Abstract: The invention pertains to a method for producing rapid setting cement and to the compositions produced therefrom. The setting time of hydraulic cement compositions comprising Portland cement and fly ash can be accelerated by controlling the pH of an activator slurry used in the composition. The pH of the activator slurry is controlled by non-stoichiometrically balancing the accelerating salts therein such that the activator slurry is alkaline, or having a pH greater than 7. The slurry activator of the present invention generally includes a base component, an acid component, and water. The base component can include any basic alkali and alkaline earth metal hydroxide, or a salt of the acid component. The acid component may include a hydroxycarboxylic acid, preferably citric acid. Mortar and concrete compositions can be prepared with this hydraulic cement wherein the compositions can achieve high strengths in a short time.

Abstract: The present invention relates to a pozzolanic admixture containing ammonia-laden fly ash, method for making the pozzolanic admixture and method for controlling ammonia gas (NH3) emission from cementitious slurries using the pozzolanic admixture. The associated hypochlorite and ammonia reaction produces monochloramine and chloride salts at relatively low concentration levels harmless to concrete and concrete applications. The resulting monochloramine and chloride salt products are stable and do not dissipate into the air, thereby, eliminating odorous emission that is produced from cementitious slurry containing untreated ammonia laden fly ash.

Abstract: Fiber reinforced aerated concrete compositions and methods of forming structural units such as blocks, panels, etc., from such compositions are disclosed. The compositions comprise a fly ash/cement slurry with a coated Al paste serving as the activator to generate the desired cellular structure. The composition can be self cured at ambient temperature and pressure without the need for ovens or autoclaves. The cured compositions can be easily cut into the desired shape by a band saw or the like.

Abstract: The invention pertains to a method of delaying the set time of cement and to compositions produced therefrom. The set time of hydraulic cement mixtures of fly ash pozzolans, specifically Class C and Class F, and Portland cement can be delayed by controlling the pH of a retarder slurry that is mixed with the dry components of the composition. The pH of the retarder slurry is controlled by balancing the salts therein such that the retarder slurry is acidic, or having a pH less than 7. The slurry activator of the present invention generally includes a pH balancing agent, an acid component, and water. The pH balancing agent can include any basic alkali and alkaline earth metal hydroxide, or a salt of the acid component. The acid component may include a hydroxycarboxylic acid, preferably citric acid. Slower setting mortar and concrete compositions having high strength can be prepared with this hydraulic cement.

Abstract: Processes for treating fly ash to enhance the fly ash as a pozzolan for portland cement mixes and to separate therefrom a substantial carbon compound and/or to increase the fineness of the fly ash include the treatment of a fly ash slurry with ultrasonic energy using ultrasonic horns immersed in a slurry of fly ash and water and imparting to said slurry such ultrasonic energy as to cause microscopic cavities to form and implode with high localized energy to break up fly ash agglomerations along cleavage lines and to break up carbon particles and matrices which have entrapped fly ash microspheres therein to release the microspheres into the slurry. A conditioner agent may be added at or during ultrasonic treatment to enhance the flotation of the carbon compound.