High SRI cementitious systems for colored concrete
IR reflective cementitious systems comprising one or more IR reflective pigments are provided. The cementitious systems of the invention may be in the form of mixtures which increase the total solar reflectivity (TSR or albedo) and the Solar Reflectance Index (SRI) of concrete are provided. The cementitious systems are infrared reflective and may be toppings mixed with water for application to existing concrete surfaces, or dry-shake hardeners for application to freshly-placed plastic concrete. The formulations of the invention utilize one or more of cementitious binder(s), graded aggregates, super-plasticizers, one or more pigments selected for improving infrared reflectivity and color composition, and/or optionally other additives, such as dry redispersible polymers or fillers to provide decorative and LEED compliant, highly durable (sustainable) concrete hardscapes and other decorative concrete.
1. A cementitious system comprising:
an infrared reflective pigment composition comprising
i) one or more infrared reflective pigments, wherein at least one of the one or more infrared reflective pigments is a black infrared reflective pigment having a percent reflectance at 1000 nm of at least 40%, as measured in white portland cement mortar, and is selected from the group consisting of manganese-vanadium oxide spinels, chromium green-black hematites, aluminum- and titanium-doped chromium green-black modified hematites, chromium iron oxides, hematite chromium green-blacks, iron chromite brown spinels, and perylene blacks; and
ii) a cementitious matrix comprising cement and aggregates,
wherein the cementitious system is colored with pigments compliant with ASTM C979.
2. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is a black infrared reflective pigment having a Solar Reflectance Index of 45% as measured in white portland cement mortar, and computed from the albedo value using the Stefan-Boltzman Constant, 5.67 E-8 watts * m −2 * K −4 and a normally assigned emittance (ε) value of, ε=0.90.
3. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is a manganese-vanadium oxide spinel.
4. The cementitious system according to claim 1 wherein the cementitious system further comprises anatase.
5. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is combined in the cementitious system to form a light gray, gray, or dark gray colored cementitious system.
6. The cementitious system according to claim 1 wherein the cementitious matrix further comprises cementitious materials to form a dry shake color hardener.
7. The cementitious system according to claim 1 wherein the cementitious matrix further comprises cementitious materials to form a topping.
8. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is a chromium green-black hematite.
9. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is an aluminum- and titanium-doped chromium green-black modified hematite.
10. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is a chromium iron oxide.
11. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is a hematite chromium green-black.
12. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is an iron chromite brown spinel.
13. The cementitious system according to claim 1 wherein at least one of the black infrared reflective pigments is a perylene black.
14. A composition for creating a colored cementitious material, comprising:
(a) cement; and
(b) one or more infrared reflective pigments, wherein at least one of the one or more infrared reflective pigments is a black infrared reflective pigment having a percent reflectance at 1000 nm of at least 40%, as measured in white portland cement mortar, and is selected from the group consisting of manganese-vanadium oxide spinels, chromium green-black hematites, aluminum- and titanium-doped chromium green-black modified hematites, chromium iron oxides, hematite chromium green-blacks, iron chromite brown spinels, and perylene blacks; and
(c) cementitious materials comprising admixtures, fillers, pozzolans, and silica fine aggregates,
wherein the colored cementitious material is colored with pigments compliant with ASTM C979.
15. The composition according to claim 14 wherein the colored cementitious material is a light gray, gray, dark gray, or black colored cementitious material.
16. A method of preparing a colored concrete comprising:
(a) providing a cement and aggregates;
(b) adding one or more infrared reflective pigments to the cement, wherein at least one of the one or more infrared reflective pigments is a black infrared reflective pigment having a percent reflectance at 1000 nm of at least 40%, as measured in white portland cement mortar, and is-selected from the group consisting of manganese-vanadium oxide spinels, chromium green-black hematites, aluminum- and titanium-doped chromium green-black modified hematites, chromium iron oxides, hematite chromium green-blacks, iron chromite brown spinels, and perylene blacks, wherein the colored concrete is colored with pigments compliant with ASTM C979.
17. A method according to claim 16 wherein at least one of the one or more infrared reflective pigments is a manganese vanadium oxide spinel.
18. The method according to claim 16 wherein the one or more infrared reflective pigments are added to the cement in the form of a topping for applying to hardened concrete.
19. The method according to claim 16 wherein the one or more infrared reflective pigments are added to the cement in the form of a dry-shake color hardener for applying to freshly placed concrete.