Investigation of the use of blast furnace slag and steel fiber in concrete pavements

In recent years, many studies have been carried out on the effects of additives that can be used to give high strength to concrete on its physical and mechanical properties. Within this scope, specimens reinforced with 60 mm long steel fibers at the rates of 0%, 0.75%, 1%, 1.25%, 1.25% and 1.50% and using BFS at the rates of 0%, 15%, 20%, 25% and 30% as a substituted for cement were designed and their usability in concrete pavements was investigated of this thesis study. In addition, the results obtained were analyzed and an evaluation was carried out on concrete specimens produced using the optimum 20% BFS ratio and the same proportions of 35 mm long steel fibers. The workability, slump, flexural strength, splitting tensile strength, freeze-thaw, abrasion resistance, electrical resistivity, conductivity and heating, SEM and XRD analysis tests were performed on these prepared specimens. Based on the test results, AASHTO 1993 and FAARFIELD concrete pavement design methods were used to calculate the concrete pavement thickness and cost for highway designs under different traffic loads with base soils of different bearing capacity. As a result, more workable concrete characteristics were observed with the use of BFS and it was seen that workability became more difficult as the steel fiber ratio increased. On the other hand, with the addition of 60 mm long macro steel fiber, compressive strength values of the specimens decreased and splitting tensile and flexural strength values of the specimens increased, while with the addition of 35 mm long macro steel fiber, compressive, splitting tensile and flexural strength values increased. The highest mass loss in the freeze-thaw cycles of the specimens was observed in the specimen containing 1.50% steel fiber. It was seen that the electrical resistivity of the specimens decreased with the addition of steel fibers to the mixtures compared to the specimens without fibers. It was determined that the lowest abrasion amount without fiber additives was observed in the concrete specimen with 15% BFS, the abrasion amounts increased as the BFS substitution increased in the specimens with more than 15% BFS substitution, and the abrasion loss of steel fiber reinforced concretes decreased with the increase in the amount of steel fiber. It is considered that BFS reinforced concrete specimens to be created under different traffic loads and on soils with different bearing strengths were found to reduce concrete pavement thickness and cost, while steel fiber reinforced specimens reduced pavement thickness but were not cost effective, and the increase in cost in the long term would not have a negative economic impact since steel fiber reinforcement has a significant effect on crack development and flexural strength and concrete pavements are mostly exposed to harsh environmental conditions during their service life.