## 4 Conclusions  
This study evaluated the strength and durability of fiber-reinforced latex-modified rapid-set cement preplaced concrete for emergency pavement repair. A variety of fiber systems were evaluated. The test results are summarized as follows:  
All HFLMC mixtures satisfied the compressive strength requirements of at least 21 MPa after 4 h and at least 35 MPa after 28 days; these are the criteria for opening traffic after an emergency pavement repair. The compressive strengths of fiber-reinforced mixtures were higher than those of mixtures without fibers. Furthermore, the hybrid fiber systems exhibited greater compressive strength than those incorporating a single type of fiber.  
All of the HFLMC mixtures satisfied the flexural strength requirements of at least 3.5 MPa after 4 h and at least 4.5 MPa after 28 days. As with the compressive strength results, the hybrid fiber-reinforced mixtures had higher flexural strengths than the single-type fiber-reinforced mixtures. Notably, the hybrid fiber-reinforced mixtures had flexural strengths exceeding 4.5 MPa after only 7 days. The highest flexural strength was obtained with the incorporation of PVA+nylon hybrid fibers.  
Similarly, all of the HFLMC mixtures satisfied the target splitting tensile strength of 4.2 MPa after 28 days. Hybrid fiber-reinforced materials showed higher splitting tensile strengths than those containing only single-type fibers. The highest splitting tensile strength was observed with the hybrid fiber-reinforced HFLMC containing PVA+nylon fibers.  
All of the HFLMC mixtures met the target chloride ion permeability of under 2000 coulombs. The amount of charge passed decreased substantially to 1000 coulombs or less, indicating very low permeability, with the inclusion of hybrid fibers.  
The inclusion of hybrid fibers also increased the abrasion resistance of the HFLMC mixtures over those with single-type fibers or no fibers. This was due to the denser structure created by the fibers and the suppression of crack formation on the surface of the concrete.  
Figure 8: Relative dynamic modulus of HFLMC mixtures.  
In freeze-thaw tests, all of the HFLMC mixtures met the target relative dynamic modulus of 80% or higher. A marked reduction in modulus was observed with plain mixtures after 90 cycles. This reduction was absent with mixtures containing either single or hybrid fibers. Incorporating hybrid fibers as reinforcement increased the relative dynamic modulus to 95% or higher, indicating excellent freeze-thaw resistance.  
Thus, this study demonstrates the benefits of incorporating fiber reinforcements, and most notably, hybrid fiber mixtures, into latex-modified rapid-set concrete pavement repair materials. Clear advantages were observed in terms of strength and durability.  
[PERSON] conceived and designed the experiments, [PERSON] performed the experiments and analyzed data, and [PERSON] analyzed data and wrote the manuscript. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
This work was supported by the research grant of the Kongju National University in 2019.  
The authors declare no conflict of interest.