To further understand engineering properties of grouted macadam composite materials (GMCM) used as a surfacing layer in pavement, the mechanical properties and durability characteristics of GMCM were evaluated, and the relevant strength mechanisms were investigated at the micro level. Results indicate that GMCM has better high-temperature stability, fatigue performance and moisture stability than that of conventional asphalt mix, while it shows an acceptable decrease in lowtemperature crack resistance due to the relative brittleness of hardened cement paste. The hardened cement paste also generates a spatial network crystalline lattice in asphalt mix skeleton to form a three-dimensional integral coagulationcrystalloid structure. This facilitates the asphalt mix skeleton and hardened cement paste to bear loads in unison and increase durability of the GMCM. Further, the fibre-like hydrated products of fresh cement slurry on the bitumen film surface increase the interfacial strength between bitumen and hardened cement paste due to toughening and bridging effects, which plays an important role to enhance mechanical properties and durability of GMCM. Finally, GMCM strength is from the internal friction of asphalt mix skeleton, the network structure of hardened cement paste and the adhesion between porous asphalt mix and hardened cement paste. It is concluded that GMCM can better meet the requirements of mechanical properties and durability characteristics than the conventional asphalt mix.

In this study, to design a satisfactory asphalt mixture skeleton for semi-flexible pavement (SFP), the effects of aggregate gradation on grouting results of porous asphalt mixture were analyzed based on the test results of 22 aggregate gradations. Moreover, the mix design method of asphalt mixture skeleton was also discussed. Results indicated that the grouting effects of asphalt mixture skeleton were affected by its internal void interconnectivity, including the morphological characteristics, structure, and size of pores, instead of the initial void volume (VV). The grouting effects of asphalt mixture skeleton were influenced by the fine aggregate at the specific particle size levels. An increase in the mixing proportion of coarse aggregates could improve the grouting effects. A valid mix design approach was developed to prepare the asphalt mixture skeleton of SFP. Finally, engineering properties of the grouted mixture specimens were validated. It was concluded that the aggregation gradation design was a very important aspect in effecting the grouting results of an asphalt mixture skeleton. Furthermore, the aggregate gradation should be selected to facilitate the cement slurry to permeate in full thickness of the asphalt mixture skeleton layer. This could be used to direct the design of asphalt mixture skeleton toward lessening field failures on the SFP.

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Fly ash, silica fume and ground steel slag are chosen to make up composite mineral admixtures. Through the orthogonal test, carbonization resistance property of High Performance Concrete (HPC) mixed with composite mineral admixtures is studied. Test results show that the carbonization resistance property of HPC can be improved with defined amount of composite mineral admixture mixed, in addition, the effect of ternary composite admixture of ground steel slag, fly ash and silica fume is more obvious than that of binary composite admixture.