Method of making structural members using waste and recycled plastics

Abstract

A composite formulation consisting of agglomerated industrial/residential sewer sludge and recycled high density polyethylene (HDPE) and/or polypropylene (PP) materials. The recycled plastic materials act as a binder for the pozzolan industrial/residential sewer sludge. The composite formulation can be produced in a batching process wherein the sieved dried sewer sludge and the recycled plastic in appropriate small cut pieces is fed into a large plastic extruder, heated and extruded into specific structures. The formulation can also be compounded using a compression mold wherein sieved dry sewer sludge are added to heated chopped recycled plastics and heat mixed to produce pellets or directed into a compression mold to create a structural member of predetermined shape.

What is claimed is: 
     
         1 . A method of making a composite member, said method comprising the steps of:
 mixing dry sewer sludge with recycled plastic to form a composite mixture;   heating one of said dry sewer sludge and said recycled plastics during said mixing step to fluidize said recycled plastic; and   form said composite mixture into a structural member.   
     
     
         2 . The method as claimed in  claim 1  wherein said recycled plastic comprises a member of the group consisting of polyethylene and polypropylene. 
     
     
         3 . The method as claimed in  claim 1  wherein said dry sewer sludge constitutes fly ash. 
     
     
         4 . The method as claimed in  claim 3  wherein said fly ash is a Type 2 Class B fly ash. 
     
     
         5 . The method as claimed in  claim 1  wherein heating one of said dry sewer sludge and said recycled plastic to a temperature between approximately 100° and approximately 230° centigrade to fluidize said recycled plastic. 
     
     
         6 . The method as claimed in  claim 1  wherein said particles of dry sewer sludge constitutes approximately 50% to approximately 80% by weight of said composite mixture and said recycled plastic constitutes approximately 20% to approximately 50% by weight of said composite mixture. 
     
     
         7 . The method as claimed in  claim 1  wherein said recycled plastic comprises a member of the group consisting of recycled polyethylene terephthalate, recycled high and/or low density polyethylene, recycled polyvinyl chloride, recycled polypropylene, recycled polystyrene, and other recycled mixed plastics. 
     
     
         8 . The method as claimed in  claim 1  wherein the step of mixing is accomplished by the screw of an extruder machine. 
     
     
         9 . The method as claimed in  claim 1  wherein the step of mixing is accomplished in a conventional mixer/grinder and routed to a compression mold machine to mold structural members shaped to desired sizes. 
     
     
         10 . The method as claimed in  claim 1  wherein said mixture of dry sewer sludge comprises a member of the group consisting of fly ash and Type 2 Class B fly ash and said recycled plastic comprises a member of the group consisting of recycled polyethylene terephthalate, recycled high and/or low density polyethylene, recycled polyvinyl chloride, recycled polypropylene, recycled polystyrene, and other recycled mixed plastic, said dry sewer sludge and recycled plastic being heated to a temperature between approximately 100° and approximately 230° centigrade to fluidize said recycled plastic, said mixture being formed into a composite structural member. 
     
     
         11 . A method of construction, said method comprising the steps of:
 producing a structural member, the producing step including   a) mixing particles of dry sewer sludge and particles of a recycled plastic to form a composite mixture;   b) heating one of said particles of dry sewer sludge and said particles of recycled plastic during said mixing step to fluidize said recycled plastic so as to obtain a good dispersal of said recycled plastic in the composite mixture; and   erecting a structure using said structural member.   
     
     
         12 . The method as claimed in  claim 11  wherein said recycled plastic comprises a member of the group consisting of recycled polyethylene terephthalate, recycled high and/or low density polyethylene, recycled polyvinyl chloride, recycled polypropylene, recycled polystyrene, and other recycled mixed plastics. 
     
     
         13 . The method as claimed in  claim 11  wherein said particles of dry sewer sludge constitutes approximately 50% to approximately 80% by weight of said composite mixture and said recycled plastic constitutes approximately 20% to approximately 50% by weight of said composite mixture. 
     
     
         14 . The method as claimed in  claim 11  wherein heating one of said dry sewer sludge and said recycled plastic to a temperature between approximately 100° and approximately 230° centigrade to fluidize said recycled plastic. 
     
     
         15 . The method as claimed in  claim 1  wherein said mixing of said dry sewer sludge within said recycled plastics is accomplished using an extruder screw of an extrusion machine. 
     
     
         16 . The method as claimed in  claim 1  wherein said mixing of said dry sewer sludge with said recycled plastics is accomplished using a commercial mixer. 
     
     
         17 . The method as claimed in  claim 1  wherein prior to forming said structural member, said composite mixture is formed into pellets. 
     
     
         18 . The method as claimed in  claim 17  further comprising processing said pellets of said composite mixture into a compression mold and molding parts therefrom.