Microstructure and pore fractal dimensions of recycled thermal insulation concrete

The compressive strength and thermal conductivity of recycled thermal insulation nano concrete with different contents of recycled aggregates were determined. By comparing the micro morphology, it was concluded that the glazed hollow beads, rather than air pores, reduced the strength loss of concrete. This was due to the tight adherence between the glazed hollow beads and the cement mortar, which is more effective than foaming the pores to strengthen concrete by lowering the thermal conductivity. Finally, the pore fractal dimension was established by mercury injection test data. The correlations between fractal dimensions under various recycled aggregate replacement rates and compressive strength/thermal conductivity were compared, and it was discovered that the macro pore fractal dimensions could be used to characterize the changes of concrete strengths and that the average fractal dimension could be employed to describe the variations of thermal conductivity of concrete.