This paper aims to better understand the mechanisms explaining the superior resistance of calcium aluminate cement (CAC) materials compared to Portland cement (PC) based materials in sewer networks. The bacteriostatic effect of CAC materials on Sulfur Oxidising Bacteria (SOB) is often argued in the literature as a possible mechanism explaining their better resistance. Reactor tests conducted on SOB demonstrated their ability to acclimatise to high aluminium contents. More generally, using a laboratory biodeterioration protocol reproducing aggressive conditions, the nature of the material (CAC or PC with different slag contents) did not significantly affect the SOB selection. Moreover the CAC materials seemed to favour the development of a higher SOB activity (and so acid production) than PC-based systems, leading to more aggressive conditions. Finally, the resistance of CAC materials to biodeterioration appeared to be mainly linked to the intrinsic resistance of phases initially present or precipitated during the deterioration process.