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US 5,346,548 AGranted
Highly durable cement products containing siliceous ashes
AssigneeThe Regents of the University of California
InventorPovindar K. Mehta
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AssigneeThe Regents of the University of California
InventorPovindar K. Mehta
Estimating the term…
Compositions particularly suitable for use in preparation of concrete and mortar products comprising at least one cement and from about 5% to about 30% by weight of the cement of siliceous ash from crop residue, wherein the ash is from about 60% to about 95% by weight silica, at least about 90% of the silica is amorphous, at least about 75% of ash particles are in a size range of from about 4 to about 75 micrometers, and the ash particles have a mean particle diameter measured by laser-light scattering of at least 6 micrometers and a B.E.T. surface area of at least 20 m.sup.2 /g. The cement employed is a portland cement or a blended portland cement. Concrete and mortar products prepared from these compositions are characterized by exhibiting after 28 days a compressive strength of at least 2500 psi and chloride permeabilities of less than 2000 coulombs when measured in accordance with AASHTO T-277.
A dry mix composition for preparation of concrete products upon addition of aggregate and water, said composition consisting essentially of:
A wet concrete composition comprising:
In a method for preparing a concrete product from a wet concrete composition comprising mixing a cement, water, and aggregate to form the wet concrete composition and curing the wet concrete composition to form the concrete product, the improvement comprising adding to the wet concrete composition from about 5% to about 30% by weight of the cement of siliceous ash from crop residue, wherein the ash is from about 60% to about 95% by weight silica, at least about 90% of the silica is amorphous, at least about 75% of ash particles are in a size range of from about 4 to about 75 micrometers, and the ash particles have a mean particle diameter measured by laser-light scattering of at least 6 micrometers and a B.E.T. surface area of at least 20 m.sup.2 /g, thereby providing a concrete product characterized after 28 days by a compressive strength of at least 2500 psi and a chloride permeability of less than about 2000 coulombs when determined in accordance with AASHTO T-277.
A method for accelerating early strength of a concrete product prepared from a wet concrete composition comprising a cement, the method comprising adding to the wet concrete composition from about 5% to about 30% by weight of the cement of siliceous ash from crop residue, wherein the ash is from about 60% to about 95% by weight silica, at least about 90% of the silica is amorphous, at least about 75% of ash particles are in a size range of from about 4 to about 75 micrometers, and the ash particles have a mean particle diameter measured by laser-light scattering of at least 6 micrometers and a B.E.T. surface area of at least 20 m.sup.2 /g, thereby providing a concrete product characterized after 28 days by a compressive strength of at least 2500 psi and a chloride permeability of less than about 2000 coulombs when determined in accordance with AASHTO T-277.
Dependencies are inferred from the claim text.