# Construction of Geosynthetic-Reinforced Pavements and Evaluation of Their Impacts
## 3 Construction Impacts on the Geosynthetic-Reinforced Pavements
### Strain within the Asphalt Binder Course  
The readings of the strain gauges (longitudinal and transverse) installed in the binder course were taken during the construction of the asphalt binder course (SP 19), and asphalt surface layer (SP 12.5). The data were collected every 10 s during the construction of the binder course, and it was collected every minute during the construction of the surface layer. Similar to the process of data of pressure cells, the measurements were offset to the zero point using the first reading. A positive result indicates the tensile strain, while a negative value indicates the compressive strain. The readings of the asphalt strain gauges during the construction of the binder course are plotted in Figure 11. These results reflect the impacts of the fibreglass geogrid in the binder course when stress was exerted on them. The readings taken from both longitudinal and transverse gauges illustrate similar trends in the three sections. The gauges were experiencing compressive strains from 9 a.m. to around 12:30 p.m., which matches the construction timeframe discussed previously in regard to Figure 9.  
Due to the completion of construction activities as well as the viscoelastic nature of asphalt materials, the strains experienced at the bottom of the asphalt layer increase after 1 p.m. In the transverse direction, the fibreglass geogrid section (Section 2) experienced lower strains during the construction. It is also notable that some exceptionally high values were exhibited in the control section in the longitudinal direction. This observation aligns with previous studies that demonstrated that the longitudinal strain is typically higher than the transverse values [36; 37].  
Figure 10: Pressure at the interface of subgrade and base during surface course construction.  
Figure 12 shows the readings of the asphalt strain gauges collected during the construction of the surface course. Similar to the reading of pressure cells, lower noise was observed due to a lower frequency of data collection, although this could also be attributed to the additional thickness of surface course material being paved. In the transverse direction, the control and geogrid composite sections both measure high strain values around 7:10 a.m. Other than these peak values, the tensile strain experienced at the bottom of the binder course reached the highest level during paving after 8:00 a.m., with the fibreglass geogrid section showing a lower level of strain. A similar trend is also exhibited in the longitudinal direction.  
As shown in Figure 12 (top), the transverse strain in the binder course caused by the construction of the surface course is reduced in the fibreglass geogrid section by more than 99% compared with the other two sections. As the fibreglass geogrid-reinforced asphalt course can better distribute stresses under loading, this leads to less disturbance to the binder course, granular base, and subgrade. In the longitudinal direction, the fibreglass geogrid can reduce about 54% and 50% strain compared with control and geogrid composite sections.  
Although higher strains in longitudinal directions are typically observed, higher longitudinal strains may also be attributed to the aperture size spacing of the longitudinal filaments of the geogrids; larger apertures may reduce the interaction between grid filaments improving the pull-out resistance in the longitudinal direction. However, the spacing between transverse members has little impact on the pull-out resistance [38,39]. With regards to the lower strain level experienced in both longitudinal and transverse directions, the results align with the pressure cell measurements observed in Figure 10, which signifies the impacts of load distribution provided by the fibreglass geogrid on the RWP.  
Figure 11: Asphal strain gauge reading during binder course construction.