This paper reports the assessment of rheological characteristics of cementitious pastes prepared with Limestone - Calcined Clay Cement, in comparison with ordinary Portland cement and Portland - Fly Ash cement. The impact on workability retention in concrete is also assessed. Further, a comparison of the performance of different commercially available superplasticizers is done using mortar flow retention tests (done on concrete – equivalent mortars) and slump retention tests on concrete. The results bring out the impact of calcined clays on increased superplasticizer demand, and also show the difficulties in retaining the workability for extended durations. © 2020 Elsevier Ltd