The performance of cement mortar can be improved with additives based on waste by-products. Synthetic zeolite polymer composites (referred as SZPC) produced from the combination of solid waste ashes with a selective acrylic compound was used as a cement mortar additive. The effect of SZPC as an additive on hydration reaction of ordinary Portland cement (referred as OPC) at different amounts of SZPC, from 1-4% of OPC weight, as well as microstructure and mechanical behavior of the cement mortar are determined. The results from the hydration reaction rate test showed that the optimum amount of SZPC as the additive was 2% of OPC weight. Compressive strength and flexural strength of the cement mortar after 1, 7, 14 and 28 days of curing increased, with the largestincreases at the early stage. Additions of SZPC, synthesized by a waste by-product, improved mechanical behavior of cement mortars supporting sustainable development and the circular economy.