A method of controlling release of an admixture in a cement-based composition involves intercalating an admixture (e.g. an accelerator, a set retarder, a superplasticizer) for the cement-based composition into a layered double hydroxide or mixture thereof. A cement-based composition prepared in such a manner and containing a cement-based material (e.g. cement, mortar or concrete) has better workability, especially in respect of slump-loss characteristics.