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• Chelator can accelerate the development of compressive strength of CO 2 curing cement paste and shorten the curing period. • The addition of chelator can improve the pore structure of CO 2 curing cement paste. • Chelator can facilitate the penetration and diffusion of CO 2 , increasing the degree of mineralization reaction. In this paper, chelator was used to accelerate CO 2 mineralization curing cement paste. The mechanical properties and microstructure of CO 2 curing cement paste with chelator were investigated through compressive strength test, low-field nuclear magnetic resonance (NMR) test, and scanning electron microscopy (SEM) observation. Next, the effect of chelator on the content of mineralized products was analyzed through X-Ray diffraction (XRD) test and thermogravimetric analysis (TGA). Finally, the CO 2 absorption capacity of cement paste with chelator was evaluated through carbon sequestration rate calculation. The results showed that the chelator could improve the strength of CO 2 curing cement paste and accelerate the mineralization reaction rate. With the increase of the chelator dosage, the compressive strength of cement paste presented a trend of first increasing and then decreasing. When the dosage of chelator was 0.5% of the cement content, the improvement effect on compressive strength of cement paste was the best, and under the premise of achieving equivalent mechanical properties, chelator could shorten the CO 2 curing period of cement paste by half. NMR showed that chelator could promote the conversion of large pores to small pores in hardened cement paste. CO 2 curing for 4 h, the porosity of pores above 40 nm in cement paste with 0.5% chelator decreased by 17.0% compared to ordinary cement paste. Based on the XRD and TGA on the mineralization reaction zone, it was found that the addition of 0.5% chelator could improve the CO 2 curing degree of cement paste. CO 2 curing for 48 h, the 0.5% chelator could effectively increase the yield of mineralized product CaCO 3 by 22.5%. CO 2 curing for 4 h and 48 h, the cement paste with 0.5% chelator could increase the carbon sequestration rate by 11.8% and 17.4% compared with ordinary cement paste, respectively. [ABSTRACT FROM AUTHOR]

To reduce fossil energy consumption and environmental pollution, in this study, SBS modified bitumen (SMB) with self-healing performance was developed through directly adding aliphatic disulfide (ALD) containing double C C bonds in the melt blending process for enhancing its service life, and sulfur/SBS modified bitumen was also prepared for the comparison of ALD/SMB performance. Fourier transform infrared spectrum analyses indicated that the disulfide bonds of ALD have been successfully introduced between SBS molecular chains. Fluorescence microscopy imageries revealed that the addition of ALD improved the network structure of SMB, and the SMB had a more complete network structure when the dosage of ALD was 0.6%. Compared to SMB, the softening point and ductility of SMB with 0.6% ALD were increased by 4.5 °C and 5.2 cm, respectively. The results of dynamic shear rheometer and bending beam rheometer indicated that ALD improved high- and low-temperature rheological properties of SMB. The fatigue healing test revealed that ALD improved the self-healing performance of SBS modified bitumen. When the dosage of ALD was 0.6%, the healing index of ALD/SMB reached 0.86, while the healing index of SMB and sulfur/SMB were only 0.51 and 0.48. The fracture healing test showed that SBS modified bitumen with 0.6% ALD had a self-healing rate of 66.3%, whereas that of SMB and sulfur/SMB were only 35.8% and 38.2% after 20 h of healing at 50 °C, indicating that ALD significantly enhanced the self-healing performance of SBS modified bitumen. • Self-healing SBS modified bitumen was successfully prepared by one-step method. • ALD made SBS modified bitumen form a better two-phase continuous structure and improve its rheological properties. • ALD can significantly enhanced the self-healing performance of SBS modified bitumen. [ABSTRACT FROM AUTHOR]

• The introduction of dynamic disulfide bonds can endow SBS with self-healing performance. • SBS containing dynamic disulfide bonds modified bitumen has excellent self-healing performance. • Dynamic disulfide bonds can improve the high and low temperature performance of SBS modified bitumen. In this study, self-healing SBS (S-SBS) was first synthesized by introducing dynamic disulfide bonds into the molecular structure of SBS. Subsequently, a self-healing SBS modified bitumen (S-SMB) was prepared by blending of S-SBS and bitumen. The chemical structure of S-SBS and S-SMB was charactered by Fourier transform infrared spectrometer (FTIR) and Raman spectrometer. The physical properties, low-temperature rheological properties and self-healing performance of S-SMB were investigated. The results of FTIR and Raman showed that dynamic disulfide bonds were successfully introduced into the molecular structure of SBS. With the increase of dynamic disulfide bonds content in SBS molecular structure, the softening point and ductility of S-SMB enhanced, and the penetration was decreased. Fluorescence microscope showed that the S-SBS in S-SMB formed a complete crosslinking network structure compared to SMB. The bending beam rheometer illustrated that the low-temperature rheological properties and the cracking resistance of SMB were improved by introducing dynamic disulfide bonds. The fluorescence microscopy observation indicated that the crack in S-SBS can self heal. The fracture healing test and fatigue healing test demonstrated that dynamic disulfide bonds endow S-SMB with great self-healing performance. The fracture healing rate of S-SMB reached 58.7% after 4 h of healing, and the fatigue healing index reached 0.93 after 1 h of healing. [ABSTRACT FROM AUTHOR]

Rheological property of bitumen is closely related to the service life of bituminous pavement, which is mainly affected by temperature, vehicle load and ultraviolet (UV) ray. In this paper, lignosulfonate intercalated layered double hydroxides modified bitumen (LLMB) were researched by Fourier transform infrared (FTIR) spectrometer characterization, aging index and storage stability test. Meanwhile, rheological properties of LLMB before and after UV aging were investigated by temperature susceptibility, dynamic viscoelastic properties and rheological model analyses. The results showed that the introduction of lignosulfonate intercalated layered double hydroxide (LS-LDHs) could strengthen the anti-UV aging ability of bitumen more effectively and had better high temperature storage stability than layered double hydroxides (LDHs). From rheological performance measurement, LS-LDHs could weaken the temperature susceptibility of bitumen observably. Compared with pristine bitumen (PB), the values including loss tangent (tan δ), complex modulus (G ∗ ) and rutting factor (G ∗ /sin δ) of LLMB got higher. According to rheological model analyses, the addition of LS-LDHs affected the models of bitumen hardly, but restrained instantaneous elastic, delayed elastic and viscous deformation. Therefore, LS-LDHs could enhance rigidity, high temperature performance and resistance to deformation of bitumen significantly. After UV aging, the rheological parameters variations and deformation arguments amplitudes of LLMB were lowest among PB, layered double hydroxides modified bitumen (LMB) and LLMB, which demonstrated that LS-LDHs improved the UV aging resistance of bitumen prominently. [ABSTRACT FROM AUTHOR]