The work presents some efficient solutions for using the plastic bottles waste (PET) in construction field. For some reinforced concrete elements like monolithically cast reinforced concrete plates, savings in concrete quantities can be achived by executing gaps with lost formworks made by PET. As well, there are presented some proposals for making mattresses, composed by attaching the plastic bottles, intended for execution of thermal-insulations for buildings and some other efficient solutions for reuse the plastic bottles waste. The presented solutions have the advantage that they try to resolve the public society concern regarding the protection of the environment against pollution (in this case, pollution with hardly degradable materials-plastic bottles).