Granulated blast furnace slag

Ordinary Portland cement of ASTM type I (ASTM C150) was obtained from Sung Shin Cement [23 ], Republic of Korea. Hwangtoh is a clay mineral widely distributed in Korea. It contains high levels of calcium potassium chloride and calcium. Clay was ground before calcination, and calcined clay was produced by calcining hwangtoh clay at 800 °C for 60 min [6 (link)]. Figure 1 shows the XRD analysis results of clay before and after calcination. We can see that the calcination eliminated the kaolinite peak (2θ = 12.37°) [6 (link)]. Limestone powder and granulated blast furnace slag were obtained from Daejung Chemical Co., Ltd. (Sinan, Republic of Korea) and Asia Cement Co., Ltd. (Seoul, Republic of Korea), respectively. Table 1 presents the chemical compositions of the cement, limestone, slag, and calcined clay. The standard deviation for the XRF analysis results in Table 1 is 0.01%. Calcined clay and slag have higher aluminum contents than cement, which can support a synergistic effect between the limestone and slag or calcined clay. Calcined clay presents a higher silicon content than cement, which can contribute to the production of secondary calcium silicate hydrate (CSH). The average particle sizes of the cement, slag, calcined clay, and limestone were 18.3 µm, 12.8 µm, 12.3 µm, and 7.4 µm, respectively.

Ordinary Portland cement of ASTM type I (ASTM C150) was obtained from Sung Shin Cement [23 ], Republic of Korea. Hwangtoh is a clay mineral widely distributed in Korea. It contains high levels of calcium potassium chloride and calcium. Clay was ground before calcination, and calcined clay was produced by calcining hwangtoh clay at 800 °C for 60 min [6 (link)]. Figure 1 shows the XRD analysis results of clay before and after calcination. We can see that the calcination eliminated the kaolinite peak (2θ = 12.37°) [6 (link)]. Limestone powder and granulated blast furnace slag were obtained from Daejung Chemical Co., Ltd. (Sinan, Republic of Korea) and Asia Cement Co., Ltd. (Seoul, Republic of Korea), respectively. Table 1 presents the chemical compositions of the cement, limestone, slag, and calcined clay. The standard deviation for the XRF analysis results in Table 1 is 0.01%. Calcined clay and slag have higher aluminum contents than cement, which can support a synergistic effect between the limestone and slag or calcined clay. Calcined clay presents a higher silicon content than cement, which can contribute to the production of secondary calcium silicate hydrate (CSH). The average particle sizes of the cement, slag, calcined clay, and limestone were 18.3 µm, 12.8 µm, 12.3 µm, and 7.4 µm, respectively.