Bitumen binders modified with chemically-crosslinked chitosan

Figures & data

Figure 1. The chemical structure of chitosan (a) and epichlorohydrin (b).

Figure 2. Scheme of the research plan.

Table 1. Labelling of samples studied in the work.

Chitosan content	0% crosslinking agent	1% crosslinking agent	2% crosslinking agent
0%	REF_0.0	CHMB_0.0_E1	CHMB_0.0_E2
1%	REF_1.0	CHMB_1.0_E1	CHMB_1.0_E2
2.5%	REF_2.5	CHMB_2.5_E1	CHMB_2.5_E2
4%	REF_4.0	CHMB_4.0_E1	CHMB_4.0_E2
5.5%	REF_5.5	CHMB_5.5_E1	CHMB_5.5_E2

Figure 3. Effect of chitosan and epichlorohydrin content [%] on the penetration of modified bitumen.

Figure 4. The chitosan cross-linking scheme with epichlorohydrin.

Figure 5. Effect of chitosan and epichlorohydrin content [%] on softening point of the modified bitumen.

Figure 6. Effect of chitosan and epichlorohydrin addition on penetration index of the modified bitumen.

Figure 7. Effect of chitosan and epichlorohydrin addition on dynamic viscosity of the modified bitumen binder at 135°C.

Figure 8. FTIR spectra of bitumen modified with different chitosan contents with the use of 0% (a), 1%(b) and 2%(c) of epichlorohydrin.

Figure 9. Cohesion energy of modified binders.

Table 2. Analysis of variance for cohesion energy.

Source	DF	Adj SS	Adj MS	F-value	P-value
%EPI	2	2.725	1.362	0.82	0.443
%CHIT	4	93.893	23.473	14.19	0.000
%EPI*%CHIT	8	200.562	25.070	15.15	0.000

DF: Degree of Freedom; Adj SS: adjusted sum of squares; Adj MS: adjusted mean squares

Table 3. Analysis of variance for dry and wet adhesion energy.

	Source	DF	Adj SS	Adj MS	F-value	P-value
Dry adhesion energy	aggregate	1	408.091	408.091	482.39	0.000
	%EPI	2	2.725	1.362	0.82	0.443
	%CHIT	4	93.893	23.473	14.19	0.000
	%EPI*%CHIT	8	200.562	25.070	15.15	0.000
Wet adhesion energy	aggregate	1	583.830	583.830	688.03	0.000
	%EPI	2	1.024	0.512	0.60	0.548
	%CHIT	4	18.715	4.679	5.51	0.000
	%EPI*%CHIT	8	35.766	4.471	5.27	0.000

Table 4. Analysis of variance for ER₁ and ER₂.

	Source	DF	Adj SS	Adj MS	F-value	P-value
ER1	aggregate	1	0.001076	0.001076	28.91	0.000
	%EPI	2	0.001067	0.000533	14.33	0.000
	%CHIT	4	0.003960	0.000990	26.60	0.000
	%EPI*%CHIT	8	0.007464	0.000933	25.07	0.000
ER2	aggregate	1	0.007441	0.007441	170.46	0.000
	%EPI	2	0.000490	0.000245	5.61	0.004
	%CHIT	4	0.001022	0.000255	5.85	0.000
	%EPI*%CHIT	8	0.002873	0.000359	8.23	0.0000

Figure 10. Dry adhesion (a) and wet adhesion (b) energy results for the tested binders.

Figure 11. ER₁ (a) and ER₂ (b) results for the tested binders.