Method of making concrete

1. A method of preparing a light weight concrete composition using expanded polymer particles comprising:

a) replacing from about 10 to about 50 volume percent of the coarse aggregate in the concrete composition with prepuff particles; and

b) preparing the concrete composition by combining ingredients comprising 3-40 volume percent cement, 1-50 volume percent fine aggregate having a fineness modulus of less than 4, 0-40 volume percent coarse aggregate having a fineness modulus of greater than 4, 10-22 volume percent water, and 5-40 volume percent of prepuff particles;

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 0.56 g/cc, an aspect ratio of from 1 to 3;

wherein the concrete composition has a density of from about 1.4 to about 2.1 g/cm 3 ; and

wherein after the concrete composition is set for 28 days, has a compressive strength of at least 126 Kg/cm 2 as tested according to ASTM C39.

2. The method according to claim 1 , wherein the prepuff particles have a continuous outer layer.

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 in the concrete composition 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 concrete 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, steel fibers, 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, pumice, perlite, vermiculite, scoria, diatomite, expanded shale, expanded clay, expanded slag, pelletized aggregate, tuff, macrolite, slate, expanded blast furnace slag, sintered fly ash, coal cinders, and combinations thereof.

10. The method according to claim 1 , wherein the water to cement ratio in the concrete composition is greater than 0.30.

11. The method according to claim 1 comprising combining the sand, coarse aggregate, cement, prepuff particles, water, and optionally a water reducer in a pan or drum type mixer.

12. A method of preparing a light weight concrete composition using expanded polymer particles comprising:

a) replacing from about 10 to about 50 volume percent of the coarse aggregate, having a fineness modulus of greater than 4, in the concrete composition with prepuff particles;

b) maintaining a fine aggregate, having a fineness modulus of less than 4, to total aggregate ratio of 0.5 to 0.8; and

b) preparing the concrete composition by combining ingredients comprising 3-40 volume percent cement, 1-50 volume percent fine aggregate, 0-40 volume percent coarse aggregate, 10-22 volume percent water, and 5-40 volume percent of prepuff particles;

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 0.56 g/cc, an aspect ratio of from 1 to 3;

wherein the concrete composition has a density of from about 1.4 to about 2.1 g/cm 3 ; and

wherein after the concrete composition is set for 28 days, has a compressive strength of at least 126 Kg/cm 2 as tested according to ASTM C39.

13. A method of preparing a light weight concrete composition using expanded polymer particles comprising:

(a) selecting a fine aggregate, having a fineness modulus of less than 4, to total aggregate volumetric ratio;

(b) selecting a target concrete density;

(c) replacing coarse aggregate, having a fineness modulus of greater than 4, with prepuff particles while maintaining the fine aggregate to total aggregate volumetric ratio to obtain the target concrete density;

d) preparing the light weight concrete composition by combining ingredients comprising 3-40 volume percent cement, 1-50 volume percent fine aggregate, 0-40 volume percent coarse aggregate, 10-22 volume percent water, and 5-40 volume percent of prepuff particles;

wherein the prepuff particles replace from about 10 to about 50 volume percent of the coarse aggregate in the concrete mix;

wherein the fine aggregate to total aggregate ratio is from 0.5 to 0.8;

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 0.56 g/cc, an aspect ratio of from 1 to 3;

wherein the concrete density is from 1.4 to 2.1 g/cm 3 ; and

wherein after the concrete composition is set for 28 days, has a compressive strength of at least 126 Kg/cm 2 as tested according to ASTM C39.