Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B14/02—Granular materials, e.g. microballoons
  • C04B14/022—Carbon
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• This invention relates to carbon loaded concrete and cementicious products having reduced thermal conductance .
• Composite thermal conductivity depends, in part, on the volume of the solid (s) versus pore volume, and the conductivity of the bulk solid.
• the relative importance of convection depends on the degree and type of porosity, for example, the pro- portion of open to closed porosity, pore diameter and shape. Below a certain pore size, in-pore gases are effectively static and convection is drastically reduced. Conversely, heat transfer by convection increases with moisture content of the concrete.
• a concrete or cementicious product having one or more forms of carbon dispersed therethrough so as to reduce thermal conductance across the product.
• a concrete or cementicious product having one or more forms of carbon dispersed therethrough in small clusters and/or agglomerates that are wholly or substantially isolated from each other.
• Particulate loadings especially carbons
• Carbons suitable for use in the present invention will typically have a BET surface area of ⁇ 550 m 2 /g.
• One typical form of carbon for use with the present invention is carbon black.
• Carbon blacks are composed of spheroidal primary particles which partially coalesce during manufacture to form interlinked clusters and chains of carbon spheres.
• the structure of a carbon black is defined in terms of the growth of the clusters and chains.
• the carbon black industry defines a "low structure” black as consisting of small clusters of spheroids, whereas a "high structure” black contains extensive chains and clusters, which tend to interlock further to form large agglomerates.
• the form(s) of carbon black suitable for use with the present invention preferably have a medium to low "structure” and a high intrinsic electrical resistivity.
• forms of carbon with a low pH in dry dispersion in cement, and/or a small particle size are also preferred in some cases.
• the "structure" of the carbon black can be defined by its DBP Index. This is the amount of di -butyl phthalate which a carbon can take up to form a paste of a prescribed consistency. A low DBP index indicates a "low structure”. DBP Index values for carbons for use with the present invention range typically from 35 to 170 ml/lOOg and more preferably have a DBP index in the range of 40 - 105 mls/lOOg.
• An aim of the present invention is to disperse a carbon through the concrete or a cementicious material so that clusters, chains and small agglomerates are largely isolated and do not form linked pathways through the block. In this way, use is made of the carbon's ability to absorb radiant heat, without creating additional routes for convection and/or conduction.
• the concrete or cementicious products of the present invention can be of any form, size, shape and design.
• One typical example is concrete blocks, from which structures can be formed and/or built.
• blocks of the Autoclaved Aerated Concrete (AAC) type are suitable for the application of this invention.
• AAC Autoclaved Aerated Concrete
• the carbon is preferably added as a percentage of the cementicious material in the range 0.2 to 3.0 wt%, preferably 0.5 to 2.0 wt%.
• Cementicious material can be: Portland Cement; Calcium Alu inate Cement; Pozzolanic materials such as Pulverised Fuel Ash (PFA) , volcanic ash etc; finely ground silica; Latent Hydraulic materials such as Ground Granulated Blastfurnace (GGBS) and other slags etc; Microsilica; Metakaolin; or mixtures thereof. This list is not exhaustive.
• Suitable forms of PFA comply with BS3892: Part 1: 1993 or BS EN 450 : 1995.
• a suitable source of PFA is from Drax power station (UK) .
• UK Drax power station
• Other forms and sources of PFA may also be used.
• a suitable Plasticiser for use in this invention is Sikament 10. Other types of plasticiser may also be used. Suitable types of Coated Aluminium Powder are Higas 100 and Higas 220. Other types of aluminium powder may also be used.
• Carbon and approximately 10% of the PFA were dispersed in approximately 15% of the mixing water containing approximately half the plasticiser in a high shear mixer.
• the mixing regime should be chosen such that substantially discrete particles of carbon are evenly dispersed throughout the mix. Overmixing of some forms of carbon may lead to agglomeration of the carbon particles and result in poor performace of the blocks. Moulds were coated with release agent . The slurry was immediately poured into the mould. The mix rises typically between 80 to 100%.
• a "plain unguarded hot plate” apparatus was set up according to BS 874 Part 2 : Section 2.2 1988.
• Fracture surfaces of autoclaved samples were gold coated and examined in a scanning electron microscope.
• the aerated commercial sample consisted of roughly spherical, blow pores of 0.1 to 1mm diameter (Figure 1) . Pores are not completely closed. Pore walls are relatively smooth (Figure 2) with further irregular, open porosity (up to 0.05 ⁇ m) between acicular crystals. The matrix between the blown pores consists predominantly of loosely bonded PFA spheres, in the size range 1 to 10 m ( Figure 3) . with considerable open porosity between.
• Carbon loaded aerated concretes have been formed with k-values lower than the standard (no carbon) aerated concrete even where the carbon loaded concretes were of increased density.
• Carbons which give the best results are for example high resistivity carbon blacks, with medium to low structures, (DBP 40 to 105mls/100g) .
• Figure 1 shows the pore structure of commercial aerated block magnified x 20.
• Figure 2 shows the pore structure of commercial aerated block magnified x 3000.
• Figure 3 shows the pore structure of commercial aerated block magnified x 3000.
• Figure 4 shows the pore structure in standard formulation x 20.
• Figure 5 shows the pore structure in standard formulation x 3000.
• Figure 6 shows the pore structure in a carbon black (Nol) loaded sample at 0.5% carbon addition x 20.
• Figure 7 shows the pore structure in a carbon black (Nol) loaded sample at 0.5% carbon addition x 1500.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Civil Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)
• Carbon And Carbon Compounds (AREA)

Applications Claiming Priority (3)

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• 1999
  • 1999-05-14 GB GB9911165A patent/GB9911165D0/en not_active Ceased
• 2000
  • 2000-05-15 EP EP20000935269 patent/EP1187795A1/en not_active Withdrawn
  • 2000-05-15 AU AU50826/00A patent/AU5082600A/en not_active Abandoned
  • 2000-05-15 WO PCT/GB2000/001845 patent/WO2000069789A1/en not_active Application Discontinuation
  • 2000-05-15 EE EEP200100602A patent/EE200100602A/et unknown
  • 2000-05-15 NZ NZ515494A patent/NZ515494A/en unknown
  • 2000-05-15 CA CA 2373436 patent/CA2373436A1/en not_active Abandoned
• 2001
  • 2001-11-13 NO NO20015553A patent/NO20015553D0/no not_active Application Discontinuation

Non-Patent Citations (1)

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