Highly reflective microcrystalline/amorphous materials, and methods for making and using the same

Abstract

Compositions comprising highly reflective microcrystalline / amorphous materials are provided. In some instances, the highly reflective materials are microcrystalline or amorphous carbonate materials, which may include calcium and / or magnesium carbonate. In some instances, the materials are CO2 sequestering materials. Also provided are methods of making and using the compositions, e.g., to increase the albedo of a surface, to mitigate urban heat island effects, etc.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Under 35 U.S.C. §119(e), this application claims priority to the filing date of U.S. Provisional Patent Application Ser. No. 61 / 943,992, filed on Feb. 24, 2014; U.S. Provisional Patent Application Ser. No. 61 / 866,985, filed on Aug. 16, 2013 and U.S. Provisional Patent Application Ser. No. 61 / 793,661, filed on Mar. 15, 2013; the disclosures of which applications are incorporated herein by referenceINTRODUCTION[0002]As the development of cities replaces natural lands, forests and open grassy fields with pavements, buildings and other infrastructures, the relationship between incoming sun radiation and outgoing terrestrial radiation has been changed. The conversion of pervious surfaces to impervious surfaces alters local energy balances through changes in (1) the albedos of surfaces; (2) the heat capacities and thermal conductivities of surfaces; (3) the ratio of sensible heat to latent heat flowing from the surface into the atmosphere. More...

AI Technical Summary

Benefits of technology

[0094]The methods and compositions, e.g., as described above, find use in any application where increasing or enhancing the albedo of a surface is desired. Applications of interest include, but are not limited to: reducing the temperature of urban heat islands, e.g., by 1° C. or more, such as 2° C. or more, including 5° C. or more; reducing lighting needs; reducing light absorption by man-made and naturally occurring structures, as well as both new structures and retrofitting existing structures, etc.Utility

[0099]The highly reflective materials, e.g., as described herein, also find use in roofing membranes. The term “roofing membrane” is employed in its conventional sense to refer to single-ply membranes that are flexible sheets of compounded synthetic materials that are configured for use in roofing applications. Roofing membranes of interest include thermoset, thermoplastic, and modified bitumen roofing membranes. Thermoset roofing membranes are made of large, flat pieces of synthetic rubber or similar materials, where the pieces are welded together at the seams to form one continuous membrane. Rubbers of interest include, but are not limited to: ethylene propylene diene monomer (EPDM), neoprene, etc. In thermoset roofing membranes, the seams are held together using suitable adhesives materials or tapes. Thermoplastic membranes are similar to thermoset membranes, where the seams are bonded melted or dissolved with heat or solvents, and can be as strong as the rest of the membrane. Thermoplastic membranes are based on elastomeric polymers that can be processed as plastics. Thermoplastic polyolefin (TPO) based roofing membranes may be a melt blend or reactor blend of a polyolefin plastic, such as a polypropylene polymer, with an olefin copolymer elastomer (OCE), such as an ethylene-3Q propylene rubber (EPR) or an ethylene-propylene-diene rubber (EPDR). TPO-based roofing membranes may comprise one or more layers. A TPO membrane may comprise base-(bottom) and cap-(top) layers with a fiber reinforcement scrim (middle) sandwiched between the other two layers. The scrim may be a woven, nonwoven, or knitted fabric composed of continuous strands of material used for reinforcing or strengthening membranes. The scrim is generally the strongest layer in the composite. The fabric can contribute significantly to the tensile strength of the roofing membrane and provide for dimensional stability. In an example, the fabric reinforcement comprises a polyester yarn based scrim. Modified bitumen membranes are factory-fabricated layers of asphalt, “modified” using a rubber or plastic ingredient (e.g., APP (atactic polypropylene) and SBS (styrene butadiene styrene) for increased flexibility, and combined with reinforcement for added strength and stability. While a given roofing membrane's thickness may vary, in some instances the thickness ranges from 0.75 mm to 1.5 mm.

[0118]One type of construction panel provided by the invention is cement board. They are formed building materials where in some embodiments, are used as backer boards for ceramics that may be employed behind bathroom tiles, kitchen counters, backsplashes, etc. and may have lengths ranging from 100 to 200 cm, such as 125 to 175 cm, e.g., 150 to 160 cm; a breadth ranging from 75 to 100 cm, such as 80 to 100 cm, e.g., 90 to 95 cm, and a thickness ranging from 5 to 25 mm, e.g., 5 to 15 mm, including 5 to 10 mm. Cement boards of the invention may vary in physical and mechanical properties. In some embodiments, the flexural strength may vary, ranging between 1 to 7.5 MPa, including 2 to 6 MPa, such as 5 MPa. The compressive strengths may also vary, ranging from 5 to 50 MPa, including 10 to 30 MPa, such as 15 to 20 MPa. In some embodiments of the invention, cement boards may be employed in environments having extensive exposure to moisture (e.g., commercial saunas). The maximum water absorption of the cement boards of the invention may vary, ranging from 5 to 15% by weight, including 8 to 10%, such as 9%. Cement boards of the invention may also undergo moisture movement (expansion or contraction) due to the absorption or loss of water to its environment. The dimensional stability (i.e., linear shrinkage or expansion) due to moisture movement may vary, in certain instances ranging from 0.035 to 0.1%, including 0.04 to 0.08%, such as 0.05 to 0.06%. The highly reflective material composition of the invention may be used to produce the desired shape and size to form a cement board. In addition, a variety of further components may be added to the cement boards which include but are not limited to: plasticizers, foaming agents, accelerators, retarders and air entrainment additives. The highly reflective building material composition is then poured out into sheet molds or a roller may be used to form sheets of a desired thickness. The shaped composition may be further compacted by roller compaction, hydraulic pressure, vibrational compaction, or resonant shock compaction. The sheets are then cut to the desired dimensions of the cement boards. In some instances, the resultant composition may also be foamed using mechanically or chemically introduced gases prior to being shaped or while the composition is setting in order to form a lightweight cement board. The shaped composition is then allowed to set and further cured in an environment with a controlled temperature and humidity. The cement boards of the invention then may be covered in a fiberglass mat on both faces of the board. Where desired, the cement boards of the current invention may also be prepared using chemical admixtures such that they possess increased fire, water, and frost resistance as well as resistance to damage by bio-degradation and corrosion. The cement board of the current invention may also be combined with components such as dispersed glass fibers, which may impart improved durability, increased flexural strength, and a smoother surface.

[0187]Unlike reaction 4, in which the co-precipitation of Ca-silicate and CaCO3 were prepared before mixing (discussed more in detail in previous section), other samples were prepared by adding silicic acid and colloidal silica directly to CaCO3 powder blends just before pressing (samples 122 and 123). The main purpose of adding silica to CaCO3 blends was to improve the strength and stability of compressed coupons and cured samples. Unlike sample 118, which the reaction completed during compression and produced a hard pellet, samples 122 and 123 were still relatively weak after compression. FTIR results of S122 and S123 coupons indicated presence of ACC, amorphous vaterite precursor / anhydrous amorphous carbonate, polymerized silica with little calcite. However, as the samples were cured, drastic chemistry changes occurred and the samples began to build very high strength.b. Curing of Compressed Samples

[0200]TPO or other polymer single or multi ply roofing membrane process include the use of a cool carbonate precipitate or a cool pigment to increase the albedo of the roofing product. Blue Planet cool pigments replace Titanium Dioxide for reflectance purposes or be used in conjunction with varying amounts of TiO2.d. Road Materials

Problems solved by technology

Elevated temperatures in summertime can impact communities by increasing energy demand, air conditioning costs, air pollution levels, and heat-related illness and mortality.

Summertime heat islands may also contribute to global warming by increasing demand for air conditioning, which results in additional power plant emissions of heat-trapping greenhouse gases.

The heat island effect is one factor among several that can raise summertime temperatures to levels that pose a threat to human health.

Extremely hot weather can result in illness including physiological disruptions and organ damage and even death.

Excessive heat events or abrupt and dramatic temperature increases are particularly dangerous and can result in above average rates of mortality.

Under certain conditions, excessive heat also can increase the rate of ground-level ozone formation, or smog, presenting an additional threat to health and ecosystems within and downwind of cities.

Exposure to ambient ozone, even at low levels, may trigger a variety of health problems, especially in vulnerable populations such as children, the elderly, and those with pre-existing respiratory disease.

Because wind can carry ozone and its precursors hundreds of miles, even residents far away from urban centers and sources of pollution can be at risk.

The specific health effects associated with ozone exposure include irritating lung airways and causing inflammation, possible permanent lung damage by repeated exposure to ozone pollution for several months, as well as resulting in aggravated asthma, reduced lung capacity, and increased susceptibility to respiratory illnesses by even low-level exposure, etc.

In addition, ozone pollution can damage vegetation and ecosystems within and downwind of cities.

For instance, ground-level ozone interferes with the ability of plants to grow and store food.

Ozone also damages the foliage of trees and other vegetation, reducing crop and forest yields, and tarnishing the visual appeal of ornamental species and urban green spaces.

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