Railway Ties and Structural Elements

Abstract

A composite structural element and a method of making the same is provided. The composite structural element comprises of asphalt, fiber-reinforced plastics and optionally other plastics such as virgin plastics and recycled blue box plastics. The composite structural element may be used as a railway tie. In the manufacturing process, the composite structural elements may be molded.

1 . A composite structural element, comprising: asphalt in a proportion of about 15% to 95% by weight; and fiber reinforced plastics and optionally plastics chosen from the group consisting of virgin plastics, recycled plastics, and combinations and mixtures thereof in which the total plastics component content is in a proportion of about 5 to 85% by weight.  
   
   
       2 . The composite structural element of  claim 1 , further comprising an elastomer in a proportion of about 0% to 80% by weight.  
   
   
       3 . The composite structural element of  claim 2 , wherein said elastomer is in a proportion of about 0% to 25% by weight.  
   
   
       4 . The composite structural element of  claim 1 , wherein said asphalt is in a proportion of about 65% to 85% by weight.  
   
   
       5 . The composite structural element of  claim 4 , wherein said asphalt is in a proportion of about 70% to 80% by weight.  
   
   
       6 . The composite structural element of  claim 1 , wherein said total plastics component content is in a proportion of about 10% to 45% by weight.  
   
   
       7 . The composite structural element of  claim 6 , wherein said total plastics component content is in a proportion of about 15% to 40% by weight.  
   
   
       8 . The composite structural element of  claim 7 , wherein said total plastics component content is in a proportion of about 20% to 30% by weight.  
   
   
       9 . The composite structural element of  claim 8 , wherein said total plastics component content is in a proportion of about 25% to 30% by weight.  
   
   
       10 . The composite structural element of  claim 1 , wherein said fiber reinforced plastics is in a proportion of about 25% to 75% by weight of said total plastics component content.  
   
   
       11 . The composite structural element of  claim 10 , wherein said fiber-reinforced plastics is in a proportion of about 30% to 70% by weight of said total plastics component content.  
   
   
       12 . The composite structural element of  claim 11 , wherein said fiber-reinforced plastics is in a proportion of about 40% to 60% by weight of said total plastics component content.  
   
   
       13 . The composite structural element of  claim 1 , wherein said asphalt is sized such that more than 75% of said asphalt would pass through a screen having 0.75 inch square openings.  
   
   
       14 . The composite structural element of  claim 13 , wherein said asphalt is sized such that more than 50% of said asphalt would pass through a screen having 0.5 inch square openings.  
   
   
       15 . The composite structural element of  claim 1 , wherein said plastics component is sized such that more than 75% of said plastics component would pass through a screen having 0.5 inch square openings.  
   
   
       16 . The composite structural element of  claim 2 , wherein said elastomer is sized such that more than 75% of said elastomer would pass through a screen having 0.25 inch square openings.  
   
   
       17 . The composite structural element of  claim 16 , wherein said elastomer is sized such that more than 75% of said elastomer would pass through a screen having 0.125 inch square openings.  
   
   
       18 . The composite structural element of  claim 1 , wherein at least some of said asphalt is recycled asphalt.  
   
   
       19 . The composite structural element of  claim 1 , wherein at least some of said fiber-reinforced plastics is recycled industrial waste.  
   
   
       20 . The composite structural element of  claim 1 , wherein said virgin plastics is chosen from the group consisting of low-density polyethylene (LDPE), highdensity polyethylene (HDPE), and polypropylene (PP).  
   
   
       21 . The composite structural element of  claim 1 , wherein said recycled plastics is composed of polymers chosen from the group consisting of polyvinyl chloride (PVC), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and combinations and mixtures thereof.  
   
   
       22 . The composite structural element of  claim 2 , wherein at least some of said elastomer is recycled tire rubber.  
   
   
       23 . The composite structural element of  claim 1 , wherein said composite structural element is a railway tie.  
   
   
       24 . The composite structural element of  claim 1 , wherein plastics component includes particulate filler.  
   
   
       25 . A process for manufacturing composite structural elements, comprising the steps of: 
 (a) introducing asphalt, plastics, and fiber-reinforced plastics into a blender;    (b) mixing and heating the materials of step (a) at a temperature in the range of about 250 to 380° F. until a homogenous blended mixture is obtained;    (c) discharging the blended mixture and subjecting the blended mixture to one of the steps chosen from the group consisting of: 
 (i) feeding the blended mixture into an forming device which molds and stabilizes the blended mixture and then conveys the blended mixture through subsequent cooling stages; and segmenting the molded blended mixture into pre-determined lengths to form composite structural elements, and  
 (ii) placing pre-determined quantities of the blended mixture into molds having pre-determined sizes and shapes and molding the blended mixture under pressure into composite structural elements.  
   
   
   
       26 . The process of  claim 25 , wherein step (a) further includes the introduction of an elastomer into the blender.  
   
   
       27 . The process of  claim 26 , wherein said plastics, said fiber-reinforced plastics and said elastomer are pre-mixed before mixing with said asphalt.  
   
   
       28 . The process of  claim 25 , wherein said plastics and said fiber-reinforced plastics are pre-mixed before mixing with said asphalt.  
   
   
       29 . The process of  claim 25  wherein at least one of said asphalt, plastics, and fiberreinforced plastics is pre-heated before introduction into the blender in step (a).  
   
   
       30 . The process of  claim 26 , wherein said elastomer is pre-heated before introduction into the blender in step (a).  
   
   
       31 . The process of  claim 25 , wherein the materials are heated at a temperature in the range of 275 to 375° F. in step (b).  
   
   
       32 . The process of  claim 25 , wherein the forming device in step (i) functions at a temperature regime of 250 to 400° F.  
   
   
       33 . The process of  claim 25 , wherein the blended mixture is molded under pressure in the range of 500 to 5000 psi.