Recently, there is an increasing demand for using refused derived fuels (RDF) as replacement for traditional fossil fuel in energy intensive industries like cement industry.  However, using such sources will affect the properties and quality of the produced cement since RDF ash was mixed with OPC clinker during production.  In the present study, four solid refused derived fuels namely; rubber waste, tree trimmings, rice straw and municipal solid wastes MSW are characterized and tested as RDF.   Also, the effect of their ash on the setting and hardening of the hardened OPC pastes was investigated. Results showed that rubber waste has the highest calorific values followed by MSW. OPC pastes mixed with RDF ash showed reduced setting times. Besides, OPC admixed with rubber wastes ash offered the highest compressive strength values between all the studied RDF sources. Phase composition of the formed hydrates is studied by X-ray diffraction analysis and results showed that the ash within OPC matrix does not change the hydration mechanisms since the same hydration products are formed.