A controlled release formulation for a cement-based composition can be produced by intercalating an admixture (e.g. an accelerator, a set retarder, a superplasticizer) for the cement-based composition into a layered inorganic material (e.g. a layered double hydroxide (LDH)). A cement-based composition containing a cement-based material (e.g. cement, mortar or concrete) and such a controlled release formulation has better workability, especially in respect of slump-loss characteristics. With such a formulation release of an admixture in a cement-based composition may be controlled.