Characterization of fiber properties towards mitigation of faulting of thin concrete pavements

Abstract

Transverse joint faulting is a major distress in thin and ultra-thin concrete pavements, particularly in regions with extreme climatic conditions like Minnesota, where freeze-thaw cycles and moisture accumulation in the subgrade magnifies the problem. Load transfer mechanisms, like aggregate interlocking, has a lesser impact in thin and ultra-thin pavements due to a reduced cross section area. Dowel bars are impractical for thinner slabs, making faulting a more persistent issue. Fiber-reinforced concrete (FRC) has emerged as a potential solution to this problem, offering enhanced mechanical properties, improved joint performance, and better resistance to faulting. However, the optimization of fibres and their contribution according to their dosage, type, joint stiffness and other mechanical properties are to be investigated in depth. To address this, the study evaluates the contribution of different fibre types to the mitigation of faulting through both field and laboratory methods. Data from the falling weight deflectometer (FWD) tests on MnDOT’s FRC pavement cells are used to establish the best parameter which correlates with faulting. Once that is established, fiber support required at the joint is quantified through FWD data. Laboratory testing is used to assess the contribution from fibers in a controlled setting. Additionally different fibre types are tested for its joint performance. The research further investigates individual fiber characteristics of these fibers using single-fiber pullout tests to understand how specific fiber properties, such as elastic limit and toughness, influence joint performance and contribute to faulting mitigation. Also, FEM (Finite Element Modelling) was used to see how fiber contribution at a pavement joint varies for different slab/base depths and for different seasons too. This multi-method approach provides a comprehensive understanding of the factors affecting faulting in FRC pavements. It was found that fibers with good elastic properties had a better chance at mitigating faulting. Also, it was learnt that increase in slab depth could give a better joint performance during summer and winters. The FEM results also reinforced the need for the fibers to have a good elastic property.