Ultra-light mineral foam having water repellent properties
A process for producing a mineral foam having water repellent properties includes a) separately preparing a slurry of cement and an aqueous foam, wherein the cement slurry includes water, at least one water repellent agent different from organosilicon compound, and Portland cement and the aqueous foam includes a co-stabiliser; b) contacting the slurry of cement with the aqueous foam to obtain a slurry of foamed cement; and c) casting the slurry of foamed cement and leave the slurry of foamed cement to set.
1. A process for producing a mineral foam having water repellent properties comprising:
a) separately preparing a slurry of cement and an aqueous foam, wherein the cement slurry comprises water, at least one water repellent agent different from organosilicon compound, and Portland cement and the aqueous foam comprises a co-stabiliser which is a salt of a maleic anhydride copolymer;
b) contacting the slurry of cement with the aqueous foam to obtain a slurry of foamed cement; and
c) casting the slurry of foamed cement and leave the slurry of foamed cement to set.
2. The process according to claim 1 , wherein the water repellent agent is an organic polymer.
3. The process according to claim 1 , wherein the water repellent agent is in an amount ranging from 0.6 wt.-% to 6.5 wt.-% expressed as dry mass relative to the dry cement mass.
4. The process according to claim 1 , wherein the aqueous foam comprises water and the co-stabiliser is in an amount ranging from 0.01 wt.-% to 0.15 wt.-%, expressed in dry mass compared to the mass of water in the aqueous foam.
5. The process according to claim 1 , wherein the cement slurry used for the preparation of the mineral foam has a water cement weight ratio between 0.28 and 0.35.
6. The process according to claim 1 , wherein the Portland cement is a cement of the type CEM I, CEM II, CEM III, CEM IV or CEM V.
7. The process according to claim 1 , wherein the Portland cement has a specific surface (Blaine) of 3000-9000 cm 2 /g.
8. The process according to claim 1 , wherein contacting the slurry of cement with the aqueous foam comprises introducing the slurry of cement and the aqueous foam into a mixer to obtain a slurry of foamed cement in a continuous manner.
9. The method according to claim 1 , wherein the water repellent agent is a vinyl chloride-ethylene copolymer or vinyl acetate-ethylene copolymer and wherein the co-stabiliser is a polyanion.
10. A mineral foam having water-repellent properties obtained by a process comprising:
a) separately preparing a slurry of cement and an aqueous foam, wherein the cement slurry comprises water, at least one water repellent agent different from organosilicon compound, and Portland cement and the aqueous foam comprises a co-stabiliser which is a polyelectrolyte;
b) contacting the slurry of cement with the aqueous foam to obtain a slurry of foamed cement; and
c) casting the slurry of foamed cement and leaving the slurry of foamed cement to set;
the mineral foam having a water absorption at 24 hours of less than 1 kg/m 2 and a density in a dry state between 50 kg/m 3 and 200 kg/m 3 .
11. The mineral foam according to claim 10 , wherein the mineral foam is formed from a water repellent agent comprising vinyl chloride-ethylene copolymer or vinyl acetate-ethylene copolymer and a co-stabiliser comprising a polyanion.
12. An insulating material comprising the mineral foam according to claim 10 .
13. An element of construction comprising the mineral foam according to claim 10 .
14. The mineral foam according to claim 10 , wherein the mineral foam has a water absorption at 24 hours of less than 0.5 kg/m 2 .
15. The mineral foam according to claim 10 , wherein the density of the mineral foam in the dry state is between 50 kg/m 3 and 130 kg/m 3 .
16. The process of claim 1 , wherein the co-stabilizer is in an amount range from 0.02 wt.-% to 0.1 wt.-%.
17. The process of claim 1 , wherein the water repellent agent is in an amount ranging from 1.3 wt.-% to 4.8 wt.-%.
18. The process of claim 1 , wherein casting the slurry of foamed cement and leaving the slurry of foamed cement to set comprises forming a mineral foam having a density in a dry state of between 50 kg/m 3 and 200 kg/m 3 .