*2.2. Test Procedures*

The setting time tests were conducted using the Vicat Needle method following ASTM C191. The flow tests were conducted in accordance with ASTM C1437. Compressive strength tests were performed according to ASTM C109 for 7 and 28 days. The average value was measured after each of the three tests. The SEM observations were made on fragments left after the compression tests, and all the tests were carried out according to the procedures specified in ASTM C1723. XRF analysis was performed on the powder (about 5 g) produced in the compression test, and the test procedure was based on ASTM C1365.

#### **3. Results and Discussion**

#### *3.1. Flowability and Setting Time*

The test results are summarized as shown in Table 3. The test results showed that the flowability of the specimen with a w/c of 0.55 exceeded the standard flowability (110%) for all groups. ggbs had better flowability when the ratio of ggbs to mixed fly ash reached 6:4. Using ultrafine fly ash instead of partially co-fired fly ash resulted in slightly lower flow values due to the ultra-fine particles. Only the final setting time was observed as a test indicator for cementless materials. Six groups were used to control the final setting time within 24 h. The final setting time can be significantly shortened to less than 8 h for specimens with a ggbs dosage up to 60% of the cementless blend. These test results were similar to those of the alkali-activated specimens with ggbs added. The setting time was accelerated when the ggbs exceeded 50%, meaning the setting times were dramatically reduced as the ggbs content increased [8,9].

**Table 3.** Results of flowability and setting time.

