### Abstract

Air permeable concrete (APC) is potentially useful as a dynamic insulator. The dynamic function is achieved by passing air through the material in the direction of heat flow to facilitate heat recovery. An APC sample of 200 mm length with 60% cement filling of large voids (between 0.5 and 5 mm), was tested between 5 and 10 Pa differential pressures; permeabilities were 0.28-0.32 m(2)/Pa h, confirming its suitability as a dynamic insulator. To characterise properties it is necessary to determine the static thermal conductivity, i.e., no air flow. A one-dimensional heat flow model for predicting the effective thermal conductivity (lambda(e)) of APC is developed using as variables the fractions of voids, aggregate and cement paste comprising the material. Measured values of lambda(e) were 0.7-1.4 W/m K. A theoretical model predicts and further improves the performance and formulation of APC. The water/cement ratio (w/c) also controls the lambda(e). Increasing w/c increases the volume of micropores, adding resistance to heat flow. (C) 2007 Elsevier Ltd. All rights reserved.

Original language | English |
---|---|

Pages (from-to) | 647-655 |

Number of pages | 9 |

Journal | Cement & Concrete Composites |

Volume | 29 |

Issue number | 9 |

DOIs | |

Publication status | Published - Oct 2007 |

### Keywords

- air permeable concrete
- dynamic insulation
- thermal conductivity
- heat recovery
- energy efficiency
- uncertainty
- systems
- packing

### Cite this

*Cement & Concrete Composites*,

*29*(9), 647-655. https://doi.org/10.1016/j.cemconcomp.2007.04.008

**Evaluation of thermal conductivity in air permeable concrete for dynamic breathing wall construction.** / Wong, Jim Min; Glasser, F. P.; Imbabi, M. S.

Research output: Contribution to journal › Article

*Cement & Concrete Composites*, vol. 29, no. 9, pp. 647-655. https://doi.org/10.1016/j.cemconcomp.2007.04.008

}

TY - JOUR

T1 - Evaluation of thermal conductivity in air permeable concrete for dynamic breathing wall construction

AU - Wong, Jim Min

AU - Glasser, F. P.

AU - Imbabi, M. S.

PY - 2007/10

Y1 - 2007/10

N2 - Air permeable concrete (APC) is potentially useful as a dynamic insulator. The dynamic function is achieved by passing air through the material in the direction of heat flow to facilitate heat recovery. An APC sample of 200 mm length with 60% cement filling of large voids (between 0.5 and 5 mm), was tested between 5 and 10 Pa differential pressures; permeabilities were 0.28-0.32 m(2)/Pa h, confirming its suitability as a dynamic insulator. To characterise properties it is necessary to determine the static thermal conductivity, i.e., no air flow. A one-dimensional heat flow model for predicting the effective thermal conductivity (lambda(e)) of APC is developed using as variables the fractions of voids, aggregate and cement paste comprising the material. Measured values of lambda(e) were 0.7-1.4 W/m K. A theoretical model predicts and further improves the performance and formulation of APC. The water/cement ratio (w/c) also controls the lambda(e). Increasing w/c increases the volume of micropores, adding resistance to heat flow. (C) 2007 Elsevier Ltd. All rights reserved.

AB - Air permeable concrete (APC) is potentially useful as a dynamic insulator. The dynamic function is achieved by passing air through the material in the direction of heat flow to facilitate heat recovery. An APC sample of 200 mm length with 60% cement filling of large voids (between 0.5 and 5 mm), was tested between 5 and 10 Pa differential pressures; permeabilities were 0.28-0.32 m(2)/Pa h, confirming its suitability as a dynamic insulator. To characterise properties it is necessary to determine the static thermal conductivity, i.e., no air flow. A one-dimensional heat flow model for predicting the effective thermal conductivity (lambda(e)) of APC is developed using as variables the fractions of voids, aggregate and cement paste comprising the material. Measured values of lambda(e) were 0.7-1.4 W/m K. A theoretical model predicts and further improves the performance and formulation of APC. The water/cement ratio (w/c) also controls the lambda(e). Increasing w/c increases the volume of micropores, adding resistance to heat flow. (C) 2007 Elsevier Ltd. All rights reserved.

KW - air permeable concrete

KW - dynamic insulation

KW - thermal conductivity

KW - heat recovery

KW - energy efficiency

KW - uncertainty

KW - systems

KW - packing

U2 - 10.1016/j.cemconcomp.2007.04.008

DO - 10.1016/j.cemconcomp.2007.04.008

M3 - Article

VL - 29

SP - 647

EP - 655

JO - Cement & Concrete Composites

JF - Cement & Concrete Composites

SN - 0958-9465

IS - 9

ER -