Investigation on the impacts of gradation type and compaction level on the pavement performance of semi-flexible pavement mixture

Semi-flexible pavement (SFP) has been widely used to address rutting distress across China in recent years. The field application shows that SFP has excellent anti-rutting performance but relatively poor anti-cracking ability when compared with flexible asphalt pavement. Formation of cementitious network is closely related to the connected voids within porous asphalt mixture (PAM). Different gradations and compaction levels would contribute to different volumetric contents and distribution of connected voids in asphalt skeleton. Thus, the pavement performance of SFP could be theoretically regulated by using different combination of gradations and compaction levels for PAM fabrication. However, the relationship between aforementioned two factors with pavement performance of SFP is not well established. Therefore , volumetric properties of PAM samples fabricated with three different gradations and three compaction levels are characterized firstly in present paper. The pavement performances of grouted samples are evaluated then. Afterwards, the relationship between volumetric parameters of PAM and pavement performance of SFP are analyzed. In the end, the reusable two-factor analysis of variance is carried out to check the significance of different factors. Results show that the 25celcius IDT strength of SFP ranges from 0.7 to 1.0 MPa while that of PAM is from 0.3 to 0.6 MPa by using different gradation types and compaction levels. TSR of all the SFP samples exceed 80%, which indicating that SFP has excellent antifreeze-thaw ability. The Cantabro loss of SFP can be approximately decreased from 13% to 9% by using finer gradation. Different SFP samples have similar flexural strengths but significantly different maximum flexural strain and modulus. It is found that gradation type has the more significantly impacts on the pavement performance of SFP than compaction level. Based on the results in present paper, SFP samples fabricated with the VCV of PAM lower than 19% exhibit excellent all-around pavement performances. The findings can provide a guidance for the design and application of SFP in the field.