# Diffusion and Consolidation of Slag-Based Geopolymer for Concrete Payment Rehabilitation
## 1 Introduction
[17] developed road grouting materials using volcanic ash and metakaolin (MK). [PERSON] et al. [18] prepared a new modified metakaolin-based geopolymer, and studied its various mechanical properties. Through indoor tests, [PERSON] et al. [19] studied the mechanical properties of the slag-based geopolymer. [PERSON] et al. [20] prepared a fly-ash-based geopolymer using different ratios of alkali activators and metakaolin. [PERSON] et al. [21] developed a green geopolymer using red mud and granulated blast furnace slag. Through indoor tests, [PERSON] et al. [22] prepared a new, cleaner double liquid alkali-activated grouting material (DLAG). [PERSON] et al. [23] studied the effected of the H\({}_{2}\)O/Na\({}_{2}\)O ratio and two acids on the hardening rates of slag-based grouts. [PERSON] et al. [24] studied the influence of nano-silica-added geopolymer-based grout mixtures. When using a geopolymer for reinforcement in concrete pavement, there are many influencing factors in the filling and diffusion of the geopolymer grouting material, so it is necessary to study the diffusion characteristics through on-site or indoor grouting tests. The indoor grouting test has a good repeatability and visualization, which can intuitively help us study the distribution of solidified slurry and analyze the diffusion law. Many scholars have developed various indoor grouting test systems and conducted a series of grouting tests. [PERSON] et al. [25] developed a grouting experimental system for studying the slurry flow through rock fractures. [PERSON] et al. [26] developed a visualized fracture grouting experimental system for simulating the flow process of the fracture network. [PERSON] et al. [27] designed a visual fracture grouting system and discussed the influences of grouting quantity on the grout diffusion distance. [PERSON] et al. [28] developed a grouting test system for a series of laboratory tests. [PERSON] et al. [29] developed a single-fracture stress-seepage coupling test system and conducted grouting material seepage tests. [PERSON] et al. [30] prepared a three-dimensional grouting experimental system and studied the diffusion mechanism of sand soil. [PERSON] et al. [31] developed a test system for grouting in rough fractured rock masses. [PERSON] et al. [32] developed a visual experimental platform for grouting in a fractured aquifer. In summary, many researchers focused on the development of various geopolymer grouting materials using slag, fly ash, and metakaolin. In terms of indoor grouting tests, many scholars developed indoor grouting test systems and conducted the corresponding grouting reinforcement research in soil layers, sand layers, rock fractures, etc. However, limited research has been conducted on the application of geopolymers in pavement rehabilitation, and the investigation of the related microstructure to mechanical consolidation, as well as the study of slurry diffusion with different aggregate gradations. This study aims to bridge that gap by investigating the diffusion and consolidation behavior of a slag-based geopolymer used for road base grouting after the homogenization of concrete pavement. A new visual indoor grouting experimental system was developed to study the diffusion and consolidation characteristics of geopolymer grouting material for single-graded aggregate. Moreover, the bonding characteristics between the geopolymer grouting slurry and aggregate were observed using SEM. Furthermore, the reinforcement effect of the slag-base geopolymer grouting slurry for the loose aggregate in the road base was studied on site after the homogenization of concrete pavement.