A new kind of foamed cement (FC) made of Portland cement (PC), fly ash (FA), steel slag (SS), and foam agent has been developed with the purpose of preparing energy-saving building materials. The effect of SS and FA on the properties such as bulk density and compressive strength of base mix was systematically investigated. The results indicated that the base mix with 50% PC, 30% FA and 20% SS showed the optimum properties. By proper control in dosage of foam agent, a series of FC with a range of bulk densities (350-1340 kg/m(3)) were obtained for the further experimental measurement. The corresponding thermal conductivity (k(e)) of the samples was measured by a guarded hot plate apparatus. In addition, k(e) was also predicted by a modified model. Comparison with the previous model, the modified model had better accuracy and shorter calculated time. Finally the predictions were compared with the experimental data and other existing analytical models. The results indicated that the predicted results agree well with the measured values. (C) 2015 Published by Elsevier B.V.