*2.1. Materials and Mix Proportions*

This study used cementless materials made from ultrafine fly ash from thermal power plants, ggbs from continuously operating steel plants, and co-fired fly ash from circulating fluidized bed boilers. The finenesses of ultrafine fly ash, ggbs and co-fired fly ash were 33,800, 5830 and 5130 cm2/g, respectively. The specific gravity and chemical composition of the three raw materials were analyzed as described in Table 1, where ultrafine fly ash and ggbs are the amorphous-oriented materials. The tests were conducted on paste specimens, and the proportions are shown in Table 2, which shows that there were 6 mixtures of various proportions for a fixed water-to-cementitious-material ratio (w/c) of 0.55. After casting, the molds were removed once the specimens had hardened at room temperature for 24 h. After demolding, each group of mixtures was kept in water and exposed to air, respectively. Relevant tests were conducted when the test age was reached.

**Table 1.** The specific gravity and chemical compositions of the three raw materials.



**Table 2.** Mix proportions (unit: g).
