Influence of fibers and hardening accelerator on the concrete for rigid pavements

The influence of the hardening accelerator and steel fiber on the concrete adhesion strength for the repair of rigid highway and airfield pavements has been investigated. The concretes were mixed based on the CEM II/A-S 42.5 and included MasterGlenium SKY 608 superplasticizer. Experiment with two variable concrete composition factors was carried out. The amount of steel fiber varied from 0 to 100 kg/m3, the amount of Sika Rapid hardening accelerator varied from 0 to 9.6 kg/m3. It was found that modified repair concretes have a sufficiently high adhesion strength to "old" concrete, from 2.30 MPa when tested by the pull-off method and from 2.05 MPa when tested by the flexural strength test method. Fiber-reinforcement increases the adhesion strength of repair concrete by 7-15% due to reducing of shrinkage during hardening. Treating the contact surface of "old" concrete with a primer additionally increases adhesion strength by 6-10%. The maximum adhesion strength of fiber-reinforced concrete to the base reaches 3 MPa. Due to the high early and design strength, modified steel fiber-reinforced concrete provides the possibility of quick resumption of traffic while ensuring the integrity of the road structure due to the joint work of the repair material with the old concrete repair area.