If your question is how to get thermal-insulating concrete, the air-entraining admixtures are used to reduce the density of concrete and hence improve its thermal isolation.
If you want Lowe down the temperature in the room with concrete slab as per my opinion you can apply some internal finishing layer of some chemical admixture that will restrain the heat to flow inside. Mostly your problem exist at the top floors in building, I will suggest during construction of top floor slab you can put some heat resisting sheets and then place concrete over that would be the better option to resist heat flow.