چكيده به لاتين
Thermal conductivity is one of the key parameters in determining the ability of
concrete to heat transfer. Concrete with low thermal conductivity is useful for
building insulation, while high-conductive concrete is useful for reducing the
thermal gradient. The thermal stresses caused by the thermal gradient may have
a negative effect on the mechanical properties of the concrete. For example,
bridges may be exposed to these tensions due to the difference in temperature
between their upper and lower levels, and therefore concrete with high thermal
conductivity can be used to build bridges and related structures. In large density
concrete such as concrete dams, high thermal conductive concrete can reduce the
cracks caused by the heat of cement hydration.
In the past studies, the effects of micro-scale additives such as wind ash and slag
have been investigated for improving the thermal performance of concrete.
However, there is no specific look at the use of emerging nanoparticles such as
graphene oxide with unique mechanical properties and ideal thermal properties.
Therefore, in this research, the effect of graphene oxide nanoparticles on the
thermal performance of cement composites has been investigated. Graphene
oxide nanoparticles were added to cement sand mortar at 0.02, 0.04 and 0.06
percent by weight, and its effect on performance, mechanical properties,
permeability, microstructure and thermal properties was evaluated. The results of
the experiments indicated that the addition of graphene oxide nanoparticles with
0.02, 0.04 and 0.06 percent increased the flexural strength by 5% , 19% and 17%
and increased the compressive strength by 13% ,18% and 17%, and 4% ,48% and
28%, respectively. Moreover, the permeability and water absorption of samples
containing graphene oxide nanoparticles were less than that of the control sample.
The investigation of the microstructure of cement mortars was shown that
graphene oxide nanoparticles create more compact hydrated products by creating
nucliation sites, which can prevent the development of cracks in the mortar as
well as reduce porosity. The results of this study can help the application of
nanoparticles in the production of more efficient and multi-purpose concrete and
provide the ground for the benefit of nanotechnology in the construction industry.
Key word: Cement composite, thermal conductivity, mechanical properties,
graphene oxide
