In order to reduce energy usage for heating, conventional practices suggests that, a building must be airtight and more insulation must be used. This has led in the past to inadequately ventilated buildings and the accumulation of high levels of volatile organic compounds and other pollutants indoors, contributing to sick building syndrome. Dynamic insulation, although a fairly new concept, is attracting attention as a means of reducing energy consumption in building while at the same time, improving indoor air quality. This thesi6 investigates and develops procedures and ,.' mix formulations for producing a concrete-based dynamic insulation material, also known as 'breathable concrete'. When used as a building envelope this special concrete must have: (i) sufficient strength to carry its 'own weight, (ii) be sufficiently air permeable as a ventilation source when subject to 5-10 Pa diff~rential pressure across the inlier and outer surface, and (iii) have low static thermal conductivity. The research investigated (a) the shape and size of aggregate, (b) quantity of cement, ' (c) the quantity of water and other admixtures, and their relevant role in the design of breathable concrete. Pre-cast concrete cylinders were made possessing the necessary target permeability of 0.05 m2/pa hr and compressive strength of> 'lOMPa. Various properties of the concrete, such as permeability, porosity, compressive strength, thermal conductivity and dynamic V-value, were determined. In conjunction with the experimentS, four experimental apparatus were developed and modified during this investigation - two for the determination ofporosity and permeability of concrete, one for determining the static thermal conductivity of concrete and one for determination of the steady- state, one-dimensional heat transfer properties. A number of theoretical 'and empirical models have also been developed for predicting the static and especially, the dynamic behaviour of breathable concrete. The results confirm that pre-cast breathable concrete blocks can be used as a sustainable building material . but further optimisation is desired; suggestions are made for further work.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485811 |
| Date | January 2007 |
| Creators | Wong, Jim Min |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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