Lightweight concrete compositions
A lightweight ready-mix concrete composition that contains 8-20 volume percent cement, 11-50 volume percent sand, 10-31 volume percent prepuff particles, 9-40 volume percent coarse aggregate, and 10-22 volume percent water, where the sum of components used does not exceed 100 volume percent. The prepuff particles have an average particle diameter of from 0.2 mm to 8 mm, a bulk density of from 0.02 g/cc to 0.64 g/cc, an aspect ratio of from 1 to 3. The slump value of the composition measured according to ASTM C 143 is from 2 to 8 inches. After the lightweight ready-mix concrete composition is set for 28 days, it has a compressive strength of at least 1400 psi as tested according to ASTM C39.
1. A method of controlling air entrainment in an article formed from a ready-mix concrete composition comprising:
forming a concrete composition by:
combining one or more aggregates, cement, water, and optionally a water reducer to form a mixture, and
adding prepuff particles that contain void spaces that contain air to the mixture; and
placing the mixture in a form;
wherein the mixture comprises:
8-20 volume percent cement,
11-50 volume percent fine aggregate,
10-31 volume percent prepuff particles,
9-40 volume percent coarse aggregate, and
10-22 volume percent water;
wherein the prepuff particles are prepared by expanding a polymer bead having an unexpanded average resin particle size of from about 0.2 mm to about 1 mm to form prepuff particles that have an average particle diameter of from 0.2 mm to 2.5 mm, a bulk density of from 0.02 g/cc to 0.32 g/cc, an inner cell wall thickness of at least at least 0.15 μm, and an aspect ratio of from 1 to 3;
wherein the void spaces in the prepuff particles entrain air in a structurally supportive manner; and
wherein the slump value measured according to ASTM C 143 is from 2 to 8 inches;
wherein after the ready-mix concrete composition is set for 28 days, has a compressive strength of at least 1800 psi as tested according to ASTM C39.
2. The method according to claim 1 , wherein the prepuff particles have a substantially continuous outer layer.
3. The method according to claim 1 , wherein the particles comprise expanded polymer particles comprising one or more polymers selected from the group consisting of homopolymers of vinyl aromatic monomers; copolymers of at least one vinyl aromatic monomer with one or more of divinylbenzene, conjugated dienes, alkyl methacrylates, alkyl acrylates, acrylonitrile, and/or maleic anhydride; polyolefins; polycarbonates; polyesters; polyamides; natural rubbers; synthetic rubbers; and combinations thereof.
4. The method according to claim 1 , wherein the cement comprises one or more materials selected from the group consisting of Portland cements, pozzolana cements, gypsum cements, gypsum compositions, aluminous cements, magnesia cements, silica cements, slag cements, Type I cement, Type IA cement, Type II cement, Type IIA cement, Type III cement, Type IIIA cement, Type IV cement and Type V cement.
5. The method according to claim 1 , wherein the composition comprises plasticizers and/or fibers.
6. The method according to claim 5 , wherein the fibers are selected from the group consisting of glass fibers, silicon carbide, aramid fibers, polyester, carbon fibers, composite fibers, fiberglass, combinations thereof, fabric containing said fibers, and fabric containing combinations of said fibers.
7. The method according to claim 1 , wherein the coarse aggregate is selected from the group consisting of stone, gravel, ground granulated blast furnace slag, fly ash, glass, silica, expanded slate, clay; pumice, perlite, vermiculite, scoria, diatomite, expanded shale, expanded clay, expanded slag, fumed silica, pelletized aggregate, extruded fly ash, tuff, macrolite, slate, expanded blast furnace slag, sintered fly ash, coal cinders, and combinations thereof.
8. The method according to claim 1 , wherein the fine aggregate comprises sand.
9. The method according to claim 1 , wherein the mixture has a density of from about 40 to about 130 lb./ft 3 .
10. The method according to claim 1 wherein the water to cement ratio is greater than 0.40.
11. The method according to claim 1 , wherein the mixture comprises one or more adjuvants and fillers selected from the group consisting of clay, fly ash, air entrainment agents, colorants, and superplasticizers.
12. The method according to claim 1 , wherein the water reducer is selected from the group consisting of lignosulfonates, sodium naphthalene sulfonate formaldehyde condensates, sulfonated melamine-formaldehyde resins, sulfonated vinylcopolymers, urea resins, and salts of hydroxy- or polyhydroxy-carboxylic acids, and combinations thereof.
13. The method according to claim 1 , wherein the mixture is formed in a pan or drum style mixer.
14. The method according to claim 1 , wherein the article is a roadbed.
15. The method according to claim 1 , wherein the article is a wall panel.
16. The method according to claim 1 , wherein the article is a tilt-up wall panel.
17. The method according to claim 1 , wherein the article is a T beam.
18. The method according to claim 1 , wherein the article is a double T beam.
19. The method according to claim 1 , wherein the article is an I beam.
20. The method according to claim 1 , wherein the article is a roofing tile or roof panel.
21. The method according to claim 1 , wherein the article is a ceiling panel or floor panel.
22. The method according to claim 1 , wherein the article is a foundation wall.
23. The method according to claim 1 , wherein the ready-mix concrete composition is substantially free of air entraining agents.