## 3 Results
### Microsurfacing Test Results
#### 3.3.3 Cohesion Test Results  
This test was carried out following the EN 12274-4 standard. Seven samples were produced for each composition and tested after 5, 10, 15, 30, 60, 90, and 120 min of curing. Figure 11 shows the molds used to produce the test samples and the samples in the curing process before the test. According to the ISSA [32], the most critical parameters assessed in the cohesion test are the torque values obtained after 30 and 60 min of microsurfacing curing. For this test, the ISSA defines the set time as the point at which the microsurfacing system reaches a minimum of 12 kgf cm torque, and the straight rolling traffic time corresponds to a minimum torque of 20 kgf cm. Therefore, a quick-set system should reach 12 kgf cm of torque within 30 min, while a quick-traffic system should reach 20 kgf cm of torque within 60 min. Figure 11: Preparation of microsurfacing asphalt samples for cohesion test: (**a**) molds used in the test and (**b**) samples in the curing process. Figure 10: Example of the different phases of the consistency test for the microsurfacing asphalt mixture prepared with one of the emulsions: (**a**) test preparation and (**b**) final result. The initial composition studied in this test for the microsurfacing mixture produced with Emulsion 1 was based on the mix design resulting from the consistency test, i.e., 52% fine aggregates and 48% coarse aggregates, 12% emulsion, 2.5% cement, and 11% water. However, the mixture did not reach the cohesion values defined by ISSA for a quick-set and quick-traffic system after 30 and 60 min of curing. Thus, new compositions were designed to improve the microsurfacing cohesion values. The second microsurfacing mixture studied increased the emulsion content to 13% while maintaining all the other composition parameters. This mixture presented a cohesion value of 17.12 kgf cm within 30 min of curing and 21.11 kgf cm within 60 min, fulfilling the target results defined by the ISSA for a quick-set and quick-traffic system and confirming that this composition can be assumed to have adequate performance. Nevertheless, new mix compositions were studied to assess the possibility of producing more sustainable solutions with equivalent cohesion values. The third mixture kept the added water at 11%, reducing the asphalt emulsion to 12% and the cement to 2.0%. This composition slightly increased the cohesion value after 30 min of curing, but decreased it after 60 min. Finally, two additional compositions were studied to evaluate the effect of increasing the emulsion content to 13% and 14%, keeping the added water at 11% and the cement at 2%. Table 2 summarizes all the results obtained for Emulsion 1. Since the amount of water was fixed at 11%, the results showed the mutual influence of the emulsion and cement contents on the cohesion test performance of these microsurfacing mixtures. The amount of Emulsion 1 showing the best compromise between the 30 and 60 min curing times was 13%, although the quick-set performance may be improved for higher emulsion contents. Increasing the amount of cement improved the cohesion values only if the emulsion content was also increased. Figure 12 shows the variation of cohesion values according to the amount of material added to the mixture produced with Emulsion 1. The second composition, with 11% water, 2.5% cement, and 13% emulsion, presented the best overall cohesion test performance and was selected for the shaking abrasion test. Figure 13 presents the final appearance of the samples after the cohesion test for the selected microsurfacing mixture. According to the visual assessment criteria defined by EN 12274-4, the samples with 5 to 30 min of curing time were considered disintegrated, those with 60 and 90 min of curing time were classified as cracked, and the sample with 120 min of curing time was considered solid. These observations demonstrate the rapid evolution of the cohesion with the curing time for this mixture composition.