Building Materials
The basic purpose of a retarder in concrete is

To render the concrete more water tight
To decrease the initial setting time of cement paste in concrete
To improve the workability of concrete mix
To increase the initial setting time of cement paste in concrete

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Building Materials
Putty is

Made with finely powdered chalk and linseed oil
Used for fixing glass panes
Softened by a solution of pearl ash and quick-lime soaked in water
All listed here

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