Study on the Modification Mechanism of Warm Asphalt Rubber Based on Stage-Extraction Method

doi:10.12141/j.issn.1000-565X.230692

Abstract

Abstract:

To investigate the performance impact mechanism of warm asphalt rubber (WAR), 2 types of asphalt rubber (AR) and 4 types of warm asphalt rubber were prepared by using 70# base asphalt, 2 types of warm mixing agents, and 2 grain sizes of crumb rubber modifier. Liquid phase and insoluble crumb rubber modifier for prepared asphalt samples were obtained by the solid-liquid phase separation. The staged extraction method was innovatively employed to systematically extract components in the insoluble crumb rubber modifier blending zone layer by layer. Through experiments, the study established the connection between the preferential absorption of crumb rubber modifier and high- and medium-temperature rheological properties represented by asphalt rubber and clarified the modification mechanism of warm asphalt rubber. Test results indicate that the improvement of asphalt rubber’s high-temperature rutting resistance and low-temperature cracking resistance performance are attributed to the particle effect generated by insoluble crumb rubber modifier in asphalt and the modification effect of the soluble components of crumb rubber modifier. The improvement of fatigue resistance at medium temperature and the increase in viscosity of asphalt rubber is mainly attributed to the particle effect generated in the insoluble crumb rubber modifier. Different types of thermal mixture have different effects on the rheological properties of asphalt rubber. The addition of the organic warm mix additive is more significant in enhancing the high-temperature resistance to rutting and medium-temperature resistance to fatigue performance of asphalt rubber. The addition of the chemical warm mix additive proves to be more effective in improving the low-temperature resistance to cracking performance of asphalt rubber. The lighter components with smaller relative molecular mass in the asphalt rubber liquid phase are more easily absorbed by the crumb rubber modifier into its blending zone. The organic warm mix additive has almost no significant effect on the preferential absorption of crumb rubber modifier, while the addition of the chemical warm mix additive not only reduces the proportion of large relative molecular mass components in the liquid phase but also weakens the preferential absorption of crumb rubber modifier. The preferential absorption of crumb rubber modifier is beneficial for improving the high-temperature and fatigue resistance properties of asphalt rubber.

Key words: warm asphalt rubber, rheological property, modification effect, particle effect, preferential absorption

CLC Number:

U414

YU Huayang, ZHANG Zheng, DENG Yihao, et al. Study on the Modification Mechanism of Warm Asphalt Rubber Based on Stage-Extraction Method[J]. Journal of South China University of Technology(Natural Science Edition), 2024, 52(8): 126-137.

Figures/Tables 15

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试验项目		试验结果	试验方法	技术要求
25 ℃针入度/0.1 mm		61.1	T0604	60~80
针入度指数		-1.25	T0604	-1.5~＋1.0
软化点/℃		48.1	T0606	≥47
15 ℃延度/cm		>100	T0605	≥100
10 ℃延度/cm		21	T0605	≥15
密度/（g∙cm^-3）		1.038	T0603	实测记录
溶解度（三氯乙烯）/ %		99.7	T0607	≥99.5
闪点/℃		345	T0611	≥260
蜡含量/%		1.67	T0615	≤2.2
60 ℃动力黏度/（Pa∙s）		194	T0620	≥180
135 ℃旋转黏度/（Pa∙s）		0.47	T0625	未作要求
旋转薄膜加热试验残留物	质量变化率/%	-0.011	T0609	±0.8
	针入度比/%	64.3	T0604	≥61
	10 ℃延度/cm	6.7	T0605	≥6

指标	试验结果		技术要求
指标	0.425 mm粒径胶粉	0.18 mm粒径胶粉	技术要求
密度/（g∙cm^-3）	1.20	1.28	1.1~1.3
水分含量/%	0.15	0.42	<1
金属含量/%	0.03	0.03	<0.05
纤维含量/%	0.24	0.21	<1
灰分含量/%	4.8	5.3	≤8
丙酮抽出物含量/%	6.6	9.3	≤22
炭黑含量/%	38	34	≥28
橡胶烃含量/%	62	58	≥48

指标	结果
指标	Evotherm-DAT	Sasobit
主要成分	脂肪胺衍生物、烷基胺	长链脂肪族烷羟
状态	液体	固体
颜色	琥珀色	乳白色
气味	类似氨味	—
25 ℃密度/（g∙cm^-3）	1.05	0.622
pH值	9~10
熔点/℃		105~110
沸点/℃	150~170
水溶性	部分可溶	不溶

沥青类型	旋转黏度/（mPa∙s）
沥青类型	135 ℃	160 ℃	180 ℃
70#BA	469	185	74
40AR	10 983	4 179	2 758
40ARE	6 415	1 849	1 363
40ARS	3 561	1 110	667
80AR	12 584	5 598	3 011
80ARE	7 325	2 142	1 550
80ARS	4 135	1 408	914
L-40AR	842	277	142
L-40ARE	568	193	102
L-40ARS	537	188	98
L-80AR	870	286	154
L-80ARE	642	213	112
L-80ARS	597	202	108

沥青类型	高温PG分级
沥青类型	老化前	老化后	最终
70#BA	PG64	PG64	PG64
40AR	PG82	PG82	PG82
40ARE	PG82	PG76	PG76
40ARS	PG94	PG88	PG88
80AR	PG88	PG82	PG82
80ARE	PG82	PG76	PG76
80ARS	PG94	PG88	PG88
L-40AR	PG70	PG70	PG70
L-40ARE	PG70	PG64	PG64
L-40ARS	PG82	PG76	PG76
L-80AR	PG70	PG70	PG70
L-80ARE	PG64	PG64	PG64
L-80ARS	PG82	PG76	PG76