One has to apply AS 26 as well as AS 28 independently.
As 26 : Amortization : It is the process of allocating an amount of expense over the period of beneficial life. So you can amortize the cost over the life of asset.
Now after amortization you have to test the asset for impairment. As 28 is applicable for the same. The asset needs to be impaired if recoverable amount is less than the carrying amount. If the asset is impaired then only follow AS 28 otherwise amortize the cost through AS 26.