate, potassium citrate and mixtures thereof,a foaming agent, andoptionally at least one or more member selected from the group consisting of secondary aggregate other than said loose aggregate, superplasticizer, set accelerating agents other than said alkali metal salt of citric acid, set retarding agents, shrinkage control agents, thickening agents, coloring agents, and internal curing agents, andreacting the mixture in situ at a temperature of about 20°
C. to 41°
C. by mixing for about 3 to 6 minutes to form aggregate particles comprising hydration products of the fly ash and calcium sulfate in the mixture and crystalline hydration products of the fly ash and calcium sulfate which are also formed in situ and are interspersed within and between the aggregate particles to bind the aggregate particles, andseparating the aggregate particles as loose aggregate particles from the mixture.
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Abstract
A method of making a rapid setting lightweight homogeneous foamed fly ash based cementitious aggregate composition with improved compressive strength for products such as panels is disclosed. The method mixes fly ash, alkali metal salt of citric acid, foaming agent for entraining air, optional foam stabilizing agent, a calcium sulfate such as stucco or gypsum, and water. Compositions are also disclosed which include mixtures of fly ash, particularly Class C fly ash alone or in mixtures with Class F fly ash, alkali metal salts of citric acid, foaming agents, a calcium sulfate such as calcium sulfate dihydrate or hemihydrate and an optional portland cement.
16 Citations
20 Claims
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1. A method of making loose aggregate particles consisting of the steps of:
forming a mixture by mixing ingredients consisting essentially of; water, cementitious reactive powder consisting essentially of fly ash and a calcium sulfate selected from the group consisting of calcium sulfate hemihydrate, calcium sulfate dihydrate, and mixtures thereof, and optional silica fume, an alkali metal salt of citric acid selected from the group consisting of sodium citrate, potassium citrate and mixtures thereof, a foaming agent, and optionally at least one or more member selected from the group consisting of secondary aggregate other than said loose aggregate, superplasticizer, set accelerating agents other than said alkali metal salt of citric acid, set retarding agents, shrinkage control agents, thickening agents, coloring agents, and internal curing agents, and reacting the mixture in situ at a temperature of about 20°
C. to 41°
C. by mixing for about 3 to 6 minutes to form aggregate particles comprising hydration products of the fly ash and calcium sulfate in the mixture and crystalline hydration products of the fly ash and calcium sulfate which are also formed in situ and are interspersed within and between the aggregate particles to bind the aggregate particles, andseparating the aggregate particles as loose aggregate particles from the mixture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of making loose aggregate particles consisting of:
forming a mixture by mixing ingredients consisting of; water, cementitious reactive powder consisting of fly ash, optional hydraulic cement, optional non-fly ash mineral additive, optional added lime, a calcium sulfate selected from the group consisting of calcium sulfate hemihydrate, calcium sulfate dihydrate, and mixtures thereof, and optional silica fume, an alkali metal salt of citric acid selected from the group consisting of sodium citrate, potassium citrate and mixtures thereof, a foaming agent, and optionally at least one or more member selected from the group consisting of secondary aggregate other than said loose aggregate, superplasticizer, set accelerating agents other than said alkali metal salt of citric acid, set retarding agents, shrinkage control agents, thickening agents, coloring agents, and internal curing agents, and reacting the mixture in situ at a temperature of about 20°
C. to 41°
C. by mixing for about 3 to 6 minutes to form aggregate particles comprising hydration products of the fly ash and calcium sulfate in the mixture and crystalline hydration products of the fly ash and calcium sulfate which are also formed in situ and are interspersed within and between the aggregate particles to bind the aggregate particles, andseparating the aggregate particles as loose aggregate particles from the mixture.
Specification