Evaluation of the Influence of Recycled Glass and Carbon Geogrids on the Stiffness Modulus of asphalt Concrete

The paper presents the findings of a study on the influence of fibers derived from recycled geogrids on the stiffness modulus of asphalt concrete. The preliminary stage of the research involved a survey, which confirmed the escalating issue of reclaimed asphalt pavement (RAP) contamination with glass and carbon geogrid fibers, as well as the limited existing knowledge regarding their impact on asphalt concrete properties. The experimental program encompassed AC16W and AC22W mixtures modified with fibers ranging from 1 cm to 5 cm in length and at concentrations of 0.2% to 1.0% by weight. Analysis of the test results revealed that the application of carbon geogrid fibers did not lead to a significant increase in the stiffness modulus compared to the reference mixtures; conversely, glass fibers exhibited a tendency to reduce it. It was established that excessive fiber length and content lead to a reduction in the stiffness modulus. Based on the analyses, optimal parameters for maintaining high stiffness modulus values were determined: a fiber content of <0.2% and a length of <1 cm, regardless of the mixture’s aggregate grading. The results indicate that geogrid recycling may represent an effective and rational approach supporting the circular economy and the development of sustainable asphalt technologies.