© author(s) or their institution(s).A laboratory study was undertaken to assess the effects of polymer treatment (PT) on the geotechnical behaviour of a low-plasticity slurry. PT was undertaken on the material using a high molecular weight polyacrylamide polymer. Slurry consolidometer and triaxial testing were undertaken to compare the geotechnical behaviour of the material following PT, compared to an untreated (UT) condition. The material was prepared from a slurry state in a nonsegregating condition, to enable comparison of uniform samples. Testing indicated that PT resulted in lower final consolidated densities at a given magnitude of effective stress, while increasing the rate of consolidation and hydraulic conductivity. Triaxial testing indicated that PT material, when sheared, appeared to exhibit a different critical state line (CSL) than UT material. The PT CSL was higher in void ratio terms than the UT CSL, and with an increased compressibility. Both PT and UT material exhibited undrained shear strengths consistent with the state of the specimen with respect to that material’s CSL. PT material exhibited higher undrained shear strengths at a given density. All the effects observed following PT appeared to persist across a wide range of effective stresses.