Process for hydrophobization of concrete
A process for hydrophobization of concrete or mortar using an aqueous dispersion containing an alkylketene dimer, at least one emulsifier and a condensation product of phenol sulfonic acid and formaldehyde, naphthalene sulfonic acid and formaldehyde, or naphthalene sulfonic acid, phenol, formaldehyde and urea; and the concrete or mortar obtainable by the process. The process allows effective mass and surface hydrophobization of concrete.
1. A process for preparing hydrophobized concrete or mortar comprising the steps of
(A) providing a cement slurry suitable for concrete or mortar preparation;
(B1) adding an alkylketene dimer in at least one of solid form or aqueous dispersion, the alkylketene dimer comprising
(a) an alkylketene dimer of the formula (I)
and/or of the formula (II)
in which
R 1 and R 2 are identical or different hydrocarbon radicals comprising 10 to 24 carbon atoms;
(b) at least one emulsifier having a nitrogen content of ≤1% by weight selected from the group consisting of a starch, cellulose, starch derivative or cellulose derivative;
(c) a condensation product of phenol sulfonic acid and formaldehyde, naphthalene sulfonic acid and formaldehyde or naphthalene sulfonic acid, phenol, formaldehyde and urea wherein the sulfonic acid groups may optionally be present in protonated or deprotonated or partly in protonated and partly in deprotonated form;
wherein the dispersion has a charge density in the range from −5 to −150 μeq/g;
and allowing the cement slurry to harden
or
(B2) allowing the cement slurry of step (A) to harden and applying said alkylketene dimer in aqueous dispersion to the surface of the hardened cement.
2. The process of claim 1 , wherein said emulsifier is selected from modified starch and modified cellulose.
3. The process of claim 1 wherein the dispersion has a charge density in the range from −10 to −120 μeq/g.
4. The process of claim 1 , wherein the at least one emulsifier has a nitrogen content in the range from 0.05 to 1% by weight.
5. The process of claim 1 , wherein the hydrocarbon radicals in formula I or II are selected from branched and unbranched C 12 -C 24 -alkyl or C 12 -C 24 -alkenyl.
6. The process of claim 1 , wherein the alkylketene dimer dispersion comprises 5 to 40 wt % of alkylketene dimer of the total weight of the dispersion.
7. The process of claim 1 , wherein the emulsifier has a Brookfield viscosity in a 10% w/w aqueous solution, when using parameters RVDV-II+PX, spindle 01, 6 rpm, 20° C., in the range from about 3 to about 200 mPas.
8. The process of claim 1 , wherein the cement slurry is provided by adding water to a cement mixture suitable for concrete preparation.
9. The process of claim 8 , wherein in the case B1 the alkylketene dimer is used in an amount of 0.1 to 10 wt % of the total weight of the cement mixture.
10. The process of claim 7 , wherein the cement slurry is essentially free of a synthetic resin other than the condensation product (c).
11. The process of claim 1 , wherein the alkylketene dimer dispersion additionally comprises a wax or a (meth)acrylate dispersion.
12. A hydrophobized concrete or mortar obtained according to the process of claim 1 .
13. A process comprising hydrophobizing concrete or mortar, by addition or application thereto, utilizing an aqueous alkyl ketene dimer dispersion comprising
(a) an alkylketene dimer of the formula (I)
and/or of the formula (II)
in which
R 1 and R 2 are identical or different hydrocarbon radicals comprising 10 to 24 carbon atoms;
(b) at least one emulsifier having a nitrogen content of ≤1% by weight selected from the group consisting of a starch, cellulose, starch derivative or cellulose derivative;
(c) a condensation product of phenol sulfonic acid and formaldehyde, naphthalene sulfonic acid and formaldehyde or naphthalene sulfonic acid, phenol, formaldehyde and urea wherein the sulfonic acid groups may optionally be present in protonated or deprotonated or partly in protonated and partly in deprotonated form;
wherein the dispersion has a charge density in the range from −5 to −150 μeq/g.
14. The process of claim 13 , wherein the alkylketene dimer dispersion is utilized for mass hydrophobization of concrete or mortar by addition to a cement slurry suitable for concrete or mortar preparation.
15. The process of claim 13 , wherein the alkylketene dimer dispersion is utilized for surface hydrophobization of concrete by applying the alkylketene dimer dispersion to the surface of the concrete.