<p>The sewage pipes cement matrix suffers from the wastewater compound. In fact, the wastewater, that contains different aggressive species, affects the mortar structure. Two phenomena are shown: the first one consists of the dissolution of portlandite (CH)¹, while the second is the decalcification of C–S–H (C = CaO, S = SiO₂, H = H₂O). Recently, many studies are interested in the development of a new material that can resist to the sewage pipes aggressivity. The washing construction sand produces a very big quantity of waste. This later contains some clay minerals in its mineralogical composition. As a result, it is studied as pozzolanic material in mortars after thermal treatment. In the sewage pipe mortars composition, the calcined waste washing sand amount is fixed to 0%, 10% and 30% by weight as cement substitution. The durability of the new cement matrix is evaluated by compressive strength on mortar bars after wastewater exposure. The microstructural analysis is studied with XRD and then confirmed by SEM observations. It is shown that the highest durability was developed by mortars containing 10% of calcined waste due to the pozzolanic reaction. The detected phases after exposure to sewage are especially gypsum, expansive ettringite, thaumasite and silica.</p>