Radial coal ash based micro-architectures and method of synthesis

Abstract

Microparticles having crystalline needle or rod-shaped structures of, for example, an ettringite mineral grown and attached radially from their surface. A method including nucleating and growing crystalline needles/rods from the surface of a particle in the presence of a solution of calcium, sulfur, and aluminum such as calcium sulfoaluminate, lime and calcium sulfate is described. One example is the radial growth of ettringite needles on the surface of fly ash particles in calcium sulfoaluminate-based cement paste and concrete.

1 . A material comprising:
 a plurality of particles each including a substrate having a plurality of crystalline needle or rod-shaped structures of an ettringite mineral attached radially to a surface of the substrate, with the plurality of particles contained in a polymer, glass, ceramic, cement, cement paste or concrete material.   
     
     
         2 . The material of  claim 1  wherein the substrate comprises fly ash. 
     
     
         3 . The material of  claim 2  wherein the particle comprises a microparticle. 
     
     
         4 . The material of  claim 1  wherein the particles have a total diameter ranging from 0.1 and 100 μm. 
     
     
         5 . The material of  claim 1  wherein the crystalline needle or rod-shaped structures have a length ranging from 0.05-50 μm. 
     
     
         6 . The material of  claim 1  wherein the crystalline needle or rod-shaped structures have a diameter or width ranging from 5 to 5,000 nm. 
     
     
         7 . The material of  claim 1  wherein the crystalline needle or rod-shaped structures comprise clusters of individual crystalline needle or rod-shaped structures of the particle. 
     
     
         8 . The material of  claim 1  wherein the crystalline needle or rod-shaped structures have no tapering in cross-section along their length. 
     
     
         9 . The material of  claim 1  wherein the crystalline needle or rod-shaped structures have a rectangular or circular cross-section. 
     
     
         10 . The material of  claim 1  wherein the total quantity per microsphere of crystalline needle or rod-shaped structures range from 10 to 10,000. 
     
     
         11 . A hydrated cement paste comprising:
 a plurality of particles each including a substrate having a plurality of crystalline needle or rod-shaped structures of an ettringite mineral attached radially to a surface of the substrate.   
     
     
         12 . The hydrated cement paste of  claim 11  wherein the substrate comprises fly ash. 
     
     
         13 . The hydrated cement paste of  claim 11  wherein the particles have a total diameter ranging from 0.1 and 100 μm. 
     
     
         14 . The hydrated cement paste of  claim 11  wherein the crystalline needle or rod-shaped structures have a length ranging from 0.05-50 μm. 
     
     
         15 . The hydrated cement paste of  claim 11  wherein the crystalline needle or rod-shaped structures have a diameter or width ranging from 5 to 5,000 nm. 
     
     
         16 . The hydrated cement paste I of  claim 11  wherein the crystalline needle or rod-shaped structures comprise clusters of individual crystalline needle or rod-shaped structures of the particle. 
     
     
         17 . The hydrated cement paste of  claim 11  wherein the crystalline needle or rod-shaped structures have no tapering in cross-section along their length. 
     
     
         18 . The hydrated cement paste of  claim 11  wherein the crystalline needle or rod-shaped structures have a rectangular or circular cross-section. 
     
     
         19 . The hydrated cement paste of  claim 11  wherein the total quantity per microsphere of crystalline needle or rod-shaped structures range from 10 to 10,000. 
     
     
         20 . The hydrated cement paste of  claim 11  with the particles embedded in a hydrated calcium sulfoaluminate cement paste.