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Influence of Properties and Proportions of Constituents of Concrete on Thermal Conductivity

  • ID:

    22

  • ESCSI:

    3204.004

  • Author:

    Valore, Rudolph C., Jr.

  • Publication Name:

    Influence of Properties and Proportions of Constituents of Concrete on Thermal Conductivity

  • Type of Publication:

    Article

  • Publisher:

    Rudolph C. Valore, Jr.

  • Dated:

    1978

  • Issue/Volume:

  • Other ID:

  • Page(s):

    1-23 + append.

  • Reference List:

    N

  • Abstract:

    Thermal conductivity of concrete in a masonry unit has a decisive influence on U-values of walls of such units, whether the units are solid or hollow, with cores empty or filled with insulating material. Curves are shown for units with cores filled with insulating material having k values of 1, 0.4, and 0.2 representing fills of expanded shale, perlite, and polystyrene or urea formaldehyde foam, respectively. These curves are derived from calculations based on a formula from the ASHRAE guide in which the masonry unit is divided into R segments (face shells) in series with R segments in parallel (webs and filled cores) which are then combined to yield U-values. The data show the importance of using units of concrete with low k values if cores are to be filled with insulation; it is also shown that U-values obtained by filling cores cannot be substantially reduced by using insulation with k below the range of 0.2 to 0.4. The efficiency of core insulation decreases rapidly as the degree of mismatch between k of concrete in the web of a unit and k of insulation increases. Calculations show that for units with k of core insultation approaching zero, U-values are reduced only 0.02 or less when compared with units with core insulation with k of 0.2.