*4.3. Geopolymer in Road Application*

The development of geopolymers in the past and present has centred on the production and use of such materials to replace cement in structural construction. There has not been a lot of research applied in road construction. Several geopolymer research reports for road applications were even at the proof-of-concept level. Tenn et al. [114] investigated the interaction between sodium and potassium-based geopolymer binders and granite or diorite pavement aggregates in order to promote the usage of geopolymer in place of asphalt cement (or bitumen). Camacho-Tauta et al. [115] demonstrated an attempt to improve road fatigue damage resistance by employing a fly ash-based geopolymer as a road base layer. To assess the study material's long-term performance, a full-scale accelerated pavement test was assigned. Compared to a non-treated road base layer, the study found that a geopolymer-treated road base layer could give a reduction in deformability. Waste material-based geopolymer has been implemented as a replacement binder to enhance the properties for road and pavement material as tabulated in Table 5.


**Table 5.** Research work utilising geopolymers in road applications.

The Netherlands was one of the first countries in Europe to use fly ash and blast furnace slag as a binder for acid-resistant pipe manufacture. Activated alkaline materials used in civil construction subsequently established enterprises in other United Kingdom countries, and eventually extended throughout the continent [120,121]. Conversely, the company with the most building applications is based in Australia. In 2007, the Melbourne-based company, E-cert, developed its own concrete. This company employs a blend of fly ash and ground blast furnace slag that has been alkali activated according to a proprietary dosage and composition. Bridges, highways, and big structures are several of the applications [122].

Figure 5a depicts a section of the Westgate Freeway in Port Melbourne's highway pavement. Since it was a different material, the project had to comply to numerous needs of the local road authority as well as more specialized technical standards in order to gain government clearance. The highway's construction and use were agreed on by a group of multinational construction corporations. Meanwhile, Figure 5b illustrates VicRoad's installation of 55 MPa E-Crete prefabricated panels. Due to the strict inspection in regard to structural concrete, this strength was required [122].

**Figure 5.** (**a**) Westgate Freeway paving in Port Melbourne and (**b**) E-Create Precast Panels. Reprinted/adapted with permission from [122]. 2012. Van Deventer.
