Gypsum-based floor underlayment
View Patent ↗A flooring composition for mixing with water to produce a self-leveling slurry that quickly hydrates to form a high strength floor underlayment comprising a dry mixture of (1) beta gypsum produced by a continuous method; (2) Class C fly ash; (3) a conventional water reducing aid such as sulfonated melamines, sulfonated naphthalenes and their related formaldehyde condensates, and (4) a conventional set retarder.
1. A dry blend of ingredients to be mixed with water to form a self-leveling slurry that hydrates to form a high strength flooring comprising:
(1) about 50 to 90% by weight of continuous beta gypsum hemihydrate;
(2) about 10 to 40% by weight of Class C fly ash
(3) about 0.01 to 10% by weight of a dispersing agent selected from the group consisting of sulfonated melamines, sulfonated naphthalenes, naphthalene sulfonate-formaldehyde condensates; melamine sulfonate-formaldehyde condensates and mixtures thereof; and
(4) about 0.02 to 1% by weight of a set retarder.
2. The dry blend of ingredients of claim 1 wherein the set retarder is sodium citrate.
3. The dry blend of ingredients of claim 1 containing alpha gypsum hemihydrate in an amount of up to 15% by weight.
4. The dry blend of ingredients of claim 1 containing calcium aluminate cement in an amount of up to 15% by weight.
5. A dry blend of ingredients to be mixed with water to form a self-leveling slurry that hydrates to form a high strength flooring, consisting essentially of:
(1) about 50 to 90% by weight of continuous beta gypsum hemihydrate;
(2) about 10 to 40% by weight of Class C fly ash
(3) about 0.01 to 10% by weight of a dispersing agent selected from the group consisting of sulfonated melamines, sulfonated naphthalenes, naphthalene sulfonate-formaldehyde condensates; melamine sulfonate-formaldehyde condensates and mixtures thereof; and
(4) about 0.02 to 1% by weight of a set retarder.
6. The dry blend of ingredients of claim 5 wherein the continuous beta gypsum hemihydrate is present in an amount of at least 60% by weight.
7. The dry blend of ingredients of claim 6 wherein the Class C fly ash is present in an amount of between 15 and 30 by weight.
8. The dry blend of ingredients of claim 7 wherein the dispersing agent is present in an amount of 0.05 to 1% by weight.