Healing Agent in Cement-Based Materials and Structures, and Process for Its Preparation

Abstract

A healing agent in cement-based materials and structures, wherein said healing agent comprises organic compounds and/or bacteria-loaded porous particles, which porous particles comprise expanded clay- or sintered fly-ash. Furthermore, said porous particles are intact spheres, broken or crushed particles derived from said intact spheres, having a specific density between 0.4 and 2 g cm −3 . Finally, the present invention relates to a process for the preparation of the healing agent.

1 . Healing agent in cement-based materials and structures, wherein said healing agent comprises either porous particles loaded with bacteria and organic compounds or a combination of porous particles loaded with bacteria and porous particles loaded with organic compounds. 
     
     
         2 . The healing agent according to  claim 1 , wherein said porous particles comprise expanded clay- or sintered fly-ash. 
     
     
         3 . The healing agent according to  claim 1 , wherein said porous particles are intact spheres, broken or crushed particles derived from said intact spheres. 
     
     
         4 . The healing agent according to  claim 1 , wherein the specific density of said porous particles is between 0.4 and 2 g cm −3 . 
     
     
         5 . The healing agent according to  claim 1 , wherein the surface pore has a width of 0.01 to 100 μm. 
     
     
         6 . The healing agent of  claim 5 , wherein the surface pore width is between 0.01 and 15 μm. 
     
     
         7 . The healing agent according to  claim 1 , wherein the size of the bacteria-only loaded particles have a particle size with a diameter of ≧0.02 mm. 
     
     
         8 . The healing agent according to  claim 1 , wherein the size of the bacteria-only loaded particles have a particle size preferably 0.02-8 mm. 
     
     
         9 . The healing agent according to  claim 7 , wherein the particles have a diameter of 0.05 to 1.0 mm and the particle surface pore a width of 1.0 to 15 μm. 
     
     
         10 . The healing agent according to  claim 1 , wherein said bacteria belong to the genera  Bacillus  or  Sporosarcina  and comprise either vegetative bacteria or their spores or a combination of the two. 
     
     
         11 . The healing agent according to  claim 10 , wherein the bacteria is  Bacillus pseudofirmus  or  Sporosarcina pasteurii.    
     
     
         12 . The healing agent according to  claim 1 , wherein the organic compounds comprise an organic biomineral precursor compound and organic bacterial growth factors. 
     
     
         13 . The healing agent according to  claim 12 , wherein the organic biomineral precursor compound comprises an organic calcium or sodium salt and the organic bacterial growth factors comprise yeast extract or peptone. 
     
     
         14 . The healing agent according to  claim 1 , wherein the particle surface pore width is 0.01-1 μm. 
     
     
         15 . A process for the preparation of the healing agent according to  claim 1 , wherein porous aggregate material, expanded clay or sintered fly ash is loaded with bacteria and organic compounds by contacting said porous particle with the bacteria or bacterial spore-containing suspension or chemical biomineral precursor compound solution, wherein first the porous particles are dried and freed from the viable environmental bacteria by drying the same overnight in an oven at a temperature of 120-200° C., followed by cooling to room temperature, subjecting the particles to vacuum treatment, while the porous particles still under vacuum the bacteria or bacterial spore-containing suspension or chemical biomineral precursor compound solution is supplied to the particles and the particles are fully submerged, releasing the partial vacuum followed by drying said suspension or solution-entrained particles at room temperature and storing the same at room temperature until further use. 
     
     
         16 . A process for the preparation of the healing agent according to  claim 15 , wherein porous aggregate material, expanded clay or sintered fly ash is loaded with bacteria and organic compounds by contacting said porous particle with the bacteria or bacterial spore-containing suspension or chemical biomineral precursor compound solution, wherein first the porous particles are dried and freed from the viable environmental bacteria by drying the same overnight in an oven at a temperature preferably 140° C. 
     
     
         17 . The process according to  claim 15 , wherein expanded clay particles are loaded with  Bacillus pseudofirmus.    
     
     
         18 . The process according to  claim 15 , wherein expanded clay particles are loaded with  Sporosaxcina pasteurii  spores. 
     
     
         19 . The process according to  claim 15 , wherein two different types of porous particles are used simultaneously, one loaded with bacteria or their spores, and the other with a chemical biomineral precursor compound.