Delivery device for concrete admixtures and process for retarding the setting of surface portion of concrete
View Patent ↗A delivery device for concrete admixtures, in the form of a film of water-soluble material, having a concrete admixture incorporated within the film. The film can be attached to a formwork for concrete and has a protective layer, which is removable to allow the water in the concrete to dissolve the film and release the admixture into the concrete. The film contains the required quantity of admixture and is weather-resistant and substantially time-insensitive.
1 . A delivery device for concrete admixtures, the device comprising a delivery film consisting of water-soluble material, having a concrete admixture incorporated within the delivery film, the delivery film having a first surface and an opposite second surface, the first surface having a means to attach the film to a formwork for concrete and the second surface having a removable protective liner, the delivery device configured so that the water-soluble material is capable of being dissolved by water in the concrete to thereby release the admixture into the concrete, wherein the means to attach the delivery film to the formwork comprises an adhesive layer applied to an adhesive support film at the first surface.
2 . A delivery device as claimed in claim 1 wherein the water-soluble material is polyvinyl alcohol.
3 . A delivery device as claimed in claim 1 wherein the adhesive layer comprises a pressure sensitive adhesive.
4 . A delivery device as claimed in claim 1 wherein the adhesive layer is provided with an adhesive release liner.
5 . A delivery device as claimed in claim 4 wherein the adhesive release liner extends beyond the length or side of the adhesive layer to form a gripping portion to assist in removing the adhesive release liner.
6 . A delivery device as claimed in claim 1 wherein the film protective liner extends beyond the length or side of the delivery film to form a gripping portion to assist in removing the film protective liner.
7 . A delivery device as claimed in claim 1 wherein the admixture is a retarder.
8 . A delivery device as claimed in claim 7 wherein the retarder is a lignosulfonate salt.
9 . A process for retarding the setting of a surface portion of concrete, which process comprises attaching a delivery device as claimed in claim 7 to a formwork, removing the protective liner from the delivery film to allow the water in the concrete to dissolve the film and release the retarder into the concrete.
10 . The process as claimed in claim 9 wherein the retarder is a lignosulfonate salt.
11 . The process as claimed in claim 9 wherein the admixture is a mixture of a plasticizer and a retarder.
12 . The process as claimed in claim 9 wherein the admixture is a mixture of a polyethylene glycol as plasticizer and a lignosulfonate as retarder.
13 . A delivery device as claimed in claim 1 wherein the admixture is a mixture of a plasticizer and a retarder.
14 . A delivery device as claimed in claim 13 wherein the admixture is a mixture of a polyethylene glycol as plasticizer and a lignosulfonate as retarder.