Additive for mortar and concrete

In a process for improving mortar or concrete in which a water-soluble, swellable polymeric substance is incorporated into the mortar or concrete in order to increase the viscosity thereof, the improvement which comprises separately preparing a storage stable, low viscosity, liquid additive for mortar and concrete composed of a water-soluble, swellable polymeric substance which is finely dispersed in its non-swollen condition in an aqueous solution consisting predominantly of water and an inorganic water-soluble salt, said salt being present in an amount sufficient to prevent dissolution and swelling of the polymeric substance, said additive containing at least about 10 percent of said polymeric substance and having a viscosity under about 200 centipoises and being further characterized by not thickening up substantially on storage and by thickening up to a highly viscous solution upon being diluted with water to a polymeric substance concentration of about 2 percent, and as needed mixing this separately prepared storage stable, low-viscosity dispersion into the mortar or concrete where the water-soluble, swellable polymeric substance is freed to swell and thereby increase the viscosity of the mortar or concrete.

In a process for improving mortar or concrete in which a water-soluble, swellable polymeric substance is incorporated into the mortar or concrete in order to increase the viscosity thereof, the improvement which comprises separately preparing a storage stable, low viscosity, liquid additive for mortar and concrete composed of a water-soluble, swellable polymeric substance which is finely dispersed in its non-swollen condition in an aqueous solution containing sufficient of an inorganic water-soluble salt or an organic solvent in which the polymeric substance is at most only partially soluble to prevent dissolution and swelling of the polymeric substance, said additive containing at least ten percent of said polymeric substance and having a viscosity under about 200 centipoises and being further characterized by not thickening up substantially on storage and by thickening up to highly viscous solution on being diluted with water to a polymeric substance concentration of about 2 percent, wherein the dispersion contains a minor amount of bentonite which is sufficient to stabilize the dispersion, and as needed mixing this separately prepared storage stable, low-viscosiy dispersion into the mortar or concrete where the water-soluble, swellable polymeric substance is freed to swell and thereby increase the viscosity of the mortar or concrete.