Performance of Fly-Ash- and Cement-Bound Granular Mixtures with Dispersed Fiber Reinforcement—A Case Study

This paper investigates the effects of incorporating dispersed fibrous reinforcement in hydraulically bound granular 0/16-mm mixtures. The evaluated fibrous reinforcement comprised a mixture of polypropylene and alkali-resistant glass fibers in a 1:2 weight ratio. The fibrous reinforcement was added to the mixtures in amounts of 0.05% and 0.10% by weight. The prepared mixtures utilized 1% of CEM II/B-V 32.5 R Portland cement together with 3.5%, 7%, and 14% of fly ash, characterized by a high content of reactive calcium oxide. It was found that the fibrous additives had only a small effect on the maximum dry densities and virtually none on the optimum moisture contents of the mixtures. The use of the fiber mix significantly improved the compressive strength of the reinforced samples resulting after 42 days of curing, with a performance comparable to a reference mixture bound with 8% of Portland cement. The addition of fibrous reinforcement increased the indirect tensile strength of the mixtures by up to 300%, resulting in a performance similar to that of a reference mixture with 5% of Portland cement. It was found that the use of this particular fibrous reinforcement significantly improved the performance of predominantly fly-ash-bound granular mixtures, allowing the reduction in cement content used in this type of material.