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

Table 2

Central composite design arrangement and responses.

Run	Factors		Responses
	EVA (%)	CR (%)	Pen	Soft	Temp (/sinδ ≥ 2.2 kPa)	Temp (/sinδ ≤ 5000 kPa)	Creep stiffness	m-Value
1	3	2	54.5	58	82.00	25	134.9	0.234
11	5	4	52	67	78.00	18	79.9	0.288
8	5	6	49	72	80.00	19	75.4	0.321
7	5	2	54	64	79.00	16	73.4	0.313
4	7	6	40	80	82.00	25	151.6	0.264
2	7	2	51	72	82.00	22	108.8	0.277
12	5	4	52	67	73.15	15	66.3	0.372
6	7	4	45	74	80.00	19	75.4	0.321
9	5	4	52	67	81.00	20	76.4	0.331
5	3	4	53.5	59	79.00	18	74.4	0.311
10	5	4	52	67	80.00	19	75.4	0.321
13	5	4	52	67	82.00	23	128.0	0.281
3	3	6	50	61	77.00	8	62.3	0.391