Lightweight concrete compositions

1. A lightweight cementitious composition comprising from 10 to 90 volume percent of a cement composition, from 10 to 90 volume percent of particles having an average particle diameter of from 0.2 mm to 8 mm, a bulk density of from 0.028 g/cc to 0.64 g/cc, an aspect ratio of from 1 to 3, and having a continuous outer layer, and from 10 to 50 volume percent of sand and/or other fine aggregate, wherein at least a portion of the sand and/or other fine aggregate has a fineness modulus of less than 2; wherein the sum of components used does not exceed 100 volume percent; wherein the cementious composition has a density of from about 40 to about 130 lb./ft 3 ; and wherein after the lightweight cementitious composition is set for seven days, the composition has a compressive strength of at least 1700 psi as tested according to ASTM C39.

2. The lightweight cementitious composition according to claim 1 , wherein the particles comprise expanded polymer particles having an inner cell wall thickness of at least at least 0.15 μm.

3. The lightweight cementitious composition 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 lightweight cementitious composition according to claim 1 , wherein the 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.

5. The lightweight cementitious composition according to claim 1 , wherein the particles comprise expanded polymer particles having an average particle size of from about 0.3 mm to about 5 mm.

6. The lightweight cementitious composition according to claim 1 as a dispersion wherein the cement composition comprises a continuous phase and the particles comprise a dispersed phase of discrete particles in the continuous phase.

7. The lightweight cementitious composition according to claim 6 containing no wetting agents or dispersing agents to stabilize the dispersion.

8. The lightweight cementitious composition according to claim 1 , wherein at least some of the particles are arranged in a cubic or hexagonal lattice.

9. The lightweight cementitious composition according to claim 1 , wherein the cement composition comprises a hydraulic cement composition.

10. The lightweight cementitious composition according to claim 9 , wherein the hydraulic 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, and slag cements.

11. The lightweight cementitious composition according to claim 1 , wherein the cementitious mixture further comprises coarse aggregate, plasticizers and/or fibers.

12. The lightweight cementitious composition according to claim 11 , 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.

13. The lightweight cementitious composition according to claim 11 , 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.

14. The lightweight cementitious composition according to claim 1 , wherein a standard 2½ inch drywall screw, screwed into the formed and set lightweight cementitious composition to a depth of 1½ inches, is not removed by applying 500 pounds of force perpendicular to the surface screwed into for one minute.

15. The lightweight cementitious composition according to claim 1 molded and set in the form of a construction article.

16. The lightweight cementitious composition according to claim 1 set in the form of a concrete masonry unit.

17. The lightweight cementitious composition according to claim 1 set in the form of a construction panel.

18. A lightweight concrete composition comprising

from 10 to 60 volume percent of a cement composition that includes type III Portland Cement;

from 20 to 78 volume percent of expanded polymer particles having an average particle diameter of from 0.2 mm to 5 mm, a bulk density of from 0.032 g/cc to 0.56 g/cc, an aspect ratio of from 1 to 2, and having a continuous outer layer;

from 15 to 35 volume percent of sand and/or fine aggregate, wherein at least a portion of the sand and/or fine aggregate has a fineness modulus of less than 2;

from 5 to 15 volume percent coarse aggregate; and

from 0.1 to 1 volume percent of one or more additives selected from the group consisting of: anti-foam agents, water-proofing agents, dispersing agents, set-accelerators, set-retarders, plasticizing agents, superplasticizing agents, freezing point decreasing agents, adhesiveness-improving agents, colorants and combinations thereof;

wherein the sum of components used does not exceed 100 volume percent;

wherein the cementious composition has a density of from about 90 to about 130 lb./ft 3 , and

wherein after the lightweight concrete composition is set, it has a compressive strength of at least 2000 psi as tested according to ASTM C39 after seven days.