The present invention relates to a concrete partition or block with thermoplastic filler for the construction of buildings with an inner oblique reinforcement, in downwards direction (Fig. 1b) or front rear (Fig. 1b). Said partitions are filled with polystyrene mixed polybutylene, molded and agglomerated with blown asphalt, whose thermal conductivity allows efficiently saving the energy, avoiding the risk of toxicity or sag, and lowering its cost.