Abstract:
In order to come to a sustainable building environment, the construction industry requires
new energy saving concepts. One method is to use phase change materials (PCM), which have
the ability to absorb and to release thermal energy at a specific temperature. PCM are added to
concrete mix designs for improving the thermal insulation of concrete in building constructions.
Such an approach can assist in energy saving through minimizing conductive heat loss through
walls, a phase change material obtained from waste candles was added to concrete as a
replacement to medium aggregate and as a replacement to cement in three different particles
sizes.
Then an experimental study was performed for investigating the effect of percentage
addition of PCM on thermal characteristics (thermal conductivity, specific heat and thermal
diffusivity). In addition, the associated impact of PCM on the concrete mechanical
characteristics (compressive strength, water absorption and concrete workability) was
investigated. It was found that adding waste candle as a replacement to medium aggregate is
better than adding it as a replacement to cement. Adding 5% waste candle as a replacement to
medium aggregate gave the best results.
A new approach is developed through surface treatment of PCM modified concrete with
sodium silicate to increase to compressive strength of concrete. It was found that increasing
compressive strength by 7.2% as a compensation for the loss due to PCM addition.
A physical model for two small rooms were constructed using PCM modified concrete (at
20% PCM as a replacement of medium aggregates) and using control concrete (standard B250
concrete). Each room was then subjected to external heating through a power supply of 1400
W for 60 min, then, each of them was allowed to be cooled by natural convection. It was found
that the internal temperature of the room with PCM modified concrete, during cooling period,
was at a higher temperature than that with control concrete by 2.5 oC. Increased the duration of
a comfortable temperature inside building and increased the energy saving in building was
happened by reducing thermal conductivity and increasing the thermal storage of walls.
