| 摘要 |
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 m2/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.
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