Rheological Evaluation of Modified Bitumen by EVA and Crumb Rubber Using RSM Optimization

Table 3

ANOVA table for penetration grade and softening point tests.

Regression characteristics	Penetration grade					Softening point
	DF	SS	MS	F-value	value	DF	SS	MS	F-value	value
Regression	5	186.758	37.3516	45.53	≤0.001	5	531.751	106.35	143.93	≤0.001
Linear	2	150.708	75.3542	91.86	≤0.001	2	529.5	264.75	358.29	≤0.001
Square	2	25.487	12.7435	15.54	0.003	2	2.251	1.125	1.52	0.282
Interaction	1	10.562	10.5625	12.88	0.5	1	0	0	0	1
Residual error	7	5.742	0.8203			7	0	0.739
Lack-of-fit	3	3.542	1.1807	2.15	0.237	3	5.172	1.057	2.11	0.241
Pure error	4	2.2	0.55			4	3.172	0.5
R-Sq	97.02%					99.04%

Note. DF, degrees of freedom; SS, sum of squares; MS, mean square.