[en] This paper discusses the results of recent studies related to the use of polyethylene and modified sulfur cement as new binder materials for the improved solidification of low-level wastes. Waste streams selected for this study include those which result from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those that remain problematic for solidification using contemporary agents (ion-exchange resins). Maximum waste loadings were determined for each waste type. Recommended waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash and 30 wt % ion exchange resins, which are based on process control and waste form performance considerations are reported for polyethylene. For sulfur cement the recommended waste loadings of 40 wt % sodium sulfate and boric acid salts and 43 wt % incinerator ash are reported. However, incorporation of ion-exchange resin waste in modified sulfur cement is not recommended due to poor waste form performance. The work presented in this paper will, in part, present data that can be used to assess the acceptability of polyethylene and modified sulfur cement waste forms to meet the requirements of 10 CFR 61. 8 refs., 10 figs., 6 tabs