Rapid hardening cement
AssigneeThe Associated Portland Cement Manufacturers Limited
InventorsLeslie Edward Shiel, Kenneth Wilson Jones
Life of this patent
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Abstract
A gypsum-free ultra-rapid hardening Portland Cement ground to a specific surface area of 3000 to 7000 cm.sup.2 /g and containing a minor proportion of an acid salt of an alkali metal, ammonium or organic base.
Claims9
A gypsum-free cement composition exhibiting ultra-rapid attainment of high early strength as compared with ordinary Portland cement containing gypsum, and with setting properties which can be regulated, which composition consists essentially of a Portland cement clinker, which does not contain gypsum, ground to exhibit a specific surface of from 3000-7000 cm.sup.2 /g, and at least one acid salt of a base in amount sufficient to impart said ultra-rapid attainment of high early strength, said acid salt of a base being selected from the group consisting of alkali metals, ammonium and organic bases with a phosphorous-free acid and being present in amount of 0.1-10% by weight of said clinker.
The method of making a gypsum-free cement composition exhibiting ultra-rapid attainment of high early strength as compared with ordinary Portland cement containing gypsum, and with setting properties which can be controlled, which comprises the steps of:
- a. grinding Portland cement clinker, in the absence of gypsum, to exhibit a specific surface of from 3000-7000 cm.sup.2 /g;
- b. controlling the hardening rate of said composition by incorporating in said ground clinker from 0.1-10% by weight of at least one acid salt of a base selected from the group consisting of alkali metals, ammonium and organic bases with a phosphorous-free acid;
- and
- c. controlling the setting time of said composition by incorporating therein a retarding agent such as hydroxy carboxylic acids and lignosulphonates in amount of 0.05-2% by weight.
Dependencies are inferred from the claim text.