Concrete formulation

Abstract

An additive for use in the preparation of lightweight concrete, said additive including a blend of from around 40% to 99% of organic polymeric material and from 1% to around 60% clean air entraining agent. The additive is particularly suitable for the preparation of lightweight concrete which uses polystyrene aggregate. It provides for excellent dispersion of the polystyrene aggregate and improved bond between the polystyrene aggregate and surrounding cementitious binder. The resultant lightweight concrete formulation may be pumped and is particularly suitable for sandwich wall construction.

1 . A polystyrene lightweight aggregate for use in the preparation of lightweight concrete, said aggregate being treated with a treatment agent including a blend of around 40% to 99% of organic polymeric material and about 1% to 60% of an air entraining agent.  
     
     
         2 . An aggregate according to  claim 1 , wherein said treatment agent including between about 10% and 50% of the air entraining agent.  
     
     
         3 . An aggregate according to  claim 2 , wherein said treatment agent including between about 20% and 40% of the air entraining agent.  
     
     
         4 . An aggregate according to  claim 1 , wherein the organic polymeric material includes one or more thixotropic agents to enhance viscosity.  
     
     
         5 . An aggregate according to  claim 1 , wherein the organic polymeric material is a cellulose derivative, a polysaccharide, or a synthetic hydrophilic polymer.  
     
     
         6 . An aggregate according to  claim 5 , wherein the organic polymeric material is selected from a the group consisting of hydroxymethylcellulose, hydroxyethyl cellulose, hydroxy propyl methyl cellulose, starch, alginate, polyvinyl alcohol, polyethylene oxide and polypropylene oxide.  
     
     
         7 . An aggregate according to  claim 1 , wherein the air entraining agent includes one or more nonionic, cationic or anionic surfactants.  
     
     
         8 . An aggregate according to  claim 7 , wherein the air entraining agent is a sodium salt of alpha olefin sulphonate, or sodium lauryl sulphate or sulphonate.  
     
     
         9 . An aggregate according to  claim 1 , wherein said treatment agent including between about 60% and 90% of the organic polymeric material.  
     
     
         10 . An aggregate according to  claim 9 , wherein said treatment agent including between about 70% and 85% of the organic polymeric material.