Lightweight concrete compositions

1. A method of placing concrete comprising:

combining sand, one or more aggregates, cement, prepuff particles; water, and optionally a water reducer to form a mixture,

making the mixture in, or placing the mixture in a cement mixer truck;

mixing the mixture in the cement mixer truck while transporting the mixture from a central plant to a job site; and

discharging the mixture from the cement mixer truck at the job site;

wherein the mixture comprises:

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;

wherein the prepuff particles have an average particle diameter of from 0.2 mm to 5 mm, a bulk density of from 0.02 g/cc to 0.48 g/cc, a continuous outer layer, and an aspect ratio of from 1 to 3;

wherein the slump value of the mixture measured according to ASTM C 143 at the job site is from 2 to 8 inches.

2. The method according to claim 1 , wherein after the ready-mix concrete composition is set for 28 days, has a compressive strength of at least 1400 psi as tested according to ASTM C39.

3. The method according to claim 1 , wherein the prepuff particles comprise expanded polymer particles having an inner cell wall thickness of at least at least 0.15 μm.

4. 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.

5. The method according to claim 1 , wherein the prepuff particles comprise expanded polymer particles prepared by expanding a polymer bead having an unexpanded average resin particle size of from about 0.2 mm to about 2 mm.

6. 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.

7. The method according to claim 1 , wherein the composition comprises plasticizers and/or fibers.

8. The method according to claim 7 , 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.

9. 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.

10. The method according to claim 1 , wherein the mixture has a density of from about 40 to about 130 lb./ft 3 .

11. The method according to claim 1 wherein the water to cement ratio is greater than 0.40.

12. 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.

13. 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.