An Alternative to Clay in Building Materials: Red Mud Sintering Using Fly Ash via Taguchi’s Methodology

Table 3

Average and main effects of ratios of pH values—Raw and 𝑆/𝑁.

Factors	Raw data, average value			Main effects		𝑆/𝑁 data, average value			Main effects (𝑆/𝑁 data)
	𝐿1	𝐿2	𝐿3	𝐿2-𝐿1	𝐿3-𝐿2	𝐿1	𝐿2	𝐿3	𝐿2-𝐿1	𝐿3-𝐿2
A	0.74	0.73	0.71	−0.01	−0.02	−1.49	−2.80	−3.01	−1.30	−0.21
B	0.72	0.72	0.74	0.00	0.02	−2.92	−2.89	−2.70	0.03	0.19
C	0.72	0.73	0.72	0.01	0.00	−2.89	−2.79	−2.83	0.10	−0.04
D	0.66	0.75	0.76	0.09	0.01	−3.62	−2.52	−2.37	1.11	0.15