Method of manufacture and installation of flowable thermal backfills

Abstract

The invention includes a method of making and using a flowable thermal backfill. The flowable thermal backfill has a low thermal resistivity, useful for filling trenches containing electrical cables and other lines that generate heat. The method includes process steps of blending ingredients of stone, sand and fly ash, making a flowable thermal fill by mixing the blended stone, sand and fly ash with Portland cement and water, and pouring the flowable thermal fill in an excavation containing heat generating lines, immediately after mixing the flowable thermal backfill.

1 . A method of making and using a flowable thermal fill, the method comprising:
 blending dry ingredients of at least sand and fly ash, thereby forming a blend of dry ingredients;   making a flowable thermal fill by mixing the blend of dry ingredients with cement and water immediately before pouring the flowable thermal fill; and   pouring the flowable thermal fill, in an excavation containing heat generating lines, immediately after making the flowable thermal backfill.   
   
   
       2 . The method of  claim 1 , wherein said blend of dry ingredients includes stone. 
   
   
       3 . The method of  claim 1 , wherein the flowable thermal fill is mixed in a mobile mixer. 
   
   
       4 . The method of  claim 1 , wherein the flowable thermal fill is poured within one minute of being made. 
   
   
       5 . The method of  claim 1 , further comprising filling the excavation to a specified level with the flowable thermal fill. 
   
   
       6 . The method of  claim 1 , further comprising continuously making and pouring the flowable thermal fill. 
   
   
       7 . The method of  claim 1 , wherein the flowable thermal fill is poured within one minute of being made. 
   
   
       8 . A method of manufacturing and installing thermal concrete and fluidized thermal backfill, the method comprising:
 homogeneously blending stone, sand, and fly ash to form a substantially homogeneous blend of dry ingredient materials;   loading the blend of dry ingredient materials into a mobile mixer;   mixing the blend of dry ingredient materials, Portland cement, and water in the mobile mixer at an installation location at a time of installation to create a flowable thermal fill; and   installing the flowable thermal fill by pouring the flowable thermal fill in a trench containing heat generating lines wherein the flowable thermal fill covers the heat generating lines.   
   
   
       9 . The method of  claim 8 , wherein the dry ingredient materials are blended using a pugmill. 
   
   
       10 . The method of  claim 8 , wherein the dry ingredient materials are blended using a layer-cake, bucket method of blending. 
   
   
       11 . The method of  claim 8 , further comprising storing the homogeneous blend of dry ingredient materials. 
   
   
       12 . The method of  claim 8 , wherein the blended dry ingredient materials include thermally conductive minerals. 
   
   
       13 . The method of  claim 8 , wherein the mobile mixer contains separate storage containers for the blended dry ingredient materials, Portland cement and water. 
   
   
       14 . The method of  claim 8 , further comprising mixing minerals at the time of installation. 
   
   
       15 . The method of  claim 8 , wherein the heat generating lines are electrical power lines. 
   
   
       16 . The method of  claim 8 , wherein the trench is used for wind farm cable lines. 
   
   
       17 . The method of  claim 8 , further comprising, pouring a first type of flowable thermal fill to a specified height above the heat generating lines, and pouring a second type of flowable thermal fill over the first type of flowable thermal fill. 
   
   
       18 . The method of  claim 8 , further comprising, pouring a first type of flowable thermal fill to a specified height above the heat generating lines, and applying a second type of fill over the first type of flowable thermal fill.