Experimental investigation of the effect of Micro Silica on roller compacted concrete pavement made of recycled asphalt pavement materials

In this study, a total of four different mixes were prepared by partially replacing natural aggregates by Recycled Asphalt Pavement (RAP) in different proportions. The results showed that adding RAP to the mixture reduced the mechanical strength of the Roller Compacted Concrete (RCC) mixture. The best mechanical strength was obtained at 50% RAP replacement. To increase the mechanical strength of RCC made with 50% RAP, Micro Silica (MS) with partial replacement of cement at 3%, 6%, 9%, and 12% was used. Increasing the MS content from 3 to 12% caused the mechanical strength of all mixtures to increase. The results showed that RCC7 with 50% RAP and 9% MS had about 20% more compressive strength. Also, the increase in tensile splitting and flexural strength was 6 and 2%, respectively. The statistical analysis indicates that there was a strong relationship (R-2> 0.98) between flexural strength values estimated from the regression model and the measured laboratory values (this relationship was about 0.84 for compressive strength and tensile splitting strength). The estimation of tensile splitting strength and flexural strength with respect to compressive strength showed that there was a strong (R-2> 0.98) and good relationship (R-2> 0.75) between them, respectively.

Automated summary

The study found that adding Recycled Asphalt Pavement (RAP) to Roller Compacted Concrete (RCC) reduced its mechanical strength. However, adding Micro Silica (MS) at a 50% RAP replacement rate increased the mechanical strength of RCC, including compressive strength.