Mixture, in particular construction material mixture containing furnace slag
The present invention relates to building material mixtures which contain slag sand and zinc salts which have from 0 to 8 carbon atoms in their structure. The invention furthermore relates to the use of zinc salts for preventing discolorations during the hardening of the building material mixtures.
1. A building material binder system containing between 5 and 50% by weight slag sand as a first binder, and between 1 and 70% by weight microsilica and/or between 5 and 90% by weight metakaolin as a second binder, wherein the binder system contains between 0.001 and 10% by weight of a zinc salt, the zinc salt having from 0 to 8 carbon atoms, and between 5 and 50% by weight of an activator comprising at least one alkali metal compound, wherein the percentages are based on the total weight of the binder system.
2. The building material binder system according to claim 1 , wherein the binder system contains fly ash as a further binder.
3. The building material binder system according to claim 1 , wherein the slag sand has a specific surface area (Blaine value) of greater than 2000 cm 2 /g.
4. The building material binder system according to claim 1 , wherein the binder system contains the slag sand, the microsilica and/or metakaolin, and optionally fly ash as a first component, and the activator as a second component.
5. The building material binder system according to claim 1 , wherein the binder system contains the activator in pulverulent form.
6. The building material binder system according to claim 1 , wherein the activator comprises at least one of alkali metal hydroxide, alkali metal silicate, alkali metal aluminate, alkali metal carbonate, or alkali metal sulphate.
7. The building material binder system according to claim 1 , wherein the binder system contains zinc oxide, zinc fluoride and/or zinc sulphate as the zinc salt.
8. The building material binder system according to claim 6 , wherein the activator comprises alkaline potassium waterglass.
9. The building material binder system according to claim 1 , wherein the microsilica is present in an amount of between 10 and 50% by weight based on the total weight of the binder system.
10. The building material binder system according to claim 1 , wherein the metakaolin is present in an amount of between 15 and 50% by weight based on the total weight of the binder system.
11. The building material binder system according to claim 1 , wherein the zinc salt is present in an amount of from 0.1 to 7% by weight based on the total weight of the binder system.
12. Jointing mortars or coatings containing the building material binder system according to claim 1 .
13. A method comprising introducing in a building material binder system based on slag sand: (i) between 0.001 and 10% by weight of a zinc salt for preventing discolorations; (ii) between 1 and 70% by weight microsilica and/or between 5 and 90% by weight metakaolin as a second binder; and (iii) between 5 and 50% by weight of an activator comprising at least one alkali metal compound; wherein the building material binder system comprises between 5 and 50% by weight slag sand and wherein the percentages by weight are based on the total weight of the binder system.