Cementitious compositions for decreasing the rate of water vapor emissions from concrete and methods for preparing and using the same
Cementitious compositions and processes for preparing and using the cementitious compositions are provided. The cementitious compositions are characterized by the property of a reduced or an attenuated water vapor emission from a cementitious mix and a concrete formed therefrom.
1. A cementitious composition for attenuating water vapor emission from a concrete made therefrom, comprising:
a hydraulic cement;
a superplasticizer;
a finely divided material having a particle size of less than 75 microns; and
a water vapor attenuation agent comprising at least one alkali metal salt selected from the group consisting of alkali metal halide salts, alkali metal nitrate salts, and alkali metal nitrite salts, the at least one alkali metal salt having a concentration of from about 0.24% to about 4.72% by weight of the cementitious composition in order to reduce internal relative humidity of concrete made from the cementitious composition and attenuate water vapor emission from the concrete.
2. The cementitious composition according to claim 1 , wherein the finely divided material is a cement replacement.
3. The cementitious composition according to claim 1 , wherein the superplasticizer is a polycarboxylate superplasticizer.
4. The cementitious composition according to claim 1 , further comprising an aggregate, the aggregate comprising a fine aggregate and a coarse aggregate.
5. The cementitious composition according to claim 4 , wherein:
the hydraulic cement has a concentration of from about 8% to about 35% by weight based on the total weight of the cementitious composition;
the finely divided material has a ratio by weight of finely divided material to the total weight of the cementitious composition of from about 0.01 to about 1.0;
the aggregate has a concentration of from about 50% to about 85% by weight based on the total weight of the cementitious composition; and
the superplasticizer has a concentration of from about 2 to about 30 ounces per 100 pounds of the hydraulic cement.
6. The cementitious composition according to claim 4 , wherein a ratio by weight of the fine aggregate to the total aggregate is from about 0.25 to about 1.00.
7. The cementitious composition according to claim 1 , wherein the water vapor attenuation agent comprises an alkali metal nitrite salt and the alkali metal nitrite salt comprises sodium nitrite.
8. The cementitious composition according to claim 7 , wherein the sodium nitrite has a concentration of from about 0.59% to about 2.95% by weight based on a total weight of the cementitious composition.
9. A cementitious composition for decreasing a rate of water vapor emission from a concrete comprising:
a hydraulic cement;
a superplasticizer; and
a water vapor attenuation agent comprising at least one alkali metal salt selected from the group consisting of alkali metal halide salts, alkali metal nitrate salts, and alkali metal nitrite salts, the at least one alkali metal salt having a concentration in a range from about 0.24% to about 4.72% by weight of the cementitious composition in order to reduce internal relative humidity of concrete made from the cementitious composition.
10. The cementitious composition according to claim 9 , further comprising a highly reactive pozzolan.
11. The cementitious composition according to claim 9 , further comprising a shrinkage reducing agent.
12. The cementitious composition according to claim 11 , wherein the shrinkage reducing agent comprises at least one of a polypropylene glycol and a polypropylene glycol derivative.
13. The cementitious composition according to claim 12 , wherein the shrinkage reducing agent has a concentration of from about 0.5% to about 3% by weight based on the total weight of the cementitious composition.
14. The cementitious composition according to claim 9 , wherein the water vapor attenuation agent comprises at least one alkali metal halide salt.
15. The cementitious composition according to claim 14 , wherein the at least one alkali metal halide salt is selected from the group consisting of a sodium halide, a potassium halide, a lithium halide, and any combination thereof.
16. The cementitious composition according to claim 15 , wherein the halide is selected from the group consisting of chloride, bromide, and any combination thereof.
17. The cementitious composition according to claim 9 , wherein the water vapor attenuation agent comprises at least one alkali metal nitrite salt.
18. The cementitious composition according to claim 17 , wherein the at least one alkali metal nitrite salt is sodium nitrite.
19. The cementitious composition according to claim 18 , wherein the sodium nitrite has a concentration of from about 0.59% to about 2.95% by weight based on a total weight of the cementitious composition.
20. A cementitious mix comprising:
a hydraulic cement having a concentration from about 8% to about 35% by weight based on a total weight of the cementitious mix on a water-free basis;
an aggregate having a concentration from about 50% to about 85% by weight based on the total weight of the cementitious mix on a water-free basis;
a densifying calcium silicate precursor having a concentration from about 2.5% to about 25% by weight based on the total weight of the cementitious mix on a water-free basis;
a water vapor attenuation agent having a concentration from about 0.5% to about 18% by weight based on a total weight of the hydraulic cement;
an amount of water sufficient to provide a water to cementitious ratio in the cementitious mix of from about 0.2 to about 0.6; and
a polycarboxylate superplasticizer having a concentration from about 2 ounces to about 30 ounces per 100 pounds of the hydraulic cement,
wherein the cementitious mix is used to prepare a concrete having an attenuated water vapor emission.
21. The cementitious mix according to claim 20 , wherein the water vapor attenuation agent is selected from the group consisting of an ultrafine calcium carbonate having an average particle size of less than or equal to about 3 microns, a highly reactive pozzolan, a shrinkage reducing agent, an alkali metal halide salt, an alkali metal nitrate salt, an alkali metal nitrite salt, and any combination thereof.
22. The cementitious mix according to claim 21 , wherein the water vapor attenuation agent comprises an alkali metal nitrite salt and the alkali metal nitrite salt comprises sodium nitrite.
23. The cementitious mix according to claim 22 , wherein the sodium nitrite has a concentration from about 0.24% to about 4.72 by weight of the cementitious mix.
24. The cementitious mix according to claim 20 , wherein the aggregate comprises a fine aggregate and a coarse aggregate.
25. The cementitious mix according to claim 24 , wherein a ratio by weight of the fine aggregate to the total aggregate is from about 0.25 to about 1.00.
26. A cementitious mix comprising:
a hydraulic cement having a concentration from about 8% to about 35% by weight based on a total weight of the cementitious mix on a water-free basis;
an aggregate having a concentration from about 50% to about 85% by weight based on the total weight of the cementitious mix on a water-free basis;
a water vapor attenuation agent comprising at least one alkali metal salt selected from the group consisting of alkali metal halide salts, alkali metal nitrate salts, and alkali metal nitrite salts, the at least one alkali metal salt having a concentration from about 0.24% to about 4.72% by weight of the cementitious mix; and
an amount of water to provide a water to cementitious ratio of from about 0.2 to about 0.6,
wherein the hydraulic cement, aggregate, water vapor attenuation agent, and water are selected and proportioned so that a hardened concrete produced from the cementitious mix achieves an internal relative humidity of no more than 75% in 50 days or less when evaluated in accordance with ASTM F 2170.
27. The cementitious mix according to claim 26 , wherein the water vapor attenuation agent is selected from the group consisting of alkali metal nitrate salts, alkali metal nitrite salts, and combinations thereof.