Microencapsulated Bio-Based Rejuvenators for the Self-Healing of Bituminous Materials

Abstract

Asphalt self-healing by encapsulated rejuvenating agents is considered a revolutionary technology for the autonomic crack-healing of aged asphalt pavements. This paper aims to explore the use of Bio-Oil (BO) obtained from liquefied agricultural biomass waste as a bio-based encapsulated rejuvenating agent for self-healing of bituminous materials. Novel BO capsules were synthesized using two simple dripping methods through dropping funnel and syringe pump devices, where the BO agent was microencapsulated by external ionic gelation in a biopolymer matrix of sodium alginate. Size, surface aspect, and elemental composition of the BO capsules were characterized by optical and scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermal stability and chemical properties of BO capsules and their components were assessed through thermogravimetric analysis (TGA-DTG) and Fourier-Transform Infrared spectroscopy (FTIR-ATR). The mechanical behavior of the capsules was evaluated by compressive and low-load micro-indentation tests. The self-healing efficiency over time of BO as a rejuvenating agent in cracked bitumen samples was quantified by fluorescence microscopy. Main results showed that the BO capsules presented an adequate morphology for the asphalt self-healing application, with good thermal stability and physical-chemical properties. It was also proven that the BO can diffuse in the bitumen reducing the viscosity and consequently self-healing the open microcracks.

Self-Healing Asphalt: A Systematic Bibliometric Analysis for Identification of Hot Research Topics during the 2003–2018 Period

“…can be used to produce microcapsules for rejuvenators in asphalt self-healing applications [ 23 ]. The chemical encapsulation methods based on polymerization are the most frequently selected technology [ 139 , 140 , 141 ], but alternatives based on gelation or coacervation have been successfully implemented [ 142 , 143 , 144 ]. The optimal size of the microcapsules is critical, and it must be controlled during encapsulation.…”

Synthesis and characterisation of biocapsules containing low-cost rejuvenators for asphalt self-healing

“…Polynuclear biocapsules were synthesised based on the ionic gelation principle using the pumping dripping technique described by Norambuena-Contreras et al [6]. For this, a syringe containing 60 mL of each O/W emulsion (Figure 2a) was placed in an automatic syringe pump configured at a rate of 2 mL/min.…”

“…When microcracks in propagation encounter capsules, they trigger to rupture, and the rejuvenator fills the cracks by capillarity reconstituting the chemical composition of bitumen caused by ageing [4]. For this, low-cost and low-environmental impact rejuvenators such as cooking oil [5] and bio-oil [6] have been encapsulated using alginate, a biopolymer presenting nontoxicity, excellent biocompatibility, easy gelation, and long-term stability [7][8][9].…”

“…On the other hand, authors such as Garcia et al [3], Micaelo et al [13] and Norambuena-Contreras et al [2,6,14] have recently proposed the preparation of O/W emulsions incorporating a biopolymer of alginate for the synthesis of capsules, based on the ionic gelation principle. These emulsions, containing sunflower oil as a rejuvenator, are expected to be stabilised by the thickening effect of the alginate used as an encapsulating agent, as proposed by Micaelo et al [13].…”

Recent Trends in Three-Dimensional Bioinks Based on Alginate for Biomedical Applications

“…Alg is an anionic polysaccharide attained through brown seaweed. The base-material taken out from seaweed is recognized as sodium Alg [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. The phrases Alg and sodium Alg have generally employed alternately [ 22 ].…”