Prediction of Marshall Parameters of Modified Bituminous Mixtures Using Artificial Intelligence Techniques

This study presents the application of artificial neural networks(ANN)and least square support vector machine(LS-SVM)for prediction of Marshall parameters obtained from Marshall tests for waste polyethylene(PE)modified bituminous mixtures.Waste polyethylene in the form of fibres processed from utilized milk packets has been used to modify the bituminous mixes in order to improve their engineering properties.Marshall tests were carried out on mix specimens with variations in polyethylene and bitumen contents.It has been observed that the addition of waste polyethylene results in the improvement of Marshall characteristics such as stability,flow value and air voids,used to evaluate a bituminous mix.The proposed neural network(NN)model uses the quantities of ingredients used for preparation of Marshall specimens such as polyethylene,bitumen and aggregate in order to predict the Marshall stability,flow value and air voids obtained from the tests.Out of two techniques used,the NN based model is found to be compact,reliable and predictable when compared with LS-SVM model.A sensitivity analysis has been performed to identify the importance of the parameters considered.

Investigation on mechanical properties and water stability of porous polyurethane concrete

Porous polyurethane concrete(PPUC)is a novel material for permeable pavements and is considered as an alternative to porous asphalt or porous cement concrete.However,studies of the mechanical properties of PPUC are still insufficient.In this study,the comprehensive mechanical properties and water stability of PPUC with different gradations and polyurethane dosages were investigated,and its water damage mechanism was preliminarily explored.The results show that the flexural strength and Marshall stability of PPUC can more easily reach the index in the standards of porous cement concrete or porous asphalt,while the compressive strength and abrasion resistance are the weak points of its mechanical properties and need to be further optimized.The mechanical properties and water stability of PPUC were effectively improved by increasing the polyurethane dosage and using continuously graded aggregates.PPUC is more susceptible to water damage because water reacts with the residual isocyanate groups within the polyurethane film to generate carbon dioxide gas,which reduces the cohesion and adhesion performance of polyurethane film.This study provides a comprehensive understanding of the mechanical properties of PPUC and an initial insight into the mechanism of water damage.