Manufacture of improved metakaolin by grinding and use in cement-based composites and alkali-activated systems

Abstract

In one embodiment, the present invention relates to a method of making a highly reactive pozzolan, involving the steps of forming a slurry comprising metakaolin and a liquid; wet milling the slurry; and separating the metakaolin from the liquid to provide the highly reactive pozolan. In another embodiment, the present invention relates to a method of making a cement-based composition involving the steps of providing a highly reactive pozzolan by forming a slurry comprising metakaolin and a liquid, wet milling the slurry, and separating the metakaolin from the liquid; and combining the highly reactive pozzolan with at least one cementitious material.

What is claimed:  
     
         1 . A method of making a highly reactive pozzolan, comprising: 
 forming a slurry comprising metakaolin and a liquid;    wet milling the slurry; and    separating the metakaolin from the liquid to provide the highly reactive pozzolan.    
     
     
         2 . The method of making a highly reactive pozzolan according to    claim 1   , wherein the liquid comprises water.  
     
     
         3 . The method of making a highly reactive pozzolan according to    claim 1   , wherein the slurry comprises from about 10% to about 90% by weight of metakaolin and from about 10% to about 90% by weight of liquid.  
     
     
         4 . The method of making a highly reactive pozzolan according to    claim 1   , wherein the slurry further comprises a dispersant.  
     
     
         5 . The method of making a highly reactive pozzolan according to    claim 1   , wherein wet milling is conducted for a period of time from about 1 minute to about 60 minutes at a temperature from about −10° C. to about 150° C.  
     
     
         6 . The method of making a highly reactive pozzolan according to    claim 1   , wherein the metakaolin is separated from the liquid by one of spray drying, flash drying, rotary drying, apron drying, oven drying, and mixing the slurry.  
     
     
         7 . The method of making a highly reactive pozzolan according to    claim 1    further comprising pulverizing the metakaolin separated from the liquid to provide the highly reactive pozzolan.  
     
     
         8 . A method of making a cement-based composition comprising: 
 providing a highly reactive pozzolan by 
 forming a slurry comprising metakaolin and a liquid,  
 wet milling the slurry, and  
 separating the metakaolin from the liquid; and  
   combining the highly reactive pozzolan with at least one cementitious material.    
     
     
         9 . The method of making a cement-based composition according to    claim 8   , wherein the highly reactive pozzolan is made by 
 heat treating hydrous kaolin,    forming a slurry comprising the heat treated hydrous metakaolin and water,    wet milling the slurry, and    separating the metakaolin from the liquid by spray drying.    
     
     
         10 . The method of making a cement-based composition according to    claim 8   , wherein the highly reactive pozzolan further comprises a dispersant.  
     
     
         11 . The method of making a cement-based composition according to    claim 10   , wherein the dispersant comprises at least one of an ammonia-based dispersant, a phosphate-based dispersant, a sulfonate dispersant, a carboxylic acid dispersant and a polymeric dispersant.  
     
     
         12 . The method of making a cement-based composition according to    claim 8   , wherein the cement-based composition comprises from about 50% to about 99.5% of the cementitious material and from about 0.5% to about 50% of the highly reactive pozzolan.  
     
     
         13 . The method of making a cement-based composition according to    claim 8   , wherein the highly reactive pozzolan comprises from about 0.1% to about 20% by weight of the dispersant.  
     
     
         14 . The method of making a cement-based composition according to    claim 8   , wherein the cementitious material comprises portland cement.  
     
     
         15 . The method of making a cement-based composition according to    claim 8   , wherein the separated metakaolin is pulverized prior to being combined with at least one cementitious material.  
     
     
         16 . The method of making a cement-based composition according to    claim 8   , wherein the metakaolin is separated from the liquid by one of spray drying, flash drying, and oven drying.  
     
     
         17 . A method of making a highly reactive pozzolan composition, comprising: 
 forming a slurry comprising from about 20% to about 80% by weight of metakaolin and from about 20% to about 80% by weight of a liquid; and    wet milling the slurry for a period of time from about 1 minute to about 60 minutes to provide the highly reactive pozzolan composition.    
     
     
         18 . A highly reactive pozzolan made according to the method of    claim 1   .  
     
     
         19 . A cement-based composition made according to the method of    claim 8   .  
     
     
         20 . A highly reactive pozzolan composition made according to the method of    claim 17   .  
     
     
         21 . A method of making an alkali-activated composition comprising: 
 providing a highly reactive pozzolan by 
 forming a slurry comprising metakaolin and a liquid,  
 wet milling the slurry for a period of time from about 2 minutes to about 30 minutes, and  
 separating the metakaolin from the liquid; and  
   combining the highly reactive pozzolan with at least one geopolymeric material.    
     
     
         22 . The method of making an alkali-activated composition according to    claim 21   , wherein the wet milling is conducted using a Chaser mill, Cowles mill, a Colloid mill, a Duncan mill, a Kady mill, a Morehouse mill, a Muller mill, a Netzsch mill, a Premier mill, a Kotthoff mill and a sedimentary delaminator.  
     
     
         23 . The method of making an alkali-activated composition according to    claim 21   , wherein the geopolymeric material is one or more of alumino-silicate oxide, sodium hydroxide, potassium hydroxide, water, sodium silicate, potassium silicate, Na 2 O, K 2 O, a zeolite, silica, and alumina.  
     
     
         24 . The method of making an alkali-activated composition according to    claim 21   , wherein the alkali-activated composition comprises from about 40% to about 99.5% by weight of one or more geopolymeric materials and from about 0.5% to about 60% by weight of the highly reactive pozzolan.  
     
     
         25 . The method of making an alkali-activated composition according to    claim 21   , wherein the metakaolin separated from the liquid after wet milling has from about 5% to about 75% reduction in pore volume compared to the metakaolin combined with water.  
     
     
         26 . An alkali-activated composition made according to the method of    claim 21   .