Electrically conductive binder for manufacturing heatable building parts
Electrically conductive binder comprising a cement, a sterically stabilizing superplasticizer, a rheology modifier, graphite particles with carbon content higher than 60%, and graphene; cementitious mixture comprising the binder, and heatable building elements, preferably underfloor heating layers and/or heating panels and/or heating layers close to a wall, as well as floors with underfloor heating systems comprising a layer from the binder.
1. An electrically conductive binder comprising a cement, graphite particles with a carbon content higher than 60%, and graphene,
wherein the amount of cement ranges from 40 to 80% by mass of the binder,
the amount of graphite particles ranges from 19.5 to 60% by mass of the binder,
the amount of graphene, calculated as dry substance, ranges from 0.005 to 0.5% by mass of the binder and
the binder contains a sterically stabilizing superplasticizer in an amount, calculated as dry substance, from 0.2 to 2.0% by mass relative to the mass of the cement, and
a rheology modifier in an amount, calculated as dry substance, from 0.01 to 0.9% by mass relative to the mass of the cement.
2. The binder according to claim 1 comprising 45 to 70% by mass cement with respect to the total binder mass.
3. The binder according to claim 1 , wherein the amount of graphite particles ranges from 25 to 50% by mass with respect to the binder.
4. The binder according to claim 1 , wherein the amount of graphene, calculated as dry substance, ranges from 0.1 to 0.4% by mass with respect binder.
5. The binder according to claim 1 , wherein the amount, calculated as dry substance, of the sterically stabilizing superplasticizer ranges from 0.5 to 1% by mass relative to the mass of cement.
6. The binder according to claim 1 , wherein the amount, calculated as dry substance, of the rheology modifier ranges from 0.03 to 0.6% by mass relative to the mass of cement.
7. The binder according to claim 1 , wherein the cement is CEM 152.58 with BET specific area of 1.1 to 2.5 m 2 /g.
8. The binder according to claim 1 , wherein the graphite has more than 80% by mass carbon.
9. The binder according to claim 1 , wherein the graphite is natural flake graphite with cumulative mass through sieve 150 mesh higher than 80%.
10. The binder according to claim 1 , wherein the graphene is graphite nanoplatelets with flake thickness around 10 nm and specific surface area higher than 30 m 2 /g.
11. The binder according to claim 1 , additionally containing an expansive mineral agent and/or a defoamer.
12. The binder according to claim 11 , containing relative to the mass of cement: 0.5 to 9% by mass of expansive mineral agent, and/or 0.02 to 0.30% by mass of defoamer.
13. The binder according to claim 1 , additionally containing metal fibers.
14. The binder according to claim 13 , wherein the metal fibers are steel fibers having an aspect ratio between 50 and 80.
15. The binder according to claim 13 , wherein the metal fibers are contained in an amount from 2 to 12% by mass relative to the mass of binder.
16. The binder according to claim 1 , additionally containing one or more of pigments, polymers, fillers, and/or silica fume.
17. The binder according to claim 1 comprising with respect to the total binder mass 50 to 65% by mass cement, 30 to 40% by mass graphite particles, and 0.2 to 0.3% by mass grapheme, calculated as dry substance.
18. The binder according to claim 17 , wherein the amount, calculated as dry substance, of the sterically stabilizing superplasticizer ranges from 0.5 to 1% by mass relative to the mass of cement.
19. The binder according to claim 17 , wherein the amount, calculated as dry substance, of the rheology modifier ranges from 0.03 to 0.6% by mass relative to the mass of cement.
20. The binder according to claim 18 , wherein the amount, calculated as dry substance, of the rheology modifier ranges from 0.03 to 0.6% by mass relative to the mass of cement.
21. The binder according to claim 20 , wherein the cement is CEM 152.51 with BET specific area of 1.1 to 2.5 m 2 /g.
22. The binder according to claim 17 , wherein the graphite has more than 90% by mass carbon and is natural flake graphite with cumulative mass through sieve 100 mesh higher than 80%.
23. The binder according to claim 20 , wherein the graphite has more than 90% by mass carbon and is natural flake graphite with cumulative mass through sieve 100 mesh higher than 80%.
24. The binder according to claim 17 , wherein the graphene is graphite nanoplatelets with flake thickness around 10 nm and specific surface area higher than 30 m 2 /g.
25. The binder according to claim 20 , wherein the graphene is graphite nanoplatelets with flake thickness around 10 nm and specific surface area higher than 30 m 2 /g.
26. The binder according to claim 23 , wherein the graphene is graphite nanoplatelets with flake thickness around 10 nm and specific surface area higher than 30 m 2 /g.
27. The binder according to claim 17 , additionally containing an expansive mineral agent and/or a defoamer.
28. The binder according to claim 17 , additionally containing steel fibers having an aspect ratio between 50 and 80 in an amount from 2 to 12% by mass relative to the mass of binder.
29. A cementitious mixture comprising
an electrically conductive binder comprising
a cement in an amount from 40 to 80% by mass of the binder,
graphite particles with a carbon content higher than 60% in an amount from 19.5 to 60% by mass of the binder,
graphene in an amount, calculated as dry substance, from 0.005 to 0.5% by mass of the binder,
a sterically stabilizing superplasticizer in an amount, calculated as dry substance, from 0.2 to 2.0% by mass relative to the mass of the cement, and
a rheology modifier in an amount, calculated as dry substance, from 0.01 to 0.9% by mass relative to the mass of the cement,
and water, wherein the water/cement ratio ranges from 0.8 to 1.5 and/or the water/solids ratio ranges from 0.48 to 0.65.
30. The cementitious mixture according to claim 29 , wherein the binder comprises with respect to the total binder mass 50 to 65% by mass cement, 30 to 40% by mass graphite, and 0.2 to 0.3% by mass grapheme, calculated as dry substance.
31. The cementitious mixture according to claim 30 , wherein the cementitious mixture or the cementitious part made from it has one or more of the following properties:
spread measured according to UNI 7044 from 170 to 230 mm;
density measured according to UNI EN 1015-4 from 1600 to 1800 kg/m 3 ,
and/or a 28 days hardened cementitious part from the cementitious mixture has one or more of the following properties:
a compressive strength measured according to UNI EN 196-1 from 10 to 20 MPa;
a flexural strength measured according to UNI EN 196-1 from 2.5 to 8 MPa,
a dry shrinkage measured according to UNI 6687 (modified by using specimens of 1 cm thickness) from 1200 to 3000 μm/mm,
an electrical resistance measured by a multimeter connected to two copper strips embedded in the cementitious part along the length from 5 to 100Ω;
an electrical resistivity calculated from the resistance ranging from 0.1 to 0.5 Ω·m.
32. A floor with underfloor heating system, wherein the floor comprises:
a basic support layer,
a layer of thermal insulating material,
a layer of concrete for floor undercoat,
a layer made from an electrically conductive binder according to claim 1 with electrical connection to an extra-low voltage AC or DC source,
an uppermost layer from ceramic or marble tiles, parquet, carpet, or laminate flooring.
33. The floor according to claim 32 , wherein the floor is assembled from precast and prefabricated slabs.
34. The floor according to claim 32 , wherein the binder comprises with respect to the total binder mass 50 to 65% by mass cement, 30 to 40% by mass graphite, and 0.2 to 0.3% by mass grapheme, calculated as dry substance.
35. The cementitious mixture according to claim 29 , wherein the cementitious mixture or the cementitious part made from it has one or more of the following properties:
spread measured according to UNI 7044 from 180 to 220 mm;
density measured according to UNI EN 1015-4 from 1630 to 1750 kg/m 3 ;
and/or a 28 days hardened cementitious part from the cementitious mixture has one or more of the following properties:
a compressive strength measured according to UNI EN 196-1 from 13 to 17 MPa;
a flexural strength measured according to UNI EN 196-1 from 3 to 6 MPa;
a dry shrinkage measured according to UNI 6687 (modified by using specimens of 1 cm thickness) from 1600 to 2500 μm/mm;
an electrical resistance measured by a multimeter connected to two copper strips embedded in the cementitious part along the length from 20 to 60Ω;
an electrical resistivity calculated from the resistance ranging from 0.2 to 0.3 Ω·m.