Abstract:
The type and proportion of materials being used in the construction of a highway facility,
as well as many other criteria, influence its comfort, ride quality, and service life. While
constructing the bituminous layers of a highway facility, the type and composition of
mixes must be carefully considered. These layers must be built with certain care since they
are directly impacted by the applied load and environmental conditions. Properties of these
layers are affected by number of factors which are described in the form of Marshal
Quotient of hot mix asphalt. Calculating the marshal quotient leads the project to an
uneconomical as calculating this parameter is based on trails and error and requires skilled
labor and extensive time for calculation. A computer-based model has been developed
using a data set composed of 110 lab experiments collected from a construction firm
working on Jehagira to Risalpur road (Khyber Pakhtunkhwa, Pakistan) that can predict the
values of marshal stability and marshal flow. The collected data was first screened and all
the inappropriate data points were removed. Prior to modeling, insignificant variables were
removed to generate a better model. Models were developed using GEP and ANN for both
Marshal Stability and Marshal Flow using seven input variables. The performance of the
models developed has been validated using coefficient of determination, RMSE, MAE and
Adjusted R2. Results shows that the GEP model performs better than ANN and has more
better predicting power than ANN. Performance of the developed model was also
validated using unseen data collected from N95 Swat (Khyber Pakhtunkhwa, Pakistan)
where the models performed significant and were able to predict the output quiet
accurately. A sensitivity analysis has also been performed to access the relative
contribution of every variable in predicting the outputs. It was also concluded that the
marshal stability increases with the increase in air voids and reduction in bitumen content
while marshal flow increases upon increase in bitumen content and decrease in air voids.
