The reinforced concrete (RC) domestic wastewater culvert systems often suffer from reduced durability due to gas condensation and subsequent oxidation to H2SO4. To address this issue, a mortar immobilizing microbiology capable of converting H2S gas produced in wastewater into stable substances within the concrete can be employed. This paper presents some preliminary experimental results on the mix proportions and properties of a biomimetic coating mortar formulated using locally available Vietnamese materials to enhance the durability of RC sewer structures for domestic wastewater drainage. The mortar’s properties were evaluated under standard conditions and in a simulated wastewater environment. Preliminary findings indicate that a biomimetic coating mortar can be produced with consistency of fresh mortar ranging from 150 to 160 mm, a unit weight of 1700 to 2100 kg/m3, a 28-day flexural strength exceeding 5 MPa, a 28-day compressive strength exceeding 20 MPa, and chloride ion penetration resistance below 1000 Coulombs.