Method for preparing an ettringite binder for producing construction materials
A method for preparing an ettringite binder from an aluminosilicate source, a calcium sulfate source and a calcium hydroxide (or slaked lime, CH) source, the binder including a catalyst and/or an activator. Also the use of the ettringite binder produced by the method for producing cement, masonry cement, mortar, concrete, road binders and/or formulated lime.
1. An ettringite binder consisting of:
at least one aluminosilicate source;
at least one calcium sulfate source;
at least one calcium hydroxide source;
at least two activators selected from the group consisting of sucrose, tartaric acid and salts thereof;
at least one alkali catalyst is selected from the group consisting of sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate and the mixtures thereof; and
optionally, at least one additive,
wherein the at least one aluminosilicate source comprises metakaolin.
2. The ettringite binder according to claim 1 , wherein the quantity by mass of catalyst is in a range of more than 0% to 20% with respect to the total quantity of the binder.
3. The ettringite binder according to claim 1 , wherein the aluminosilicate source comprising metakaolin is selected from the group consisting of a pozzolan, a fine originating from the production of chamotte, and calcinated clay.
4. The ettringite binder according to claim 1 , wherein the calcium hydroxide source is selected from the group consisting of slaked lime, hydraulic lime, quick lime, delayed-effect quick lime, air lime, conventional slaked lime, and any commercial lime.
5. The ettringite binder according to claim 1 , wherein the calcium sulfate source is selected from the group consisting of anhydrite, natural gypsum and gypsum obtained as a by-product of industrial reactions.
6. The ettringite binder according to claim 5 , wherein the gypsum is selected from the group consisting of desulfogypsum, titanogypsum, fluogypsum, and phosphogypsum.
7. The ettringite binder according to claim 1 , wherein the aluminosilicate source is characterized by a pozzolanic activity index (IPZ), determined by the Chapelle test method, of from 200 to 2200 mg/g.
8. The ettringite binder according to claim 1 , wherein the additive is selected from the group consisting of a slag, a blast furnace slag, and an amorphous aluminate slag.
9. The ettringite binder according to claim 1 , wherein the binder does not require producing a clinker at high temperatures ranging from 1200-1300° C.
10. A method for preparing an ettringite binder according to claim 1 , comprising mixing:
an aluminosilicate source comprising metakaolin;
a calcium sulfate source;
a calcium hydroxide source;
at least two activators selected from the group consisting of sucrose, tartaric acid and salts thereof;
at least one alkali catalyst is selected from the group consisting of sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate and the mixtures thereof; and
optionally, at least one additive,
wherein the at least one aluminosilicate source comprises metakaolin.
11. The method of preparation according to claim 10 , wherein the temperature at which the mixing is carried out is from more than 0° C. to 50° C.
12. A method for preparing cement, masonry cement, mortar, concrete, road binders and/or formulated lime, comprising adding the ettringite binder accorder to claim 1 to said cement, masonry cement, mortar, concrete, road binders and/or formulated lime.