Aggregate Gradation Influence on Grouting Results and Mix Design of Asphalt Mixture Skeleton for Semi-Flexible Pavement

Abstract

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.

Influential Factors and Evaluation Methods of the Performance of Grouted Semi-Flexible Pavement (GSP)—A Review

“…For example, a given continuous gradation may also contain larger-tier aggregate. The reason may be that the influence of gravel morphology and fine aggregate is overlooked which needs further research [52]. In our opinion, the two viewpoints are all correct, though only the applying scope of these principles is different.…”

“…A lower residual void rate of GSP will be obtained after grouting [50,51]. Overall, a coarser aggregate gradation can be more conducive to forming a larger void space, which has better interconnection, to make the grouted cement mortar more easily able to penetrate the OMA mat [46,52]. Subsequently, flexural tensile strength and compressive strength of the following GSP are also be improved, which are positively linked with low-temperature performance and high-temperature performance, respectively [49].…”

Cementitious Grouts for Semi-Flexible Pavement Surfaces—A Review

“…It can be seen that the main difference is the nominal size, between 8 to 14 mm, and most of the gradation is single-sized, with very low percentages of fine aggregates, which makes the porous asphalt skeleton. However, the common goal is to achieve the target 25–35% air voids in the mixture, in order to ease the quick infiltration of grouts due to void interconnectivity and high porosity [ 40 , 53 , 54 , 55 ]. Nevertheless, in Malaysian specifications, the nominal size is 20 mm for type-1 and 14 mm for type-2 gradation systems used in the porous asphalt skeleton for semi-flexible pavement surfaces [ 56 ].…”

Cementitious Grouts Containing Irradiated Waste Polyethylene Terephthalate

“…Similarly, another study was conducted by Hou et al, on the random selection of 22 aggregate gradations by varying percentages of coarse aggregates, fine aggregates, and fillers. The effect of grouting on these gradations was evaluated by volumetric analysis, cantabro and binder drainage test as well as wheel tracking and bending tests [42]. It was revealed that grouting ability of OGAM is not only influenced by initial air voids but also on void interconnectivity, morphological characteristics, and size of pores.…”

“…The fluidity of grouts is usually determined by flow-cone, however, the flow-out time depends on the geometry of the cone. Ordinary Portland cement (OPC), water (different ratios), and/or sand, fillers, and other supplementary cementing materials (such as fly ash and silica fume) Air voids before and after grouting [42].…”