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A low or no fines lightweight concrete mixture. The mixture comprises one part by volume of a cementitious binder, 2-10 parts inert coarse aggregate, a cement additive in an amount of 0.05 to 0.3% by weight of the cementitious binder and an effective amount of water, the additive including 40-99% of

A low or no fines lightweight concrete mixture. The mixture comprises one part by volume of a cementitious binder, 2-10 parts inert coarse aggregate, a cement additive in an amount of 0.05 to 0.3% by weight of the cementitious binder and an effective amount of water, the additive including 40-99% of a viscosity enhancing agent, which in water either dissolves or forms colloidal dispersions, and 1-60% of an air entrainment agent/surfactant adapted to entrain air when mixed with water and/or pumped. The mixture is particularly suitable for constructing a building panel where a frame is prepared, the front and rear faces being covered by fibre reinforced cementitious sheets and the cavity there between at least partially filled with the lightweight concrete mixture which flows in a manner similar to loose fill.

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1. A lightweight concrete mix comprising 1 part by volume of a cementitious binder, 2-10 parts inert coarse aggregate, a cement additive in an amount of between 0.05-0.3% by weight of the cementitious binder, and an effective amount of water,the additive comprising 40-99% of a viscosity enhancing ag

1. A lightweight concrete mix comprising 1 part by volume of a cementitious binder, 2-10 parts inert coarse aggregate, a cement additive in an amount of between 0.05-0.3% by weight of the cementitious binder, and an effective amount of water,the additive comprising 40-99% of a viscosity enhancing agent, which in water either dissolves or forms colloidal dispersions, and 0-60% of an air entraining agent/surfactant adapted to entrain air when mixed with water and/or pumped. 2. The lightweight concrete mix as claimed in claim 1, wherein the additive comprises 60-90% of a viscosity enhancing agent.3. The lightweight concrete mix as claimed in claim 2, wherein the additive comprises 70-85% of a viscosity enhancing agent.4. The lightweight concrete mix as claimed in claim 1, wherein the additive comprises 10-50% of the air entraining agent/surfactant.5. The lightweight concrete mix as claimed in claim 4, wherein the additive comprises 20-40% of the air entraining agent/surfactant.6. The lightweight concrete mix as claimed in claim 1, wherein the viscosity enhancing agent comprises one or more thixotropic agents which either dissolve in water or form colloidal dispersions in the presence of water to produce an increase in the viscosity of the water.7. The lightweight concrete mix as claimed in claim 6, wherein the viscosity enhancing agent is selected from the group consisting of cellulose derivatives, polysaceharides, and synthetic hydrophilic polymers and copolymers.8. The lightweight concrete mix as claimed in claim 7, wherein the viscosity enhancing agent is selected from the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose.9. The lightweight concrete mix as claimed in claim 7, wherein the viscosity enhancing agent is selected from the group consisting of starches and alginate.10. The lightweight concrete mix as claimed in claim 7, wherein the viscosity enhancing agent is a synthetic hydrophilic polymer or copolymer selected from the group consisting of polyvinyl alcohols, polyethylene oxides, and polypropylene oxides.11. The lightweight concrete mix as claimed in claim 1, wherein the air entraining agent comprises one or more nonionic, cationic, or anionic surfactants.12. The lightweight concrete mix as claimed in claim 11, wherein the air entraining agent is selected from the group consisting of sodium salts of alpha olefin sulphonates, sodium lauryl sulphate, and sodium lauryl suiphonate.13. The lightweight concrete mix as claimed in claim 1, wherein the cementitious binder is an inorganic material comprising calcium, aluminium, silicon, oxygen, or sulphur compounds with sufficient hydraulic activity to solidify or harden in the presence of water.14. The lightweight concrete mix as claimed in claim 13, wherein the cementitious binder is selected from the group consisting of common portland cements, fast setting cements, extra fast setting cements, sulphate resisting cements, modified cements, alumina cements, high alumina cements, calcium aluminate cements, and cements containing secondary compounds.15. The lightweight concrete mix as claimed in claim 1, wherein the coarse aggregate has a size range of between 5-20 mm with 5% maximum aggregate coarser than 20 mm and 10% maximum finer than 5 mm size.16. The lightweight concrete mix as claimed in claim 15, wherein the coarse aggregate is gap graded as a single size with the highest proportion being between 10-20 mm.17. The lightweight concrete mix as claimed in claim 15, wherein the coarse aggregate contains between 0% and 10% by weight of fines.18. The lightweight concrete mix as claimed in claim 1, wherein the coarse aggregate is inert with respect to the other components of the mixture and is selected from the group consisting of washed river gravel, crushed igneous rock, crushed limestone, lightweight aggregate, pumice, scoria, expanded shale, foamed clay, artificial aggregates, crushed hard-burnt clay bricks, and air-cooled blast furnace slag.19. The lightweight concrete mix as claimed in claim 1, wherein for load bearing purposes, the mix further comprises up to about 40% of a thickener, high reactive pozzalanes, water sealing agents, water reducing agents, setting rate modifiers, hardeners, plasticisers, water-proofing agents, or a combination thereof.20. The lightweight concrete mix as claimed in claim 1, wherein the water to cement ratio is 0.3-0.8.21. The lightweight concrete mix as claimed in claim 20, wherein the water to cement ratio is 0.4-0.7.22. A method of constructing a panel comprising erecting a substantially rigid frame, attaching to the frame front and rear fibre reinforced cementitious sheets to form a cavity there between and providing to the cavity a lightweight concrete loose fill comprising 1 part by volume of a cementitious binder, 2-10 parts inert coarse aggregate, a cement additive in an amount of between 0.05-0.3% by weight of the cementitious binder and an effective amount of water,the additive comprising 40-99% of a viscosity enhancing agent, which in water either dissolves or forms colloidal dispersions, and 1-60% of an air entraining agent/surfactant adapted to entrain air when mixed with water and/or pumped. 23. The method as claimed in claim 22, wherein the entire cavity is filled with the lightweight concrete loose fill.24. The method as claimed in claim 22, wherein the cavity is partially filled with the lightweight concrete loose fill, the remainder being left dry or filled with another material.25. The method as claimed in claim 22, wherein the additive comprises 60-90% of a viscosity enhancing agent.26. The method as claimed in claim 25, wherein the additive comprises 70-85% of a viscosity enhancing agent.27. The method as claimed in claim 22, wherein the additive comprises 10-50% of the air entraining agent/surfactant.28. The method as claimed in claim 27, wherein the additive comprises 20-40% of the air entraining agent/surfactant.29. The method as claimed in claim 22, wherein the viscosity enhancing agent comprises one or more thixotropic agents which either dissolve in water or form colloidal dispersions in the presence of water to produce an increase in the viscosity of the water.30. The method as claimed in claim 29, wherein the viscosity enhancing agent is selected from the group consisting of cellulose derivatives, polysaccharides, and synthetic hydrophilic polymers and copolymers.31. The method as claimed in claim 30, wherein the viscosity enhancing agent is selected from the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose.32. The method as claimed in claim 30, wherein the viscosity enhancing agent is selected from the group consisting of starches and alginate.33. The method as claimed in claim 30, wherein the viscosity enhancing agent is a synthetic hydrophilic polymer or copolymer selected from the group consisting of polyvinyl alcohols, polyethylene oxides, and polypropylene oxides.34. The method as claimed in claim 22, wherein the air entraining agent comprises one or more nonionic, cationic, or anionic surfactants.35. The method as claimed in claim 34, wherein the air entraining agent is selected from the group consisting of sodium salts of alpha olefin sulphonates, sodium lauryl sulphate, and sodium lauryl sulphonate.36. The method as claimed in claim 22, wherein the cementitious binder is an inorganic material comprising calcium, aluminium, silicon, oxygen, or sulphur compounds with sufficient hydraulic activity to solidify or harden in the presence of water.37. The method as claimed in claim 36, wherein the cementitious binder is selected from the group consisting of common portland cements, fast setting cements, extra fast setting cements, sulphate resisting cements, modified cements, alumina cements, high alumina cements, calcium aluminate cements, and cements containing secondary compounds.38. The method as claimed in claim 22, wherein the coarse aggregate has a size range of between 5-20 mm with 5% maximum aggregate coarser than 20 mm and 10% maximum finer than 5 mm size.39. The method as claimed in claim 38, wherein the coarse aggregate is gap graded as a single size with the highest proportion being between 10-20 mm.40. The method as claimed in claim 38, wherein the coarse aggregate contains between 0% and 10% by weight of fines.41. The method as claimed in claim 22, wherein the coarse aggregate is inert with respect to the other components of the mixture and is selected from the group consisting of washed river gravel, crushed igneous rock, crushed limestone, lightweight aggregate, pumice, scoria, expanded shale, foamed clay, artificial aggregates, crushed hard-burnt clay bricks, and air-cooled blast furnace slag.42. The method as claimed in claim 22, wherein for load bearing purposes, the mix further comprises up to about 40% of a thickener, high reactive pozzalanes, water sealing agents, water reducing agents, setting rate modifiers, hardeners, plasticisers, water-proofing agents, or a combination thereof.43. The method as claimed in claim 22, wherein the water to cement ratio is 0.3-0.8.44. The method as claimed in claim 43, wherein the water to cement ratio is 0.4-0.7.45. A building panel comprising a substantially rigid frame defining front and rear faces, front and rear fibre reinforced cementitious sheets attached to the frame to form a cavity there between, the cavity being at least partially filled with a lightweight concrete loose fill,wherein the lightweight loose fill comprises 1 part by volume of cementitious binder, 0-10 parts inert coarse aggregate, a cement additive in an amount between 0.05-0.3% by weight of the cementitious binder and an effective amount of water, the additive comprising 40-99% of a viscosity enhancing agent, which in water either dissolves or forms colloidal dispersions, and 1-60% of an air entraining agent/surfactant adapted to entrain air when mixed with water and/or pumped. 46. The building panel as claimed in claim 45, wherein the entire cavity is filled with the lightweight concrete loose fill.47. The building panel as claimed in claim 45, wherein the cavity is partially filled with the lightweight concrete loose fill, the remainder being left dry or filled with another material.48. The building panel as claimed in claim 45, wherein that portion of the cavity filled with a lightweight concrete loose fill has, on curing between 20-40% by volume of interconnected pores/voids.49. The building panel as claimed in claim 45, wherein the additive comprises 60-90% of a viscosity enhancing agent.50. The building panel as claimed in claim 49, wherein the additive comprises 70-85% of a viscosity enhancing agent.51. The building panel as claimed in 45, wherein the additive comprises 10-50% of the air entraining agent/surfactant.52. The building panel as claimed in claim 51, wherein the additive comprises 20-40% of the air entraining agent/surfactant.53. The building panel as claimed in claim 45, wherein the viscosity enhancing agent comprises one or more thixotropic agents which either dissolve in water or form colloidal dispersions in the presence of water to produce an increase in the viscosity of the water.54. The building panel as claimed in claim 53, wherein the viscosity enhancing agent is selected from the group consisting of cellulose derivatives, polysaccharides, and synthetic hydrophilic polymers and copolymers.55. The building panel as claimed in claim 54, wherein the viscosity enhancing agent is selected from the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose.56. The building panel as claimed in claim 54, wherein the viscosity enhancing agent is selected from the group consisting of starches and alginate.57. The building panel as claimed in claim 54, wherein the viscosity enhancing agent is a synthetic hydrophilic polymer or copolymer selected from the group consisting of polyvinyl alcohols, polyethylene oxides, and polypropylene oxides.58. The building panel as claimed in claim 45, wherein the air entraining agent comprises one or more nonionic, cationic, or anionic surfactants.59. The building panel as claimed in claim 58, wherein the air entraining agent is selected from the group consisting of sodium salts of alpha olefin sulphonates, sodium lauryl sulphate, and sodium lauryl sulphonate.60. The building panel as claimed in claim 45, wherein the cementitious binder is an inorganic material comprising calcium, aluminium, silicon, oxygen, or sulphur compounds with sufficient hydraulic activity to solidify or harden in the presence of water.61. The building panel as claimed in claim 60, wherein the cementitious binder is selected from the group consisting of common portland cements, fast setting cements, extra fast setting cements, sulphate resisting cements, modified cements, alumina cements, high alumina cements, calcium aluminate cements, and cements containing secondary compounds.62. The building panel as claimed in claim 45, wherein the coarse aggregate has a size range of between 5-20 mm with 5% maximum aggregate coarser than 20 mm and 10% maximum finer than 5 mm size.63. The building panel as claimed in claim 62, wherein the coarse aggregate is gap graded as a single size with the highest proportion being between 10-20 mm.64. The building panel as claimed in claim 62, wherein the coarse aggregate contains between 0% and 10% by weight of fines.65. The building panel as claimed in claim 45, wherein the coarse aggregate is inert with respect to the other components of the mixture and is selected from the group consisting of washed river gravel, crushed igneous rock, crushed limestone, lightweight aggregate, pumice, scoria, expanded shale, foamed clay, artificial aggregates, crushed hard-burnt clay bricks, and air-cooled blast furnace slag.66. The building panel as claimed in claim 45, wherein for load bearing purposes, the mix further comprises up to about 40% of a thickener, high reactive pozzalanes, water sealing agents, water reducing agents, setting rate modifiers, hardeners, plasticisers, water-proofing agents, or a combination thereof.67. The building panel as claimed in claim 45, wherein the water to cement ratio is 0.3-0.8.68. The building panel as claimed in claim 67, wherein the water to cement ratio is 0.4-0.7.