Reinforcement insert for a structural member and method of making and using the same

A method for reinforcing a hollow structural member comprising the steps of:

• placing a precast composite insert inside said structural member, said precast composite insert including a plurality of pellets formed of a thermoplastic resin and unexpanded, thermally expandable microspheres, said pellets being retained in a matrix of expanded polystyrene and said thermoplastic resin resisting thermal disintegration up to a preselected temperature T.sub.a ;
• thermally disintegrating said expanded polystyrene matrix by heating said insert to temperature T.sub.a ;
• expanding said unexpanded, thermally expandable microspheres in said pellets and substantially simultaneously partially melting said thermoplastic resin by continuing to heat said precast composite insert to partially bond said pellets to one another and to said structural member;
• and
• solidifying said thermoplastic resin by cooling said precast composite insert below the melting point of said thermoplastic resin.

A method of forming a precast composite plastic insert for reinforcing a hollow structural member comprising the steps of:

• loading a mold cavity with a substantially uniform mixture of thermoplastic pellets and unexpanded polystyrene beads, said thermoplastic pellets being formed of a thermoplastic resin and unexpanded microspheres;
• heating said mixture of said thermoplastic pellets and unexpanded polystyrene beads to form an expanded polystyrene matrix encasing said thermoplastic pellets to form said precast composite plastic insert;
• and
• unloading said precast composite insert from said mold cavity.

A method for reinforcing a hollow structural member comprising the steps of:

• placing a precast composite insert inside said structural member, said precast composite insert including a plurality of pellets formed of a thermoplastic resin and a heat activated blowing agent, said pellets being retained in a matrix of expanded polystyrene and said thermoplastic resin resisting thermal disintegration up to a preselected temperature T.sub.a ;
• thermally disintegrated said expanded polystyrene matrix by heating said precast composite insert to a temperature T.sub.a ;
• activating said heat activated blowing agent in said pellets and substantially simultaneously partially melting said thermoplastic resin by continuing to heat said precast composite insert such that said pellets bond to one another and to said structural member;
• and
• solidifying said precast composite insert by cooling said pellets below the melting point of said thermoplastic resin.

A method of forming a precast composite plastic insert for reinforcing a hollowing structural member comprising the steps of:

• loading a mold cavity with a substantially uniform mixture of thermoplastic pellets and unexpanded polystyrene beads, said thermoplastic pellets being formed of a thermoplastic resin and a heat activated blowing agent;
• heating said mixture of said thermoplastic pellets and unexpanded polystyrene beads to form an expanded polystyrene matrix encasing said thermoplastic pellets to form said precast composite plastic insert;
• and
• unloading said precast composite insert from said mold cavity.